So, to rule out other potential sources of error, I tried a white, flat wall instead of my flat field mask to create the flats. Later on, I also replaced my C8 with a fisheye lens on the camera. But that doesn't change the fact that my master flats remain overcorrected! The lights I get are also very unclean as a result.
I naturally ask myself why I didn't notice this earlier. That's probably because I've only been creating flats for a relatively short time and the black level in my few previous attempts was always set to 0 or at least to a very low value, the effect of which I had hardly noticed visually at first. It was only during my last attempts to take solar photos and calibrate everything that it became really noticeable...
The number of possible causes is now pretty limited:
1. I'm caught in a serious mistake in my thinking or operation! In this case, please tell me what it is...
2. All three of my astrocams are defective...
3. The ToupTek drivers used (native
and ASCOM) are unreliable.
Here is a request to all readers of this thread: Please, maybe someone with a camera from another manufacturer and otherwise similar equipment can provide evidence to the contrary by reproducing the above process with a non-ToupTek (or its re-brand) camera...
4. The problem lies in SharpCap's internal processing. In this case, it must have something to do with the black level in combination with the bias frames / flat darks and the offset-value in the FITS-Filename.
Note: The cause of the overcorrection was not (as initially suspected) in the FITS header ("ROWORDER"). The fact that the overcorrection disappeared during my experiments with ROWORDER was simply because I renamed the file names and the offset entry was thus unconsciously overridden.
Regards
StarFlea
