# Surefire K2 KROMA & KROMA Milspec



## curse (Jul 17, 2006)

*Surefire K2 KROMA & KROMA Milspec*​






Specification of K2 Kroma

[font=돋움]K2 Kroma[/font][font=돋움]Battery[/font][font=돋움]Two 123A Lithiums[/font][font=돋움]Bulb[/font][font=돋움]White, Blue, Red LEDs[/font][font=돋움]Material[/font][font=돋움]Aerospace-grade aluminum, tempered Pyrex Lens;[/font] [font=돋움]Color[/font][font=돋움]Black w/ Mil-Spec Type III hard-anodized[/font][font=돋움]Weight
(with battery)[/font][font=돋움]8.7 ounces[/font][font=돋움]Length[/font][font=돋움]5.5 inches[/font][font=돋움]Run Time[/font][font=돋움]High White LED 1 Hour
Low White LED 3 Hours
Color LED's 80 Hours[/font][font=돋움]Maximum Output[/font][font=돋움]High White LED 60 Lumens
Low White LED 15 Lumens
Color LED's 3 lumens[/font][font=돋움]Special Features[/font][font=돋움]Momentary on/off 2 stage switch for low/high beam, twist tailcap for constant on; LED selection: (5) position rotating ring for (blue low, blue high, red low, red high, white low)[/font]






Left from right : Surefire U2, K2 Kroma, Kroma Milspec.






K2 Kroma is little shorter than U2.

Because of head bezel' lenth.

U2 uses deep reflector, K2 Series use T.I.R Optic.

And these models use same body and two CR123A battery.






Kroma can chageable three color light by needs - White, Red, Blue 

White color for normal use.

Red color for signal use & hunting.

Blue color use serching for blood at hunting.

And each color can control brightness.(Hiigh/Low)






Kroma have 3W LED at center and 16 leds.

3W LED is white beam.

Half of 16 leds are blue, rests are red.











Red light.






Blu light






Low mode of blue light






High mode of blue light






Blue light for picture






Blue light for picture






Black light for picture






UV light for pictire






Orange goggle for forensic.






This goggle is included ARC4+ Forensic kit






Blue light for picture.(View from orange goggle) - Same sa UV Effect, but blue color not seen.



Beam shot(distance on 16.5 foot)






Kroma White low mod






U2 Level 3(Brightest mode is 6)






Kroma White high mode.






U2 Level 6(Brightest mode)



Beam shot(distance on 33 foot)






Kroma White low mod.






Kroma White high mode.






U2 Level 6(Brightest mode)



Kroma Blue light beam shot(distance on 16.5 foot)






Blue low mode






Blue high mode



Kroma Blue light beam shot(distance on 33 foot)






Blue low mode






Blue high mode.



Kroma Red light beam shot(distance on 16.5 foot)






Red low mode.






Red high mode.

Kroma Red light beam shot(distance on 33 foot)






Red low mode.






Red high mode.






Specification of Kroma Milspec

[font=돋움]K2 Kroma Mil-Spec[/font][font=돋움]Battery[/font][font=돋움]Two 123A Lithiums[/font][font=돋움]Bulb[/font][font=돋움]White, Blue, Red, IR, and Yellow-Green LEDs[/font][font=돋움]Material[/font][font=돋움]Aerospace-grade aluminum, tempered Pyrex Lens;[/font] [font=돋움]Color[/font][font=돋움]Black w/ Mil-Spec Type III hard-anodized[/font][font=돋움]Weight
(with battery)[/font][font=돋움]8.7 ounces[/font][font=돋움]Length[/font][font=돋움]5.5 inches[/font][font=돋움]Run Time[/font][font=돋움]High White LED 1 Hour
Low White LED 3 Hours
Color LED's 80 Hours[/font][font=돋움]Maximum Output[/font][font=돋움]High White LED 60 Lumens
Low White LED 3 Lumens
Color LED's 3 lumens[/font][font=돋움]Special Features[/font][font=돋움]Momentary on/off 2 stage switch for low/high beam, twist tailcap for constant on; LED selection: (5) position rotating ring for (blue low, blue high, red low, red high, white low)[/font]

Kroma and Kroma milspec use same boy, tailcap.

And two model's length, color, way to use are same.

The difference of Kroma and Kroma milspec is formation of light color.

Kroma have 6 type of lighting operation : white low, white high, blue low, blue high,red low, red high.

Kroma Milspec have 6 type of lighting operation : white low, white high, blue, red, yellow green, IR.

Kroma Milspec have 16 color leds same as Kroma which 4 leds for each color.











Blue mode of Kroma Milspec






Red mode of Kroma Milspec.






Yelloe green mode of Kroma Milspec






White low mode of Kroma Milspec






IR is not seen to human eyes.

On mode of IR like indicator.

Kroma Milspec beam shot(distance on 16.5 foot)

Kroma milspec's white high mode is same as Kroma.






Kroma Milspec blue mode






Kroma Milspec red mode






Kroma Milspec yellow green mode






Kroma Milspec white low mode



Kroma Milspec beam shot(distance on 33 foot)






Kroma Milspec white blue mode






Kroma Milspec red mode






Kroma Milspec yellow green mode






Kroma Milspec white low mode



U2 & Kroma Series beam shot(distance on 16.5 foot, White mode)








U2 & Kroma Series beam shot(distance on 33 foot, White mode)








Kroma Series beam shot(distance on 16.5 foot, Blue mode)








Kroma Series beam shot(distance on 33 foot, Blue mode)








Kroma Series beam shot(distance on 16.5 foot, Red mode)








Kroma Series beam shot(distance on 33 foot, Red mode)








Kroma beam shot(distance on 16.5 foot)








Kroma Milspec beam shot(distance on 16.5 foot)








Kroma beam shot(distance on 33 foot)








Kroma Milspec beam shot(distance on 33 foot)






* I can't write English very well. So I'm studying English now


----------



## ianb (Jul 17, 2006)

Thats excellent, the difference between Milspec and standard in Red and blue is quite pronounced. That is a very extensive and useful set of comparison beamshots, well done! 

Ian


----------



## Planterz (Jul 17, 2006)

Dude, you rule. Awesome beamshot pictures. I haven't been terribly interested in the Kroma (another TIR SF? *Yawn*), but I can see that the Kroma actually has usable side spill to go along with the focused TIR beam. I'd personally rather see a UV/Red version rather than IR or blue, but my interest is finally piqued.


----------



## ICUDoc (Jul 17, 2006)

Great post, thanks Curse!


----------



## Mark2 (Jul 17, 2006)

Thank you very much! Good work!


----------



## Luna (Jul 17, 2006)

Have you taken any lux mesurement?


----------



## Kiessling (Jul 17, 2006)

Very very nice comparison shots there !!!
Thanx a bunch for the hard work and time invested ! :thumbsup:
Really appreciated !!! 
bernie


----------



## albino (Jul 17, 2006)

great work !!!

thams :goodjob: , ahhh ... thanks


----------



## jdriller (Jul 17, 2006)

Wow, excellent.


----------



## wquiles (Jul 17, 2006)

Outstanding job on the review and the beamshots :bow:

Thanks much for all of the hard work :goodjob:

Will


----------



## NoFair (Jul 17, 2006)

Great review! Wonderful beamshots!

Makes me even more happy with my U2


----------



## jch79 (Jul 17, 2006)

Am I the only one that loves their U2 (pending my lux & runtime measurements this week) even more after seeing the beamshot comparisons?

Edit: NoFair, you beat me to the punch!!


----------



## Flashdark (Jul 17, 2006)

Curse,

THANK YOU VERY MUCH!!!! You cleared up a lot of questions. I have both versions coming and will do a complete review with runtimes as soon as possible. You are plowing a lot of the road for me. Thanks again!

Flashdark sends.


----------



## UKSFighter (Jul 17, 2006)

Awesome beamshots and review. Thanks a bunch.


----------



## Josey (Jul 17, 2006)

Thanks, Curse. That's awesome work. The U2 is a great, great light, and the Kroma looks like the perfect companion to it. --Josey


----------



## cue003 (Jul 17, 2006)

Wow, curse, you really did it up here and I sincerely thank you. I was having a hard time making a decision on Kroma vs Kroma MilSpec vs U2 and you have 110% answered all my concerns.

Huge thanks again for the time and effort to put this detailed comparo together.

Curtis


----------



## MicroE (Jul 17, 2006)

How did you get both versions for a comparison?


----------



## PoliceScannerMan (Jul 17, 2006)

Very nice, who ever he is, he has got alot of Sf's. Including 3 purple A2's! :goodjob: 

Nice review! I cant wait to get my MilSpec K2! :huh:


----------



## cobra-ak (Jul 18, 2006)

Awesome thread! just gotta wait till the production ships.


----------



## Haz (Jul 18, 2006)

Great review Curse, interesting and amazing first few posts you have made so far.


----------



## carl (Jul 18, 2006)

Great review and pics! thank you for all that hard work. The U2 puts out a lot more light at full blast than the kroma and still lasts about 1 hour on full / just as long as the kroma. So the question is, where is all the light in the kroma going?


----------



## daloosh (Jul 18, 2006)

Thanks curse, nice job!

daloosh


----------



## AlexGT (Jul 18, 2006)

Wow very nice review! Thanks! Man you should introduce yourself to CPF! you have quite an astounding collection of lights there.

AlexGT


----------



## Ice (Jul 18, 2006)

Great pictures!
I have one more question: How is ist with the infrared beam? Since normal digital cameras should be able to "see" most of that frequency range, could you make a picture of that as well? Moreover, can one use such a camera-flashlight-combination as a (very) cheap night vision tool (with an ilumination that no one can see)? Thanks!


----------



## Chehalis (Jul 18, 2006)

Why does the Kroma Milspec have such a weak low white mode compared to the regular Kroma and why does it have such a nasty ring pattern in blue while the regular Kroma does not? I thought the only difference was the number (4 vs 8) of blue LEDs. Clearly these two lights have *very* different designs that is not evident from the specifications.


----------



## Sixpointone (Jul 18, 2006)

Hi Curse,

Firstly, Thanks for the great review!

I do have two quick questions for you...

1) Might you know if the SureFire Z60 Tailcap Lanyard Ring, as used on the A2, L2 and L1, fits on the K2 Kroma and Kroma Milspec Lights?

2) Does the Kroma Milspec have the "PK" etching on the body of the Light, or does it say "KROMA" as shown on the K2 Kroma pictures.

All My Best,
John


----------



## CM (Jul 18, 2006)

Nice review :thumbsup: Though I have one on order, I may end up selling it after playing with it. We'll see. The U2 just kicks arse :nana:


----------



## curse (Jul 19, 2006)

Hi,John

Good Question,

I don't think about your idea.

I tried.

But Z60 doesn't fit Kroma's tailcap.

It's very little bigger than A2/L1/L2's

So, I think that if you more try(such as sandpaper grinding), 
your idea is possible.

Kroma Milspec have the "PK" etching logo on the body.

Best regards.

curse




Sixpointone said:


> Hi Curse,
> 
> Firstly, Thanks for the great review!
> 
> ...


----------



## carl (Jul 19, 2006)

CM said:


> Nice review :thumbsup: Though I have one on order, I may end up selling it after playing with it. We'll see. The U2 just kicks arse :nana:


 
I agree. The U2 has greater throw and spill. Both the U2 and Kroma last about 1 hour on high which makes it seem the Kroma is much less efficient by a long shot. I suspect this is partly because the Kroma has to shoot through TWO lens (TIR and front glass) while the U2 has only one lens.

This is interesting. Anybody else out there venture to guess why?


----------



## cheapo (Jul 21, 2006)

seems like with the k2 you are paying mostly for the colored LEDs than for throw or output.... glad i bought my u2.

-David


----------



## Archangel (Jul 21, 2006)

I can see the Kroma having a very wide - albeit comparatively dim - spill.


----------



## KDOG3 (Jul 21, 2006)

Wow, I'm suprised at the difference between the U2 High and the Kroma High. The U2 smokes the Kroma on high....I was going to get a Kroma but I think the U2 might be better for me.....


----------



## Brangdon (Sep 11, 2006)

Chehalis said:


> Why does the Kroma Milspec have such a weak low white mode compared to the regular Kroma


The usual reason for a dim light is either to give white light without much spoiling night vision or disturbing other people, or to give longer run time. One of the commonest complaints about the U2 is that the dimmest beam is too bright.


----------



## LED61 (Sep 19, 2006)

I have read that the original design of the military restricted Kroma had a Luxeon 5 watt inside for high beam, which would have made the low mode for 25 lumens and the high for 100, compared with the 15 low-60 high we are getting in the authorized "civilian" version. A 5 watt LED inside would have been fabolous throw, maybe longer than the U2. But the U2 would always have wider beam spill due to its reflector only nature. The TIR lens can be compared to the projector lenses in fancy headlamps for example, where the light is reflected inside and further focused by the lens. Thus the beam pattern is more organized.


----------



## McGizmo (Sep 19, 2006)

I too am confused by the stated runtime of the K2 on high and suspect it may be an error. However, it may be the case if the selector ring is set on the high blue LED's as you will have both the Luxeon at full power and the blue LED's at full power? Now if the selecter was set at the luxeon on low and you shift to high, you are only driving the luxeon and the run time would increase, me thinks. :thinking: I have no time to do a run time test myself but I am suspicious that the 1 hour is conservative.


----------



## leukos (Sep 20, 2006)

:goodjob: Curse, nice pics, and I understood your english well enough, thanks! Are you a store owner, or are those cases your collections?


----------



## LED61 (Sep 21, 2006)

Curse, that's a great job!!! can you tell us friend if you have any experience with the Kroma and Kroma Milspec with rechargeables, what can it handle??


----------



## Flashdark (Sep 29, 2006)

Review deleted. Comments incorporated into Post #40 for consolidation and convenience purposes.

Flashdark


----------



## :)> (Sep 29, 2006)

McGizmo said:


> I too am confused by the stated runtime of the K2 on high and suspect it may be an error. However, it may be the case if the selector ring is set on the high blue LED's as you will have both the Luxeon at full power and the blue LED's at full power? Now if the selecter was set at the luxeon on low and you shift to high, you are only driving the luxeon and the run time would increase, me thinks. :thinking: I have no time to do a run time test myself but I am suspicious that the 1 hour is conservative.



This was my question also. The low output is similar but I would say a bit lower than the PD is on low. The runtime on the PD is way longer than the stated runtime of the Kroma on low even though the Kroma has 2 batteries. The output of the Kroma on High is very similar to the output of the PD on high and it's runtime estimate of 1.5 hours is similar to what the PD gets from 1 battery. 

I am interested in seeing runtime tests done but I am too lazy to do them. Sorry for that.

-Goatee


----------



## Flashdark (Sep 29, 2006)

*K2 Kroma Test:*
*Last Updated - 03/24/07 (Updates in Blue)*

Runtime tests have been completed. Evaluation is pretty well complete except for minor details to be added in the future. Item #11 in "Overall Conclusions" below, has been substantially revised, so as to consider the possibilities of playing "Surefire Legos" with the K2/K2MS/U2 parts. This aspect will be periodically updated. Photos and beam shots have been added.

*Photos:* (courtesy of "Curse". Thanks "Curse"!)
Additional photos are available by "Curse" in Post #1.


From left to right: U2, K2 Kroma, K2 Kroma MilSpec.









A central LuxIII LED enveloped in a TIR optic, surrounded radially by 16 "3mm" LEDs, 8 Red, and 8 Blue. 







*Beam shots:* (courtesy of "Curse". Thanks "Curse"!)
Additional beam shots are available by "Curse" in Post #1.


U2 & Kroma Series beam shots (distance - 16.5 feet, White mode)








Kroma beam shot (distance - 16.5 feet)







*Introductory Remarks:*

My runtime tests tend to be "to-the-death" or "lowest useful output", NOT the 50% point (unless otherwise noted). The High/Blue + High/White combo will have the brightest "perceived" output. The High/Red + High White combo will have the shortest runtime and produce the most heat, as a result of having the highest amperage draw. (Even though the literature says that the High Blue output is 4 lumens, and the High Red output is 5 lumens, the eye perceives the High Blue as MUCH brighter than the High Red, being much more sensitive to the Blue/Green spectrum). The following order of brightness has been observed to be factual, no matter what the literature states. 

*Runtime Results:* "High White" COMBO testing has been repeated to acquire a revised runtime recommendation. Please exercise extreme caution against high heat buildup!

*High White+High Blue combo* - brightest (54 Lumen output)..........*15 min. recommended, 20 min. max*, due to high heat buildup. This is the position of brightest output, as perceived by the human eye, due to color sensitivity. 1006 mA draw observed by LEDMuseum on their DMM's 4A scale ("High White Only" is 819 mA). With the very slightly lower amperage draw than the "High White + High Red" combo, the runtimes might be expanded by a couple of minutes, and indeed, the temperature of the light felt a couple of degrees cooler, but I did not pursue things to a numerical conclusion.

Runtime test was ended at 20 minutes due to high heat buildup. At the 20-minute point, the whole body of the light was very warm, and the head was almost too hot to hold. Please keep in mind that heat continues to build up to the 60-90 minute point!!! 20 minutes was about the limit of my sense of humor for heat buildup. The F-70 filter was removed during this test to allow the heat to escape more easily. Ambient temperature was 70'F. You might get away with longer runtimes in the winter with colder temperatures for heat dissipation, but NOT during high ambient temperature conditions. The light was disassembled for cooling, as a courtesy to the LED head.

(The first, early runtime test ended in a panic due to very high heat buildup. When I picked the light up after 41 minutes, I could not hold it in my hand. I ended the test for fear of damage to the LED head. I won't do that again. Combos are for short runtimes only!! There seemed to be no reduction in output when I quit the test, but the heat buildup was fierce! I actually disassembled the light to cool things down faster (and it was difficult to touch the parts). It was so hot that this action seemed to be prudent. An F-70 filter was on the head at the time, helping to hold in the heat, and this was almost certainly part of the problem. I never should have let it go this long! You guys do what you want, but I think that if you ran this light for the advertised 1 hour+ runtime in ANY "High White" combination mode, you would be able to light your campfires with it by just throwing the thing into the middle of the damn woodpile. It gets that hot!)

*High White+High Red combo* - 2nd brightest (55 lumen output)......*15 min. recommended, 20 min. max*, due to high heat buildup. This is the position of highest heat buildup, highest amperage draw, fastest battery drain, and the broadest color spectrum. 1023 mA draw observed by LEDMuseum on their DMM's 4A scale ("High White Only" is 819 mA). 

Runtime test was ended at 20 minutes due to high heat buildup. At the 20-minute point, the whole body of the light was very warm, and the head was almost too hot to hold. Please keep in mind that heat continues to build up to the 60-90 minute point!!! 20 minutes was about the limit of my sense of humor for heat buildup. The F-70 filter was removed during this test to allow the heat to escape more easily. Ambient temperature was 70'F. You might get away with longer runtimes in the winter with colder temperatures for heat dissipation, but NOT during high ambient temperature conditions. The light was disassembled for cooling, as a courtesy to the LED head. 
*High White+Low Blue combo* - 3rd brightest (50.5 lumen output)....*20** min. recommended, 25 min. max*, due to high heat buildup. Slightly lower amperage draws equal longer possible runtimes before high heat buildup, but not by much.

*High White+Low Red combo* - 4th brightest (50.5 lumen output).....*20 min. recommended, 25 min. max*, due to high heat buildup. Slightly lower amperage draws equal longer possible runtimes before high heat buildup, but not by much.

IT IS NOW VERY OBVIOUS THAT THERE IS NOT ENOUGH METAL IN THE HEAD FOR *LONG* RUNTIMES IN ANY "HIGH WHITE" COMBINATION MODE , UNLESS AMBIENT TEMPERATURES ARE COLD. OTHERWISE, YOU HAVE TO KEEP RUNTIMES TO MODERATE LEVELS, OR RISK DAMAGE &/OR DETERIORATION TO THE LED HEAD.

I have copied the milliAmp-draw information from the LEDMuseum test on the K2, in the hopes that this will "shed some light" (sorry) on the heat problem of "High White Combos". They found that "High White Only" drew 819 mA on their DMM's 4A scale. Then they measured a 1023 mA draw for "High White+High Red", and a 1006 mA draw for "High White+High Blue". You may remember from above that the "High White+High Blue" output is the one that scared me so bad with the heat output, and this draw is less than that measured for "High White+High Red". I am not even remotely qualified to interpret this data and convert it into heat output danger, but someone may. If 819 mAs for "High White Only " translated into 132'F on "RadarGreg's" test, then 1023mA for "High White+High Red"............????!!!!

*High White Only *- 5th brightest (50 lumen output).........................*4+ hours *(6 hours possible, especially with the assistance of adding "High Red", as needed, toward the end of the battery life). Continuous use probable, depending upon ambient conditions. Substantial heat buildup possible. Results have been duplicated several times. 819 mA draw observed by LEDMuseum on their DMM's 4A scale.

1st test.....4+ hours total, 1 1/2 hours full power, light reached 132'F @ 60-90 min., ambient temp during test was 74'F. Data from "RadarGreg". See full report below. Thanks "RadarGreg"! It was because of your work that I was motivated to duplicate your results for the benefit of all!

2nd test....4+ hours total, (6 hours possible, especially with the assistance of adding "High Red", as needed, toward the end of the battery life), ~1 1/2 hours full power, light reached ~ 130'F @ 50-100 min., ambient temp during test was 70'F. My results duplicated "RadarGreg's" results not just once, but twice. My results also showed that after 4 hours, my "high" position put out the same amount of light as the "low" position on fresh batteries - namely, .8-.9 lumens. Usable light (but very minimal) was still being produced at 6 hours. The maximum temperature reached on both "RadarGreg's" test, and mine, is just about the limit of my sense of humor concerning heat buildup (inexperience on my part?!). (The test was arbitrarily ended so that I could, once again, experiment, as I did at the end of test #3 under "Low White". Results of this 2nd experiment were identical to the 1st. When I asked for a "Blue" mode to be added to "High White" (it didn't matter which one, "low" or "high" because they were both the same intensity at this point), the spill angle and output increased, and the light was usable out to a slightly greater distance. Selecting "low red" also increased spill angle and output, but not as much as the Blue. Throughout each of these 3 selections, Low/High Blue or Low Red, there remained a central TIR hotspot for true-color assistance and "core" illumination. HOWEVER, when I selected "High Red", output GREATLY increased, the white TIR hotspot disappeared completely, and it was very obvious that this was the position of greatest output. (Keep in mind that we are splitting hairs about .1-.2 lumens). An additional fact noted was that the Red LEDs obviously draw more power than the Blue. You can tell this by the change in intensity of the White LED as you engage the Red modes over the top of "High White". (Whereas adding Low/High Blue does almost nothing to the White LED output level, "Low Red" does drop it somewhat and "High Red" eliminates it completely. The LEDMuseum mA draw measurements confirm this. This phenomenon was noted below, under the "Low White" test #3 results, but NOT the reason for it.)

3rd test....4+ hours total, (6 hours possible, especially with the assistance of adding "High Red", as needed, toward the end of the battery life), ~1 1/2 hours full power, light reached ~ 130'F @ 50-100 min., ambient temp during test was 70'F. The 3rd test results duplicated the 1st and 2nd test results exactly, complete to the experimentation at the end of the test. You could "copy" the results from test #2 and "paste" them here in test #3, word-for-word.

"LED61" successfully ran a BS 17650 in his Kroma and got 2 hours in "High White" with no reported problems as far as "powering" the light. However, see item #20 in "Overall Conclusions" below for another issue that emerged. Thanks "LED61"!

Thanks to the efforts of "RadarGreg", we have an idea of what "High White Only" will now do. He has the K2 Kroma, Milspec version, and my results for the regular K2 KROMA were identical with his. I quote his work:




> "Ok, for all those that like to see numbers and measurements, I took a new set of Panasonic CR123A batteries and ran them in my Kroma MS on high white LED only. I wanted to see just how hot it got and how long it would run. The batteries tested 100% on my Ansmann Energy-Check LCD tester. The ambient temperature in my office here remained a steady 74 degrees Fahrenheit. My Kroma-MS was at ambient temperature of 74 degrees when I stated the test and I placed it on a small stand to isolate it as much as possible from any heat sink source. Below are the times and temperatures as I measured them on the head of the Kroma with an IR thermometer.
> 
> TIME TEMPERATURE(Fahrenheit)
> 09:58 74
> ...



Technical note: On every test, just like clockwork, the temperature of the light began to fall just before the 1+40 hour point. This is a positive indication that the lumen output (and the resultant heat production) began to fall off just before that point, causing the temperature to fall. Thus, ~1 1/2 hours of full-power output is verified, and just seemed longer due to the eye's inability to perceive a small drop in lumen output. Coming off of "peak" output, a falling temperature is an immediate and FAR more accurate gauge of output reduction than the human eye.

Apparently, on my first, early test, I came within 14'F of "RadarGreg's" max. temperature, at my 17 minute point, and then "chickened-out". Thanks to "RadarGreg's" persistence, we have the above "High White Only" results, and I have been able to verify them twice. However, during my very first test of the "High White/High Blue" combo, the temperature appeared to be MUCH higher. Approach "High White" combos with extreme caution, please!!! Thus, my time-limited recommendations. Thanks "RadarGreg".

*High Blue* - 6th brightest due to eye sensitivity (4 lumens output).....*20 hours*. Continuous use ok. No heat buildup observed.

Test terminated at 20 hours. Remaining output semi-worthless. As High Blue dimmed, Low Blue was also dimming underneath it. By the time I had reached 19 1/2 hours of runtime, High and Low Blue were identical in output - an "almost useless, moon-mode" output level. I could read my watch with it, but not much more. Interestingly enough, Low White was more useful at this point as a result of it's also limited (but focused) output. Even more interesting, Low Red was still usably bright, and High Red far brighter.

*High Red* - 7th brightest (5 lumens output)...................................*21 hours*. Continuous use ok. No heat buildup observed.

At 20 1/2 hours runtime, High Red was still performing, albeit dimly. It was still visibly brighter than Low Red, but aside from reading in close, reading your watch, finding a keyhole, or puttering around within 6-12" inside of a pack, the overall light output was useless. Let's call it "moon-mode" only. Low Red could still be used at this point, to read print or read your watch, but only if you held the light in contact with the object. The light output was that dim in Low Red. Just as we suspected, no other positions would function. Oh, with fully, night-adapted eyes, you could tell that there was current going to the White and Blue LEDs, but there was no usable output at all. At 21 hours, only High Red worked and the test was ended. However, when I turned the light off, to rest the batteries for a few seconds, then turned the light back on, Low Red began to work again, everything got a little brighter, and we were back to the "20 1/2 hour characteristics" mentioned above. Battery rest will rejuvenate the light for extended runtime.

I forgot to mention something when I was testing High Blue. As the light output began to diminish, two out of eight of the LEDs were noticeably dimmer than the rest (bad LEDs?, bad wiring?). Well, the same thing occurred when testing High Red, and these were different LEDs?! It didn't seem to affect the output, or beam symmetry at any output level. It was more of a curiosity. 

Another curiosity observed was the sensitivity of the head position to lumen output. When I "giggled" the head a little, around the correct "detent" position for High Red, the output got noticeably brighter! The same was true for the Low Red position. Apparently, the contacts in the head are very sensitive to "exact position" for "maximum" output. This sensitivity is not apparent when the batteries are fresh, but it certainly is when battery strength becomes very low. See item #5 in "Runtime Test Conclusions" below. For reasons unexplained, this phenomenon did not seem to come into play during the testing of "Low Blue" or "Low Red". I can't explain it. Perhaps breaking in a new light or whatever!?

Just as we suspected, when battery strength is lowest, the last position that will give you enough output to "see" is "High Red". Therefore, "when the batteries are about dead, go High Red"! This was again confirmed after the "Low White" test.

*Low Blue* - 8th brightest due to eye sensitivity (.5 lumen output).....*46 hours*. Continuous use ok. No heat buildup observed.

1st test........>45, <48 hours - a failure. Bad batteries? Continuous contact with metal? Insulated for 2nd test.
2nd test.......>46, <58 hours.
3rd test.........46.5 hours.

Very disappointing! Surefire projected 80 hours!

This was the position that I was counting on to come through for us. The only way to explain the poor performance in runtime is an efficiency loss in the head. If we are not going to be rewarded with long runtimes, there is no reason to choose one color over the other, unless a special function is required. It looks like we are going to end up with a tri-colored U2. No matter what "Low" position we choose, we will get about 45-50 hours of runtime. Choose the color for the function. I am currently doing runtimes on "Low Red", but that position is not powerful enough to be very useful beyond 5-8 feet, and thus does not affect the end result, philosophically speaking. Only "Low White" & "Low Blue" can be used for any distance application.

*Low White* - 9th brightest (.8-.9 lumen output - observed)..............*50 hours*. Continuous use ok. No heat buildup observed.

1st test........>43, <55 hours. 
2nd test.......>30, <37 hours. Very disappointing. (Results discounted due to probable weak batteries.)
3rd test........>53 hours. 
4th test........>50, <57 hours.

Surefire advertises 20 hours. It looks like we can expect 50(+?) with good batteries, 30-35 with weaker ones. 

During the 1st test, the last time that I observed the light was 43 hours after the test began. At that time the output looked normal (evidence of GOOD regulation). When I returned home 12 hours later, at the 55 hour mark, the light was dead. Thus the above result. >43 hours, <55 hours. Since this test is important, as are all of the "LOW" runtime tests, I immediately started the second test. During the 2nd test, no one was more surprised than I when I awakened at the 37 hour point and the light was dead. It was alright when I went to bed 7 hours earlier. I know that Surefire only rates this position for 20 hours, but.....I can only assume, based on the results of the other three tests that test #2 was the result of weak batteries. 

