Re: ATM - Help finding materials for cassegrain project.??

[Michael Lindner <mikel@att.net>]

Frank Ward wrote:
> 
> Ken,
> 
> I didn't imply a Schmidt, nor did you mention one.  I was just
> wondering where the 10" BK-7 was going to be used in a Cass.
> 
> Now I see.  The correctors are 10" each. One is double convex
> and the next is double concave. You are attaching the convex
> secondary to the inside of the concave corrector.
> 
> So, if I have this right.  You are going to make R1 R2 R3 R4 Primary
> R5 and for a f/6.3 you will add a R6 the meniscus.
> 
> I personally have never heard of this design.  What are it's advantages
> other than the spherical figures for  null testing?
> 
> Frank Ward
> Atlanta, GA
> ----- Original Message -----
> From: Noesgaard,Ken <Ken.Noesgaard@siemens.ca>
> To: 'Frank Ward' <thewards@mindspring.com>
> Sent: Monday, December 13, 1999 6:17 PM
> Subject: RE: ATM - Help finding materials for cassegrain project.??
> 
> > The project in question is not a SCHMIDT cassegrain. It's more along the
> > line of a Maksutov without the hideously expensive and difficult to make
> > maksutov corrector. The corrector is instead a double convex lens followed
> > by a double concave lens...

It's a houghton derivative.

--
Mike Lindner