Hi John,
I think that 5 min exposures at 1600 iso would be enough for this galaxy and you have stacked quiet a few so should be a good signal to noise ratio. I find that the darks never seem to remove all the amp glow. I usually crop that bit off, mine is in the lower left corner. Maybe its in the way you have processed the picture?
As for the flexture. I am getting the same thing with my new newtonian, its driving me nuts...
. I know its not the mount or my guidescope and always a steady image shift the same way as gravity pulls on the scope, I thought it was my guiding to start but I imaged 4 different things and still the same shift and the stars are oval usually in the same direction as well so things are moving as the image is being taken while the star does not move in the guidescope..maybe the primary cell holder or tube rings or dovetail bar??? made the newt very strong so am very baffled???
Anyone have any suggestions for me and John? or we will end up bald...
Cheers Gary