I use an N10 with an SBIG STL-11K camera, and a LRGBHa filter set from Baader. I have always had corner artifacts that are not corrected using twilight flats. Please use the following link to download files to help me iagnose this problem:
I have posted raw and calibrated single frames, the twilight flat used to calibrate (stack of 16) and the finished image. My Ha filter does not show this defect, but all the others do to varying degrees. I can just about correct this using DBE, but I do have to crop at least a little, and I would rather not have to do this.
Anyone have any ideas what could be causing this? It's like the flat is overcorrecting the corners. I am considering upgrading to a camera with a larger chip (e.g. 16803). Perhaps my current camera is not ideal for a scope this fast? In that case, what large chip camera do people recommend for use with this scope?
Thanks for your insights and advice.