Flashlights: Red vs. Green for preserving night vision

Factual Questions
1

Any pilots, astronomers, servicemen, hunters care to weigh in on this?

Currently I’m neck deep in these high-output LED flashlights you newly see on the market. I’m reviewing them for White Water and (probably) Outdoor magazine.

Typically, each manufacturer has provided two: a white example and a colored “map reader” (my term) intended for preserving night vision. Usually the Map Reader provided is the traditional red, but several examples are green/turquoise and, in one case, amber.

Is this a new school of thought? My ex-Air Force Uncle swears by the red for preserving night vision whereas two current private sector pilots I know say green leaves less phosphenes (spots before the eyes) after use. My personal observation was that red had a marginally faster night recovery whereas green provided better color accuracy when reading maps.

Anybody care to share their opinion?

2

I am both a private pilot and amateur astronomer. I’ve always been taught, and found myself in practice, that red lights are best for preserving night vision.

The reason given in my piloting texbook (Jeppesen)is that the rods of the eye are least responsive to red light. I recall reading elsewhere (can’t remember exactly where) that green light is the quickest to reduce your night vision. Bright light of any color also.

If the conventional wisdom has changed, it’s news to me.

3

Apparently, the military has switched to green or blue-green lighting for night vision friendly flashlights. Green provides better detail resolution as well as better color differentiation. However, if the brightness level of the light passes a certain point, green will decay the user’s night vision more than red will. Check it out here or here. The second link has much more detail.

4

Thanks very much Purd. That’s exactly what I was after.

5

Part of the confusion may be a result of night vision device compatible lighting utilized on military aircraft.
While “red” light will not affect night vision in humans, it will interfere with night vision devices much the same as “white” light. A type of “blue-green” flashlight lens is compatible with current generation night vision devices.