Ring around Stars

[bjgiii]

I've got these weird rings around my stars. Does anyone know what causes this and how to reduce/fix it? Thanks

[Carlos Milovic]

Could you provide your workflow? There are many possible culprits, specially deconvolution.

[Harry page]

Hi

What scope are you using

Harry

[bjgiii]

This was stacked with pixinsight. The only thing done to the image was ABE and DBE. The image looks like this after just a STF. This was shot with a full spectrum Canon T3i, ccd cls filter and a WO STAR71. Could this be caused from the LP filter or a improper stack? Its been awhile since I worked on this image. I believe it was 60 lights, ISO 800@ 120s each. Also darks and bias, but I don't recall how many I used in the stack.

[Harry page]

Hi

Looks like a scope problem to me , what does a single sub look like

Harry

[bjgiii]

Here's one zoomed in.

[topboxman]

Looks like out of focused stars. I don't think I've seen out of focused donuts shaped stars from refractors before. Out of focused stars from SCT usually results in donuts shaped stars.

Peter

[Harry page]

Hi

Yes very out of focus , then the stacking gives emphasis  the problem

harry

[bjgiii]

Thanks everyone. Another lesson learned.

Bobby

[TobiasLindemann]

Hi Bobby,
the first picture looks to me like, some of the images are out of focus and others are sharp. Maybe you have a focusdrift, caused by cooling down or other reason. I think you should check all images in your series. Maybe there are some sharp ones, you can use.

Tobias

[Carlos Milovic]

You may use the SubFrameSelector script to reject the blured images, or inspect them with the Blink tool.