(A interesting side bar to the results of test #3: At the 53 hour point, when lumen output was approaching moon-mode status, I decided to arbitrarily end the test and experiment with the results of various combinations. When I selected "High White", the light output increased by a factor of 2 or 3. When I asked for a "Blue" mode to be added to this (it didn't matter which one, "low" or "high" because they were both the same intensity at this point), the field of view (spill angle) tripled, output increased, and the light was usable out to about 30' with fully night-adapted eyes. Selecting "low red" also increased spill and output, but not as much as the Blue. Throughout each of these 3 selections, Low/High Blue or Low Red, there remained a central TIR hotspot for true-color assistance and "core" illumination. HOWEVER, when I selected "High Red", output GREATLY increased, the white TIR hotspot disappeared completely, and it was very obvious that this was the position of greatest output. Once again, our axiom was validated - "When the batteries are about dead, select "High Red"!)

A thought: I had expected the runtime to be about 100 hours +/- because the lumen output has been observed to be half that of the U2. Since my first three runtimes were similarly disappointing, I must suspect inefficiencies of the regulation circuit in the head. With the complexity of the head design, this would not surprise me, but I had hoped for better. See Item #20 in "Overall Conclusions" below. 

*Low Red* - 10th brightest (.5 lumen output)...................................*46 hours*. Continuous use ok. No heat buildup observed.

1st test........>46, <47 hours. About the same runtime as "Low White" & "Low Blue". 
2nd test.........47 hours.

Very disappointing! Surefire projected 80 hours!

*Runtime Test Conclusions:*

*1.* *"High White" combinations are the problem as far as heat-buildup goes.* Stay away from those settings and you probably have a continuous-duty light.

*2.* To avoid LED deterioration &/or destruction, *limit your runtime when using "High White" combination modes in any capacity*. I conservatively recommend 15 minutes normal runtime, 20 minutes maximum, a little longer for "low red" or "low blue" combos. Times can vary quite a bit due to outside air temperature and wind. Experiment with caution. This thing is too damn expensive to be careless. *My runtime **recommendations for the "High White Combos" above are based upon taking you to about the same temperatures reached in the "High White Only" mode (130-135'F), where the head was just about too hot to touch. This is the limit of my sense of humor for heat-abuse in a $300 light. From here on, it's up to you. Others, with more LED experience, will have to fine-tune these figures upward.*

*3.* I doubt that we will acquire a *runtime* for any *"High White"* *combination mode* due to the detrimental and dangerous heat buildup. Not with MY light anyway. If Surefire wants to claim 1 hr. +, that's ok with me. If you guys want to test this with YOUR light, that's also fine with me. My life depends upon how long the other modes work, not the "High White" combination modes. When I originally made the above statement, I included "High White Only" as well, and then, sure enough, "RadarGreg" DID test "High White Only" with HIS light, with the following results: 1 1/2 hrs. of full, regulated power. Max temp of 130-132'F, reached between 60 & 90 minutes. 4 hrs. of total light. Excellent. See details of his work above under "High White Only". (Thanks "RadarGreg". Apparently, I got within 14' of your results on the "High White Only" test and "chickened-out". His results have since been confirmed and expanded upon.

*4.* *Battery rest will rejuvenate the light for extended runtime.* I had a chance to play with this a little after the "Low Blue" testing, and learned the following: The longer you let the batteries rest, the longer they will work when the light is reactivated (within limits). In addition, it was again demonstrated that the position that will give you the most light upon reactivation is "High Red".

*5.* One curiosity observed was the *sensitivity of the head position to lumen output.* When I "giggled" the head a little, around the correct "detent" position when testing High Red, the output got noticeably brighter! The same was true for the Low Red position. This also appears to be true for the High/Low Blue positions. Apparently, the contacts in the head are very sensitive to "exact position" for "maximum" output. This sensitivity is not apparent when the batteries are fresh, but it certainly is when battery strength becomes very low. For reasons unexplained, this phenomenon did not seem to come into play during the testing of "Low Blue" or "Low Red". I can't explain it. Perhaps breaking in a new light or whatever!?

*6.* Just as we suspected, when battery strength is lowest, the last position that will give you enough output to "see" is "High Red". Therefore, *"when the batteries are about dead, go High Red"! This was again confirmed after the "Low White" test. *

*7.* *All runtimes tests have been as good or better than advertised by Surefire, except "Low Blue" and "Low Red".* See item #26 below.

*8.* *"Low White"* will *run* the* longest* of the "Low" positions, but not by much. *"High Red + High White"* will *run* the *shortest* time.

*Overall Evaluation / Conclusions:*

*1.* *How does it work?* There are 21 lighting modes for this light: Position 1: Locked out. Then, rotate the tail cap 360' clockwise to **** the light for the next five functions and start: (with the head rotated full counterclockwise, push for Position 2: High Blue. Rotate the head one position clockwise and push for Position 3: Low Blue. Rotate the head one position clockwise to the middle position and push for Position 4: Low White. Rotate the head one more position clockwise to the right of center and push for Position 5: Low Red. Rotate the head one position clockwise to the full clockwise position and push for Position 6: High Red. Then, rotate the tail cap 360' clockwise again to **** the light for the next five functions and start again: (with the head rotated full counterclockwise, push "easy" for Position 7: High Blue. Push harder to add High White. Rotate the head one position clockwise and push "easy" for Position 8: Low Blue. Push harder to add High White. Rotate the head one position clockwise to the middle position and push "easy" for Position 9: Low White. Push harder for High White. Rotate the head one more position clockwise to the right of center and push "easy" for Position 10: Low Red. Push harder to add High White. Rotate the head one position clockwise to the full clockwise position and push "easy" for Position 11: High Red. Push harder to add High White. Then, rotate the tail cap slightly clockwise again to engage the next five functions of "constant on" and start again: (with the head rotated full counterclockwise, you are engaged in "constant on" Position 12: High Blue. Push to add High White. Rotate the head one position clockwise and you are engaged in "constant on" Position 13: Low Blue. Push to add High White. Rotate the head one position clockwise to the middle position and you are engaged in "constant on" Position 14: Low White. Push for High White. Rotate the head one more position clockwise to the right of center and you are engaged in "constant on" Position 15: Low Red. Push to add High White. Rotate the head one position clockwise to the full clockwise position and you are engaged in "constant on" Position 16: High Red. Push to add High White. Rotate the tail cap quite a bit more to the "constant on - High White" position and you begin the last five functions. With the head at full counterclockwise, you will be at Position 17: High Blue + High White "constant on" (Brightest Position available - shortest runtime - hottest). Rotate the head one position clockwise and you will be at Position 18: Low Blue + High White "constant on". Rotate the head one more position clockwise to the center position and you will be at Position 19: High White only "constant on". Rotate the head one position clockwise and you will be at Position 20: Low Red + High White "constant on". Rotate the head one position clockwise to the full clockwise position and you will be at Position 21: High Red + High White "constant on".

*2.* *High Blue + High White* is the *brightest* output combination when you need maximum perceived brightness. *High Red + High White* will give you the *broadest color spectrum*, produce the most heat, draw the most power, and drain the batteries the fastest.

*3.* *Low white* is an excellent close-up, true-color, work light for night-adapted eyes. It needs an F-70 or FM-64 to soften it for a flood effect. Otherwise, you will have an irritatingly small square of light to work with due to the TIR optic. Low White with an F-70 or FM-64 is comparable to but slightly dimmer than the L1/F04 combo on "low". Perfect for getting you to the bathroom without burning the back of your retinas out. Despite what the literature states ("Low White - 3 lumens / 20 hrs. runtime"), Low White is closer to about .8-.9 lumens / 50 hours runtime. It's output is less than the L1 on "low" (1.1 lumens) and half of what the U2 is on "low" (2 lumens). This is actually a good thing for both runtime, and night-adapted utility purposes.

*4.* *Low Blue* is suitable for cross-country navigation. *High Red* is better from a night-vision adaptation standpoint. I understand that Red light is invisible to deer and possibly other game so High Red would have to be used in walking to a hunting stand. Low Blue will run twice as long as High Red. Please consider this when battery life is critical. Low Blue is also suitable for short-range blood-trail tracking. It's bright enough. *High Blue* will reach out a lot farther. It is much brighter. *High Red* is better for x-country travel than the "Low" position on the L1-RD. That always was a little too dim with too little spill for the job. The *High Red* position of the K2, without the F-70 filter, is perfect. 

*5.* *High Blue* is also a very nice short-range floodlight or camp-light flood.

*6.* *Low Red* is very good for very short-range work with fully night-adapted eyes. 12-36" work in "Tactical Red" (Illumination at distances beyond 5-8 feet is very marginal). Far too dim to be used for safe or rapid movement of any kind. You will have to use Low Blue or High Red for this.

*7.* *High white* has a very nice beam without the filter, a very nice short-range flood with the filter. Equivalent to the U2 on "level 4-5" if "level 1" is the dimmest. Adequate for most needs. Has the typical focused distance aspect of the TIR optic but with some spill for a more acceptable beam shape. Although the U2 has a better-shaped beam and puts out a little more light, the K2 out-throws it by a hair.

*8.* *Versatility* is the name of the game for this light. I theorized that it would be the ideal "hunter's" flashlight, so I sent it off to Henderson, Tennessee with a friend for just such an evaluation. He has now returned and here are his impressions. He liked the light, overall. He is not used to using "red" light for "night-navigation" so he was not all that impressed with the feature. Another man with which he was hunting (a world champion archer) liked the "red" feature a lot. I also do a lot of night-navigation in rough country and I like the "red" feature as well. I think that the power level of "High Red" is "perfect" for this task. The Blue levels were appreciated for shorter-range campsite duties. He did not have a chance to do any blood trail tracking at night. He did his tracking during daylight hours. However, he did confirm that the Blue levels did show up blood as "black spots". (I understand that if you use "white" light with a "blue" filter, blood spots will phosphor somewhat and will be redder in color - someone please confirm. If so, you have an interesting combo possible for forensics or hunting - blood shows black under the Blue LEDs or phosphor red under the white beam if you had a blue filter on the front - interesting). The White levels were described as "adequate" for all required tasks. He liked the F-70 beam shaper filter on the front for the flood characteristics during several activities. Another interesting comment made by him is his admitted prejudice for a smaller light (ala E1L, E2L) for the sake of weight, bulk, and convenience. As a result, his "guarded approval" of this light is all the more significant. More recently, he voiced a preference for a smaller light (ala E1e/KL-1, E2L, L-1), regardless of how this would result in a loss of features - (old school, where weight and convenience is paramount).

I recently queried another hunter/outdoorsman about his impression of the K2, and he was effusive in his praise. He said that it was the most "full-featured light" that he had ever seen. He did not like the F-70 on the front of it. He felt that it cut down on the output too much. (Indeed it does! That flexibility is precisely what I do like, as well as the additional protection to the head). Just our opinions.

This light might also be the "Holy Grail" for aviators, as well as hunters. It does everything better than the "A2". Indeed, it is like a "tri-color", Hi/Lo A2. Now, you have the versatility of 3 LED colors, not just one, and each color has a Hi/Lo option. Blue is useful in the detection of hydraulic fluid, and should make it show up "black" on the pre-flight "walk around". You have two levels of "Red" for night-vision preservation with "utility" power, as well as two levels of "White", "Low" for close-up work and "Hi" for distance. "Low White" is now dim enough for true-color, close-up work, while preserving night vision. It also runs for 50 hours on 2 batteries instead of 10 hours. With an F-70 "slim line" beam shaper on the front, you protect the lens, and now have 12 options of Hi/Lo, flood/spot instead of just the 2 options on the A2. What's not to like about this?!

It is only in the "tactical capacity" that I will reserve judgment (for now). There is no argument, thus far, that the K2 functions brilliantly as a multi-purpose, backup, "utility light" in the field. The only question is whether or not you have need of the "yellow/green" and "infrared" compatibility with night-vision equipment. The military felt that you did, and that is why we have two versions of the K2/K2MS. If you do not have need of this capability, my preliminary feeling is that you would be better served by the civilian K2, with it's more versatile "Hi/Lo Blue" and "Hi/Lo Red" options. (After all, with the primary gun light task being assigned to another, more suitable unit, such as an M3 or something else, and the "emergency backup" task being taken care of by something like an L1 /F05, the only purpose of this light is "primary, multi-purpose, utility". So, the question that begs answering is "How much utility vs. how many purposes?"). This aspect will be investigated at length when I post my review of the K2MS. 

*9.* Do NOT use the Z-60 lanyard on the K2. Yes, you can sand down (open up) the inside diameter of the split ring attachment piece with a piece of sandpaper wrapped around a pipe of a slightly smaller diameter, but when you attach the split ring to the K2, you CANNOT use the Z-60 lanyard with it's metal clip on the end. The split ring hole is now so close to the metal on the tail cap that, when it rotates, the metal clip at the end of the Z-60 lanyard will scratch the metal on the tail cap very quickly. You will have to remove the metal clip and just use the Para cord, or something that will not scratch the metal on the tail cap. Other than that, the *Z-60 split ring attachment can be sanded down to work just fine.*

*10.* *The U2 body is interchangeable* with the "sleeved" (?) K2 body, so if you have an early "wide-open" U2 body, this will allow you to use about any battery you desire if you swapped out the bodies. I could not tell for sure but it looks like the K2 body might have a removable sleeve (ala U2 body / gen. 2). Someone else will have to report on this. I am not knowledgeable enough to do this. If you more knowledgeable people decide that the K2 body is indeed sleeved, please provide a link as to how we might best remove it so as to acquire a more utilitarian battery shell. Very Important! See #20 below!

*11. Surefire "Legos".* You cannot swap the heads or tail caps with the U2. They will not work right.

*Section A: What can you do with the U2/K2/K2MS bezel or head? *

Recently, *"grnamin"* mated the U2 head with an A21 (Surefire, weapon light module) and the tail cap, for a 1-battery, U2 "Shorty". This same configuration is possible on the K2 and K2MS!!!!! It looks like an R123 battery is required to power any of the heads properly. When a CR123 primary was tried on two different U2 "Shorties", neither would function. When a CR123 was tried on a K2 "Shorty", the five positions of the head would function, but "High White" would not. It was also obvious that "High Blue" and "High Red" were NOT up to full speed. This thread is on the CPF "LED" forum. So far, it looks like the following combinations are possible if you have sufficient voltage available for proper operation:

*A.* Tail cap + A21 + U2/K2/K2MS head. 1-battery "Shorty". 3.6-3.7 volts needed for proper operation.
*B.* Tail cap + MH-90 + U2/K2/K2MS head. The MH-90 gives you a 2-battery, "quick-release", gun light body.
*C.* Tail cap + A19/MC123/Detonator + A21 + U2/K2/K2MS head. 2-battery "slim line" body. Z-26 lanyard ring use possible. The "Tail cap + A19 + A21 + Head" combination worked better than anything else for me in both form and function. 
*D.* Tail cap + A21 + A12 + U2/K2/K2MS head. 2-battery "slim line" body. Z-26 lanyard ring use may or may not be possible. This combination did not work for me unless I used the Z73 tailcap (the new G-2 "lockout" tail cap), or the Z48/49 "clickon" combat tail caps. The Z41, Z58/59 failed to function correctly. Although the combination allows a very nice, smooth, slimline body, you could achieve almost the same effect by using the above combination in "C", which would then function properly with all tail caps. You could also just take the pocket clip off of the K2/U2 body, and still retain proper, designed function. Either of these solutions is probably the smarter move. 

