# The Great LF HO-A2 Bulb Shimmer Debate



## AvroArrow (May 24, 2008)

*Moderator's note: The following posts were split off from **this thread**, as they were taking it off topic. The thread had started with a discussion of frosted and unfrosted versions of the Lumens Factory HO-A2 lamp assembly.*

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I just got my 2 unfrosted bulbs yesterday and noticed something odd, well, it seems odd to me. I noticed that the brighter middle ring beam kind of... pulses or wavers while it's on. I have 2 of the unfrosted bulbs and they both exhibit this behavior in the 2 different A2s that I have. The stock SF MA-02 lamps do not exhibit this behavior. I don't have the frosted LF bulb nor the Strion kit so I don't know if this is normal behavior. Anyone else notice this?


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## Yoda4561 (May 24, 2008)

*Re: SF A2 Outdoor Comparison Beamshots - Stock A2 vs. LF HO-A2: Frosted & Unfrosted*

It's probably an optical illusion caused by small movements while holding it. Try setting it on a table or clamping it to a tripod and see if it does the same thing. I've found that ringy beams make this stand out more than a smooth one.


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## RichS (May 24, 2008)

*Re: SF A2 Outdoor Comparison Beamshots - Stock A2 vs. LF HO-A2: Frosted & Unfrosted*



AvroArrow said:


> I just got my 2 unfrosted bulbs yesterday and noticed something odd, well, it seems odd to me. I noticed that the brighter middle ring beam kind of... pulses or wavers while it's on. I have 2 of the unfrosted bulbs and they both exhibit this behavior in the 2 different A2s that I have. The stock SF MA-02 lamps do not exhibit this behavior. I don't have the frosted LF bulb nor the Strion kit so I don't know if this is normal behavior. Anyone else notice this?



I really can't imagine what would cause it a pulse like that. Neither of my LF lamps - frosted or unfrosted - do this at all. I know a lot of folks here have the HO-A2 frosted lamp, and I've never heard anything like this reported. In fact I've never had any incandescent light do anything like that. What kind of batteries are you using? Are they primaries?


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## ampdude (May 24, 2008)

*Re: SF A2 Outdoor Comparison Beamshots - Stock A2 vs. LF HO-A2: Frosted & Unfrosted*

I know the strion bulb is pretty overdriven in the A2, I would imagine it's pretty bright though. I think lamp lifespan and reliability would probably be a serious issue with the strion socket mod.

Gunnerboy, what is your experience with it so far and any chance we can get some outdoor and farther away beamshots so we can better judge the brightness?


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## AvroArrow (May 24, 2008)

*Re: SF A2 Outdoor Comparison Beamshots - Stock A2 vs. LF HO-A2: Frosted & Unfrosted*



RichS said:


> I really can't imagine what would cause it a pulse like that. Neither of my LF lamps - frosted or unfrosted - do this at all. I know a lot of folks here have the HO-A2 frosted lamp, and I've never heard anything like this reported. In fact I've never had any incandescent light do anything like that. What kind of batteries are you using? Are they primaries?



My two A2s are only fed a diet of Surefire CR123s because my Li-ions don't fit. I did some more testing and the pulsing is only visible when the light is shining up vertically, at a ceiling for instance, which is when I first noticed it. When shining it horizontally, like in regular use, it doesn't pulse/waver. It's not my hands shaking either because I have OS tail guards on them so they can stand vertically on a table. 

It's most noticable between 4-6ft away from the ceiling. Closer or farther away and it's still there, but not as evident. And it's only that brighter middle ring/dark area that wavers, the center hotspot and outer most spill ring don't waver. It's really odd. 

If you look at Gunnerboy's 1st beamshot of the unfrosted bulb (the one in the middle), from center to the outside you see the hotspot>corona>dark ring>*bright ring*>dim ring. The area that wavers on both of my bulbs is the bright ring between the dark ring and the dim outer-most ring. It's probably not noticeable in real world use, but the wavering beam just gives me an odd feeling that it'll blow up or something at the most inopportune moment, that's why I am asking if anyone else noticed this. I'd take a video of it if I had a video cam, but I don't. I may try the video clip mode of my old digicam and see if it'll capture it.


