Re: Astrosib RC's

<> wrote

If the ATM approach is workable and OMI-Torus figures RC optical sets,
that would seem to be the only way to go. I have seen OMI's optical
work and it is far superior to Star Optical. Portability is obviously
not a design goal here. You don't load big RC's with their mounts in
the back of your car.

RCOS would seem to have a HUGE profit mark-up in their RC scope
assembly offerings; probably OGS does as well.


OMI will make you the entire telescope. Both Parallax and OGS will make you
a scope with what ever optics you want, so you can order OMI optics or
Russian optics.

I own scopes with both OMI-Torus and Star Instruments optics, but the Torus
is a 20" F/5 Newt, not an RC. I have interferogram tests on the 10 & 20 RC,
and the 20-inch Torus Newt. The Torus mirror is superior in all ways -
except coma - which is of course why I own an RC to begin with. If you're
not doing imaging an RC is waste of money. The main error on both Star
Insturments mirror sets is astigmatism: about a fifth wave on the 20 and an
eighth wave on the 10. I'm not sure if OMI RC optics are any better than
SI's, and for the most part it wouldn't matter. All three scopes are
excellent for 'real world' use. OGS does not make much money - for years it
was a losing enterprise. It's just John's "hobby" business and provides
employment for about 5 full timers and another 10 or so part timers - and
gives John and his friends a chance to use the scopes before he ships them.
John makes his 'real money' as the owner of the Stiles Funeral Home. (OGS is
in the basement of the funeral home!!) BTW, for 16-inch and larger
telescopes OGS does on-site installation, polar alignment, collimation, and,
if you don't like it, you get your money back and he takes it away. One
final point: I'm not sure if this is true with RCOS, but OGS scopes have
primary mirror blanks that are slightly larger than the stated size. The
outer quarter inch or so is masked by the mirror mount and is actually
unfinished - as a precaution against turned-down-edge. So the blank in the
20 RC I use is 20.75 inches, but only 20 inches is used.

George N


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