Using Dark Flats, or Not, to Calibrate Flat Frames for Astrophotography
We continue our study of flat frame calibration issues by comparing a stack of M51 light frames taken with my ZWO ASI1600MM and Celestron C9.25 SCT that have been calibrated, with PixInsight, using a master dark-flat with the same M51 stack calibrated with the master bias and "optimized" master dark frames. We also look at the effect of the dew shield on light frame calibration.