[The_bluester (Paul)]

Good to see that you are getting there, good flats do make a big difference.

Originally Posted by gregbradley

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.

Using Astro Pixel Processor the workflow seems to avoid any double dipping. If you load a master bias frame, a master flat will be created with the master bias subtracted (And if you load bias frames, a master bias is created and then that is subtracted) but if you load a master dark flat, that will be subtracted instead, and the master dark flat will have been created without the master bias being subtracted from it, so it does not double dip.

Same deal with a master dark, they are created from darks only so the bias information is included in that master. If you calibrated lights with a master bias, it will be subtracted but if you load a master dark as well, only that is subtracted form the lights, not both.