Quote:
Originally Posted by Atmos
At this stage I don't think it is astigmatism, I'm pretty sure that was being caused by the mirror clips (pinching the mirror). The in focus stars appear nice, at least as nice as they could while the mirror was still cooling. They were round little fluff balls 
I looked at Saturn and I could see the Cassini Division quite cleanly but it was lacking the detail/colour on Saturn itself. This was what I was expecting due to the cooling mirror. |
Ok,
astigmatism will look circular at focus.
It will look bean shaped outside of focus.
The long axis of the bean will flip 90 degrees inside of focus.
Typically, if the mirror clips are stressing the mirror the distortion will be trefoil.
~c