Chromatic Aberration

I'm currently doing research for a book on insect pigmentation, which is fun because I'm learning a lot about things I never studied before, like vision, which involves several kinds of pigments. Here's something amazing that I found out reading about animal visual systems concerning chromatic aberration , which refers to the phenomenon that different colors do not refract identically in a lens, resulting in slightly different focal distances and colored "fringes" around images. This is a problem both in photography and in biological vision (where it may interfere with depth perception).

this is from: Kirschfeld, K. 1982 Proc. Roy. Soc. Lond. B 216: 71-85

"...we [humans] see over the whole range from 400 to 700 nm, and to reduce the incidence of short wavelength light therefore cannot, in principle, overcome the problem of chromatic aberration , which from 400-700 nm corresponds to more than 2m^-1. This aberration is considerable and corresponds e.g. to a change in the distance of an object from our eye from 100-40 cm. Indeed, there are many kinds of psychophysical experiments that demonstrate the existence of chromatic aberration, which our nervous system has obviously learned to deal with. Among the most convincing demonstrations are experiments in which human observers wear prism glasses that artificially introduce a kind of chromatic aberration: all edges viewed through the glasses appear with coloured fringes. These fringes diminish and disappear over a 3 day period, and if the prisms are removed complementary 'phantom' fringes are seen (review: Stronmeyer 1978). Such observations indicate that our nervous system should be capable of matching the different 'colour extracts' of an optical scene detected by the three different cone types in such a way that the chromatic aberration does not become conscious."

Weird eh?

The Stronmeyer reference is:
Stronmeyer, C.F. 1978 Form-color aftereffects in human vision. pp97-142 in Handbook of Sensory Physiology Vol. 8, eds. Held, R., Leibowitz, H.W., and Teuber, H.-L. Berlin, Springer-Verlag.