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## batman (May 31, 2008)

*Re: SF A2 Outdoor Comparison Beamshots - Stock A2 vs. LF HO-A2: Frosted & Unfrosted*

Avro,
I too have the same issue with my A2. It does this with the stock LA, and Lumens Factory LA. I sent it to SF to have it checked out,..it was returned to me and still exhibits the behavior so I guess it's normal? (SF does not leave notes with their warranty repairs.)
However, this is my 3rd A2 aviator to own,..my previous A2s either didn't exhibit this behavior or I just didn't notice it,..not sure. I'd sure like to know what's up though. 


AvroArrow said:


> My two A2s are only fed a diet of Surefire CR123s because my Li-ions don't fit. I did some more testing and the pulsing is only visible when the light is shining up vertically, at a ceiling for instance, which is when I first noticed it. When shining it horizontally, like in regular use, it doesn't pulse/waver. It's not my hands shaking either because I have OS tail guards on them so they can stand vertically on a table.
> 
> It's most noticable between 4-6ft away from the ceiling. Closer or farther away and it's still there, but not as evident. And it's only that brighter middle ring/dark area that wavers, the center hotspot and outer most spill ring don't waver. It's really odd.
> 
> If you look at Gunnerboy's 1st beamshot of the unfrosted bulb (the one in the middle), from center to the outside you see the hotspot>corona>dark ring>*bright ring*>dim ring. The area that wavers on both of my bulbs is the bright ring between the dark ring and the dim outer-most ring. It's probably not noticeable in real world use, but the wavering beam just gives me an odd feeling that it'll blow up or something at the most inopportune moment, that's why I am asking if anyone else noticed this. I'd take a video of it if I had a video cam, but I don't. I may try the video clip mode of my old digicam and see if it'll capture it.


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## Gunnerboy (Jun 1, 2008)

*Re: SF A2 Outdoor Comparison Beamshots - Stock A2 vs. LF HO-A2: Frosted & Unfrosted*



batman said:


> Avro,
> I too have the same issue with my A2. It does this with the stock LA, and Lumens Factory LA. I sent it to SF to have it checked out,..it was returned to me and still exhibits the behavior so I guess it's normal? (SF does not leave notes with their warranty repairs.)
> However, this is my 3rd A2 aviator to own,..my previous A2s either didn't exhibit this behavior or I just didn't notice it,..not sure. I'd sure like to know what's up though.




batman,

Do you still have your other A2's, or someone else's, that you can try swapping heads with? At least try to isolate if the problem is in the head or circuit-board.

Gary


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## batman (Jun 2, 2008)

*Re: SF A2 Outdoor Comparison Beamshots - Stock A2 vs. LF HO-A2: Frosted & Unfrosted*

unfortunately no, I gave them away to friends/family


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## RichS (Jun 3, 2008)

*Re: SF A2 Outdoor Comparison Beamshots - Stock A2 vs. LF HO-A2: Frosted & Unfrosted*



AvroArrow said:


> My two A2s are only fed a diet of Surefire CR123s because my Li-ions don't fit. I did some more testing and the pulsing is only visible when the light is shining up vertically, at a ceiling for instance, which is when I first noticed it. When shining it horizontally, like in regular use, it doesn't pulse/waver. It's not my hands shaking either because I have OS tail guards on them so they can stand vertically on a table.
> 
> It's most noticable between 4-6ft away from the ceiling. Closer or farther away and it's still there, but not as evident. And it's only that brighter middle ring/dark area that wavers, the center hotspot and outer most spill ring don't waver. It's really odd.
> 
> If you look at Gunnerboy's 1st beamshot of the unfrosted bulb (the one in the middle), from center to the outside you see the hotspot>corona>dark ring>*bright ring*>dim ring. The area that wavers on both of my bulbs is the bright ring between the dark ring and the dim outer-most ring. It's probably not noticeable in real world use, but the wavering beam just gives me an odd feeling that it'll blow up or something at the most inopportune moment, that's why I am asking if anyone else noticed this. I'd take a video of it if I had a video cam, but I don't. I may try the video clip mode of my old digicam and see if it'll capture it.



