Katelyn Beecroft:
It looks to me like dew on the camera sensor. Is it in every sub? Or if you blink through the subs do you see it start to appear?
DavesView:
Does the camera have a dew heater on the glass in front of the sensor and are you turning it off/on?
Oskari Nikkinen:
Im not convinced dew or ice on the sensor window is to blame, at least not going to lean towards this without additional info.
Looked at your posted images and it appears you are using a Canon R6 so the camera is not cooled and there is little to no risk of dew/ice. With Canon cameras you dont want to use darks and you would need to subtract the default offset value of 2048 in calibration. The reason you dont want to use darks is that Canon cameras have an auto offset level of 2048 regardless of exposure time, so darks will just not work and if improperly taken will do nothing but add noise, and if light leaks were involved will just make flat calibration impossible. You can use darks, but they have to be properly taken in a fully dark environment and even then its better to just not use them.
If you could upload a single frame of all the types of calibration frames you are using (1 flat, dark, darkflat/bias if you are using them) i would like to have a look at them. They need to be raw frames, so you could upload to google drive or any other file sharing place of your choice. Chances are something has gone wrong with them and they are to blame. When i used to image with a 550D i saw this exact ring many times when i had incorrect calibration frames.
*edit: Also please add a light frame from the night you had this issue
Konstantin:Oskari Nikkinen:
Im not convinced dew or ice on the sensor window is to blame, at least not going to lean towards this without additional info.
Looked at your posted images and it appears you are using a Canon R6 so the camera is not cooled and there is little to no risk of dew/ice. With Canon cameras you dont want to use darks and you would need to subtract the default offset value of 2048 in calibration. The reason you dont want to use darks is that Canon cameras have an auto offset level of 2048 regardless of exposure time, so darks will just not work and if improperly taken will do nothing but add noise, and if light leaks were involved will just make flat calibration impossible. You can use darks, but they have to be properly taken in a fully dark environment and even then its better to just not use them.
If you could upload a single frame of all the types of calibration frames you are using (1 flat, dark, darkflat/bias if you are using them) i would like to have a look at them. They need to be raw frames, so you could upload to google drive or any other file sharing place of your choice. Chances are something has gone wrong with them and they are to blame. When i used to image with a 550D i saw this exact ring many times when i had incorrect calibration frames.
*edit: Also please add a light frame from the night you had this issue
I get these rings when i only stack light frames too, and when i stack flat frames and biases, i never used darks. Then its slightly reduced but still prominent. I tried heating the camera but that did not work at all.
Konstantin:Oskari Nikkinen:
Im not convinced dew or ice on the sensor window is to blame, at least not going to lean towards this without additional info.
Looked at your posted images and it appears you are using a Canon R6 so the camera is not cooled and there is little to no risk of dew/ice. With Canon cameras you dont want to use darks and you would need to subtract the default offset value of 2048 in calibration. The reason you dont want to use darks is that Canon cameras have an auto offset level of 2048 regardless of exposure time, so darks will just not work and if improperly taken will do nothing but add noise, and if light leaks were involved will just make flat calibration impossible. You can use darks, but they have to be properly taken in a fully dark environment and even then its better to just not use them.
If you could upload a single frame of all the types of calibration frames you are using (1 flat, dark, darkflat/bias if you are using them) i would like to have a look at them. They need to be raw frames, so you could upload to google drive or any other file sharing place of your choice. Chances are something has gone wrong with them and they are to blame. When i used to image with a 550D i saw this exact ring many times when i had incorrect calibration frames.
*edit: Also please add a light frame from the night you had this issue
I get these rings when i only stack light frames too, and when i stack flat frames and biases, i never used darks. Then its slightly reduced but still prominent. I tried heating the camera but that did not work at all.
MaksPower:
This is dew on the camera sensor cover. Have seen before.
Use a cameras with a heater and make sure it is turned on.
andrea tasselli:
You may have a serious problem with stray light when you take your flats. So the question is how do you take your flats and with what?
andrea tasselli:
*Of course it didn't work, it isn't the camera it's the optical train ahead of it that's the issue.
Konstantin:
Its was the adapter from M42 to M48, there is a flat internal protruding ring when the camera is inserted with it, i put tape on the ring to diffuse the reflections, and it worked, of course the tape ruins the contrast but the point being was to prove whether that was the cause, so now i am looking for black paint or a new adapter, if you have any advice on black paint and preferably any the will stick to aluminum metal with relative resistance to water would appreciate it. Thanks for the help.
Konstantin:
if you have any advice on black paint