I have a S50 and S30 and on the S30 I have noticed oblong stars in the upper left corner area, to some degree in the other corners but not like the upper left. This happens with 18 of the 22 targets I have shot. I contacted ZWO and they said the scope meets specifications but I have heard many people on the S30 FB pages say they get all round stars.
What gets me is that for example with M45 I did imaging runs 3 nights in a row and 2 of the 3 have round stars and the 3rd even in the first 10 second sub frame you can see the oblong stars! Not sure why I would get about 20% of the images having round stars and the rest noticeably oblong stars ( they all have round stars in the center).
ZWO said crop the images to only show the center of the object but if I wanted to do that I would use my S50. I got the S30 to do large objects so I wouldn't have to do mosaic with the S50 having limited sky area due to trees.
High Point Scientific where I bought the scope after I mentioned the issue tested one of theirs and have the same issue. They suggested I used a leveler, which I DO and usually get it to 0.2 on the green balls so I don't think it is a leveling issue, they then suggested I use BlurXTerminator which helps but is not perfect.
I realize I am probably hoping for more than the S30 can deliver but I am hoping for the best out of it.
Does anyone have an S30 that gives round stars in the corners on all images? Or is it a design limitation, wide field inexpensive scope?
