"matt" wrote in message ...

....
If you can , meaning if you have the time
and will , please learn a little about testing telescopes and mirrors.
There's plenty of free info on the internet , and testing devices can be had
or built easily and for very little money and not much effort . Then measure
your primary and decide if it's crap , great or in between . There are lots
of people out there who are holding some piece of paper from an optician
that states their mirrors have a Strehl of 1.001 or whatever and have a very
elitist attitude . These people are deluding themselves that they have a
lambda/1million telescope , when they really are at best having a 1/4 or 1/8
instrument .
....

Hi Matt,

Good advice. I have a fair amount of practice with the star test
method as described by Suiter, and have used enough scopes to know an
average optic from a good one (but to be honest I can't practically
tell a good optic from a great one). I've been observing for a few
years now (first with a C8 and lately with an MN61). At my
intermediate skill level, I am still more limited by observing
technique, viewing conditions, and scope collimation/cooldown than I
am by the difference between good and great optics.

Mostly I'm interested in building a Dob for the challenge of it ... as
an opportunity to experiment with a different design and learn new
techniques. Learning to do benchtop evaluation of a mirror would sure
fall into that category.

Cheers,
Nate