P3D Focusing with glasses off

[fj834@xxxxxxxxxxxxxxxxxxxxx (Dr. George A. Themelis)]

Brian Raynolds writes:

>I have never looked at 35mm stereo slides with a viewer, so I hope
>everyone will forgive me asking a stupid question.  Doesn't the Red
>Button viewer allow for focussing?

Yes it does... but the range is not very wide and you cannot focus each
individual eyepiece.

>As an amateur astronomer who enjoys taking his telescopes to public
>star parties I know how important it is for each observer to focus for
>their individual eyesight.  Although I've worn glasses since the fifth
>grade, I never look through a telescope or binoculars with my glasses
>on.  About the only reason for wearing glasses while looking through
>an optical instrument is to correct for astigmatism in the user's eye.

It is easy to focus an instrument for one eye.  But what do you do if
you have a binocular instrument which does not allow you to adjust
the individual eyepieces and your eyes have different problems or
degrees of a problem in each eye?

I personally recommend that when a viewer is passed around, people should
keep their glasses on.  I don't think it is polite to pass around a 
misadjusted viewer.

George Themelis


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End of PHOTO-3D Digest 2422
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