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    Re: Lunar distance accuracy
    From: Michael Daly
    Date: 2007 Oct 26, 01:34 -0400

    Greg R. wrote:
    >> One alternative explanation offered was that
    >> the eye pupil becomes larger in the darkness:-)
    >
    > Agreed - which would reduce the depth-of-field, but how exactly would
    > that improve the eye's resolution?
    
    A larger pupil exposes more of the cornea/lens to the light and allows
    more opportunity for astigmatism to come into the image.  If you have
    generally good vision but off-axis astigmatism, it is not noticeable
    until the pupil is large.  Larger pupils can also reveal early cataracts
    (they tend to start from the outside of the lens) that can mess up the
    image.
    
    These kinds of things start to show up in daylight for some folks who
    start using various eye medications that cause pupil dilation (like some
    glaucoma meds).
    
    Mike
    
    
    
    
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