Now I have started to make a calculator that indicate the theoretical bit resolution that's needed.
Lot of work left but you can already now see my idea behind it.
At the moment it can take bits from camera and number of sub darks used, or even zero darks.
Update:
Now most of the functions are in place. Still big risk of errors in the equations. But I correct then and then.
You can try it here:
http://www.astrofriend.eu/astronomy/...esolution.html
Play with the figures!
Everything can be wrong now in the beginning!
/Lars