Quote:
Originally Posted by The_bluester
Regards different methods. I have found some data sets quite tolerant of calibration with a master bias and master flat (Which itself is produced from flats calibrated with the same master bias) but on others it led to brightened corners. Typically narrowband or LRGB images where I am trying to get away with the shortest subs I can, so the background is only just above the noise floor, master flat/master dark calibration proved better on some of those.
I have not found a data set of my own where calibrating with a master dark and master flat that that was calibrated with a master bias is worse than using a master bias instead of master dark, so I just do everything that way now. But everyone is free to use whatever process gets them a result they are happy with, many ways to pluck that running chicken!
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I generally do not subtract a bias from my flats as its double dipping and I have seen it result in a poor calibration. I can always specify subtract a bias from the flat when calibrating in CCDstack.
With CMOS i read its often recommended to do flat darks rather than a bias.
But the pain there is these CMOS cameras don't have a shutter so it makes taking darks a more tedious process due to having to cap the camera
Greg.