On 5 Jan 2005 15:23:54 -0800, wrote:


Vader wrote:
Nothing common between Meade RCX and true Ritchey-Chretien.
The only common is aplanatism - coma-free.

Calling these new scopes as Ritchey-Chretien is nothing, but
marketing hype to catch public attention. Peoples heard, that
Ritchey-Chretien are the best two mirror telescope systems.
But most of them don't know exactly what is what.

For CCD photography these new scopes will be not better, than
traditional SCT with focal reducer-comacorrector. Field is quite
enough, it is flat and coma-free.

New telescopes will have huge field curvature and will be
worser for visual observing - because of higher aspherics (less
smooth optics) and larger central obstruction.

If one will ask which scope I will use personally new RCX or
same size SCT, I will choose a SCT.


VD


Does it have a hyperboloidal primary and secondary? If it does, then
why wouldn't it be a variation of a R-C? It's funny that they say the
front corrector will eliminate the contrast robbing diffraction of
spider vanes, yet it must have about a 40% linear obstruction! Even if
the design is sound, I don't have too much confidence in their
execution.

Jim Johnson

40% isn't much large than the obstructions in Meade SCTs.
-Rich