Hello all  i m strugglin since a few hours to process the file of job 1196.  i cant find a way to calibrate correctly Lum file . all the fits of this job are shoot in september so i use the latest calib file . Here is the result of the integration with WPBB with Lum file and calib file:  We can see lots of dust donut  i try all sort of combination of calib file , corrected flat film by adding some value , it doesnt work  after a while i integrated without any flats :  And here is my flat file used before :  we can see that the big donut low-left , is not exactly at the same place on the flat file than on the integration file.  it is obvious if you switch rapidily between frames in pixinsight.  I think that the cam has rotate since the flat have been shoot or that dust have move .  As it is an open scope , i think that flats have to be taken more more often than one each 6months Also , with this camera , you should take way longer flat .  the LUM flat are 0.02s long exposure. I ve read that on some cmos camera , very short exposure raise problem. I think you should try a dimmer flat planel and have flats shoot with +1s long exposure .  i dont know if somebody have succeeded to deals with L file on this scope but if yes, please share the recipe   thansk  florent