Re: RTMC

PFAFF2@delphi.com
Wed, 01 Mar 1995 23:51:10 -0500 (EST)

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> From: markv@roger.pixar.com (Mark VandeWettering)
> Subject: Re: RTMC
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> If this was the Schupmann that was there last year, I advise everyone
> to stop by and have a peek. A beautiful telescope. It makes me drool.
> The gorgeous high contrast views were amazing. These unobstructed
> telescopes are fantastic. Ditch your icky old Newtonian.
>
> For those of you unfamiliar with the Schupmann design, it is an all
> spherical "medial" telescope, sort of a cross between a reflector and
> a refractor. It is totally free from color, but uses only commom BK-7
> throughout, and only spherical surfaces. One such design was presented
> in (the first?) issue of the Amateur Telescope Making Journal which was for
> a 6" f/15. I believe Jerry Logan's was a 7" f/10.
>
> The primary objective is a single lens of BK-7. A relay lens is positioned
> at the yellow focus of the primary, and tilted to send the beam out to
> a Mangin mirror (a back silvered mirror) also of BK-7. The power of
> the Mangin is carefully calculated to add just the right amount of negative
> chromatic aberration to the system. The rest of the aberrations are pretty
> trivial. Very nice system. I'd love to build one some day.
>
> Check it out. Anybody who wants to chat some more about unobstructed
> telescopes give me a buzz in email. I have no experience with building
> them (yet) but would like to give them a shot.
>
> Mark VandeWettering
> markv@pixar.com
> http://webspace.com/markv/
>
>
>
Jerry hopes to have a 10.25" folded Schupmann for RTMC this year. The tube asm. will be less then 5 ft. long. This guy knows glass so do stop by. Bob Pfaff