[AZ-Observing] Re: Telrad stellar limit

15480 Empire Rd.
Benson, AZ 85602
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That may be so for dim objects, Brian, but when you look at the moon (say) 
through the eyepiece of a telescope and then withdraw your eye, only the one 
doing the observing is affected. The other eye is still relatively dark 
adapted. It would be interesting to see how the irises of both eyes compare 
after that observation. Certainly, only the one eye that did the observation 
has the after-image! 
Clear skies, 
Wayne (aka Mr. Galaxy)

-- Brian Skiff <bas@xxxxxxxxxx> wrote:
>>  First, there is some pupil constriction (only in that eye)....

>>  Does all this seem reasonable?

    I have two reactions.  It seems that if there's any significant
pupil restriction, then the brightness is set way-way too high.
    The "only in that eye" business seems to be wrong, too.
I've noticed the following when lying in bed (for instance),     
staring at some little bright spot like a light-leak in a curtain,
or similar.  Without glasses or other correction, the spot/patch
is a big blur.  Cover one eye, and the other eye pops open a little,
then closes down partway, but stays wider than with both eyes open.
You can see this readily since the size of the spot/patch changes
directly with pupil size (basically a depth-of-field effect---closing
the eye down means the spot is less out-of-focus).  Repeat in various
ways to see the funny stuff your eye does.
    Anyway, my conclusion, assuming I'm no weirder than anybody else,
is that the idea that exposure of one eye to bright light leaves
the other other eye unaffected (at least as regards pupil size)
is incorrect.  One more visual astronomy myth that should be avoided!


\Brian
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