I see it now! Ok, I pointed mine at the ceiling the other night showing someone the beam pattern with the new unfrosted LF bulb, and I instantly saw the wavering of one of the rings. We both were surprised to see it - it was very apparent and looked very odd. So I did some testing tonight. I secured my A2 in a glass and pointed it at the ceiling about 5 feet away. It continued to waver even when I wasn't holding it, but not quite as much. I also tried the same test with my LF frosted bulb, and saw the wavering on it as well, but the flickering ring was further to the outside of the spill beam on this lamp, and not as pronounced. I then tried my stock A2 lamp, and could not see any wavering or flickering at all. I tried holding it, shaking it, and moving it at different distances and it does not give any type of a flicker or waver, so I've concluded that it must be coming from the LF bulbs. 

Now, when holding the light horizontally the wavering of the LF lamps stops completely, which is why it is not at all noticeable in normal use. Very strange - I haven't ever seen anything like this before. But based on others that have noticed this - some even with the stock lamp - I'm not at all worried and consider it just a characteristic of the individual lamps. Now, if I made a habit of laying in the floor and shining my A2 on the ceiling, I might have an issue with it...:duh2:


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## ampdude (Jun 3, 2008)

*Re: SF A2 Outdoor Comparison Beamshots - Stock A2 vs. LF HO-A2: Frosted & Unfrosted*

Ha! I just pointed mine at the ceiling and it does it too. Looks kinda cool. :devil:

I can't see it either unless I point it at the ceiling. Even then it's barely noticeable, I had to look at the outside of the spillbeam like you mentioned.

I hope nobody sent their A2 back to Surefire over that!  LMAO dudes


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## AvroArrow (Jun 4, 2008)

*Re: SF A2 Outdoor Comparison Beamshots - Stock A2 vs. LF HO-A2: Frosted & Unfrosted*

RichS & ampdude,

Whew! I thought it was just my eyesight going bad or my imagination going wacko.  Glad I'm not the only one that sees it. I guess it's normal behavior for the LF lamps then since your frosted LF lamp does the same thing, but to a lesser extent. I wonder if it's because the frosting is smoothing out the ring and blending it in with the spill so that it's not noticeable as the unfrosted lamp. Anyway, since it's also happening to others I'll quit worrying about it and use just use it.


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## ampdude (Jun 6, 2008)

*Re: SF A2 Outdoor Comparison Beamshots - Stock A2 vs. LF HO-A2: Frosted & Unfrosted*

I will check out later whether or not the stock lamp does it as well on mine. Doesn't really matter to me though. :shrug: I don't see an issue at all.


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## batman (Jun 6, 2008)

*Re: SF A2 Outdoor Comparison Beamshots - Stock A2 vs. LF HO-A2: Frosted & Unfrosted*

I double checked mine,..yes my LF does it when i point up only. weird.


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## Gunnerboy (Jun 7, 2008)

*Re: SF A2 Outdoor Comparison Beamshots - Stock A2 vs. LF HO-A2: Frosted & Unfrosted*

Both my frosted and unfrosted HO-A2's have that same pulsing, only when pointed upwards...

Edit: not pulsing, "shimmering"


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## DM51 (Jun 7, 2008)

*Re: SF A2 Outdoor Comparison Beamshots - Stock A2 vs. LF HO-A2: Frosted & Unfrosted*

Are you guys sure this is pulsing, not just heat shimmer?


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## Gunnerboy (Jun 7, 2008)

*Re: SF A2 Outdoor Comparison Beamshots - Stock A2 vs. LF HO-A2: Frosted & Unfrosted*

I believe it is heat shimmer, since I can see it happening almost across the whole spill radius.


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## ampdude (Jun 7, 2008)

*Re: SF A2 Outdoor Comparison Beamshots - Stock A2 vs. LF HO-A2: Frosted & Unfrosted*

Looks like mystery solved.


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## RichS (Jun 7, 2008)

*The Great A2 Bulb Shimmer Debate*



ampdude said:


> Looks like mystery solved.


