Best for preserving night vision?

i was wondering does red or green LED light preserve night vision better?

This page should answer your question:

http://flashlightreviews.home.att.net/qa.htm#nightvision

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This has been addressed quite a lot on the forum.

Here is a link to a post I did some time ago that includes two nice discussions of night vision. It is part of a total thread that is very interesting IMHO.

Someone correct me if I'm wrong, but the one word answer is "red."

What Chris, ikendu and Ron said ... /ubbthreads/images/graemlins/grin.gif

The objective, bottom line, is to not affect the receptors that work for night vision, and to do that you need to use the long visible wavelengths (red). Why is that? because the "night vision" receptors can't see red ... /ubbthreads/images/graemlins/smile.gif

WOW! As soon as I saw the title of this post I was putting on my boxing gloves getting ready for a battle royale in my continuing crusade against the misconception that green is anything but worthless for preserving human night vision, and it turns out everyone beat me to it!

Your rods (the night vision part of your eyes) are blind to red light so you can use red light and preserve your night adapted vision. Green completely fries your night vision at any level where you can actually detect the color of the light and not just "light". This applies to any color besides red.

Green is used in conjunction with military night vision equipment for several reasons and has nothing at all to do with human night vision preservation. It's a common misconception that is being propigated by marketers trying to part you from you money by selling green LED products.

I have to admit that I tune into every new "color" oriented thread just to see you lace 'em up, Quickbeam! Always well done.

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Low intensity Red is the correct color to preserve true Scotopic night vision -

But just for "mitigation".....

Since a lot of us live in urban environments and there are very few places that are truly dark - so I doubt if true Scotopic (rods only) "night vision" is actually being used.
(Note: when using true Scotopic "night vision" one does not see colors, objects are blurry and for a lot of people the vision is very uncomfortable - and the environment would normally be regarded as "pitch black", as it would take several minutes before one can "see" anything at all.)

Probably a lot of people just want a light to see reasonably well by and preserve whatever "dark adaption" our eyes have acquired -
in this case then any low intensity light of any color including "white" that does not dazzle, glare or "shock" the eyes will work - since it is NOT true Scotopic "night vision" that's actually being used (or needing to be "preserved").

I happen to like (dim) yellow as I seem to see well by that mono-color light and the dim level disturbs my dark adaption minimally - but this is a personal choice that works for me.

Well put Vincent.

I am almost never truely in the DARK, as I work downtown and live in the 'burbs. As a result, the colors that I find most useful are truqouise and green; they give me a lot of light and since I can generally still make out some colors with the ambient light, they just boost what I can already see.

Red is good for wandering around the house at night, and I take a red Infinity with me on trips to light up dark hotel rooms at night, but for day to day use I will stick with green/turq.

In some thread someone posted an adjustable LED light for Astronomers. I was impressed and present the link here for your information! /ubbthreads/images/graemlins/smile.gif

Rigel Systems Starlite $24 adjustable Red LED

Yes, I remember finding those Rigel Systems astronomers LED flashlights when we were talking about preserving night vision in the other thread.

I like the Rigel Skylite -

the Skylite has both a red and white LED that probably makes it more versatile - I guess Rigel Systems the makers of these astronomers flashlights think so too.

I got to borrow one of these lights from another CPFer around a month back... my review of it is right here if you're interested.

My favorite for "keep it dim" (not necessary night vision) work is green. I can navigate ahout the house with red, but trying to read the LCD screen of my Palm Pilot with red causes some genuine eyestrain. (I use the Palm to read in bed.) Green gives much better contrast for this sort of work.

Haven't tried amber yet.

[ QUOTE ]
JJHitt said:
I can navigate ahout the house with red, but trying to read the LCD screen of my Palm Pilot with red causes some genuine eyestrain. <snip>
Haven't tried amber yet.

[/ QUOTE ]

I found that although I can "see" under red it was hard to get good contrast and definition for my eyes - this was most evident when I used a red LED light on a Victorinox Classic "SwissLite" (Swiss Army Knife) to help find a dropped item in the dark and couldn't really see more than just a few inches from the LED.

That was round about the time the Photon microlights were starting to be popular (we're talking Mk.I only here - and only in red and yellow) - I bought the yellow just because at that time the Photon I was was just so cool (actually it still is, although I'd now get the Photon II) - and I could see so much better under yellow - to the point that I felt under similar intensity levels I may actually see better with yellow than white - obviously not for color rendition but in pure contrast and definition.

Just to be clear - I was not using true Scotopic "night vision" but merely fumbling in dimmly lit conditions.
I find the relatively dim yellow seems to shock my eyes less - but I can still see well - and I can continue to use whatever dark adaption I had acquired for the conditions.

Dim light and red light aren't really good for reading. The idea of night vision is to see large objects, so you don't walk into another person or a tree.

The Rigel System light looks really nice. Maybe I'll buy one or try to make something like it.

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paulr said:
Dim light and red light aren't really good for reading. The idea of night vision is to see large objects, so you don't walk into another person or a tree.

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Right.

There may be some misconception about Red light being a panecea for preserving Scotopic night vision.

It is true that the eye's rods are insensitive to wavelengths longer than 620nm ie: red - but if one uses too high an intensity red to be able to "see well" - like my case of searching for a dropped small object - then the light level/intensity itself may affect one's night vision since the level of light may flood the cones and leave after images.

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Quickbeam said:
Green is used in conjunction with military night vision equipment for several reasons and has nothing at all to do with human night vision preservation. It's a common misconception that is being propigated by marketers trying to part you from you money by selling green LED products.

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I'm curious about where you got this information. All I've ever seen are red, and some blue filters that came with the angleheads people bought. I've seen some green led lights sold by like, US Cavalry or Brigade Quartermasters saying they were for use in conjunction with NVG's, but I can't recall ever seeing an issued green light or filter.

from -
USAF Flight Surgeon's Guide
Chapter 8
AEROSPACE OPHTHALMOLOGY
Thomas J. Tredici, M.D.

http://wwwsam.brooks.af.mil/af/files/fsguide/HTML/Chapter_08.html

QUOTE
Cockpit Illumination: The use of red light (wavelength greater than 650 nanometers) for illumination of the cockpit is desirable, because it, like red goggles, does not affect dark adaptation. Red cockpit lighting has been traditional since World War II. The intent was to maintain the greatest rod sensitivity possible, while still providing some illumination for central foveal vision. However, red cockpit lighting did create some near vision problems for the pre-presbyopic and presbyopic aviators. With the increased use of electronic and electro-optical devices for navigation, target detection, and night vision, the importance of the pilot's visual efficiency within the cockpit has increased and new problems have been created. Low intensity, white cockpit lighting is presently used to solve those problems. It affords a more natural visual environment within the aircraft, without degrading the color of objects. Blue-green cockpit lighting is used in aircraft in which night-vision devices are used because, unlike the human eye, these devices are not sensitive to light at that end of the visual spectrum. In addition, blue-green light is the easiest for accommodative focus and is seen by the rods more readily than any other color. It is not seen as blue-green, however, but only as light. However, the enemy can easily see a blue-green light, under scotopic conditions, in any position of his peripheral field, whereas a low intensity red light would be invisible unless viewed directly.
UNQUOTE

Also check out the Mil Specs
MIL-1472D General Requirements -

http://members.cox.net/rigelsys/why_red.html


Here's another great detailed thread on this topic that I finally managed to find again in the Night Vision section:
Red "nigh tvision"?

Thanks UnknownVT.

Unicorn, please read the post above to answer your question.

"presbyopic" seems to be doctor talk for "needs glasses".

Which would explain why I likes green....