Odd vignette on Canon 250D sensor

Canon EOS 250D / Rebel SL3 / Kiss X10 / EOS 200D Mark II DSLR Vignetting Troubleshooting
6 replies•174 views
AttiC avatar
AttiC avatar
Hi!
I've been successfully using a modified (baader-bcf) Canon 250D for the past 2 years w/o particular issues, however, recently a very strong vignetting on 1 side of the image started to appear.  I ruled out the optics, as it manifests with all my scopes and lenses, even without a lens attached. It also doesn't seem to have anything to do with exposure time or temperature either. It happens on all ISO levels as well.
Again, it only started appearing recently, this winter. I never did flats with this setup as it didn't seem necessary until now.

Attached is a skyflat (1/4000 exposure, iso800) to demonstrate the issue:

And how it manifests when imaging:


What puzzles me the most is that it is changing sides on the image, doesnt seem to be the same side always. For example it is the top side of the image, even if i rotate the camera 180 degrees (with auto-rotation turned off)...

Did anyone else experience such issues with this sensor (or any other camera as a matter of fact), or have any idea what could this be and how to fix it?
Is the sensor going toast? Tbh i've been using it a lot in out-of-spec temperatures in winter night sessions.

Thanks!
Attila
Helpful Engaging
andrea tasselli avatar
andrea tasselli avatar
Try a dark frame of length equal to your typical expsoure and same ISO settings. If the issue is related to some sensor malfunction it should show up there as well. If not then is related to the baader filter.
Helpful Concise
AttiC avatar
AttiC avatar
andrea tasselli:
Try a dark frame of length equal to your typical expsoure and same ISO settings. If the issue is related to some sensor malfunction it should show up there as well. If not then is related to the baader filter.

Thanks for the reply! Yes, i forgot to mention in the post, that the defect doesn't show up on dark frames, nor on bias frames..
I am now thinking maybe the sensor or the filter got loose and is moving a bit? That might explain why it is always the top part vignetted, regardless to sensor orientation. I kind of also hear a very faint rattling if i shake it that i just discovered..
Insightful Respectful Concise Engaging
burkle1990 avatar
burkle1990 avatar
The first one looks like the mirror System is causing vignet. Had a simular issue my 6d. 

The second one looks like the filter is causing vignet in combination with Light pollution. Try ha nb filter, educated guess it might not have that problem. Good luck.
Sean Mc avatar
Sean Mc avatar
If it’s moving when you rotate the camera, I’m guessing it’s not the camera.
Well Written
AttiC avatar
AttiC avatar
The first one looks like the mirror System is causing vignet. Had a simular issue my 6d. 

The second one looks like the filter is causing vignet in combination with Light pollution. Try ha nb filter, educated guess it might not have that problem. Good luck.

Thanks for the hint! The image in question was made with l-enhance duo-nb filter, and is a dithered livestack straight out of asiair.
Well Written
burkle1990 avatar
burkle1990 avatar
The first one looks like the mirror System is causing vignet. Had a simular issue my 6d. 

The second one looks like the filter is causing vignet in combination with Light pollution. Try ha nb filter, educated guess it might not have that problem. Good luck.

Thanks for the hint! The image in question was made with l-enhance duo-nb filter, and is a dithered livestack straight out of asiair.

*** did you compare the two single subs? ***
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