SL3d, focusing of eye

[P3D Peter Abrahams <telscope@xxxxxxxxxx>]

>> we "know" not only that we are re-focusing, but whether we are focusing
closer or farther.
>Also you can get some idea of distances of objects even without focusing on
>them by the amount of blur (absolute or relative to other objects).. ..
there are two solutions
>(in front of and beyond the focal distance), so additional information is
>needed to resolve the issue.
I once asked a friend who teaches at a school of optometry, 'what's some
interesting work in your field lately?'  He told me that some research has
shown that the eye uses chromatic aberration to cue the ocular muscles for
increased or decreased accomodation.  I have no citation for this. There is
other work I have heard of that details how the  eye has difficulty focusing
in monochromatic light.
How might this work? (Speculation:) Since blue refracts more than red, the
blue fringes on the image would move or snap to focus more dramatically than
the 'main' image.  Or: The near object would be more refracted in the eye &
have more fringing.
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  Peter Abrahams    telscope@xxxxxxxxxx
the history of the telescope, the microscope,
   and the prism binocular


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