Re: Largest SCT ever built and Date was: ?

From: Ed Majden (epmajden_at_shaw.ca)
Date: 12/22/04 

Date: Wed, 22 Dec 2004 17:55:18 GMT

in article Nemdnf9mAqgVOlTcRVn-2w@bresnan.com, Tim Killian at
TJK@notmyrealemail.com wrote on 12/22/04 8:57:

> Very interesting. So where is the commercial advantage in selling SCTs
> vs. say a classical Cassegrain with its secondary mounted on a plane
> parallel window? Is the aspheric primary that much more costly to make
> than the big corrector plate?
>
>
    Mass production of Conventional Cassegrain optics would be difficult.
The primary is parabolic like a Newtonian and the secondary is hyperbolic
and difficult to figure. Schmidt Cass optics that are commercially produced
are for the most part spherical and easy to make. The corrector plate is
deformed by a vacuum apparatus and ground flat. When the vacuum is released
it forms the correct curve. An easy process for mass production.

Ed Majden

Quantcast