# Red Filter vs Red LED for night vision?



## John N (Sep 20, 2005)

I'm curious if someone could contrast the advantages and disadvantages of a red filter ( like the SF F05 ) vs direct use of a red led(s) in terms of perserving night vision? I'm interested in the technology and physiology, not costs or practicality.

For example, if a red filtered incandecent of a given output is the same as the output of a red LED in terms of preserving night vision, that's what I'm trying to find out.

I would assume there are some differences between the range of wavelengths output by both, but don't any details or if they matter.

I'd also like to know if one or the other is more "stealthy".

Thanks,

-john


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## xpitxbullx (Sep 20, 2005)

I have a red LED light and a red filtered light. All I can say is that the LED light is much more powerful than the filtered version.

Jeff


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## NikolaTesla (Sep 20, 2005)

Red filters waste 95% of the light. LED's are pure red, no waste. My toy NightCutter RED puts out more than A filtered SureFire.


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## John N (Sep 20, 2005)

NikolaTesla said:


> Red filters waste 95% of the light. LED's are pure red, no waste. My toy NightCutter RED puts out more than A filtered SureFire.



Is that different if it is filterning a white LED vs an incadecent?

Thanks,

-john


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## beezaur (Sep 20, 2005)

Hi John,

I read you question, and immediately grabbed my handy-dandy rip-off-o-matic pocket spectroscope to check this out (actually the scope is pretty cool, just not real quantitative).

I have a SureFire red filter (the push-on kind, similar in construction to the F04 Beamshaper) that I used on my McLuxIII-PD, a stock MiniMag with a red filter from Mag, a red SureFire A2, a red CMG Infinity, and an Aleph 3 with a red-orange LuxIII.

Both filters gave pretty much the same spectrum. It peaks in the red, tails off into infrared, and stops abruptly in orange. The Mag filter is actually more red -- the SF filter goes farther into the orange.

The Surefire A2's red LEDs are the most red of the LED sources, but the spectrum does very faintly taper off to the first parts of green. The Infinity has a definite green component to its spectrum, and the Aleph's R/O has the barest hint of blue on that end of its spectrum.

What that means for physiology, I can't tell you. But here is a link to the "USAF School of Aerospace Medicine FLIGHT SURGEON'S GUIDE." Check Chapter 8: OPHTHALMOLOGY AND SPECIAL PROBLEMS OF THE EYE, especially the section on night vision.

http://wwwsam.brooks.af.mil/af/files/fsguide/HTML/00_Index.html

Hope this helps.

Scott

PS: You also asked if one was more stealthy.

I think so. I think the redder lights (to include both filters and the A2) are much more difficult to see from a distance. There is something strange about red where, below a certain intensity, your eyes just don't detect it well. You can verify this by taking two lights of approximately the same brightness -- one red -- and shining them on the ground outside. Gradually point them up and into the distance. The red light will fade out much faster than the other.

The best light I have for preserving night vision AND remaining functional is my SureFire A2 in yellow-green. Its LED spectrum covers most colors in enough intensity to make them out. You can read the vast majority of features on a road map with it, where you cannot with a red light. However, red is still best (in my opinion) for astronomy and other apps where maximum night vision is required.


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## Blackbeagle (Sep 20, 2005)

You have to think of it this way: A LED puts out a "pure" color (yeah, not really, but close enough) and no energy goes to waste. An incandescent puts out all colors and then you filter it so only red goes out. You waste all the energy produced in creating all the other colors.

Energy-wise, a LED will be more efficient in producing the light costing you less battery power. In addition, a filter on a higher powered incandescent will result in heat buildup since it is absorbing all the energy. Whether that's stealthy depends on whether someone is using thermal detection on you.


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## MaxPowers5 (May 17, 2011)

If I am looking for a light with the brightest red and don't want to spend $200 on the Surefire A2, what would be brighter. A white light incandescent flashlight with a red filter or a white light LED flashlight with the same filter?


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## angelofwar (May 17, 2011)

Incan with a (quality) red filter. Grab an E2e on the Marketplace, and try an MN03 or MN02 bulb, with an F05 filter. Red filters only allow red light to pass (which LED's don't emit alot of), so red filters block MOST of the useable light an LED emits. An LED with a red emitter is also another good option. I know Streamlight used to make the Stylus available in red.

