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[OM] Re: Coma (was 35-80/2.8)

Subject: [OM] Re: Coma (was 35-80/2.8)
From: Sean Chan <sean@xxxxxxxxxx>
Date: Tue, 10 Aug 1999 08:27:12 +0800 (WST)
> Catadioptric scopes (those with a corrector lens at the front) are made
> in two optical designs... either Maksutov or Schmidt-Cassegrain.  The
> Maksutov corrector  plate is a very thick meniscus lens with the
> secondary mirror being an aluminzed spot on the back of the corrector
> plate.  The Maksutov design is used for mirror camera lenses, spotting
> scopes and astronomical telescopes.  The corrector plate gets heavy and
> hard to manufacture as the aperture goes up.  The Questar 7-inch
> telescope may be the largest commercially available Maksutov design.
> 
> The Schmidt corrector plate appears to be a flat piece of glass with the
> secondary mirror mechanically mounted via holes drilled in the middle. 

Vixen makes a telescope VISAC (Vixen's 6th Order Aspherical Catadiptric)
which has a Ritchey-Cretion (spelling??) design. This scope boasts
pinpoint sharp stars (0.35 micron or 35 micron??) till the edge of 35mm
film. I bought this scope 3 years ago.

This scope also lead me to the purchase of my first Olympus OM-1 last
year which now my Oly system has grown to an OM-4Ti plus a few lenses.
Although I've yet to come up with an astrophotograph with my gear, you
lot will be the first to know and see when I do :-).

Sean
--
Sean H.Y. Chan   ICQ# 28162308   sean@xxxxxxxxxx
IT Consultant        http://www.tsm.com.au/~sean
DSM Group Pty. Ltd.       +61 (0)500-888-117 (W)
PO Box 1493, West Perth, 6872, WESTERN AUSTRALIA


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