Currently with my ASI294MC Pro I am using SGP v188.8.131.52 and the ASCOM driver. After having captured with unity gain (setting: 120) for a while, I now for the first time tried to capture at a higher gain (setting: 200). Whereas I got matching values in the FITS header with unity gain (GAIN 120 Camera gain, EGAIN 1.0022 Electrons per ADU), now the information is sometimes conflicting. I am getting images that show all possible combinations of the two GAIN and EGAIN values, right and wrong:
GAIN EGAIN comment 120 1.0022 matching 200 1.0022 not matching 200 0.3989 matching 120 0.3989 not matching
I would like to know why that happens. If I understand it right, the GAIN is the setting that I set, and the EGAIN is the response from the camera. There are two possibilities to set the gain: either in the ASCOM driver or in the Control panel/camera for each binning setting.
How can it occur that EGAIN does not correctly correspond to GAIN in the FITS header?
Which information is the correct one, if the values don’t match?