I have noticed that some of my integrated images have black spots in them. I use three 6nm narrow band filters with a cooled ASI1600MM Pro mono camera. The latest problem occurred with an AT65ESQ scope, 4 minute subs, gain 200, binned 2x2. The master dark was created with the same settings. The image looks like someone spilled pepper on it.
. 99.9% of the spots disappeared when I aligned and integrated my subs without image calibration. I stretched the master dark but couldn't see anything obvious. Any suggestions as to the likely cause?