*WARNING!! Experimenting with the A21 + A12 combination will cause you to screw the tail caps on with quite a bit of force in an attempt to get them to function properly. This will cause substantial deformation to the negative ends of the batteries with results that are unknown to me. I threw my batteries out after seeing the damage!!*

*E.* Tail cap + A12 ( by itself) + U2/K2/K2MS head. WILL NOT FUNCTION PROPERLY!!! The tail cap will not screw on far enough. The A12 is made to attach to the "front" of the light, extend the light for 1 battery length, and accept the threads on the head, then have an A21 screw on to the back of it. It will not handle the threads of the tail cap.
*F.* The A19, MC123, and "Detonator" parts, by themselves, WILL NOT FUNCTION PROPERLY!!! The head will not screw into the front of the part far enough to tighten properly. They are made to attach to the "back" of a light, extend the light for 1 battery length and accept the threads of the tail cap.
*G.* The A21 will do both jobs by itself. It will accept both the threads of the head on the front end, and the tail cap on the back. The only problem now is finding a battery with a voltage that will allow the light to function properly. 
*H.* The *primary problem* is the inside diameter of the various parts, and the batteries they will now accept for use. It looks like you will need 3.6 to 3.7 volts minimum to make the lights work properly. *Otherwise, the light seems to drop out of regulation.*
*I.* Tail cap + U2/K2/K2MS body + A12 (with 2x17500s) + U2/K2/K2MS head. For extended runtime (per "Chronos". Thanks "Chronos".) I don't know about the voltages involved. *(As a cautionary note, the A12 addition now allows a 3xCR123 battery body.* *The U2 does not like 9 volts (3xCR123s)!! After my experience on the U2, I am not going to try 9 volts on the K2!)*

*NOTE:* The A12, A19, MC123, A21, and (probably) the "Detonator" parts are not bored out as widely as the U2 body (gen. 1), and will, as a result, probably limit which batteries can be used with these particular parts. Plan accordingly. Since I do not use rechargeable batteries, I know absolutely nothing about the required dimensions for their use. Others, more knowledgeable than I, will have to chime in here. I believe that Posts #68-77 in this thread were discussing battery dimensions in detail and this will help.

*Photo of a U2 "Shorty":* (courtesy of "Grnamin". Thanks "Grnamin"!)






*Section B: What can you do with the U2/K2/K2MS body?*

If you are married to the idea of a "bezel-down" pocket clip, or just like the "form" of this body, you can use the U2/K2/K2MS body with the "LU-60" adapter piece screwed into the front end, and then use it with any standard bezel (i.e. C2/M2/KL-5/KL-3/Z-32 etc.). The U2/K2/K2MS bodies are dimensionally identical, so an early U2 body, bored out, or with the sleeve removed on the gen. 2, will give you more battery flexibility. Possible combos include:

*A.* K2 tail cap + K2 body + "LU-60" adapter piece + KL5 or KL-3 gives you a 2-stage LED light. (However, since the K2, 2-stage, White LED is very effective and you also pick up "High/Low Blue" and "High/Low Red", I don't know why you would want to do this.) 
*B.* U2 tail cap + U2 body + "LU-60" adapter piece + C2/M2/Z-32 etc. for an incandescent light with a "bezel-down" pocket clip. Adding the A12 on the front of the body, or an A19/MC123/"Detonator" on the back of the body gives a 3-battery possibility (or the use of 2x17500s for extended runtime).

*NOTE:* Since the U2/K2/K2MS bodies are functionally identical, the key is in the tail cap. If you want an incan light, you must use a single-stage tail cap. I have successfully used the Z41, Z73, Z58, Z59, Z48, & Z49 on the U2. I understand that the SW01 and SW02 will also work. The key here is SINGLE-STAGE! You cannot use dual-stage tail caps on incandescent bulbs. They don't like the low voltage put out by the first stage.

*Section C: What can you do with the K2/K2MS 2-stage tail cap?*

*A.* 2-stage K2/K2MS tail cap + L5 = a 2-stage L5. (Both the K2, and the U2, are better lights, and throw farther.)
*B.* 2-stage K2/K2MS tail cap + L6 = a 2-stage L6. WARNING! I do not know what 9v will do to the resistor in the 2-stage K2/K2MS tail cap over time, since it is designed for 6v. I know it works but I have no idea about any long-term damage!!! More knowledgeable people will have to chime in here.
*C.* 2-stage K2/K2MS tail cap + a 2,3, or 4-battery body + a "Milkyspit" M/X-series head = a 2-stage "Milkyspit" light. WARNING! I do not know what 9v-12v will do to the resistor in the 2-stage K2/K2MS tail cap over time, since it is designed for 6v. I THINK it works, as it has been proven to do in the L6, but I have no idea about any long-term damage!!! More knowledgeable people will have to chime in here. Ask Milkyspit first!!!
*D.* In the same philosophical vein, the "LU-60A" adapter piece from the Surefire "Scout light" kit, will adapt a KL-3 or KL-5 to a Surefire L-1 or L-2 (or A2?) for the same result giving you a "slim line" mini-body (with the L-2 [or A2?]) or a "Shorty" (with the L-1). From my own experience, the L-1/LU-60A/KL-3(gen. 2, v. 3) is the best of the bunch! Beautiful!!

*There are many other things that we CAN do. Just because we CAN, does not mean that we SHOULD. I hope some of this helps.*

*12.* *The o-ring on my K2 seems to be oversize.* This makes rotation somewhat more difficult, but waterproof characteristics should be better as a result, and the tail cap will be more resistant to inadvertent movement. One drawback of this tighter o-ring is that it is much more difficult to use one-handed.

*13.* *With regard to the F-70 or FM-64 beam shaper filter* on the front of the light, there are pros and cons. The beam shaper will protect the head (a BIG point in it's favor on a $300 light). It is necessary to soften things up in "Low White" for close, night-adapted work. It is necessary for a nice short-range "High White" camp-flood. It gives you 12 levels of light instead of 6. It is better when off or flipped up for "Low/High Blue" work, or "High Red" night-navigation. It is also necessary for it to be up or off for distance "High White" work. For "Low Red" work up close, it is a personal preference toss-up.

*14.* *There are five rather subtle click-stops on the head* of the light as you rotate the head from the full-counterclockwise position to the full-clockwise position. Since it would be fairly easy to rotate the head inadvertently off of a desired position, I used a silver-metallic "Sharpie" marker to mark the middle "Low White" position, and thus have a confirmed reference point every time I activate the light. I did the same thing on my U2 for "low" position, and that head is much more resistant to movement. I also do this to the witness marks on every one of my tail caps. It is more important on the tail caps of the L1, L2, A2, U2, K2, and K2MS than the rest of the Surefire lights because you will be going through several rotations to access all of the functions on these particular lights. Just a thought. See item #1 above to reference the complexity of the selection process. It is not nearly as bad as it first seems once you have the light in your hands, but it does save time not to have to fumble with a desired starting point.

*15.* *I like this light.* I like almost everything about it and I'll tell you why. I like it for it's small, lightweight, multi-function design philosophy. Instead of another "boat anchor", to be lugged around by the troops, Surefire created a compact, utilitarian instrument, which is really quite elegant. I think that it approaches "Holy Grail" status as a hunter's flashlight. It has everything a hunter needs. If I were a hunter, I would add an L1, with a set of F0x filters as a backup, and call it quits. I think that it also approaches "Holy Grail" status as an aviator's flashlight. You now have a "tri-color, Hi/Lo A2" that runs for 50 hours on 2 batteries instead of 10 hours. In a tactical capacity, since you are going to have a primary gun light, this light serves as an excellent multi-function backup. I know the U2 is far superior for "white light" versatility, but do you really *need* the versatility? This light has a more functional "low" position - exactly what everyone wanted from the U2. As a matter of fact, this light has a "hatful" of multi-use "low" positions. The "high" position is reasonable, with a decent beam. In between, you have Low/High Blue and High Red to fill the gaps between "low white" and "high white". Additionally, you have "Low Red" tactical. Like the U2, "High White" can be flooded-out with an F-70 or FM-64 for a decent camp flood. Of course, other lights do each of these things a little bit better, but this light does all of them fairly well. It remains to be seen if the K2MS will do anything that much better, or if it will just be different. I suspect the latter. I ordered both just to see. *This light has now replaced my U2 as my primary "utility light".*

*16.* *Battery rest will rejuvenate the light for extended runtime*. I had a chance to play with this a little after the "Low Blue" testing, and learned the following: The longer you let the batteries rest, the longer they will work when the light is reactivated (within limits). In addition, it was again demonstrated that the position that will give you the most light upon reactivation is "High Red".

*17.* One curiosity observed was the *sensitivity of the head position to lumen output.* When I "giggled" the head a little, around the correct "detent" position when testing High Red, the output got noticeably brighter! The same was true for the Low Red position. This also appears to be true for the High/Low Blue positions. Apparently, the contacts in the head are very sensitive to "exact position" for "maximum" output. This sensitivity is not apparent when the batteries are fresh, but it certainly is when battery strength becomes very low. For reasons unexplained, this phenomenon did not seem to come into play during the testing of "Low Blue" or "Low Red". I can't explain it. Perhaps breaking in a new light or whatever!?

*18.* When I was testing High Blue, as the light output began to diminish, *two out of eight of the LEDs were noticeably dimmer* than the rest (bad LEDs?, bad wiring?). The same thing occurred when testing High Red, and these were different LEDs?! It didn't seem to affect the output, or beam symmetry at any output level. It was more of a curiosity. 

*19.* Just as we suspected, when battery strength is lowest, the last position that will give you enough output to "see" is "High Red". Therefore, *"when the batteries are about dead, go High Red"!* This was again confirmed after the "Low White" test.

*20. Voltage Sensitivity. **"RadarGreg"* and others more knowledgeable than I, have begun to experiment with *different batteries* on the K2MS model. They have begun to pick up evidence that the "head" (and it's resulting conduct) is very particular to "supplied voltage". I too am beginning to pick up evidence that the regulation circuit of the K2/K2MS is very sensitive to what powers it. There are apparently, inefficiencies &/or limitations in the head that make it very particular. I do not have the expertise to understand just what these peculiarities are, just that they are present. My runtimes are not nearly as long as I expected from a light with this power output. I also accidentally discovered that the light will not go to "High-White" in any switch position if you have a bad, low-voltage battery in the mix. *See item #11 above.*

"LED61" has successfully run the K2 in "High White" for 2 hours on a BS 17650 with no reported problems as far as "powering" the light. However, he also reports:




> "I discovered a potential pitfall in using the rechargeable 17650. While the battery powers the light just fine at least in my case, and going back to the fact that it goes into the flashlight very tight and in a specific way, I accidentally dropped the light the other day and BAM!! all of the sudden no light. Turns out that the reduced length of the battery and the impact displaced the battery in such a way that it broke positive contact. So no matter how far I screwed the tailcap in it would not turn on. It was necessary to unscrew the tailcap, and press from the negative end until positive contact was reestablished. You would not want to mess around in this fashion in whatever emergency you needed the light for and so for serious use better use CR123's, or until I can figure out what sort of spacer I can insert in the negative end to insure there are no lose ends."


 

Thanks "LED61"!

So, even though, you may be able to "power" the light with a wide variety of batteries, by switching out the K2 body with a early U2, or just by using a different type of battery, the head may not tolerate it. So far!, the head seems very honest about displaying it's displeasure with what you are feeding it, but be careful folks. I'm not qualified to comment further. 

*21.* *"RadarGreg"* brings the first *"combat-application" report* to the review. I quote him as follows:


> "For the ones wondering if the Kroma can perform well in a tactical environment with the lumen output, I can say it did perform well. I had the chance to so shooting with several of the German CPF members this weekend, and we practiced illuminating targets at 15 meters and shooting them. (metal knockdown plates, not Tangos, hehe). The Kroma-MS illuminated the plate very well and gave enough sidespill to see several meters to either side as well. This would be important if in a dark area there was a second "bad guy" trying to hide just outside the hotspot. "


 Thanks "RadarGreg"!

*22. Quality Control report:* There is a small smudge at the very apex of the TIR optic, on the inside of the TIR optic, that does not seem to affect the beam characteristics in any way. There is a "scuff" on the black plastic ring that holds the pocket clip in place on the light. Interestingly enough, it is identical to the scuff on my U2 and in exactly the same place?! (Same part, same assembly line process). The "click-stops" on the LED head have a minute amount of play in them.

*23.* *Multiple LEDs* in the head eliminate the possibility of the light failing due to a single bulb or LED failure. Now, your possible points of failure are reduced to batteries (always a possibility), tail cap (total failure doubtful), and regulation circuitry.

*24.* *Beam Quality.* The TIR optic assembly, which envelops the central Luxeon III LED, was incorporated to achieve maximum throw with minimum power consumption ("focused output"), ala L-1 (gen. 2) and KL-3 (gen. 2). Additionally, just like the other TIR-optic lights, there is a distant and irritating, circular artifact on both "Low" and "High". As a result, this "concentrated" beam needs to be softened with an F-70 or FM-64 for close-up work on "Low", or for use as an area camp flood on "High". However, a side benefit of this design is a very modest "distance capability" on "Low" and the ability to slightly "out-throw" the U2 on "High". The TIR optic appears to be a gen. 2 design because the "hotspot" is softer on both "Low" and "High" than the L-1 (gen. 2) and KL-3 (gen. 2), and the beam quality on "High" is "acceptable" without the F-70/FM-64, and has modest spill. There is no evidence of "Fresnel Lens" tinkering with the optic, but it is softer nonetheless. 

Because of the multiple, radial LEDs for both Blue and Red, beam artifacts are minimal, and indeed, I doubt that you will notice them or be bothered by them during practical use. The primary purpose of using the F-70/FM-64 with these colors would be to give you 4 levels of intensity instead of 2. It really does make a substantial difference, especially on "High".

*25. Odds & Ends.* The light has a 1.47" bezel diameter, so all F-7s & FM-6x filters fit (anything that fits on an M-2, KL-3, or KL-5 etc). Bezel is lightly scalloped to visually warn you that the light is still on. The pocket clip is the bezel-down design, ala U2. Indeed, the body (only) is identical to and interchangeable with the U2. The central "WHITE" LED is a LuxIII in an "enveloping and focusing" TIR optic structure. This is surrounded radially by 16 "3mm" LEDs, 8 for "RED" and 8 for "BLUE". Since the light does not use a reflector, it is shorter and smaller than the U2. This is the result of the more compact and truncated head design, characteristic of a TIR optic assembly. This light is a "little" large for an EDC but smaller and shorter than the U2, and indeed, only 1/4" longer than the C2, with a slightly larger head. Finish is HA-"Black", ala U2.

