A "simple" question, what is a good number of flats to take and why?
Wherever I read about it the flats get put in the same basket as the darks and the biases. For example, the
DSS page talks about all three at the same time and about needing up to a 100 (of each) for the best results.
Now, in the dark/bias images the dark/bias signal has a similar order of magnitude as the noise. Making lots of images will smooth out the noise and leave almost only the dark/bias signal. Flats on the other hand have a very large light component, much larger than the noise. So why do we need lots of flats?
Just trying to reduce time standing in the cold
Thanks in advance,
Luka