I'm not so sure about that. If this is just heat shimmer, wouldn't I see this at least at some level on my other incan lights? Just to test this out, I just pulled out all my incan lights and pointed them at the ceiling to see if any of them had even a slight "shimmer" anywhere in the spill. I (and my wife - an unwilling participant - "it gives me a headache!"..:shakehead) could not see even the faintest sign of a flickering, shimmering, or anything remotely close to this with any other light/bulb config. I tried holding each of them at different heights, and setting each on the floor with negative results. Here are the lights I tried:
Rattlesnake w/ HO-9L
Eagle-3 stock
Raider HO-9
SF M6 HOLA
TL-3 w/ Carley 1499
Mag85
Mag61
Of course I already tried the A2 stock and saw no shimmer/flicker, it was only with HO-A2 frosted/unfrosted that it was seen. 

So since they all produce significant and varying amounts of heat, shouldn't I see at least some amount of this shimmering/flickering with one of these other lights? In addition, with all the discussion about beam patterns, and white wall/ceiling bounce tests on this forum, this is the first I've heard about any light/bulb config doing this unless I've missed this mentioned in other posts.

So for me, mystery still unsolved.


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## Gunnerboy (Jun 7, 2008)

*Re: SF A2 Outdoor Comparison Beamshots - Stock A2 vs. LF HO-A2: Frosted & Unfrosted*

.


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## ampdude (Jun 7, 2008)

*Re: SF A2 Outdoor Comparison Beamshots - Stock A2 vs. LF HO-A2: Frosted & Unfrosted*

Now my curiosity is peaked..

Could it be some type of digital pulsing from the regulator? If the stock bulb doesn't do it, maybe the (assumed cooler) temperature it runs at or the bulb frosting hides the effect?

Does the frosted version of the HO-A2 do this as well? If so maybe the bulb is just burning hotter than the stock one. Maybe Mark from LF has an answer for us?

It really is a barely noticeable, but kind of cool effect. I'm sure I never would have noticed it if nobody here had said anything!


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## RichS (Jun 7, 2008)

*Re: SF A2 Outdoor Comparison Beamshots - Stock A2 vs. LF HO-A2: Frosted & Unfrosted*

Ok, just so we all know what we're talking about here - what this "flickering/shimmering looks like and how noticeable it is - I did my best to take a video of it. I'm using the unfrosted HO-A2 in this video. The frosted version does it as well, but it's not as noticeable as with the unfrosted version.

http://www.youtube.com/watch?v=B6T7XIKJTBs


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## ampdude (Jun 7, 2008)

*Re: SF A2 Outdoor Comparison Beamshots - Stock A2 vs. LF HO-A2: Frosted & Unfrosted*

The first 1/3 of the video shows it well. I don't think mine is that noticeable though. Or maybe the nature of the video just exaggerates the effect.


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## RichS (Jun 7, 2008)

*Re: SF A2 Outdoor Comparison Beamshots - Stock A2 vs. LF HO-A2: Frosted & Unfrosted*



ampdude said:


> The first 1/3 of the video shows it well. I don't think mine is that noticeable though. Or maybe the nature of the video just exaggerates the effect.


The video isn't exaggerating the effect - that is exactly how I see it with my eyes. However, it doesn't do it quite to that extent every time I turn it on and point it up. It doesn't consistently do it with the same amount of wavering, but it always does it. I turned it off/on a few times before taking the video so I could capture it at it's worst so it would be easy to see.


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## ampdude (Jun 7, 2008)

*Re: SF A2 Outdoor Comparison Beamshots - Stock A2 vs. LF HO-A2: Frosted & Unfrosted*



RichS said:


> The video isn't exaggerating the effect - that is exactly how I see it with my eyes. However, it doesn't do it quite to that extent every time I turn it on and point it up.



Okay, I haven't seen where mine does it quite that much. Usually it's just one band that flickers a little.

I'm trying to think about this logically... they all exhibit the same behavior. It only happens when it's pointed upwards. Why would it ONLY do it when it's pointed UPWARDS.. I'm drawing a blank. :shrug:


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## Aussie Cheese (Jun 7, 2008)

*Re: SF A2 Outdoor Comparison Beamshots - Stock A2 vs. LF HO-A2: Frosted & Unfrosted*

yep, mine does that (HO-A2 unfrosted) and also my p90

i think its just as you say, heat shimmer, which i believe is from a convection current setup inside the bulb envelope(since it is orientated standing upwards , for maximum convection)

at first i thought it was a manifestation of overtones in the A2's PWM(i have an older one with an audible hum) but the flickering is too fast for that and its only visible in the outer rings.

the frosting does minimise this effect somewhat, but my p90 bulb is frosted, but isn't centered correctly.


