Nate Perkins wrote in message
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Tim Auton wrote in message
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(Nate Perkins) wrote:

I'm looking at sources to buy an elliptical secondary (around 2.14")
for my first Dob project. I see a lot of variation in prices ...
reading some Google archives gives me the impression that the
secondary quality doesn't matter overmuch. Is this the right
impression? I'm interested in thoughts and recommendations.

What's your primary? If it's a 1/30th wave Zambuto then find something
as awesome as possible and pay the premium, if it's a home-made 1/4
wave then a top-grade secondary might not be the best use of your
cash.

It's certainly not a Zambuto! It's Chinese (blush).

I'll take your advice and go with a lower cost secondary.

Thanks, Nate

Do not take that advice please. 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 . Do yourself a favor and learn to test yourself, since you want
to build a dob, and not have to rely on assumptions or other people's
representations , especially people who have a vested interest and
consequently a large bias . Also regarding big name secondaries do yourself
a favor and search the saa history, there have been numerous negative
experiences with various brands. Learn which were these and how to measure
those types of problems.
After that, shop around and buy , but be ready to measure and send back if
it doesn't comply with the official bragging (loosely called specs by
vendors) .

best regards,
matt tudor