Re: Do certain color led\'s put out more light?
greenlight,
Here's a sensitivity chart broken down into photopic and scotopic response:
The green curve representing scotopic sensitivity is actually showing what frequencies of light your
rods are sensitive to and how sensitive they are to various wavelengths. Green has the potential to whack your scotopic vision quicker than any other color because of the eye's greater sensitivity to that range. Note that the scotopic (dark adapted) curve pretty much peters out above 620 nm. (Right at what is commonly referred to as 'red'). That's why wavelengths above 620 nm are used to preserve night vision -- the rods don't fire in that range.
Actually,
ANY common color may be used to preserve dark adapted vision
if it is dimmed down enough. For example, if you take a green light
which is infinately dimmable, like the Rigel Systems Mil-Skylite and sit in a dark room until you are dark adapted, you may then slowly turn up the Rigel (from off)
just to the point where objects become recognizable by shape. If this is done carefully you won't see any green from the beam -- only greys. At this point you are seeing
with your rods only since the intensity is not enough to fire the cones. Many say that this will have no effect on your night vision.
When this method is used with a white light it may represent the best of both worlds for preserving night vision
and still having some color recognition. If you need to recognize a color (on a nautical chart, for example) you may slowly increase the intensity only enough to identify the color and then turn it right back down again. This will destroy a very small quantity of rhodopsin (visual purple) but such a small amount that it will be replenished very qickly.
When I looked into 'night adapted vision' last year I was amazed at what a
controversial subject it is. I spent the better part of a couple of nights trying to get a handle on it. There is much information out there and many different approaches.
Here are some links for the interested. They also contain some secondary links which are very good:
Human Night Vision Preservation
Preserving Night Vision - Colors?
The Red Myth
joys of a DIM flashlight