*26.* All *runtimes tests* have been as good or better than advertised by Surefire, except "Low Blue" and "Low Red". As a *result*, we are now faced with the prospect of* a tri-color U2* with 45-50 hours of runtime in a selected "Low" position (the U2 does about the same). OK......... I have to think about that for a while. The first thought that comes to mind is .....Do you want a tri-color, two-position K2 (Hi/Lo) or a single-color, 6-position U2? Then there is the K2MS, a 5-color light with "Hi/Lo" White. Apparently, as a result of the complexity of the head design, there are substantial efficiency loses, and we will not realize the 100+ hour runtimes expected, based upon lumen output. Not with the regular K2 anyway. I guess, when you start wiring 17 LEDs together in a rotating selector head, things begin to get complicated and efficiency begins to plummet! It is probably a miracle of design excellence that it works as well as it does. So, if you are not going to get increased runtimes with the K2 (over the U2), *we are back to the color priority. If you need Hi/Lo Blue and Red, get the K2, if you don't, get the U2. Simple!* (Until the K2MS enters the scene and complicates the issue!!!!)

*27. I have decided to take my own advice and NOT purchase the K2 KROMA MilSpec. Since the red/blue options and red/blue beam-quality are FAR superior on the K2 KROMA, and I do NOT need the IR or yellow/green night-vision aspects of the MilSpec version, the K2 KROMA is a much better light for me.* 
 
*28. This concludes my K2 KROMA review. As of 03/24/07, I do not plan to add any more information to this thread unless something develops. I hope that this report has been useful to all.* 

Hope this helps,
Flashdark sends,
Flashdark spends.


----------



## Sixpointone (Sep 29, 2006)

Flashdark,

I simply wanted to post to Thank You for the time, effort, and incredible detail put into this review.

Regards,
John


----------



## Flashdark (Sep 29, 2006)

Sixpointone,

You are very welcome sir.

Flashdark sends


----------



## :)> (Sep 30, 2006)

Flashdark,

I also want to thank you for your time and effort. I would not have guessed that the light would get hot after awhile... wierd and too bad. 

I will try mine out for an extended period of time and see how hot it gets to see if this is indicativ of the light in general. To this point, I have only used it for short periods of time. 

-Goatee


----------



## Nebula (Sep 30, 2006)

Flashdark,

My new Kroma arrived yesterday. Your insightful, timely, and extremely well done review is very much appreciated. Kudos! Kirk


----------



## :)> (Sep 30, 2006)

I fell asleep with the Kroma on last night when trying to do a simple test to check the heat. I woke up and the light was operating on the low level instead of the high level because the batteries were near exhausted... of course it was not warm then. 

I did notice that the light did warm up after about 10 to 15 minutes of constant on and the heat did begin to radiate to the handle. It never got too hot to hold but it was noticeable warm. About the same heat as my HDS EDC U60GT on high before the step down. 

-Goatee


----------



## Flashdark (Sep 30, 2006)

*Goatee,*

I am not use to running my high-powered lights for very long, and the heat buildup in them after a short period of time makes me a bit nervous. In the incans, this is not a problem. The batteries have a thermal protection circuit and the bulbs can be replaced, but, in an LED, where heat equals death over time, I get a little paranoid. Probably a character flaw on my part coupled with a lack of experience. When I picked this K2 up after 41 minutes of runtime on it's highest setting (High White + High Blue), I was stunned and a bit frightened at the temperature, especially in the head. More experienced individuals than I will have to advise our forum as to just where the danger point is in terms of heat vs. damage. My personal and inexperienced comfort level was reached at about 15 minutes. More experienced voices will probably expand this envelope a bit in the future. Thanks for your input. 

*Nebula,*

You are most welcome sir,

Flashdark sends.


----------



## LED61 (Oct 2, 2006)

Flashdark, another big thank you for your tremendous effort. i hope you have not damaged your light testing it for all of us!!!


----------



## :)> (Oct 2, 2006)

Flashdark,

Does the Kroma run hotter than your KL4 or your L4? 

-Goatee


----------



## :)> (Oct 2, 2006)

UPDATE!!!

I just finished baking my Kroma in the oven at 350 F for 1.5 hours to simulate the heat produced by the LED while running the Kroma for extended periods of time. 

You will all be happy to know that even though the light came out scalding hot (I had to use a pot holder to hold it) there was no damage... to the oven. 

The good news is that it came out just marginally hotter from the oven than it feels after extended use at room temperature with the LED on high. 

-Goatee


----------



## Flashdark (Oct 3, 2006)

*Goatee,*

*I can't believe you baked a $300 flashlight in the oven at 350'F!*

As to your earlier question, I have never left my L4 on long enough to even remotely approach the heat level reached on the K2 in the first test (and I never will). I have heard that it will get pretty hot after a while.

*LED61,*

You are most welcome sir.
*Flashdark sends, stunned!*


----------



## LED61 (Oct 3, 2006)

I hope all you guys are enjoying your K2 Kromas as much as I´m enjoying mine.


----------



## Archangel (Oct 3, 2006)

Nice review, Flashdark. Were you holding it when you did the run-time test on high?


----------



## Flashdark (Oct 3, 2006)

*Archangel,*

No sir, I wasn't. On all of the tests, the light was sitting on a rather cool, formica table-top. Thus, it wasn't affected by body heat. We need someone with a lot of LED experience to comment knowledgeably about the heat level tolerances for this head. I have no knowledge at all, as to what level of heat might cause damage. I'm just playing it safe with *MY* light, and my *recommendations*. I have heard on this forum about the danger of high heat because of the damage it can cause to an LED head, and the way it can shorten it's lifespan, so when my light became so hot that I could not hold it in my hand, the alarm bells went off, and I reported it as such.

Any intelligent input in expanding the runtime envelope would be appreciated. Meanwhile....

Flashdark sends, *cautious*.


----------



## Archangel (Oct 3, 2006)

Flashdark- it wouldn't've gotten as hot if you were holding it. Much of the heat would've been transfered to your hand to your blood to the rest of your body.


----------



## Geogecko (Oct 4, 2006)

Well, considering the maximum junction temperature of a Luxeon III LED is 135C (275F), according to the datasheet, then one could possibly say that you may have damaged it by heating it to 350F (depending on the LED used in the K2, this may be slightly different, but is usually pretty consistant).

Why would anyone put a $300 flashlight in the oven at 350F? Is there ever a reason to believe the flashlight would have approached this temperature on it's own? I just skimmed this thread, so I may have missed something. I've left my U2 on for several minutes at a time, and while it got warm to hold (head was hot, but not hot enough that I couldn't touch it), it never got that hot. You'd know for sure if it was getting 350F, that's for sure.

Sometimes I'm just amazed at what people do...


----------



## Flashdark (Oct 15, 2006)

*To All:*

My K2 Kroma is due back Monday, 10/16/06, from the Tennessee hunting trip. The "hunter's" evaluation will be included in the updated Post #40, "Overall Conclusions". All remaining runtimes will be completed in the next two weeks. *"RadarGreg" etal* are doing battery and voltage evaluations. When things begin to clarify, I will also include them in Post #40. 

Hope this helps,
Flashdark sends.


----------



## Sixpointone (Oct 15, 2006)

Hi Flashdark,

I must compliment everyone involved in this detailed and inforative review on post number 40.

Might there by chance be a possibility of a similar type overview on the Milspec version of the Light in the future?

All My Best,
John


----------



## RadarGreg (Oct 16, 2006)

Excellent information, Flashdark! I don't think I could add anything further to the runtimes for the Kroma-MS. The milspec doesn't have the low-blue, low-red modes of operation. You get either blue, red, IR, yellow-green or low white at the first stage on the push switch, or you can get blue-high white, red-high white, IR-high white, yellow-green-high white, or high white output at the second stage of the push switch. My feeling is SF designed it this was so you could use the colored or low power white while doing a more covert search, and then kick in the high power white LED to really light up an area or assailant. For the ones wondering if the Kroma can perform well in a tactical environment with the lumen output, I can say it did perform well. I had the chance to so shooting with several of the German CPF members this weekend, and we practiced illuminating targets at 15 meters and shooting them. (metal knockdown plates, not Tangos, hehe). The Kroma-MS illuminated the plate very well and gave enough sidespill to see several meters to either side as well. This would be important if in a dark area there was a second "bad guy" trying to hide just outside the hotspot. 

If anyone is considering using the Kroma as a duty carry light, I can say it would be quite acceptable and compared well to the Gladius, SF 6P and other typical duty carry lights. Be sure to practice with it though. With any light, trying to hold the beam on your target with one hand and the gun in the other sounds easier than it really is. You can do it, but I usually ended up having the light on longer than would be prudent if the target also had a gun. You lose the advantage of temporarily blinding your target if you keep the light on. From the LEOs I was shooting with, the procedure would be, illuminate-shoot-light off. With practice, you can get the hotspot on the target the first time, get a shot off and then switch the light back off. I hope this info is helpful. Thanks,


----------



## RadarGreg (Oct 16, 2006)

Ok, for all those that like to see numbers and measurements, I took a new set of Panasonic CR123A batteries and ran them in my Kroma MS on high white LED only. I wanted to see just how hot it got and how long it would run. The batteries tested 100% on my Ansmann Energy-Check LCD tester. The ambient temperature in my office here remained a steady 74 degrees Fahrenheit. My Kroma-MS was at ambient temperature of 74 degrees when I stated the test and I placed it on a small stand to isolate it as much as possible from any heat sink source. Below are the times and temperatures as I measured them on the head of the Kroma with an IR thermometer.

TIME TEMPERATURE(Fahrenheit)
09:58 74
10:00 84
10:05 104
10:10 115
10:15 118
10:20 121
10:30 123
10:35 125
10:45 128
11:00 130 Still as apparently bright as at the start
11:20 132
11:30 130
11:35 131
11:45 126 Appears a bit dimmer that at full charge
11:50 120
11:55 108
12:00 99
12:20 87
12:25 83
12:30 81
13:00 76
13:15 77
14:00 74 Light is still burning, but high power is now about at bright as low power on fully charged batteries.

Test was stopped at this point. The final battery readings on the Ansmann were 0% for both batteries and 1.09 VDC each. The Kroma was still able to produce useable light but nowhere nearly as much as the low power white level. 

My overall expectation was to see just how hot the head would get and if it would be enough to cook the LEDs to a level where it might damage the circuitry. At a maximum temperature reading of only 132 degrees, I don't think that is hot enough to kill the electronics. However, in an environment where the ambient temperature is much higher (Iraq in the Summer, burning building, etc.) the Kroma would get hotter as there is less cooling air.

I don't think I'll be doing a runtime test on the other LED modes for the Red, Blue, IR and Yellow-Green. With the main white LED running for four hours and still producing useable light, I'd have to probably watch the blue LEDs burn for days, possibly a week. I hope you found this information useful. Thanks,


----------



## Geogecko (Oct 16, 2006)

Most electronic integrated circuits can withstand an operating temperature of 125C, or about 250F. So I'd say you are not getting anywhere near the danger point.

Even if you were in the middle of the summer in Iraq, at say, 110F, if you took the 58F delta between ambient and highest temperature, and applied that to 110F, that still only puts you at 168F, still well below 250F, and I doubt you would have the same delta at 110F, so it would probably be lower.

This of course, assumes that no one is holding the light, which tends to make the light hotter, since there is not a heat sink source to reduce the temperature. (Context sensitive comment here, it's NOT holding the light that makes it get hotter. Holding the light acts as a heat sink, once the light gets past normal body temperature.)


----------



## Flashdark (Oct 17, 2006)

*Sixpointone,*

Yes sir. I plan to do a similar test on the K2MS when I receive it. I am currently #20 on the list at Spyder Tactical (Tacticalsupply.com) with Steve Fergeson (Sp?).

*RadarGreg,*

I tend to agree about the design of the light. I will be VERY curious about the runtimes vs. useful power output of the 4 different color positions. It is beginning to be fairly obvious that there are substantial inefficiencies (loses) in the regular K2 Kroma head. I guess that this is to be expected with the design complexity involved but it's still a little disappointing. I am hoping for an improvement with the MilSpec version, that will give better runtimes.

I very much appreciate your input on the K2MS runtime in "High White". The temperatures are encouraging as well as 1 1/2 hrs. at max. power and 4 hrs. of total light in this position. Thank you. With your permission, I will include various aspects of your input in the test report, not only from this thread, but from the battery thread over in the LED forum.

Flashdark sends.


----------



## LED61 (Oct 17, 2006)

In conclusion the Kroma can be run at high beam for the full duration of the batteries, and the runtime is indeed the advertised 1 hour 30 minutes by Surefire, and not hot enough for damage to the head.
One last question, if one holds the light in the hand body temperature is at 98.5 F, after 100 degrees is pierced to the upside would the hand holding the light act as a heat exchanger and actually cool the light? I´m asking this because someone on a previous post mentioned the hand holding the light would contribute to heat.


----------



## Flashdark (Oct 17, 2006)

LED61,

Indeed, welcome news about the probability of "continuous-duty" in "High White Only" mode, but be darn careful about the heat generated by the "combo" settings of "High White" + "something else".

In answer to your second question, yse sir, I assume so. Anything touching  the light, that is cooler than the light, would have to transfer heat away from the light. This would be especially true with blood circulating throughout the hand, like the cooling fluid in a radiator. Just armchair thermodynamics and assumptions on my part.

Hope this helps,
Flashdark sends.


----------



## Geogecko (Oct 18, 2006)

LED61 said:


> One last question, if one holds the light in the hand body temperature is at 98.5 F, after 100 degrees is pierced to the upside would the hand holding the light act as a heat exchanger and actually cool the light? I´m asking this because someone on a previous post mentioned the hand holding the light would contribute to heat.



This comment?



> This of course, assumes that no one is holding the light, which tends to make the light hotter, since there is not a heat sink source to reduce the temperature.



I should clarify that, what I meant was, that since no one is holding the light, it will get hotter, because the body acts as a heat sink (once over the 98.6F, of course).

I can see how my comment could be misinterpreted. You have to read it in context to what I was talking about, but then it's still hard to really know what I'm saying...might have to go edit that.


----------



## Flashdark (Oct 18, 2006)

*Geogecko,*

I heard a great line that perfectly lampoons the confusion:

*"I'm not sure that I think I understand all I know about what you just were alledged to have said!"*

Flashdark sends, I think....


----------



## :)> (Oct 18, 2006)

Flashdark said:


> *Goatee,*
> 
> *I can't believe you baked a $300 flashlight in the oven at 350'F!*
> 
> ...



I just checked back in and realized that my joke may have been taken seriously. I was being a little sarcastic about the heat that the LED produced. 

Oops

-Goatee


----------



## Geogecko (Oct 19, 2006)

: )>~


----------



## LED61 (Oct 19, 2006)

Guys, I ran my Kroma through two batterystation RCR123A's last night. I've posted the results in this thread

http://candlepowerforums.com/vb/showthread.php?t=137545

Flashdark, thanks for all your efforts, they were very inspiring and of great help.


----------



## LED61 (Oct 24, 2006)

The light works perfectly on BS 17650 rechargeable...for over two hours on high beam. I have updated my post above.