Hope this helps, and welcome to CPF!


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## MaxPowers5 (May 18, 2011)

Thanks for the advice. I wouldn't feel comfortable buying something from someone on a forum because I have never done it before and don't use paypal. Those lights are also expensive. I was looking for a solution for between $60-$100. I need a decent run time and common batteries so if I run out I can easily acquire more AA or AAA. Was looking at a fenix LD20 or LD40 with a red filter. Can the LD40 take a filter? 
Any incans that take common batteries, adjustable brightness, decent runtime (5+hrs) and can put out good red light with filter for under $100?


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## Solscud007 (May 18, 2011)

My pentagon Molle Light has a red filter that unscrews from the tailcap and screws onto the front of the bezel.

http://milspecmonkey.com/equipment-page/illumination/101-pentagon-molle-light

But the red is SUPER low. I find it only good for close up work in the dark. Not for general illumination. Compared to my Kroma, Milspec, and L1-RD, I would use the L1-RD for punchy red LED. However my kroma, milspec and SF helmet light produce more than enough red light to navigate in the dark.


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## RWT1405 (May 19, 2011)

Might want to try a Streamlight Night Com LED Flashlight 51056 $41.95 @ Bright Guy

http://www.brightguy.com/products/Streamlight_Night_Com_LED_Flashlight_51056.php

The Streamlight Night Com C4 LED flashlight has a unique mode-select switch that allows you to choose from 3 lighting options - bright white C4 LED, 2 Nichia ultra-bright red LEDs or a single night vision protection LED (meets or exceeds the requirements of MIL-1472D for true night vision preservation). Safety mode is also available. When in safety mode, the flashlight cannot be turned on.

Rotate the mode select switch to choose the safe position or any of 3 lighting positions:
1. Lo power indicator type LED (for maximum night vision preservation); <0.05 lumens
2. Two Ultra-Bright RED LEDs; 2.5 lumens with up to 28 hours of run time
3. Center C4 bright white LED; 105 lumens with up to 3.5 hour run time

My .02 FWIW YMMV


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## angelofwar (May 19, 2011)

MaxPowers5 said:


> Thanks for the advice. I wouldn't feel comfortable buying something from someone on a forum because I have never done it before and don't use paypal. Those lights are also expensive. I was looking for a solution for between $60-$100. I need a decent run time and common batteries so if I run out I can easily acquire more AA or AAA. Was looking at a fenix LD20 or LD40 with a red filter. Can the LD40 take a filter?
> Any incans that take common batteries, adjustable brightness, decent runtime (5+hrs) and can put out good red light with filter for under $100?



As RWT1405 mentioned, a "combo light" with red emitters would be your best bet. Other than the stream-light nightcom, a few others are the Sidewinder, and the Energizer Tactical. No battery powered incan will give you 5 hours of useful runtime. SF's MN02 tops it out at 25 lumens for 2.5 hours, and just starts tapering off at the end. A Mag-lite on alkalines begins dimming as soon as you fire it up, and the light out-put is about useless after the first 15-30 minutes, depending on model. Look at these other models mentioned, and hope this helps!


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## Helmut.G (May 19, 2011)

if you want efficiency, go for a red LED.
a white led or incandescent bulb with a filter will be (much) less efficient.


I don't know about the night vision preservation or stealthyness ect but I'm sure there is a difference, because of the different spectra.


red LEDs emit a very simple spectrum, with a very narrow peak, while white LEDs emit a spectrum with two peaks, a narrow blue one and a broad yellow one and incandescent bulbs emit a very broad spectrum without any peaks etc.



you can see incandescent vs. white led spectra here:
http://ledmuseum.candlepower.us/led/a2.htm

red led here:
http://ledmuseum.candlepower.us/seventh/k2.htm

and, *red filtered* white led as well as red filtered incandescent here:
http://www.ledmuseum.candlepower.us/led/spectra0.htm


I think the best way to find out the advantages or disadvantages it to try it.


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## DivineStrike (May 19, 2011)

holy thread revival!!!!!!!! but anywho to the revivalist, here: http://www.batteryjunction.com/olight-m20-crimson.html $89.95


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## ASheep (May 19, 2011)

That M20 Crimson caught my eye a while back when I saw it announced... The only descriptions I can find list it as 105 lumens only. 
Sure its 105 lumens of pure red light so it wont blow your night vision as badly as white, but its still really bright right? 
That M20 crimson may just make it as a night hunting light... I have my 85Tr for close work, and a red thrower would be sweet...


