Colored Lights

Boeing B-52 Cockpit

At night the military uses red light to illuminate instruments on all kinds of equipment: aircraft, ships, vehicles, radar, what-have-you, the reason being that it has the least effect on your night vision. When we got our 2006 Mitsubishi Endeavor, I was disappointed to find that it had blue indicator lights on the dash. I suppose that was the fashion back then, and I guess it doesn't matter so much in a car, after all you've nice bright halogen bulbs to illuminate the road, so your night vision's probably worth shit anyway, so the color of the indicator lights isn't going to make any difference.

Audi S4 Cockpit

    Tonight I got a ride in a new Audi S4 and it had red marker lights all over the dash. They were not the kind of subdued red you see in military equipment, it was more of a a candy-apple, in-your-face, high fashion kind of red. Can't really tell from the difference from these pictures since they have been translated to bits and then reconstituted using the RGB pixels in your monitor. The original colors in the Audi are probably not even really red, probably made of ultraviolet crossed with infrared to give the illusion of red. The fashion in dashboard lights has changed. Imagine that.
    Recently someone was trying to justify using blue lights in the instruments. Our eyes have two kinds of cells that detect light: rods and cones. Cones are used for normal, daylight color vision. Rods are used for black and white, low light (nighttime) vision. Rods are sensitive to blue light, but insensitive to red light. So blue will work at night, and you should be able to get by with much dimmer blue lights than if you used red, but using red lights will not impact your night vision.