----------



## umc (Oct 30, 2006)

Hey all,

Does anyone know who has the regular Kroma in stock?

I just ordered one from optics HQ and then got an email saying they didn't have any in stock.

I canceled that order and called Surefire and they were on back order as well but said the word is that they're supposed to get more about the first of November so I placed an order with them. That date isn't guaranteed though.

So, anyone know who does have them in stock now?


----------



## dchao (Oct 31, 2006)

umc said:


> So, anyone know who does have them in stock now?


eBay


----------



## MKatzpp (Nov 1, 2006)

so this is my first post. i monitor this board constantly and love reading what most of you have to say. but unlike most of you flashlight-philes i dont want a zillion different kinds of flashlights--just the best of the best.

i actually had almost ZERO interest in high end flashlights until about 8months ago. i always liked getting maglights for xmas or little keychain lights to help me tinker around the house. the truth is, i really had NO clue what was out there. after doing research for about a month i jumped into getting a streamlight strion. it seemed to be the most powerful light in its size and the range was amazing. some guy at copquest spent like an hour talking to me about what i wanted it for. for me i have only 2 uses, tinkering around the house and walking/hiking at night with my dog. so the strion it was...

after spending $99 on it and 2 chargers i was a happy camper. but not for long. once you get a taste of the good life you always want more. now i'm not one that needs to count pennies so if i want something i buy it (and lie to the wife about what it costs) so to me $99 was a lot for a flashlight, but not very much in general and not a lot for something of high quality. so after more research i decided to buy the ultrastinger so i could see 1000 football fields away. i figured since i had the baby (strion) the daddy would be even nicer. as with the strion the beam was well focused and had an amazing throw. so i again, was content for a while...

until may, when i decided after reading about the surefire U2 as being the most versatile and high quality light out there. after a good month of reading up about it i decided to brightguy the light for $279ish but when i got it i was SO disappointed. the light itself didn't shine nearly as far as the strion and seemed to generate only as much as the strion up close. so my conundrum was, "how in the world was this a better flashlight, especially for 3x the cost?" additionally the beam had a donut hole (that everyone wrote about in reviews). so i called surefire and figured i would keep it for close to the 30days brightguy had for returns and see if it grew on me. unfortunately for my wallet it did grow on me. my initial impressions were pretty far off. the beam itself is pure white and amazing. it illuminates a wooded area with an amazing focused beam plus a great secondary (spill) area. basically it would light up 3 walls of a room as opposed to JUST a straight shot beam (strion). and of course its usefulness with the low settings makes it a much better light to help fix things. i dont need to be blinded by 80-100 lumens when 5-15 is just perfect for fixing something.

so of course i decided to hold onto it and what a great toy it is. and for those of you who love the idea of rechargeable lights (as i initially did with the streamlights) their usefulness is limited over longer periods of time. the surefires just keep pumping out more light for longer plus a quick battery change as opposed to a long recharging process. so again i was happy...for a bit.

it wasn't long after that i started reading about the surefire kroma. now for me, as this point, quality and uniqueness is really all i want. there comes a time when you dont need anymore flashlights to get by in day to day life. i'm sure most of you would disagree, but that's just a flashaholics take. reality is...1-2 versatile flashlights is perfect for about 99% of occasions. so for me the kroma was more of a neat toy rather than something useful. 

i again did a TON of research, but the kroma was still months away from being readily available so the research was thin. after about a month i decided $300 for another flashlight might be pushing it with my wife. her questions about "is that ANOTHER flashlight in a 4 month period" and "how much did THIS one cost?" were getting too close together. so i let the matter drop until about a week ago. it appeared as if they were out there and being shipped around so after seeing steve from tacticals ad about 20% off to cpf members i couldn't resist any longer.

it arrived today and i'll give some initial impressions based on house use in the daytime and using it in darkness in the bathroom only. i will put a + next to the number when i feel its good and a - when i feel its a negative...obviously


1)+the low white beam is better than the u2 lowest setting. its probably half as strong making it more usable for everyday non-blinding use.

2)-the high beam white is somewhere in the u2 4-5 setting neighborhood. its hard to pinpoint exactly how bright it is comparatively. but its far from the u2 6 setting. for me this is somewhat disappointing. personally i'd like a massive power output to illuminate the woods 800 feet away, but that's me. one thing i've learned about flashlights is that 98% of needed light can either be VERY dull or VERY bright. i say this because there are very few times i use the u2's 2-5 settings. so for my own personal use and findings something should be like 10lumens or 200 and that would take care of almost every problem out there. bottom line, i'd like the white high to be probably double what it is now. 

3)+both the blue and red are very nice, however i find the 2 different settings (high and low) to be of almost no use. this is a tough balance for the flashlight because the milspec one uses 4 LEDs for each of the 4 colors whereas this uses 8 leds for the 2 colors. the red/blue lows dont seem to be useful and could've been replaced with a different setting of some sort. of course i know this to not be possible since red/blue high each use 8 leds so there wouldn't be room for anything else.

4)+the quality is like every other surefire. good solid build, strong feel, easy grip, etc. the one gripe i have about surefire is i feel they might be TOO well built. the truth is the metallic sandpaper grip makes it impossible to stick in your mouth. i'm sure you're all like "WHAT?" but think about how often you're holding something in one hand, a screwdriver or wrech in another hand and you've got the flashlight in your mouth trying to make what you're doing easier to see. anyway, whenever i do that with a surefire it feels like my tooth enamel is being ground away by the metal grooves. the weight seems a little off too. almost seems too light and less strong than the u2. has a slightly less quality feel to it. obviously its not of lower quality tho.

5)-a lot of people dont like the click cap to turn the u2 on. personally i LOVE it. i dont like having to turn the bottom to keep something on. grabbing a flashlight and using it with one hand to activate is great. its quick and easy. this one has a momentary on but you MUST turn it to keep it on. not really a fan. its one of the reasons i wanted a surefire in the first place. the strion must be turned and i wanted to see how other things went. i like the tactical aspect of momentary on or perma on using the click button. thats just me maybe. all the aspects of use take a little getting used to. you turn the bottom for on. turn it more for higher white. push the button for low on, push it more for high on. its just too much for that bottom to do. its a little annoying to have to pay THAT much attention down there. and of course low light vs high light momentary on takes some exact pressing for periods of time possibly. just not a fan.

6)+the indicator clicks (to choose, blue/red/white) as opposed to just turning on the u2. i like the easy swivel of the u2, but i can see why this needs to be different. you need to know exactly what click you're on and it needs to stay there. so no big deal imo.

7)+the beam itself is a square up close. again no big deal. more importantly there is no donut on this light. its seems to be fairly uniform. the spill is a little weak too. on the bright side the beam is even more white than my u2. i wasn't sure that was possible but this appears to be more of a purer white. i love the more white color this seems to be.


a lot of my interpretations and reviews are subjective obviously. they should be taken with a grain of salt for a few reasons. 1) i hated the u2 when i first got it and now i would probably jump off a cliff if it was taken away from me or i ever forgot to bring it out at nighttime or if i ever went on vacation without it. 2) i haven't had a great chance to test my new light yet. shining on walls and in a bathroom doesn't do a flashlight justice.

i will say with definitive certainty the low light is just more useful than other high output flashlights for working within a 2-3ft distance of your eyes. for now i dont have any beamshots and cant think of anything else to write. 

as for recommendations. for now i can say 100% that the u2 is a better all purpose light. without being a scientist or a hunter the red/blue is more of a novelty meant to calm a 30yr olds need for a new toy, rather than something of extremely high necessity. i will hopefully repost later with updates.


----------



## MKatzpp (Nov 1, 2006)

i also have a follow-up question...


i guess since i'm relatively new to flashlights, what exactly is a "18650 cell" battery? how big are they, what would the output difference be in either a kroma or a u2, etc. does the flashlight need modifications in order to use the 18650? can someone fill me in on the details/specifics? can i just buy one or two and plug it into one of my 123A flashlights?

thanks in advance.


----------



## LED61 (Nov 1, 2006)

An 18650 cell is a li-ion rechargeable cell that holds anywhere from 1800 to 2600 mah capacity. That is the big attraction as it can be used on some U2´s but no go on the Kroma. The 18 in front stands for 18 mm diameter (fat cell), and the 650 means 65 mm in length. By comparison a primary CR 123 would be a 16400 cell, 16mm diameter, 40mm length. You can fit a 17670 rechargeable with 1500 mah capacity into the Kroma though, at least in mine. i have found this to work just fine for a long period of time--over two hours on high beam. The output is unchanged from primaries. Do some research in this forum before you start messing around with rechargeable batteries, or other lithium batteries for that matter. lithium batteries can explode if overdischarged, and you should never mix used with new batteries in series in a flashlight.


----------



## Chronos (Nov 1, 2006)

LED61, 

Did you have to do anything to your Kroma to make it work with the 17670? The reason I ask is I have the latest 17670 from AW and it doesn't work. Do I need to extend the spring in the tailcap a bit, or is there a way to position the cell so it works? Any input would be greatly appreciated.

Thanks


----------



## LED61 (Nov 1, 2006)

Chronos, my 17670 is from Kevin at batterystation.com, so diameter may vary slightly. The battery goes in very tight. It is necessary to open the light from both ends and push down from the positive side toward the tailcap end. For some reason the battery will not go in if pushed from the negative side. And, you must do the final gentle push with led head screwing it back in so that positive contact is assured in this way. If you push too far, the battery will be so tight that the negative end will not be able to push the battery to ensure positive contact. I have found that the light runs great with this battery and actually a much cooler for long periods of time. Good luck


----------



## :)> (Nov 1, 2006)

Chronos,

I had intermittent success with the 17670's. Some times they would work and sometimes they did not. I had better success with the batteries that did not fit so snuggly that they did not move easily in the tube. 

One way to reduce the diameter of the battery is to take the coating off of it and replace it with a layer of packing tape. This reduces the diameter of the battery a little and it makes it so that it can slide in and out easier. 

It will definately work, the question is how to get it to work consistently.

-Goatee


----------



## Flashdark (Nov 2, 2006)

*To All:*

*Testing has been completed for the K2 KROMA in Post #40. Minor odds & ends will be added in the future, if appropriate. *

*Awaiting the K2 KROMA MilSpec for the side-by-side comparison. **That review will be posted in this thread and will follow the same format.*

*Hope some of this helped,*
*Flashdark sends.*


----------



## umc (Nov 2, 2006)

MKtazpp,

Boy that was a long post. ;P 

Anyway, I read it all and hear ya.

I have many Surefire lights and love them all. My U2 sits next to my bed and gets up with me in the middle of the night, it reads in bed with me, etc.

Now it's been great for that and I love it although I've had times when I felt low was too high. My Kroma came in today and the testing has begun. I think it will work better for me at night as a low light, umm well light. It will be better for not disturbing my wife next to me sleeping if I'm reading in bed with it. I'll find other uses for the red and blue as well.

So far I do agree that I wish high white was a lot higher about x2 like you said. I knew it was 50 lumens when I bought it so that's fine, I accept this. I rarely set my U2 to 6 only if I was out and about on the town or in the woods but I have other lights for that, the U2 is primarily at home. Thing is because it's so functional I like to use it else where. Oh well.

So going forward I like the Kroma so far (only 4 hours to this point) and know it will work out well for what I have intended for it. Now on my wish list though is a Kroma that goes to 100+ lumens on high and a clicky cap.

Thing is I can't turn the tailcap with one hand without turning the "light selection" dial.


----------



## rgp4544 (Nov 4, 2006)

TOY????? A lot of these comments have steam coming out of my ears.

Sometimes I wonder why people buy stuff they don't need...and I try to ignore reviews of lights from people who didn't need the capabilities but for some bizarre reason had more money than brains and had to run out and buy a new toy. Don't confuse compulsive shopping with need.

Keep in mind the Kromas were designed to meet a specific work related need and the need exists, it isn't just there for hobbyists to have a light with pretty colors. Some of us have an actual need and really aren't interested in buying another light unless it meets a specific need. Personally, I've ordered a Kroma Mil Spec to meet a specific set of work requirements.

Richard


----------



## Flashdark (Nov 4, 2006)

*rgp4544,*

Richard, *what* specific set of work requirements were you trying to satisfy, and did the light perform adaquately?? Mine was tactical/utility backup, so my review in Post #40 was probably slanted in that direction. We need to hear from more people like yourself. What was *your* need and how did the K2 work out for you*??!!* ("Inquiring minds want to know")

Flashdark sends.


----------



## LED61 (Nov 4, 2006)

rgp4544 said:


> TOY????? A lot of these comments have steam coming out of my ears.
> 
> Sometimes I wonder why people buy stuff they don't need...and I try to ignore reviews of lights from people who didn't need the capabilities but for some bizarre reason had more money than brains and had to run out and buy a new toy. Don't confuse compulsive shopping with need.
> 
> ...


 
Exactly right!!! we should not measure a flashlight performance based on lumen output alone, but for how well they meet the task they were designed to do. For instance, a live memory of a potentially dangerous situation dating back to around 1985 when I was in a cross country night flight in VFR conditions and I had an alternator failure in the piston single airplane. Well, the airplane's battery continued to put out power for the essentials but this only lasted for 25 minutes, after which I had me a complete blackout in airplane. I had a flashlight of course, not near the capability of the surefire Kroma or aviator or similar. And the flashlight I had served me well to illuminate my instruments thank God, but that capability came nowhere near what the Kroma offers now. I could have used the Kroma to preserve my night vision better inside the airplane with high red, and it is now a much better beam to do my 360 pleflight walkaround!! ideal light for a pilot,


----------



## Flashdark (Nov 4, 2006)

*LED61,*

I too am a pilot, and I can't remember what color light will show up hydraulic fluid (hydraulic leaks) on the ground during a "walkaround". Do *you* know??!! Someone asked me if the K2 would be useful for this on "preflight" but I couldn't remember.

Thanks,
Flashdark sends.


----------



## LED61 (Nov 4, 2006)

Flashdark, the blue color would be the most suitable for this task.


----------



## Flashdark (Nov 4, 2006)

*LED61,*

What does the hydraulic fluid look like under "Blue" light?? How does it show up??

Thanks,
Flashdark sends.


----------



## LED61 (Nov 4, 2006)

BTW Flashdark, I discovered a potential pitfall in using the rechargeable 17650. While the battery powers the light just fine at least in my case, and going back to the fact that it goes into the flashlight very tight and in a specific way, I accidentally dropped the light the other day and BAM!! all of the sudden no light. Turns out that the reduced length of the battery and the impact displaced the battery in such a way that it broke positive contact. So no matter how far I screwed the tailcap in it would not turn on. It was necessary to unscrew the tailcap, and press from the negative end until positive contact was reestablished. You would not want to mess around in this fashion in whatever emergency you needed the light for and so for serious use better use CR123's, or until I can figure out what sort of spacer I can insert in the negative end to insure there are no lose ends.


----------



## Flashdark (Nov 4, 2006)

LED61,

Thanks for the info. I'll update Post #40.

Flashdark sends.


