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Subject: Re: [M]: re:focal planes
From: Dave Sage
Reply To: mapug@shore.net
Date: Fri Dec 27 07:16:56 1996

>>I've had to refocus for many reasons with many kinds of telescopes,
>>but never have seen anything to suggest the moon comes to a different

The other more obvious answer to this is that when you are looking into a
predominently black field your pupil opens up and when you are looking at
the moon (bright) it closes. This (like in a camera) will yield different
depths of field for you eyes optical system, like if you need glasses how
everything is in focus if you look through a pin hole. Perhaps you require a
different amount of correction (turn the focus knob) to compensate for the
difference in depth of field of your eye on dark and bright objects.

SAGE