|
I would not glue a 1/30 secondary. Get a proper holder with a lip for it. It will sit in place without stress if properly packed and the lip will mask any surface defects at the very edge of the secondary.
As for size it depends on the fully illuminated field you want as well as how much magnitude drop (if any) you want at edge of field for your lowest power eyepiece. You need to provide a few more measurements to determine secondary size correctly. Search for Mel Bartels secondary sizing.
|