----------



## LED61 (Nov 4, 2006)

Flashdark said:


> *LED61,*
> 
> What does the hydraulic fluid look like under "Blue" light?? How does it show up??
> 
> ...


 
WELL!!! I am not an airline pilot and hydraulic fluids are used mostly on jets, not pistons. But, hydraulic fluid is really hydraulic oil with some additives and depending on whether it is fresh out of the bucket or used it would turn slightly redish. Viscous redish fluids tend to contrast a lot with the blue light and its pretty much a black and white situation from there on. those type fluids also tend to reflect the blue light rather than absorb it. And keep in mind it would differ if your airplane was sitting on pavement-wet or dry or a concrete whitish ramp.
An airline pilot with this light in use would be better qualified to answer your question though. Sorry if all this is slghtly OT.


----------



## Flashdark (Nov 18, 2006)

*To All:*

*Post #40 has been updated to reflect CPFers attempts at "leggo-ing" the U2, K2, & K2MS into a "Shorty".* See item #11, "Overall Conclusions", near the end of the report, for these results. In addition, the last two dozen posts in this thread have also addressed battery size and capability.

Flashdark sends.


----------



## Chronos (Nov 18, 2006)

FWIW one can use the LU60 kit to enable the use of other C-body bezels and lamp assemblies on the K2/U2 bodies. I've been able to use setups such as:

KL5 + K2 body + K2 tailcap for 2-stage KL5
KL5 + K2 body + Detonator + K2 tailcap for extended runtime (2x17500) and 2-stage KL5
K2 Kroma bezel + A12 + K2 body (2x17500) + K2 tailcap for extended K2 runtime
M2 bezel + K2 body + SW02 tailcap for incan use


----------



## rgp4544 (Nov 18, 2006)

Flashdark said:


> *rgp4544,*
> 
> Richard, *what* specific set of work requirements were you trying to satisfy, and did the light perform adaquately?? Mine was tactical/utility backup, so my review in Post #40 was probably slanted in that direction. We need to hear from more people like yourself. What was *your* need and how did the K2 work out for you*??!!* ("Inquiring minds want to know")
> 
> Flashdark sends.



Flashdark,

The standard Kroma appears to have been designed specifically for pilots and mechanics and since I could think of no use for the IR beam on the Mil Spec I switched my order to the regular red-blue-white one.

Right now I've only had a Kroma for a little over a day and am still playing with it to get used to the switching mechanisms - the switch is a bit more sensitive than an A2. I haven't really used blue light before but the Kroma really is the first really practical light I've seen that has both red and white low output and I've looked for 20 years for such a light. For the past two or three years I've carried two lights - one red A2 and one white A2 - and before then there really wasn't a single decent light on the market.

My needs if broken down are basically:
1) preserving night vision for which the low level dual output red is ideal
2) occasionally needing a very low output white light
3) preflighting an aircraft which requires some good white light, preferably dual output white light.

#1 generally requires an extremely dim low level red light similar to the Kroma's low output red because if dark adapted more light tends to erase details and you can't see a chart or a paper well if a light is too bright. Even the red output from an A2 Aviator is enough to cause a lot of glare to bounce back from a piece of paper. The Kroma's low output red is actually better than the A2's red.

Thus far the Kroma appears to be an ideal working light, although it is a bit large, and I think most pilots and mechanics would love it.

After I get used to operating it with one hand and after the tailcap twisty smooths out with practice I'll fly with it and can report on results then, because right now it seems too easy to flash a white beam.

I'm still not sure exactly how I'm going to carry this thing though...it needs an adjustable neck lanyard...

Richard


----------



## Flashdark (Nov 18, 2006)

*rgp4544,*

I pretty much agree 100% with everything you said. Right now, I have a Z60 lanyard clipped to the pocketclip. I also sanded down the inside diameter of the 2-piece Z60 circumferential attachment ring and have that on the tail cap as a backup attachment point. I didn't want to use the Z60 with this attachment ring because the metal clip from the Z-60 scratches the tail cap when it rotates. (The attachment hole now sits so deep into the tail cap slot after the inside diameter was sanded down that the Z60 clip always seems to rub the tail cap when it rotates.) 

This light has now replaced my U2 as my primary utility light. Right now, I am experimenting with an A21 + A12 combo for a "slimline" 2-battery version without the pocketclip. If I can use the Z-26 tail cap lanyard ring with this combo, I may stick with this. 

Thanks for your input.
Flashdark sends,
Flashdark spends.


----------



## rgp4544 (Nov 19, 2006)

Flashdark,

I'm also trying a Z60 attached to the pocketclip and it appears as though it might be a functional solution.

The other item I want to try is just clipping the Kroma onto a Billabong nylon neck lanyard but I can't find where that lanyard is right now.

Richard


----------



## Archangel (Nov 21, 2006)

Just a quick addition... Seems that, unlike the U2 (and like the Inova XO3), the Kroma won't regulate off of a single li-ion. Fresh off the charger, output using a 17670 was slightly less than it was using 2x123, but i was able to watch the numbers tick down slowly. The difference at first wasn't enough to matter, but things will only get "worse" over time.


----------



## Chronos (Nov 21, 2006)

I'll back up this observation. I realized that with 1x17670 that I'm not seeing regulation. The Kroma does dim as the cell depletes. However, I saw a dramatic fall off in lighting level when my 2x123 primaries depleted. Interesting. Does the light have some boost converter that has a threshold from somewhere around 3v to 6v... below 3v (or so) there is no boost?

I'd like to test out the theory with my 2x17500s but I'm sending my light in for surgery.


----------



## LED61 (Nov 22, 2006)

I'll use my Kroma on my 17670 for play or non essentials. When I go flying, I'll make sure I have primaries. Try dropping the light guys and the battery will displace itself back and break positive contact. You will have to open the light and push the battery forward to regain it. Bad bad bad in an emergency.


----------



## CM (Nov 22, 2006)

The Kroma uses a buck converter. With single Li-Ion, it will not regulate since Vf is close to cell voltage - diode drop. They're still using their low tech converters which are not of the synchronous type, hence you get a few hundred millivolts less than the cell voltage going to the LED.


----------



## benighted (Nov 23, 2006)

I've had my Kroma a few days now. I like the extra capability of the colored LED's and the tightness of the white beam but I still like my white A2 better as my general use EDC. 

The white A2 has brighter low and better high beam and a high beam runtime not much shorter than the KROMA. 

I haven't had a whole lot of time to test it out in the real world but I'm leaving to Alaska on Friday so I'll have a good chance to use it in real world conditions. I'll report back here in about 2 weeks unless I can get service on my PPC phone then it might be sooner.


----------



## rgp4544 (Nov 23, 2006)

The runtime on the Kroma's high beam might be understated by Surefire, I've been playing with mine a lot to get used to the function and I think I may have used the high beam for over an hour.

Richard


----------



## Flashdark (Nov 24, 2006)

*rgp4544,*

The runtime of the "High White" beam on the KROMA, as well as all other positions, is detailed in Post #40. ~1 1/2 hours of full power, followed by the power falling off to approximately "Low White" output by the 4-hour point. Power continues to fall off, and by the 6-hour point, you still have usable illumination if you select "High Red". Beyond this point, we are in "moon-mode".

Hope this helps,
Flashdark sends,
Flashdark spends.


----------



## rgp4544 (Dec 1, 2006)

Flashdark,

Thank you, that is a ton of detail in post #40...meanwhile even though I've started carrying an A2 again I'll be keeping the Kroma with me when out of the country for a few months.

I have also noticed after days of carrying a Kroma that the instant I picked up an A2 again it was immediately obvious how much larger and bulkier the Kroma feels even though it doesn't look like much of a difference.

Richard


----------



## Archangel (Dec 1, 2006)

LED61 said:


> Try dropping the light guys and the battery will displace itself back and break positive contact. You will have to open the light and push the battery forward to regain it. Bad bad bad in an emergency.


Stretching the spring slightly will solve that. (I'm not recommending it to anyone else, etc etc etc.)


----------



## dchao (Dec 1, 2006)

LED61:

Unprotected 17670 will fit inside the K2 perfectly, so the tailcap spring can maintain the battery's positive contact all the time.


----------



## LED61 (Dec 2, 2006)

True dchao, but I just don't like to fiddle with unprotected cells.....especially in a low power light like the Kroma where it's hard to tell when it dims and need recharging.


----------



## dchao (Dec 3, 2006)

I am sure the LED's won't even turn on when the voltage drops lower than 3.0V. Whereas the Li-Ion's over discharge protection voltage come on at a much lower 2.40V. 

Also lots of people run 18650's with SF U2's, and have no problem so far. So I think it's OK to run unprotected with Kroma as well.


----------



## Aepoc (Jan 13, 2007)

Can I use two 3.7 v rechargeable 123's in the Kroma without having to worry about overheating or causing other damage?


----------



## roy123 (Jan 15, 2007)

I wish I can afford one of this


----------



## dchao (Jan 15, 2007)

Aepoc said:


> Can I use two 3.7 v rechargeable 123's in the Kroma without having to worry about overheating or causing other damage?


You are wasting battery power by using two 3.7v batteries (total=7.4) One cell, like the 17670, is sufficient to power the Kroma.


----------



## Aepoc (Jan 22, 2007)

What do you mean wasting battery power? Won't it be brighter with more voltage? Increased output does not equate to wasted battery power. 

I don't want to worry about the bad connection with the 17670's due to their shorter length.

Will the two 3.7v's significantly decrease the life of the LED's or cause damage to the circuitry of the Kroma?


----------



## Strauss (Jan 22, 2007)

Aepoc said:


> What do you mean wasting battery power? Won't it be brighter with more voltage? Increased output does not equate to wasted battery power.
> 
> I don't want to worry about the bad connection with the 17670's due to their shorter length.
> 
> Will the two 3.7v's significantly decrease the life of the LED's or cause damage to the circuitry of the Kroma?


 
Boy, thats a good question :thinking:


----------



## xtoy (Jan 23, 2007)

carl said:


> I agree. The U2 has greater throw and spill. Both the U2 and Kroma last about 1 hour on high which makes it seem the Kroma is much less efficient by a long shot. I suspect this is partly because the Kroma has to shoot through TWO lens (TIR and front glass) while the U2 has only one lens.
> 
> This is interesting. Anybody else out there venture to guess why?


 


for LED,less lumens,more efficiency;on the contrary,more lumens,less efficiency.

200lumens seems hard for cree LED.


----------



## Aepoc (Jan 24, 2007)

I have had two 3.7v's in the Kroma for about two days now... 

The colored leds are significantly brighter on both high and low.
The single Luxeon III is not noticeably brighter then with the primaries.

The only negative with the 3.7v's is that I cannot go from the high beam to the low beam without first turning the flashlight off. Other then that, everything works fine.

I have not tried any runtime tests. I haven't even had the flashlight on long enough to heat up. I am still worried about burning out the leds if i run it for too long. This could be an irrational fear, but for a $300 flashlight, I don't want to take any chances yet.


----------



## Aepoc (Jan 29, 2007)

OK, so I finally broke down and bought some RCR123 3v to throw in the Kroma. Doing this allows me to gain all of the functions of the tail-cap. I can go from high output to low output with the Luxeon. As mentioned previously this function was lost with the higher voltage batteries. With the two 3v's, the Kroma runs like it is being run by primaries. I am not afraid of ruining anything with these batteries so i am going to try and do a runtime test as soon as my charger gets here.

As for the 3.7v's... They will be my back up batteries. The light will not be on for any extended amount of time with these batteries powering it. Somebody else is going to have to do a runtime test with the 3.7v's. I already had a close call with my ROP this weekend... I don't need two.


----------



## dchao (Feb 12, 2007)

Aepoc,

Why don't you try the new Ultra Fire Button-Top unprotected 17670. At 3.7V, there is enough voltage to power the Luxeon III without suffering any reduction in its output (compare to the original 6V from the 2 x 3V 123's). The 17670 is rated at 1800mAh , and will keep your K2 on high white for close to 2 hours.


----------



## Aepoc (Feb 19, 2007)

How does the reduction in voltage lead to the same output? 

Would the circuitry in the Kroma essentially protect the unprotected batteries (turn the light off before completely draining the batts)?


----------



## GreySave (May 3, 2007)

I recently purchased a Kroma from Steven at Tactical Supply based largely upon Flashdark's excellent assessment of the Kroma. Although I have only had it a short time I have to say that I think this is going to be an excellent utility light. No, it does not have the punch of a U2 or Cree powered light. Based upon the numbers it comes in even a little lower than an A2, but that's not all bad. As others have said, I am finding this to be a well balanced light. Excellent low level output and a main beam that is adequate for most normal uses. It fills a specific need well. If you have a use for the low power colored output I would not be put off by the 50 Lumen main beam. 

I have already decided that this is one of two or perhaps three lights that will accompany us on vacation in the mountains later this fall. It will probably be joined by an A2 for its incan main beam and either an L4 or Huntlight Cree for flood. Then again, it I take Flashdark's suggestion and get the FM-64 beam shaper I can probably do without the L4 or Huntlight.......


----------



## Archangel (May 31, 2007)

Just some quick impressions...

I gave the Kroma shorty (A21 w/ R123) a solid workout over the weekend, using it as my main torch when we went camping. The red was great for not blinding me, but i made the mistake of bringing a red pen, which apparently is the exact same shade as the Kroma, because it made the writing *completely* invisible. Low blue was plenty for the tent and enough for walking around, though i generally used high blue for the latter. Low white didn't really serve a purpose. It definitely has more throw than the blue, but felt too much like i was in battery conservation mode. (For distance, that is; it was too hot for close-range stuff.) That would be the reason i'd upgrade the main LED, but apparently that just gives more output, not more throw. High had enough reach to get the job done and i'd actually rather have this output for twice as long rather than twice the output. (Remember: it's a generalist: i'll use a thrower if i really need a thrower.)


----------



## waterboiler (Jun 1, 2007)

I have similar feeling about this light as a few of you. To me it is a great utility light. I have used it around the house for a few months and really like the low blue for midnight throne-room runs. High blue is pretty good if I want to light up an area but find if I need a flood type low output light that I prefer white. Have not used red too much but I can see it comming in handy in the woods, I use a used to use a red filter at times - one less thing to carry.

I like the two levels on each and agree that low white is the least used. I guess I would like to see a 'medium' white about 50% brighter than current low and a high white that is all about throw and output - think CREE. The blue/red modes suit me fine for flood applications, even the output levels seem to work well. Just wish the white was higher on both counts.

All that said, this light to me is about balance and utility. It will be coming with me into the bush this season, along with a M3T for throw and an L1/F04 combo for backup. This light would really benefit from a CREE transplant if not for more output ( since IIRC throw is really about TIR/reflector design ) but for runtime on white.

Last season I learned that less is more in true dark ( wilderness ) conditions and as such now seek less for output and more for runtime with my bush lights. This is where the Kroma fits in, low level when needed with brighter just a twist away.


