Probs with darks, flats and bias subtraction

[Russe]

Yeah, the lights were clearly rubbish. But these were done on an Alt/Az mount in windy conditions...

What I'm getting more and more confused about is flats. Everyone seems to say smth else.

How long would you expose a flat for? And what sort of brightness and gain settings would you use?

The histogram idea seemed like a good one in order to control over exposure??

[NickK]

I'll get to this later tonight.