I was using Siril for preprocessing and when calibrating my lights I was getting an error message that 99% of my pixels have negative values after subtracting darks. After some troubleshooting I found that the average pixel values of my darks and biases were about three times higher then the background of my lights. I retook my biases to check if my lens cap was not fitting correctly and the new biases were no different. How is this possible? Has anyone else experienced this? As a work around I stretched the lights and then performed calibration, but there must be some explanation of why my darks and biases are too bright.
My flats and darks are brighter than my lights
Well Written Engaging
The most likely explanation is that the lights were taken with rather different settings (offset and gain) than the bias/darks. As a workaround add the required offset to the lights.
Well Written Concise
Thank you, and I believe your correct. I took all the calibration frames a day after taking my lights and I must have changed settings.
flats overcorrecting in siril?
=MsoNormal I shoot with a Canon DSLR/Tamron zoom, and collect lights, darks, flats, and flat darks each session. I shoot from a somewhat light-polluted suburban location (Bortle 7?). Here is an example sub of CrB using the Histogram autostretch view ...
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