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## DM51 (Jun 7, 2008)

*Re: SF A2 Outdoor Comparison Beamshots - Stock A2 vs. LF HO-A2: Frosted & Unfrosted*

Lol, I think this may well turn out to be one of the great debates of the decade, if not the century.


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## Illum (Jun 7, 2008)

*Re: SF A2 Outdoor Comparison Beamshots - Stock A2 vs. LF HO-A2: Frosted & Unfrosted*



ampdude said:


> Now my curiosity is peaked..
> 
> Could it be some type of digital pulsing from the regulator? If the stock bulb doesn't do it, maybe the (assumed cooler) temperature it runs at or the bulb frosting hides the effect?



If you recall js's A2 thread discussing the LVR regulator.
THE A2 USES PWM TO DELIVER CONSTANT CURRENT TO THE LAMP
the LF-A2 lamp assembly apparently cools faster than the MA02 assembly probably due to the difference in lamp envelope thinkness or a different structure in the filament coil used.

I would say its a normal occurance, but as I am unsure of how to disassemble the A2 driver, I don't know how you would increase the pulse frequency.:candle:

I'm surprised a man as brilliant as DM51 [or js himself] hasn't voiced the PWM nature of LVR driver after all these postsoo:


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## js (Jun 7, 2008)

*Re: SF A2 Outdoor Comparison Beamshots - Stock A2 vs. LF HO-A2: Frosted & Unfrosted*

Hey guys. SilverFox mentioned this thread to me and I thought I'd check it out. Watched the video, and tested my own A2 (with stock MA02 LA) while on the phone with SilverFox. I see nothing like what is seen in the youtube video. Nor does my black A2 exhibit this.

The LVR3L is indeed a buck PWM regulator, but the PWM frequency is much higher than the flickering rate shown in the video--so fast I highly doubt you'd ever notice anything. If I remember correctly it's around 20kHz ??? But I may be confusing that with the TL fast charger circuit using the MAX 712 fast charge controler IC. It's certainly high enough to avoid this type of flickering, though. And keep in mind that the regulator doesn't have to go to really low duty cycles for a low-level output like some of the multi-level output LED lights. On top of that, the filament has a thermal mass and continues to glow for many mili-seconds after the current is stopped.

So . . . how to explain?

I can think of a couple things off the top of my head. If the filament isn't held securely in the molybdenum leads/support posts, an internal convection inside the lamp envelope could be causing the hot filament to vibrate. If you read Osram's Tungsten Halogen Low Voltage Lamps Photo Optics, on p. 35 they talk about burning positions of lamps:



> For all types of lamps manufacturers always and standards sometimes specify a permitted range of burning positions. Fig. 33 shows some examples of this. English documentation frequently uses the terms "base up" and "base down", followed by an angle of inclination. For example, "bd20" would mean the same as "s20."
> 
> It is essential that lamps are only inclined perpendicularly to the long axis of their filament. Otherwise the filament leads will be subjected to highly variable thermal and mechanical loads, with possible consequent deformation of the filament, or short-circuit between filament coils.



I remember back when I first read that publication seeing this section and going "Huh? We flashaholics tilt our lights all sorts of crazy ways and nothing ever comes of it :thinking: ". I figured flashlight lamps must have reinforced filament leads or something.

Well, maybe not! Or maybe not enough to prevent some noticeable effects appearing under certain conditions.

As for thermal convection _inside the head of the A2_, between the lens and the reflector, there's no way it would cause this amount of flicker. You'd have to have a virtual windstorm in there! Light just isn't bent that much due to air pressure variations. So, I think it has to be inside the lamp envelope. I could be wrong of course, but that's my take on it.

The other thing that comes to mind is that there is some defect or problem with the A2's exhibiting this amount of flicker. But I find it hard to imagine why it would only appear with the light pointing directly upwards!

