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Old Apr 13, 2012, 08:12 AM   #38
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Originally Posted by The PyroPath View Post
[never mind, you don't talk about the stereotyped misconception about rods and cones, misread it. I'll just leave it here to lift us up from general ignorance]

Don't be fooled by the rod & cone stuff they teach you in most schools. The general perception that you see colors with cones and black and white with the rods is wrong, period. Allthough the rods have no color sensitivity they are mostly used to see contrast in extremely dark sistuations. The funky thing is, you don't use them above more then minimal light intensities. They are used in situations where color information is almost absend and light conditions are extremely low. They use an amplification system that responds to even 1 single photon. Because of this, even at moonlight situation the rods are way too sensitive. Have a look at some "real" textbooks about the inner workings of the eyes and eyenerves and you'll be amazed about the ingenuity of the organ and the processes that take place inside it.
After doing a little more reading it does appear from a couple studies that visual acuity (sort of like eye resolution) is not very color dependent. It seems like it really has more to do with the ability of one's eyes to properly focus the light. My assumption that an eye would have greater visual acuity with white lite was based on the idea that white light is seen with all the cones while a pure red, green or blue light has to rely on a single set of cones. In practice this doesn't really seem to be the limiting factor.

BTW, apparently the theoretical limit of acuity is 20/8 vision (the ability to distinguish lines separated by 8 mm 0.08 in at 20 ft) . This is based on diffraction of light as it passes through the pupil. For comparison, normal vision is 20/20.

edit: wikipedia says that the denominator is in mm but I don't think that can be right. I know I can distinguish 0.01" at around 1 foot. 20 mm would be almost 1" which is certainly wrong. mm are also metric and mixing metric and English doesn't seem right either. I am guessing they meant 0.02" (centiinch?)
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Last edited by aviphysics : Apr 15, 2012 at 09:54 AM.
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