Primary mirror selections?

I haven't been involved that much in the hobby (using a telescope) in
several years. I have been using binocculars since they are effortless
in setup but do miss the higher power and image quality a scope yields.
I was thinking of finally getting a new 8" primary and started looking
at some old bookmarks for people who would custom make mirrors.

Looks like either the hobby or the economy has taken a turn for the
worse. Discovery and University Optics were on my list for mirrors at
lower cost, looks like neither makes them anymore (there goes my
budget). I see Royce, Swayze, Zambuto are still out there but not all of
these high quality mirror makers will make an 8" mirror. And then there
is the $$$ factor.

I'm sure that one can get their money's worth from the big name guys but
as rare as I used the scope in recent memory it's tough to justify the
cost. I know a well made mirror will provide the best possible viewing
but wonder if anyone still makes a compromise between cost and quality
among the people who make the mirrors.

I've also looked at the way they spec the mirrors, a bit confusing,
wavefront P-V, surface P-V, RMS wavefront, Strehl ratio, diffraction
limited.

Someone told me that getting a 1/10 wave surface would yield the best
potential from the mirror with atmospheric conditions being what they
are. So I assume a 8" f6 can be made to the above spec without serious
effort on the part of the maker, right? wrong?

Not looking for perfection (where could I setup and find great
conditions for using such a scope anyway?) but want to enjoy seeing
better than the mass produced mirrors may yield. I did look at
http://ben.davies.net/telescope.htm#Mirrors for help but finding a maker
of 8" mirrors is not as easy as a 17" or larger mirror. Anyone know of
some lesser known people making quality mirrors in the 8" range? Or
should I just give up looking and buy an expensive one?

Try Parks Optical:

http://www.parksoptical.com/index2.p...mary+Mirr ors

They tend to be around 1/8th wave RMS *wavefront* accuracy or better
(occasionally, a *lot* better). 1/10 wave *surface* accuracy amounts to
only about 1/5th wave wavefront error, so you have to watch what the
manufacturers actually are saying (the Rayleigh limit is about 1/4 wave
on the wavefront). The Parks mirrors tend to be fairly good, although
not exactly cheap. For "cheap", you can try the Orion components, but
it is kind of a crapshoot as far as the exact wave rating is concerned
(some are fairly decent and some may not be). Clear skies to you.
--
David W. Knisely
Prairie Astronomy Club: http://www.prairieastronomyclub.org
Hyde Memorial Observatory: http://www.hydeobservatory.info/

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On Mar 12, 12:21 am, Joseph wrote:
I haven't been involved that much in the hobby (using a telescope) in
several years. I have been using binocculars since they are effortless
in setup but do miss the higher power and image quality a scope yields.
I was thinking of finally getting a new 8" primary and started looking
at some old bookmarks for people who would custom make mirrors.

Looks like either the hobby or the economy has taken a turn for the
worse. Discovery and University Optics were on my list for mirrors at
lower cost, looks like neither makes them anymore (there goes my
budget). I see Royce, Swayze, Zambuto are still out there but not all of
these high quality mirror makers will make an 8" mirror. And then there
is the $$$ factor.

I'm sure that one can get their money's worth from the big name guys but
as rare as I used the scope in recent memory it's tough to justify the
cost. I know a well made mirror will provide the best possible viewing
but wonder if anyone still makes a compromise between cost and quality
among the people who make the mirrors.

I've also looked at the way they spec the mirrors, a bit confusing,
wavefront P-V, surface P-V, RMS wavefront, Strehl ratio, diffraction
limited.

Someone told me that getting a 1/10 wave surface would yield the best
potential from the mirror with atmospheric conditions being what they
are. So I assume a 8" f6 can be made to the above spec without serious
effort on the part of the maker, right? wrong?

Not looking for perfection (where could I setup and find great
conditions for using such a scope anyway?) but want to enjoy seeing
better than the mass produced mirrors may yield. I did look athttp://ben.davies.net/telescope.htm#Mirrorsfor help but finding a maker
of 8" mirrors is not as easy as a 17" or larger mirror. Anyone know of
some lesser known people making quality mirrors in the 8" range? Or
should I just give up looking and buy an expensive one?

You might have to decide between buying an 8-inch mirror that is known
to be of excellent quality or buying a complete 10-inch or 12-inch
scope, of similar price, that will be more difficult to transport, but
that could provide better views.

The prices for Parks Optical mirrors seem very reasonable. You could,
of course, try making your own mirror.

Anyone know of
some lesser known people making quality mirrors in the 8" range? Or
should I just give up looking and buy an expensive one?

Our club has, in the past year, run a couple of telescope building classes.
We buy the optics/spider/focuser and build the rest. We have gotten only
very good mirrors from http://www.e-scopes.cc/ as well as great service.
Don't settle for a mediocre mirror, don't settle for a mediocre mirror,
don't settle for a mediocre mirror, ...

Dennis

Discovery and University Optics were on my list for mirrors at
lower cost, looks like neither makes them anymore (there goes my
budget).

WRT Discovery, contact Ostahowski Optics. 10-inch is the smallest he
offers.
--
Curtis Croulet
Temecula, California
33°27'59"N, 117°05'53"W