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## srfreddy (May 19, 2011)

Red is percieved as much less bright as say, green by your eyes.


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## Helmut.G (May 19, 2011)

srfreddy said:


> Red is percieved as much less bright as say, green by your eyes.


true, the same amount of energy in form of red light will be perceived muss less bright than green, but lumens are corrected in a way that lets us perceive 1 red lumen with the same brightness as 1 green lumen or 1 lumen of any other color with normal vision, that is not night adapted vision.


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## MaxPowers5 (May 20, 2011)

Okay thanks for the info. 
So I guess I will drop my battery life requirement.
So what flashlight do you think will be the brightest with a red filter on it? Needs to be AA or AAA and under $100. I would also like a high/low function


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## angelofwar (May 20, 2011)

MaxPowers5 said:


> Okay thanks for the info.
> So I guess I will drop my battery life requirement.
> So what flashlight do you think will be the brightest with a red filter on it? Needs to be AA or AAA and under $100. I would also like a high/low function


 
Steamlight sidewinder or energizer tactical. Both take 2ea. AA's (Lithium or Alkies). The SL Sidewinder is the better, because is has more settings.


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## radioactive_man (May 20, 2011)

ASheep said:


> That M20 Crimson caught my eye a while back when I saw it announced... The only descriptions I can find list it as 105 lumens only.
> Sure its 105 lumens of pure red light so it wont blow your night vision as badly as white, but its still really bright right?
> That M20 crimson may just make it as a night hunting light... I have my 85Tr for close work, and a red thrower would be sweet...


 
I have a M20S with a red filter, and the filter throws a ring of white light to the sides. If I wanted to be stealthy, I certainly would NOT use this light. The M20 Crimson is a much better solution since no white light can leak out of a red light.


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## MaxPowers5 (May 20, 2011)

sorry for posting so much, I just want to get this right
After looking around I am thinking about going with the following
Fenix LD20 with red filter (When I look on amazon I see a 180 lumens version and like a 205 version. Is this a marketing scheme or an update?)
headlamp: TACTIKKA PLUS
and I will try out this Red LED light. Probably garbage but its only $20
This is for night land navigation during military classes where white light is completely unauthorized.


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## radioactive_man (May 20, 2011)

MaxPowers5 said:


> sorry for posting so much, I just want to get this right
> After looking around I am thinking about going with the following
> Fenix LD20 with red filter (When I look on amazon I see a 180 lumens version and like a 205 version. Is this a marketing scheme or an update?)
> headlamp: TACTIKKA PLUS
> ...


 
In my experience the LD20 leaks a wee bit of white light from the rear of the filter. Also the filter doesn't screw on, you press it on, so if you bump the edge of the filter against something, and the filter falls off, you have given away your position. If you're going to use this light for military classes, you should probably go with something from the Army authorised flashlight list. How about a Tomahawk NV?

AFFL Flashlight list

Also, do you really want to experiment with lights that are "probably garbage"? I wouldn't trust an UltraFire farther than I could kick it.


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## SemperAptum (May 23, 2011)

beezaur said:


> The best light I have for preserving night vision AND remaining functional is my SureFire A2 in yellow-green. Its LED spectrum covers most colors in enough intensity to make them out. You can read the vast majority of features on a road map with it, where you cannot with a red light. However, red is still best (in my opinion) for astronomy and other apps where maximum night vision is required.


 
I totally agree. They don't seem to sell super well (which is awesome for guys like us 'cause they're often on clearance!) but they're really fantastic. I don't really care about the new LED Aviators but it kind of sucks they stopped doing the yellow-green combo - although I'm not surprised in the slightest.


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## Greenbean (Jan 3, 2016)

MaxPowers5 said:


> Okay thanks for the info.
> So I guess I will drop my battery life requirement.
> So what flashlight do you think will be the brightest with a red filter on it? Needs to be AA or AAA and under $100. I would also like a high/low function



Yes I did post in a thread a few years old because I need assistance and have the answer to this question IMHO, 

My Surefire E2D LED version, has been an absolutely favorite with the red filter on it, Forgot the nomenclature....

