[avandonk]

If you use ICNR for your flats you are already subtracting a dark in camera if the exposure is one second or more.

Before I built the fridge I always used to use ICNR for flats and lights. With the camera inside the fridge and the ICNR off for collecting data (lights) it is impractical to switch the ICNR on just for the flats.

I got a very obvious banding pattern in one of my HDR images and it was coming from even seven second exposures at 200 ISO to get the trap in M42! There is no noise in a seven second exposure at 200ISO is a very wrong assumption!

It took me a while to figure out what was going on. I thought I would pass on the info.

Below are a couple of images showing the effect. One is a crop from the top left corner.

Bert