light color

[fhapgood]

I've been surprised to find LED flashlights with different beam colors. I understand that red lights are supposed to do less damage to dark adaptation, but if you have a flashlight why are you worried about dark adaptation at all? Are there any disadvantages to a red light? And why would anyone want a flashlight with a green color?

 

[MrBenchmark]

Why worry about dark adaptation if you have a flashlight?
Well, for one thing, you might be trying to look at the stars. If you are out of the city, someplace pretty dark, it is amazing what you can see naked eye. Bright lights reduce your ability to perceive faint light very, rapidly, and it takes a while for your eyes to adjust back.

Another reason, is that if you are around a group of people doing astronomy, especially folks taking photos, they will likely be very, very hostile to you if you spoil THEIR dark adaptation or photos with your bright flashlight. Most groups outright ban white light after a certain time in the evening.

The main point of red light is that your eyes aren't very sensitive to it, so it reduces your dark adaptation less than other lights, provided you don't just use a much, much brighter red light to compensate.

Disadvantages to a red light? Yes - your eyes are less sensitive to it, your ability to perceive color is about zero.

You'd be very surprised at how much you can see in very low light levels once your eyes are dark adapted. (Sorry if this is heresy in a forum devoted to lights - every now and then darkness has it's uses.)

BTW, I think this is only really useful someplace pretty dark. In the city where I live, my eyes are very rarely completely dark adapted almost anywhere I go outdoors.