Critical warning in flat field calibration

Dear Mabula, all,

While trying to calibrate data, I ran into a critical warning during the process to generate a master flat image.

I think I found the source of the issue, but I cannot solve it. A few days ago I generated a BPM and master bias for my camera. I used data obtained from a Nikon D600 dSLR full frame camera, via an ASIAIR unit to do so. 

Using the MB frame I want to calibrate some older flat frames I made in 2021 and generate a master flat. I know this is not ideal, but I could not find the MB I made back then, so I figured using the current MB is better than nothing.

Anyway, there is some issue in combining these old flat frames and the newer MB frame. It states that it cannot properly perform the flat field calibration properly and that the flat frames require a MB with the same ISO/gain as the flat frames. But this IS the case, since my MB frame and the flat frames are both shot with the same camera and at ISO400.

The only difference is that the MB is generated with Nikon D600 data obtained using an ASIAIR. The flat frames are obtained from my Nikon D600 camera directly. I see in the dimensions header that there is some difference between the MB frame and the flat frames. Next to the flat frames it gives a range of resolutions... But when I look at the resolution from the flat frames in windows explorer, it exactly matches the MB frame (6034 x 4028).

Am I doing something wrong, or is this possibly a bug in APP?

I am using the most recent version, 2.0.0-beta29.

Best regards,

Rob