I hope you guys are doing great, I wanted to say thank you for this awesome community. I've learned a lot here through the years.
Recently I stumbled into a problem I can't figure out. I seem to have some sort of burn-in/reflection/shadow on the long exposures pictures I've been taking.
I haven't changed anything on the camera side, same telescope and filter. I thought it was some sort of reflection from the full moon or something, but not the case. I also thought it was the viewfinder that has a light leak of sorts, or even a gap between the camera mount and sensor. I wrapped out everything with a cloth, nothing changed. Another thing I tried was to put a delay between the mirror flip and the actual opening of the shutter, 2, 4, 6 seconds, and no change. It's really driving me crazy!
This ghost rectangle has proven to be hard to remove on the final stack, I suppose that due to the color tint the stacking software sees it as a nebula.
Any help is greatly appreciated.
Canon T4i with the IR cut filter removed
Optolong L enhance
Orion 1x field flattener.