A question of darks

[TrevorW]

This may have been asked before and I missed it

can the exposure time for darks be greater than that of the lights or must they be the same

????:shrug:

[Terry B]

Yes they can but it simplifies things if they are taken at the same temp and exposure. You can then just subtract a master dark frm your images with no fiddling.
Many programs have an algorithm to divide the darks by the appropriate amount to adjust for the diffenrence in exposure time. Iris and CCDSoft are both examples that do this.