Meade RCX400 is NOT Ritchey-Chretien.

and a damned poor marketing ploy too. Negative publicity Meade does
not need.





Vader wrote:

wrote:

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

Only in this case (both mirrors are hyperbolical) this system will be
a variation of a Ritchey-Chretien system.

However, this is a very hard task to accomplish two highely aspherized
mirrors along with flat optical window. This is a well known fact, that
it is more difficult to make flat, than average paraboloid. However,
here
are 2(!) flat surfaces.
Also, this system has very fast primary mirror - about F/2. This does
mean, that aspherics here is about 2.1x higher, than in traditional for
R-C systems F/3 primary. This also means, that aspherics on a secondary
mirror is also higher. The main problem is correct collimation of this
system, because it is much more sensitive to cillimation, that a system
with F/3 primary.
Meade says, that a primary mirror has no collimation. This does mean,
that a primary mirror is a sphere, because a sphere has infinite number
of optical axes and the only collimation require is secondary mirror
tilt. Corrective plate is not sensitive to collimation.

I bet, that with 99.99% probability this system consist aspherized
secondary and aspherized corrective plate.
Even in this case, this system will be WORSER visually, than
traditional
SCT, because it has aspherized secondary mirror. It is not easy tast at
all to make a smooth small convex hyperboloid or oblate spheroid. And
in any case it can't be made in large number and very smooth. Very
smooth aspherics requite a time, slow speed polishing with frequent
enough testing procedures.

2 Rich A. 40+% c.o. is really worser, than 33% or 35%. More and more
energy pulled out of Airy disk to diffraction rings and contrast
becomes lower and lower. According to your logic, 50% c.o. is not much
worser, than 40%. ;)

Conclution (with 99.99% probability). These RCX are not
Ritchey-Chretiens. Just marketing step.

VD