Which brings me to my next question, I have a small Pelican 1300 that has a red filter of sorts in it from pelican however the led gets tinted more
orange then a true deep red. I patrol residential neighborhoods and have to sign off on paperwork afterwards all in the dark in the patrol vehicle. 
Yes we do have a very bright red led in the dome light but it's to much. I love the output of the small Pelican but want to find if possible the filter 
material used by Surefire for their smaller red filters. I also have a G2 with a red filter on it but the thicker glass types are to large for my needs
and carrying the filter on my E2D is not an option while on duty as it's my backup to my carry light. Also the Pelican can easy be clipped to my shoulder tab opposite my mic.the Pelican can if need be but not recommended put between the teeth or lips in your mouth and since it's all plastic it's not as hard on the mouth s trying to hold an E2D, hahaha

If worst comes to wort I may just butcher a Surefire red filter for an E2D and try and shape it best I can to fit in the Pelican 1300.

Pelican on top, Surefire E2D on low on bottom.
Note 2 phone pic from maybe twp feet away from a white wall.


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## BachelorJack (Jan 11, 2016)

Does anyone make a drop in Red Led tower for surefires?


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## Greenbean (Jan 12, 2016)

There are modded pills that have red LEDs in them, however I really am hoping to find a way to put a better lens in front of the little Pelican light.

I scored three red filter glass pieces off an auction site but now the hard part is carefully cutting them to fit. I don't know how to start...
I mean a belt sander would probably be best, lol... I can't even tell if they are glass or some very hard plastic. Good thing is I can remove an original Pelican lens and I have a 
traceable pattern to grind down to. 

Might be my project next week I'm off work.


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## CelticCross74 (Jan 18, 2016)

I bought a 3xled RGW multi LED reflector/driver from I think Kai Domain a long time ago to fit a 3 D Mag. The red LED puts out the brightest reddest beam I have ever seen. I mean the red emitter must be putting out well over 300 lumens. Then I have other lights with red filters. None of the filters come close. The new NC MH27 has a nice brighter than average red...


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## chillinn (Jan 18, 2016)

I came across this very thread a couple years ago when researching red lights for nesting-sea-turtle watching. The info posted regarding the efficiency of red LED over white LED with red filter seemed to contradict the later info posted in this other later thread, but since this thread was so old, I didn't resurrect it. Since someone else decided to ressurect it, I'll thus ask: which is correct?

This current thread's posts claim red LED is desired for efficiency over using a fliter. The 2013 thread seems to have info claiming white LEDs are so much more efficient than red LEDs that red filtering a white LED, if it has enough red in its spectrum, will be more efficient than a red LED. 

Which is it, folks? Does the information conflict? Is this due to misconception or because things change fast in LED manufacturing?

I hope Anders Hoveland and SemiMan see this and chime in on this thread as their posts in the other thread sound pretty confident.


----
I ended up with three red lights,
*Gerber Task Light with Red LED
FourSevens Atom A0 with Red LED
ThruNite TiSvn with XPE Red LED *(Aaaah-mazing. Though I kind of wish I had sourced the Cree XPE Photo Red LED, it is still the best flashlight I own)


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## Greenbean (Jan 18, 2016)

I do know this as of now my favorite "red" light is my E2DL with the F05 filter on it. Comes on in high and second click is low but the filter is such a deep red it's fantastic. I keep another one just inside the door so when I come home off night shift it's ready and it also uses worn out CR123s as when they are low enough they won't work on hi in the E2DL so they go into the low only light a home. 

I keep a Streamlight Night Com in my car bag because the two red less are pretty bright but the LEDs are on my list to get sanded and the single red led is supposed to be a military spec red for night adapted vision preservation and it's very very low. So low it's best use is after you wake up and your eyes are used to the pitch black back of your eyelids. So it doesn't get used much...

Now I've never had a need for a red light with throw, guess I could put the P91 in a host a dry my old Surefire red filer for my 6P.


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## bykfixer (Jan 18, 2016)

I've used both. To be honest without knowing what lab testing says about it...I prefer the filter. 

Both to my eyes cannot discern much difference, yet having a filter allows me to go back to regular output using the same light. 
A cool emitter with a filter vs a red emitter.


Now using a blue biased, or warm beam I can tell the difference...big time. But my Streamlight C4 beams with a filter works well for my eyes.


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