Re: Refinishing 16-inch mirror

I'm thinking of having my 16-inch (2-inch thick) f4.5 mirror refinished,
which I understand might improve its optical performance somewhat and
enhance its reflectivity. It has worked great for viewing the Messiers,
but it doesn't seem to handle higher powers very well regardless of
collimation.

On nights of good seeing, you should do a star test. Also, you should park
it next to another similar sized dob of known optical quality and compare
the views. How about a 7" off-axis mask - at f10 you should get great
planetary views. This will give you an idea of the quality of the mirror.
Of course, you can send it off to any numbr of optical shops who will
evaluate it for you, and refigure it if you decide it is worth it. However,
I don't think evaluating it yourself is that hard, and you will learn a lot
in the process. In our club, there are a number of folks who would gladly
help you (one guy even has a homemade interferometer) - aren't there any in
your club?

Dennis


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