Haloes suddenly appearing

[pmrid]

Zoom into the attached. The stars are all like little oysters.

This is new. The camera is an ASI533MC Pro. I've used it without any issues on m 94EDPH SharpStar scope but NOW, when I use it on a brand new scope in it's first light trials, I am getting these artifacts.

Focusing is as good as I can make it. The guiding likewise. Seeing mediocre.

The new scope seems likely to be the villian. I have tried it with other camera - ASI071MC and ASI1600MM.

The scope is supposedly an APO made and sold by ZWO. These artifacats appear whether I use their proprietary Reducer (X 0.7) or not. It does seem the only other element is the filter - an Optalong L-Enhance - but I have used it on the SharpStar scopes without these issues.

The AOP is supposedly a quad and according to the blurb should be CA free.

Any suggestions?

[Nikolas]

Looks like star bloat do you have a larger image? Also which scope?

[pmrid]

Hi Nik.

Here's a crop of an enlarged section.

The scope is a ZWO FF107 APO quadruple with a 0,75 x reducer.

Peter

[Nikolas]

if the issue only occurs with the filter see if it is dirty or fogged those halos look like donuts

[ronson]

This looks like a post processing artefact. Can you show a single stretched frame.

[pmrid]

I'll try. Trouble is the original subs run to about 17MB. I've reduced a sub down to 5 MB or so but getting it into IIS limits would render the image a but less than useful.

But having said that, it does seem that individual subs do not exhibit the same artifacts that the processed (DSS) result shows.

SO you're probaby right. All I have to do now is see which of DSS's setting I need to tweak.

[ronson]

Maybe try another stacking application to confirm if it is DSS causing the issue. Siril (https://siril.org/) is free and does a pretty good job.

[pmrid]

I just renewed my subscription to AstroPixelProcessor and ran the same subs through it. The result is markedly different. Here is a close crop of the same general area. Marked difference!

Added a full-screen image (shrunk by 80%).

[Nikolas]

ok if it's DSS turn off cosmetic correction and try it again

[AWOL]

There is no way it's the scope. That scope will give you pinpoint stars right across the image.
Your problem is happening after you have stacked and created your master files. I would bet my house the stars in your master lights are perfect.
I use Pixinsight from start to finish and I had the same problem. Mine was caused by Multiscale Linear Transformation, which I was using for noise reduction after the EZ suite stopped working because of an update. I stopped using it and the problem disappeared.

PS. That ZWO scope is a badged version of the PHQ range manufactured by Sharpstar/Askar.