Also, failing CR123A's or a buildup of contact resistance also came to mind, but again, hard to see how it would only selectively appear in the upward light position.

So, thinking it over, my money is on convection currents internal to the lamp environment. That sort of thing is, after all, exactly how the halogen cycle works in a lamp--by convection.


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## RichS (Jun 7, 2008)

*Re: SF A2 Outdoor Comparison Beamshots - Stock A2 vs. LF HO-A2: Frosted & Unfrosted*

js - thanks for weighing in on this and for all the good information. So just to clarify, you're thinking that convection currents internal to the lamp are causing the filament to vibrate, causing the flickering? If so, I would agree with you.

I wanted to capture video showing how the flicker happens only when pointing the light up, and then goes away as you point the light in a horizontal position. This second video captures that pretty well. While doing this, I found something else. The flicker occurs on the side of the beam opposite the direction you are tilting the light when holding it vertically. To clarify, when I pointed the A2 at the ceiling and tilted it forward slightly, the flickering was in the back part of the spill beam. When I tilted the A2 backward, the flickering moved to the front of the spill beam.

http://www.youtube.com/watch?v=cUL3JvW0CtQ

Prognosis: This test seems to validate that the vibrating filament caused by convection currents in the bulb is causing the pulsing/wavering in the spill beam. Why just this bulb? Not sure, but must be the design of the leads/support posts and position of the filament that causes it to be more susceptible to this.


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## DM51 (Jun 8, 2008)

*Re: SF A2 Outdoor Comparison Beamshots - Stock A2 vs. LF HO-A2: Frosted & Unfrosted*



Illum_the_nation said:


> I'm surprised a man as brilliant as DM51 [or js himself] hasn't voiced the PWM nature of LVR driver after all these postsoo:


Lol! I did think briefly about the driver causing it, but any brief electrical spikes/pulses would be completely ironed out to flat by the slow response time of the filament. 

My own observations of this mysterious phenomenon were brief and wholly inconclusive. I sat in a chair with an A2 in each hand, switched them on and pointed them at the ceiling. I doubt the lights even had time to warm up to maximum operating temperature before I realised that I had developed a painful and distracting crick in my neck from having to look upwards at the ceiling to see what (if anything) was happening. 

I considered lying down to continue, but the terrible risk of my falling asleep and accidentally setting fire to myself dissuaded me. I therefore decided to discontinue the experiment and leave this dangerous and crucial research to CPFers with more of a pioneering and adventuresome spirit. 

Good luck, guys. I'm right behind you on this one. You have my 100% support on your great scientific quest. 

LOL


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## js (Jun 8, 2008)

*Re: SF A2 Outdoor Comparison Beamshots - Stock A2 vs. LF HO-A2: Frosted & Unfrosted*



RichS said:


> js - thanks for weighing in on this and for all the good information. So just to clarify, you're thinking that convection currents internal to the lamp are causing the filament to vibrate, causing the flickering? If so, I would agree with you.
> 
> I wanted to capture video showing how the flicker happens only when pointing the light up, and then goes away as you point the light in a horizontal position. This second video captures that pretty well. While doing this, I found something else. The flicker occurs on the side of the beam opposite the direction you are tilting the light when holding it vertically. To clarify, when I pointed the A2 at the ceiling and tilted it forward slightly, the flickering was in the back part of the spill beam. When I tilted the A2 backward, the flickering moved to the front of the spill beam.
> 
> ...



Nice experiment, RichS! It was a little difficult to make out, but I think you're right. I think you've added some experimental support to the internal-convection/vibration theory.

DM51,

You're a wise man, my friend. The danger of burning oneself up in a pyrotechnic conflagration whilst testing the possible flickering of an LF HO-A2 LA is well documented and justly feared risk. No sense in that happening, mate. Good on you! :devil:


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## RichS (Jun 8, 2008)

*Re: SF A2 Outdoor Comparison Beamshots - Stock A2 vs. LF HO-A2: Frosted & Unfrosted*



DM51 said:


> Lol! I did think briefly about the driver causing it, but any brief electrical spikes/pulses would be completely ironed out to flat by the slow response time of the filament.
> 
> My own observations of this mysterious phenomenon were brief and wholly inconclusive. I sat in a chair with an A2 in each hand, switched them on and pointed them at the ceiling. I doubt the lights even had time to warm up to maximum operating temperature before I realised that I had developed a painful and distracting crick in my neck from having to look upwards at the ceiling to see what (if anything) was happening.
> 
> ...



