You've hit upon something that has been niggling at me. All of the calibration files were shot when I had the bad camera driver installed
I think you may have found it.
Either way, I think the differences in our cameras is going to make my masters not useful for comparison.
My unity gain darks are around 709ADU, your 50second unity gain dark is ~1900 and the 300s is ~1950. I'm surprised by that difference but don't know enough about the QHY offering to know if that's significant. When I calibrate your light, as I'm sure you've seen, it way overcompensates using the dark supplied.
The 300s light has a median ADU of 2160. Even with a 3nm filter, I have a hard time buying that a 300s exposure would only get 200ADU above a dark frame on such a bright object.
I re-wrote the fits header of the 50s dark flat, to 300 seconds to see what would happen if I used the dark flat as a dark for the 300s light. It did reduce the amp glow as I would expect for only being a 50s exposure. So it does appear that for some reason the 300s dark is seemingly way overexposed even though it was taken correctly.
I too couldn't get the flats to calibrate the light, but as I'm sure you've seen the dark flat does look like it's doing it's job. Perhaps it's the focus difference?
Wish I could be of more help, but my ASI 183's seem to be too different.
Edited by kingjamez, 15 September 2019 - 03:05 PM.