Re: ATM Ritchey-Chrétien

[Adam Perkins <scopeguru@yahoo.com>]

--- "Asaf S.-T." <dark_observer@yahoo.com> wrote:

> I was wondering, anyone of you has built a
> Ritchey-Chrétien? Richar Schwartz told about it to
> me,
> and I thought I might use my 16" future mirror for
> that kind of scope. 


Hey,

One thing to consider is the primary of a Ritchey-Chretien may not be
used with a flat secondary.  That is, If you have a R.C. primary, you
may not mount the mirror as a newtonian, it must forever be used with
its matching secondary.  The secondary of the R.C. is used to correct
the Primary's image.  

A "classical" cassegrain primary may be used in a newtonian if you
wish, it is a paraboloidal mirror.

The option of using the objective as a Newtonian would provide a much
smaller focal length (f/d 4 or 5), useful with small CCD chips for
obtaining a decent field of view.  Remember, a 16" scope of f/9 or 10
has a LONG focal length...

Texereau has some comments on the design, if you are considering any
type of cassegrain, buy the book.

There is a reason I usually don't dispense optical advice, someone
speak up if I'm wrong.

Clear Skies,

Adam Perkins
Covington, Louisiana



P.S.- 
Optical Guidance Systems (O.G.S.) manufactures R.C.s, they may have
info on their web page...

_________________________________________________________
Do You Yahoo!?
Get your free @yahoo.com address at http://mail.yahoo.com