Whoa, I had no idea the danger I was in when conducting these experiments! But you know, when on the verge of major scientific discovery, one must sometimes accept enormous risks to their own safety for the advancement of civilization and flashlights.

You guys crack me up...


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## Illum (Jun 8, 2008)

*Re: SF A2 Outdoor Comparison Beamshots - Stock A2 vs. LF HO-A2: Frosted & Unfrosted*



DM51 said:


> I sat in a chair with an A2 in each hand, switched them on and pointed them at the ceiling. I...



*HINT* 




it could also be your hand oscillating due to some ingrown stimulant that aids to your excitement while doing ceiling bounces. I'm sure most of us flashaholics know that excitement.:nana:



RichS said:


> Whoa, I had no idea the danger I was in when conducting these experiments!


All great scientific discoveries require the endurance of some pain
A. G. Bell got a chemical burn
Newton got a bruise
Faraday got shocked
Von Braun burned a few of his masterpieces
and now DM51 got a cric in his neck while attempting to reveal an unknown secret to the forum...


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## DM51 (Jun 9, 2008)

*The Great A2 Bulb Shimmer Debate*

NOTE: This thread has now been split off from the original discussion of frosted vs. unfrosted versions of the Lumens Factory HO-A2.

The debate continues...


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## Aussie Cheese (Jun 9, 2008)

*Re: The Great A2 Bulb Shimmer Debate*

what debate?:thinking:

the evidence seems conclusive, at least to me

it cant be PWM cause of thermal inertia so .. :shrug:


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## Sgt. LED (Jun 11, 2008)

*Re: The Great A2 Bulb Shimmer Debate*

I have 2 A2's and just can't see the effect mentioned here.


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## batman (Jun 11, 2008)

*Re: The Great A2 Bulb Shimmer Debate*

I think I"m convinced that's it's just thermal convection,..i can believe that easily enough. But I do'nt think this should be anything to be concerned about right? The only thing that could make this circle more complete is if the master PK himself chimed in...


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## RichS (Jun 11, 2008)

*Re: The Great A2 Bulb Shimmer Debate*

Just to be clear, this phenomenon occurs with the Lumens Factory HO-A2 lamp, not the stock A2 bulb. When the short run of clear HO-A2 lamps were released, this was first noticed. Then looking more closely it could be seen with both the frosted and unfrosted versions of the HO-A2.

It's fine that a new thread was created for this since my A2 lamp comparison thread was getting off topic, but this title is misleading. Instead of "A2 Bulb" it should say "LF HO-A2 bulb".


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## RichS (Jun 11, 2008)

*Re: The Great A2 Bulb Shimmer Debate*



Sgt. LED said:


> I have 2 A2's and just can't see the effect mentioned here.


 Are you running the LF HO-A2 in both of your A2s? This only happens with the LF HO-A2 lamps.


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## knightrider (Jun 12, 2008)

*Re: The Great A2 Bulb Shimmer Debate*

Had a LF HO-M3T setup that I would notice this phenomenon with as well. And just like stated here, it happened only when doing a tail stand on the shrouded Leef switch I have. I thought the filiment was vibrating but wasn't sure if I was crazy.  Glad I found this thread! Weird stuff.....

Heat waves like off the street? Like a visual illusion?....


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## alantch (Jun 12, 2008)

*Re: The Great A2 Bulb Shimmer Debate*

If it happens when the light is pointed up but not when held horizontally, what about pointing the light down vertically? My A2 is still on the way to me so I'm just wondering about that.


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## AvroArrow (Jun 23, 2008)

Wow, I didn't even know this got spun off into it's own topic and me the thread starter.  

Thanks for all the great info guys, especially RichS for the videos and experimentation. BTW, my LF HO-A2 (unfrosted) doesn't shimmer as much as yours does, only the middle band/ring shimmers on mine. I've also updated the thread title to be more specific so people don't confuse this with the stock Surefire MA02 lamp.


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