[Shiraz (Ray)]

trying to remember what I did...I think that the following is the philosophy used.

Using DBE to extract the flat from a sub will give a flat that includes the bias and dark current - which have to be removed. With a cooled Sony CCD, it was good enough to just subtract a fixed bias value, but with a DSLR, you will probably need to subtract the master dark (which should include the bias) from the chosen sub before doing the DBE background extraction (could either do a dark-only calibration on the single sub that you want to use or just use pixelmath to do the subtraction). Then you will end up with a flat that has no bias or dark, so will not have "calibrate" checked for the flat when you do the final calibration of the subs.

IF the Master Dark includes the Bias THEN
sub - masterdark
DBE
ELSE
sub - masterdark - master bias
DBE
ENDIF