Quote:
Originally Posted by Shiraz
if the secondary is a bit bent, it would also produce astigmatism on axis.
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Forgot that one. The slightest pull on the secondary glass (glue/silicon dabs, etc...) will create astigmatism so something to check first is the mounting. If you haven't fiddled with the secondary then rotate the primary in increment of let's say 10 degrees and check for the star shape intra/extra focus until you find a sweet spot. You usually don't have to recollimate so it's fairly easy to do. Not very scientific I know but it worked for me.