----------



## Draz (Aug 7, 2007)

ok I bought a used kroma and I have a problem. I assume the previous owner put some kind of "locktite" on the bezel threads. Well I was using some force to take off the top of the light and well the selector ring spun out. It works fine, it just doesn't "stop". Two questions. Did surefire put anything besides a rubber seal between the bezel and lense or was it indeed the previous owner. I scraped all the "gunk" out from the threads and it seems to be water tight for now and will the selector ring cause any problems in the future. Surefire said they can "repair" it but I really don't wanna send it off and whatnot. Thanks for the input.


----------



## FiftyCalAl (Aug 7, 2007)

SF has one of the best and easiest warranty/repair/replacement policies in the industry. If you send it in, most likely they will send you a new light, unless the 'fix' is incredibly simple. The only reason not to send it in would be if the serial number is recorded somewhere for some reason that a person may not want to have it noticed.  Anyway, I don't have your answer; but just send it back to SF and they'll take care of it.


----------



## Draz (Aug 8, 2007)

Yea I have an RMA and am shipping the Kroma off today, but here are some of my points on the reviews.

1. The 50 lumen is plenty of light for the average person. I have never had anything stronger than a L4, so 50 lumens with throw is spot on for myself.

2. The high red is very nice at lighting entire rooms as well as the high blue, the low counterparts are good like everyone said...ie. rumaging around in tents or navigating to the bathroom in total darkness or just simply "playing" with. It does have tons of "playing" time.

3. Low white is comparable to the new generation Inova X1's imho, perhaps just tad dimmer.

Now for the Ugly

4. It has an UGLY square beam at close up due to the TIR and has its share of freaky artifacts:shrug: I have heard of others as well as mine having dust and what looks like fibers or perhaps very very small scratches on the TIR visible only when light is one. Mine had a smudge on it before the damn adhesive was even broken ....

5. The selector ring will "strip" very easily from what I have seen, I was taking off a rather tight mind you bezel to clean dust from the inside and my hand slipped and totally murdered the ring. I can't tell if I actually like it better when it spins freely or when it works and stops on each mode. I can deal with the "loose" ring, makes one handed operation easier. I called surefire and since the modes are activated by a magnet, the stripped selector ring should not pose a problem unless you want the "bumps". I actually can deal with it being like the U2 and smooth.

6. Water proof up to 33 meters or whatever SF says doesn't apply to my Kroma..I can't say for others. After I replaced the o-ring that broke the first time I changed batteries and after the replacing of the o-rings underneath the lense it stil leaks water...bad actually. Sumerging it for any more than 30 secs invites water into the tail cap, head threads, and under the lense. I have replaced the ladder 2 o-rings so perhaps its user error but the tail cap 0-ring is still in perfect shape and loves letting water into the light. 

*EDIT* I can admit when I'm wrong, as of now I lubed everything up real good with some gun grease(only thing I had at the time) after cleaning the left over adhesive and gunk out and it appears to be once again water proof, will keep ya posted on that

7. I'm sending my new Kroma off today to surefire and I pray I get a Surefire quality light back. The ring was my fault but the o-rings and the dust and "crap" that finds it way under the lense constantly is on them.

*EDIT* Not gonna send it off now, will wait to see if the stripped selector ring poses a problem with reliability or the water problem arises again. Sides, I dont wanna wait to have it back...mine had a few problems but I LOVE IT

Besides the problems....The Kroma is a bad *** light, fun as hell to play with and very handy. I highly recomend it..just be carefull with the Selector ring and I hope yours has a clean and nice TIR lense.


----------



## Draz (Aug 22, 2007)

Decided to do a new post instead of editing the last post again

Got the new Kroma in from Surefire after only 12 days round trip

Unlilke the old one when I press the tail cap for "high" white, it stays on after I depress it if a color is selected. I didn't remember my old one doing that. Took it for a night walk with the wife and dog through a dim light citylike street, low blue was the best overall light imho. Bright blue was blinding on the road, low red was almost not there and high red just didn't look to good for me. Low white or low blue with a couple of street lights here and there was awesome. Never needed to use "high" white unless we were goofing and shinning it at house or just down the street. 

The kroma is a great overall light and has been proven to be so over and over again. Kinda hard to justify the 300 dollar price tag, specially when a A2 is much cheaper, but if you can afford one...go for it, it's a nice hunk of metal The problems with my last one was mostly due to human error, but surefire sent me a brand new one and everything is working great so far.


----------



## Force Attuned (May 18, 2008)

To the author - great review!!


----------



## benighted (May 18, 2008)

necro


----------



## Dave63 (Nov 17, 2008)

Does anyone know how the Kroma compares to the Smith & Wesson Powertech Galaxy 28 LED Flash-Lights?


----------



## Solscud007 (Nov 18, 2008)

well im not familiar with that light, but after reading a little about it and seeing pictures, it is not quite like the Kroma. of course the S&W is inexpensive. you can buy a whole bunch. 

But playing with my Kroma and Turbo Kroma, it is a thing of beauty. I was luckily enough to not pay retail on them. $177 shipped for the Kroma and thanks to CURSE for the Turbo kroma at only $380. Nearly the price of a regular kroma at retail.

anyway the bigges difference is the TIR optic. that really focuses the light to a nice hotspot. I blinded my neighbor the other day as he was playing a joke on me when i was in my basement. Our basements share a common hallway in our townhouse. my door was cracked open and my back was turned to the door. he peeks in and whispers somethign inaudible. so i didnt know what it was, I quickly turned around with Kroma already in hand, and blasted him right in the face. it was hilarious. he was moaning in agony haha.

Anyway the UI of the Kroma is something you need to get used to. But looking at the S&W, I am a firm believer in tailcap switches. it is always there for access. no need to fiddle with the light to find the switch. now given that the kroma has a selector ring, I dont like the way it is designed. I much prefer the selector switch of the Gladius by blackhawk. it is all contained in the tailcap. I realize this makes for a more complicated system, but that is the for the designers and engineers to figure out. All I care about is ease of use. and the gladius is great. But so is my kroma. I just wish it had a clicky design to it in full production and not just prototyped.

but going back to your question, I think the Kroma is better and brighter. easier to use in the dark cause the the location of the tailcap switch.


----------



## Dave63 (Nov 18, 2008)

Thanks for the reply. I was mostly wondering how the beam compared (Kroma Vs. Smith and Wesson 28 LED Galaxy). I have the S&W and find it a little weak on the main (white) beam. I don't have any idea how many lumans it puts out though as there doesn't seem to be any written data anywhere. I like the multi color functionality so was thinking of getting the Kroma if it would prove to be a more powerfull light.


----------



## Solscud007 (Nov 18, 2008)

Im almost positive it will be more powerful. The full white of a kroma is very concentrated. I would prefer a little more spill on the light. I guess that is why DaFAB modded his with a reflector and took out the optic.


----------



## gottawearshades (Nov 19, 2008)

Personally, I think the white Lux beam of the Kroma is under-appreciated. I bought a K2MS mainly to try a Surefire with all the colors and such. I was pleasantly suprised, and I don't understand why there hasn't been more talk on CPF about the main beam.

It throws very nicely, and the beam and the two levels are very similar to the L1 Cree.



Solscud007 said:


> Im almost positive it will be more powerful. The full white of a kroma is very concentrated. I would prefer a little more spill on the light. I guess that is why DaFAB modded his with a reflector and took out the optic.


----------



## AA6TZ (Dec 5, 2008)

*curse* -- Congratulations, Sir, for performing such an incredibly thorough, labor-instensive review! I'm looking forward to reading your future posts. :thanks:

-Clive


----------



## tobrien (Sep 21, 2013)

any idea if Surefire changed the emitter for the *1*50 lumen Milspec? I have the old non-MILSPEC 50 lumen Kroma and I'm assuming it's one of those old Lux III emitters if I had to guess, but what are they putting in current MILSPEC Kromas to get 150 lumens? XP-G?

edit: I realize this is an aged-to-perfection (old) thread but I didn't think my question needed its own thread

-Sent from my Google Sock inside a Sperry loafer


----------



## Greenbean (Jan 11, 2016)

tobrien said:


> edit: I realize this is an aged-to-perfection (old) thread but I didn't think my question needed its own thread



It is B/C of this review I recently acquired a terrific deal on a Kroma MilSpec, 

I just want to say thanks to the OP for the time and work he put into the review from years back and wish I could give him a whole case of 
Oreos because the PICS STILL WORK!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! lovecpf


----------



## T_zero (Apr 17, 2016)

hello.

can anyone recommend a good UV filter for the Kroma milspec?


----------



## Greenbean (Apr 17, 2016)

T_zero said:


> hello.
> 
> can anyone recommend a good UV filter for the Kroma milspec?



You needing more UV output than the LEDs already in there? 

They aren't for distance are they, I'd question what the capabilities are on the M1 illuminator. 

Not sure Surefire ever made a filter with the correct diameter to fit the Kroma...


----------



## desert.snake (May 14, 2018)

It's time to ask some questions.

My friend gave me his Kroma Mil Spec.
Judging by the new logo, Kroma is still produced, although this is not on the SF site.

It has the same square ray. It seems that this is not a TIR, it's an aspherical lens
as LensLight, but motionless.

Regarding management, it is changed relative to what was described in 2007.

The ring has 5 pure modes + you can set it in an intermediate position between all.

I.e






Another interesting moment - the strong white mode is activated only in white light mode.
That is, if the control ring is in any non-white mode,
any pressing of the button does not change the brightness.
To turn on strong white light, you must return to white light mode!

Personally for me it is not very convenient.
I would like, that in any color mode it was possible to turn on strong white light, as in A2.

Now some photos


































































































Tell me, please, who has new Kroma on his hands - control is the same as I described?


When I took photos at the same time as both U2 and Kroma, I set my eye on that mode in U2,
in which the central spots have approximately the same brightness.
That is, one spot does not stand out against the background of the other if they are shifted in to 1 point.
U2 XP-G2 - 4 mode, U2 original - 2 mode


----------



## DayofReckoning (May 15, 2018)

DesertSnake, I just received a brand new Kroma Milspec, with serial number *B86xxx. *

Mine was manufactured much later than yours. My sample performs exactly as you described yours. Not being able to activate the high white mode in the color mode is so that one may not destroy their dark adapted vision by accident. I used to own the civilian model Kroma, and I'll admit that I like that part of the regular Kroma better. But other than that, I'm loving this milspec so far!


----------



## desert.snake (May 15, 2018)

DayofReckoning that's cool!Tell me, please, do you have a version of 50 or 130 lumens and which form of ray?
I read that the newer version has a smaller squared shape in beam , but has I not yet found any pictures.


Yesterday and today I walked with a Kroma constantly.
You're right! the preservation of night vision is really achieved by the absence
of white light in any color mode.


The only thing I want now - the ring to switch with clicks, like on a new Ultra UM2,
then you can turn on the light exactly to come to the desired mode before switching on,
and turn it on after, already knowing in what mode the light will work.


Now the ring is soft to go into the desired mode, you need to switching on the light
and choose the modes by turning


----------



## DayofReckoning (May 15, 2018)

desert.snake said:


> DayofReckoning that's cool!Tell me, please, do you have a version of 50 or 130 lumens and which form of ray?
> I read that the newer version has a smaller squared shape in beam , but has I not yet found any pictures.
> 
> 
> ...



Hi Desertsnake. I have the newest 130 lumen model, with white, blue, red, yellow green, and Infared. 

Mentally comparing my new Kroma to the old 50 lumen Non Milspec Kroma I used to own, this new one is much brighter than my old Kroma, much more so. 

The white led's beam shape and hotspot on this new one is much less of a square shape than my old Kroma. I don't know if it because of the increased output this one has, or if something has changed in the design, but shining the beam on a wall, the hotspot is certainly not as square shaped as my old kroma. The beam is not as squared shaped as the one in your photos. It is more diffused and round.

The Red and Blue leds produce a square like shape when shined closely on a wall, and the yellow green are very ringy. I believe that the colored beam was better and smoother on the old non milspec Kroma I had. 

The selector ring clicks nicely into each mode, however, again, if my memory serves me correctly, my old Kromas selector ring was "soft" like you describe. I think this might possibly have to do the ring wearing a little over time. I would not be surprised if I find this new Kroma to become "soft" over time. Only time will tell.

I hope this answers your questions.


----------



## xcel730 (May 16, 2018)

I still have my old civilian Kroma.

I have a question regarding the mil-spec version. In Kroma, there's low red, low blue, along with high red and high blue. Does the mil-spec version have hi/low for the color LEDs?


----------



## DayofReckoning (May 16, 2018)

xcel730 said:


> I still have my old civilian Kroma.
> 
> I have a question regarding the mil-spec version. In Kroma, there's low red, low blue, along with high red and high blue. Does the mil-spec version have hi/low for the color LEDs?



No. The Mil spec only has one level of brightness for each color. The overall brightness is in between the low and high of the regular Kroma colors. I personally wish the mil spec red mode was a little dimmer.


----------



## xcel730 (May 16, 2018)

Thank you. I still love the Kroma despite it's outdated LED. I will be on the look out for a milspec.


----------



## xcel730 (May 16, 2018)

Okay, I finally broke down and got the Kroma milspec. 

All this talk about it and DayofReckoning pointing out that Surefire website have it on sale for $179 made it a little easier to pull the trigger. I'm most likely to sell my civilian model to the bay to recoup some of the cost.


----------



## WarriorOfLight (May 17, 2018)

The Kroma MILSPEC is a great light, I use my 50 Lumens Version since years. This light is my travel companion when I am back from home in a not well known Environment.

Here a nice comparsion between the 50 Lumens and the 130/145 Lumens Version:
https://www.messerforum.net/showthr...ire-Kroma-MILSPEC-quot-die-helle-Version-quot

The newer Version has the bettwer beam profile and tint, but the 50 Lumens Version is not bad at all.


----------



## DayofReckoning (May 17, 2018)

I don't know what kind of LED they upgraded the Kroma with but the efficiency on this new Kroma is quite outstanding. I was curious to see how it would run on a single IMR 16340 (with dummy cell).

Not only does it output the full 130 lumens, but after 1 hour of constant on, the light was still going strong. I stopped the test there. Not sure how much longer it would have ran, but I'm impressed.

I also noticed that there is not nearly as much heat with the new model. My old Kroma used to get really hot when constant on, not this one.


----------



## DayofReckoning (May 17, 2018)

I also noticed in that review in the link that their Kroma manual says 145 lumens, while mine says 130. Stranger yet, the serial number on theirs is 72xxx while mine is 85xxx. Goes to show that Surefire's lumens rating really don't mean anything.


----------



## teak (Jul 10, 2018)

I picked up one from surefire for 179. 
My serial number is B86xxx. Funny as surefire advertised itas the 50 lumen model but in the manual says 130. Its definatly brighter then the old 50 lumen rated models. Good beam as well. The kroma is so versatile even by today's standards. Too bad they dont continue to make new updated versions. 


DayofReckoning said:


> I also noticed in that review in the link that their Kroma manual says 145 lumens, while mine says 130. Stranger yet, the serial number on theirs is 72xxx while mine is 85xxx. Goes to show that Surefire's lumens rating really don't mean anything.


----------

