Re: [ATM] Re: Aplanatic Gregorian

[Jarvis Krumbein <jkoptic@juno.com>]

A Gregorian Mersenne would use parabolic curves for both primary and
secondary.  The difference between the Cassegrain and Gregorian systems
would be concave secondary for the Greg and convex for the Cass versions.
 In the Greg, the f# of both the primary and secondaries would be the
same.  It should be easier to make the Greg secondary than the Cass
secondary but other than that, I can see no advantage.

Jarvis Krumbein

> I have not seen yet any reference to a Gregorian Mersenne 
> arrangement . Is
> there any book, article, publication that treats it in detail ? I 
> found
> historical references, and short of simulating it myself in Oslo is 
> there
> any way to avoid reinventing the wheel ? There are large 
> professional
> Gregorian instruments that are used in Mersenne configuration, but 
> besides
> pretty pictures very little in the way of optical prescriptions or 
> clear
> details is available on their websites. I have done a complete ATM 
> list
> archives search and only came up with a few relatively well known 
> and little
> talked about scopes, like Clyde Bone's plus a couple of older ones . 
> Clyde's
> scope was apparently featured in the September 1999 S&T issue, but 
> other
> than that, no other web references with images, data etc.
> 
> best regards,
> matt tudor
> 
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> ATM mailing list http://www.atmlist.net/
> 
> 

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