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Thanks Malcolm.
I did read a thread on Cloudy Nights where it stated that ZWO recommended you don't use bias frames with ASI cameras and better to use flat darks (ie a dark same exposure length and temperature as the flat).
I don't know why but I did notice that the noise grain on the ASI6200 seemed to be unstable between images on the posted darks earlier in this thread.
I checked my darks for my KAF16200 and it did not do that. So perhaps the Bias is unstable and drifts in these cameras. That would explain it.
Its not the end of the world it just means you need to understand the character of the camera and how to use it to its best advantage. These cameras are so clean do even need bias and darks? I doubt it. StrongmanMike and me do not (did not) use calibration frames with a Trius 694 camera. I would use bias frames occasionally as that camera would sometimes give fixed pattern noise (a gridlike structure).
Greg.
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