night light

Gila Hemi said:

Red is best if you want to see what you're doing and not mess with your night vision.

Click to expand...

"So - to your question. Let’s consider first the light you can detect best
when the intensity is low. You would select light that activates the
rods. This is light in the yellow-green part of the spectrum. Infrared
converters used in night-vision goggles convert light to this wavelength,
and when viewed through these goggles all the world turns a strange yellow-
green.

If you wish to see with your cones without activating the rods, you would
select a wavelength of light to which your rods are relatively
insensitive. Furthermore, it would be logical to select a color close to
the maximum sensitivity of the L, M or S cones. There are many more L and
M cones in the human eye than S cones, so the color that activates the L
and M cones, a red color, would probably be your best bet. Be aware that
in order for you to see, the red light you use to activate the L and M
cones has to be brighter than the yellow-green light you would use to
activate the rods."

In other words green light will activate the rods in your eyes at a much lower intensity which are your night vision receptors, yet you could activate the cones also with red light but it would take a much higher intensity.

So back to my point. The optimum light wavelength for optimum night vision acquity is the green wavelength of light. Yes red can be used, but it is not as efficient.