Hi everyone,
I’m seeing a circular artifact in my image after running WBPP. I used dark frames and the attached master flat. The artifact closely matches the flat frame, so I suspect it may be an issue with my flats. If that’s the case, I can reshoot a new set.
For this image, this issue occurs on all of my filters.
Any suggestions would be appreciated.
Thanks!
đź“· Screenshot 2025-09-29 at 16.37.37.png
đź“· Screenshot 2025-09-29 at 16.38.15.png
Hey Andrea! Thanks for replying. Yes, I do have some vignetting, but I would expect flat frames to fix that. Here is another picture that shows better the ring/gradient I am writing about. I am not sure if this is because my flat frames are bad or maybe my dark frames have an issue. I already applied DBE and Gradient Correction, but the result is still bad.
đź“· Screenshot 2025-09-29 at 22.36.26.png
Flats should correct most vignette. If not, then i’d start chasing a light leak. First step i’d recommend is using bias instead of darks. If that doesn't alleviate the issue, the start shining a flashlight around your scope while looping exposures.
@andrea tasselli @Brian Puhl Thank you for comments. I did re-shoot my flats last night. I forgot to move the focuser close to focus position while acquiring the initial batch of flats. The problem is now gone.
Catalin Iordache · Sep 30, 2025, 11:28 AM
The problem is not gone.
…or did you mean to type “now gone”?
Before:
After: