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OK, I did some work on this last night.
At the weekend I compiled a new library of dark, bias and flat frames. A heap of them.
I then compiled master dark and master bias frames in PI last night. They were integrated separately ie the bias frames didn't come near the darks.
When severely stretched, I see readout artefacts in the same columns for both the master dark and master bias frames. They also line up with the lights.
So the bias frames aren't adding to the problem - its inherent in the camera readout.
So I'm back to 2 alternatives - a hot pixel that gets shuffled along a column till its read - assuming that the KAF16803 chip is read along the bottom rather than at the side - or I have a few column defects.
Could it be anything else?
Playing with Cosmetic Correction in PI last night, I also found that the most troublesome defect - which only extends about 1/3 of the way up a frame - wasn't being corrected as I had set the column number incorrectly. Moving it by 1 pixel seemed to deal with it. I need to play with it a bit more this evening but I'm hopeful that I can simply remove these in calibration.
I've posted on the other thread dealing with overscan. I'd like to play with that feature in PI but I don't think that it will solve this readout issue.
Pete
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