[Aavso-photometry] Dark-subtracting flat frames

[Greg Crawford]

In the world of pretty picture imaging there is some discussion about not
needing to dark-subtract flat frames. I wonder how well this applies to
photometric imaging?

I normally operate an ST9E at -20C and take flats frames of 2 seconds duration
for V,R & I; and 15 seconds for B. My normal routine is to do 32 flat frames per
filter and median combine each filter's flat frames, then dark subtract a master
flat-dark made from either 32 x 2 second dark frames (for V,R, & I), or 32 x 15
second dark frames (for B).

Am I adding noise to the master flats, wasting my time, or improving the quality
of my photometry?

Greg Crawford