Re: ATM Adding a Prism Diagoanal

["Frank" <thewards@mindspring.com>]

A prism acts exactly like a secondary mirror......it is a surface
at 45 degrees to the axis.  You won't have to change the length
of the tube because of the actions in the focal path.  You will have
to change it to accommodate the prism.  You can't just stick a prism
diagonal into a focuser and add an eyepiece.  The body of the prism
will take up enough room necessitating shortening the tube.


IMHO


Frank Ward
Atlanta, GA
Today I celebrate Freedom of Thought and Action ......world-wide.
-----Original Message-----
From: davebevel@mindspring.com <davebevel@mindspring.com>
To: Bzjatoo@aol.com <Bzjatoo@aol.com>; atm@shore.net <atm@shore.net>
Date: Sunday, July 04, 1999 1:32 AM
Subject: Re: ATM Adding a Prism Diagoanal


>
>
>
>
>>
>>I'm adding a diagonal to my Copy Scope should I shorten the main tube to
>alow
>>for the diagonal. Or will it extend the the focal length of the scope?
>>
>>
>>Bruce
>
>A good question Bruce.  I would say you may need to sorten slightly.  After
>I
>mounted my diagonal/image iinverter with the eye peice all the way in I
>am barely in focus.  Unlike you I didn't consider the effects such a device
>would have. I have always meant to fix that but never seem to get around
>to doing so.  I really don"t know if thats why mine is off or I just messed
>up
>on the original calculation.  Okey panal, lets hear from the experts.
>
>David H. Bevel
>davebevel@mindspring.com
>http://www.mindspring.com/~davebevel/index.html
>Norcross, Ga.
>