Hi
I’ve been taking flats using the t-shirt over lens and pointing at the sky method, however the exposure varies quite strangely between shots. Most of the time I get images with the max and median values down in the low thousands and minimum down in the hundreds but sometimes I get ones where the values seem to be maxed out pretty much at 16384 (14 bit camera). I’m taking the images at 0.001 secs exposure with a sub second download time so I don’t think the sky brightness is changing that rapidly to cause this.

I also seemed to have similar problems determining a suitable exposure to actually take them at with a seemingly random correlation between exposure time and the statistics in the fits viewer.

This is using a sony a7rii camera connected to an astroberry running the latest kstars.

Has anyone noticed this with their setup?

Regards

Nigel

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