Following on from
Collimating a Fast Newt and with all the help I got with this 10" Astrograph from you guys, I just could not get it right. I had misshaped stars no matter what I did. Even with excellent results from CCDI the stars where still wrong. So much for software alignment. By pure accident I found that lifting the tube off the bench caused alignment to be lost. I tracked this down to the weight of the secondary, twisting the spider and pushing the prostar tube out of shape at the business end of the scope
I got a spare 10" ring and wrapped it around the scope near the spider to force the tube to retain it's shape and now I have round stars.
However I still have artifacts on stars as shown in this image. It looks like an extra diffraction spike. Any tips on what is causing this one? I'm sure it's the stuffed spider but would like another opinion.
This is a single 1 sec sub of achernar.