strmy

Thanks for reply! Then i will just have to live with this apparently. Of course i suspected that, because of above mentioned position of mirror, but hoped that i'm wrong. I am used to all sorts of light pollution associated trouble, but here i just think my flats weren't the best. Clear skies!

Hello, I have recently bought new telescope, Skywatcher Quattro 8" f/4. When i use it with my Canon 800D (APS-C) and coma corrector i get some normal vignetting, but also "bottom edge" of image is darker. I have come to conclusion, that this must be DSLR mirror shadow. Now the question for you all is - have you come across this and how to get around it if it is possible at all. I Have previously imaged with f/12 scope, so i did not have such problem. With flats i can of course mitigate this problem a bit, but because shadowing is so severe, there is much less signal present, and this bottom edge becomes useless for processing. Attached is one stack without flats (first 2 images) and one with flats. As you can see, even flats don't completely resolve the issue. They are taken with white shirt over tube, lit from distance with lamp to achieve even light density across diameter. Thanks for any thoughts and suggestions!