Can I use a bad pixel map as a dark flat ?

[View2]

Can you use a bad pixel map for a dark flat frame?

[ollypenrice]

5 hours ago, View2 said:

Can you use a bad pixel map for a dark flat frame?

Old thread!

The answer is no. The dark flat does not just remove noise, it removes the bias offset as well. If this is not done you may well find that your flats over-correct.

Assuming your flats are shot at short exposure times there is no significant build up of thermal noise so a dedicated dark shot at the same exposure as the flats will be no different from a master bias, so just use a master bias as a dark for your flats. If it helps your sanity you could always rename a copied master bias, calling it Dark Flat.

I'm a great believer in not doing more work than is necessary!

Olly