So I tried using just flats without dark flats and still got the same result. Huge vingetting. Any other suggestions?
I can tell you what it's not. The histogram. You just need to be away from the edges.
Beginners often have this problem. By far the most common cause is doing something wrong when calibrating the images in the software. Not in taking the flats. Unless you've changed the orientation of the camera re the scope. Disassembling the setup, and reassembling, does not work.
So, you're using DSS? What's your workflow? Are you changing the defaults?
It's possible (but unlikely) to cause vignetting so severe that flats can't fix it. You could, for example, put a 1.25 inch tube somewhere in the optical path. Could you post two pictures of the setup? One of the whole thing, one that shows the specific area between the end of the scope and the camera. Or upload a light, straight from the camera, to something like Dropbox, post the link, and ask that someone looks at it.
Edited by bobzeq25, 03 August 2021 - 01:27 AM.