Re: [ATM] Ritchey Chretien

[Mike Lockwood <melockwo@uiuc.edu>]

Francis,

Francis J. O'Reilly wrote:
> I am just thinking, but as I compete my outstanding projects, I
> need to start a new project, because a telescope maker just isn't a
> telescope maker if he's not making telescopes!
> Does anyone on the list have experience with building a telescope
> using a Ritchey Chretien design. Does anyone know anything about
> the hyperboloidal curves needed for the design or about literature
> relating to the design?

I have refigured a very fast R-C and made several classical Cassegrains.

Understand that an R-C does not need a super-fast primary.  You can 
still build an F/10-F/12 R-C (or a classical Cass) with an F/3 or F/4 
primary, and the secondary will generally be easier to make because 
the system is slower.

Also understand that in my F/12.5 classical Cassegrain, even at 100X 
(with a 41mm Panoptic) coma is not really visible at the edge of the 
field.  The RC design really is for wider field imaging rather than 
visual use.  (On-axis, in theory, a D-K, classical, and R-C all have 
essentially the same performance if the secondary sizes are the same.)

My F/12.5 classical (with F/4.2 primary) could have been an R-C if I 
added ~5% more correction to the primary and figured the secondary to 
a more aspheric hyperbola.

You can find design equations, tips, and suggestions on my Cassegrain 
page:
http://bi-staff.beckman.uiuc.edu/~melockwo/mirror_making/cass_info/cass_info.html

	Mike Lockwood


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