I managed to get out for an hour or so last Thursday... I would have stayed longer but the clouds arrived. I took three dark frames, moved the equipment indoors and then it rained!
So, this is 14x2 minutes at ISO800 with the EOS 1000D and CLS clip filter through a megrez 72 telescope with flattener III (344mm f4.8 ) mounted on an astrotrac.
Processed with deep sky stacker and pixinsight LE, this is the first time I have used flat fields. The reason I tried is that I was getting some distinctive vignetting... dark top corners and a dark band all along the bottom of the frame. It was in all my images taken with this configuration. My theory is that it is the frame of the clip filter (which has a flat bottom). It doesn't show in pictures with camera lenses and the clip filter... maybe the image circle of the scope is larger?
Anyway, the flat fields solved the problem nicely. So well that I haven't done background synthesis and subtraction. I re-processed my Aldebaran picture too and the flats made it much less noisy (due to no subtraction I think).
I'll try the Pleiades again... next time I'll go for 3 minute subs!