To: atm{at}shore.net
From: tkrajci{at}san.osd.mil
Reply-To: tkrajci{at}san.osd.mil


> From: "Rob" 

> BTW why don't more people build Ritchies? Or have I just missed them all?

I must have missed them too.  I'm eager to learn what websites there are
out there of 'amateur R-C scopes' that work well, and weren't too
challenging to fabricate.

(This reminds me of a thread along the lines of one person asking: 
"hey, how about if I make a bunch of small mirrors to make a large
amateur multiple-mirror-telescope?"  My response was...show me some
websites of other amateurs that have successfully done this.  I not
received a response to my question.)

>...Yes, the main reason I want to build an R-C is photography..

Depending on the film/CCD size you want to use, the area of sky
coverage...and other performance considerations...an R-C may be overkill
for you.  Other, simpler optical setups may meet your needs.

See:
http://overton.tamu.edu/aset/krajci/
and specifically:
http://overton.tamu.edu/aset/krajci/scope-design.htm
as one example of performance goals being listed, and then various design
options being discussed.  (The performance goals are probably different
than yours, but this may still be a useful example for you.)

>...It seems like the best of a cassagrain and a
> newtonian merged together with a nice flat field..

Flatness of field is largely controlled by the 'multiplacation factor' of
the secondary mirror in R-C and Cass systems.  You can make them flat
field, or very curved field.  Again, it depends on the size of film/CCD you
want to cover.  You may be able to get away with a curved field if you use
smaller film/CCD formats.

>...but it's similar in size to a cassagrain..

And when you include decent baffling/light shielding on the sky end of your
tube assembly...you may be surprised that it's not a super compact setup. 
On my Celestron C-11, my current light/dew shield extends 28 inches beyond
the end of the corrector plate.  It's shorter than most 11 inch newt's
....but not by very much.

Good luck,
Tom Krajci
Tashkent, Uzbekistan

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