Long time since i last tried M51, the Whirlpool Galaxy, now with 500PF on D500, 30sec exposures at ISO 1600 during the narrow slot of dwindling dark around 1:45 am on two different nights, first one at f/5.6, next on at f/6.3, each about 1-2 hours of accumulated 30 sec exposures., the third is a combination stack of the two. Eventually I plan to use a front aperture on the lens - I will initially try an 82mm step-down ring at f/6.1 to minimize diffraction spikes on the stars. Ideally the flat exposures should be done with the hood in place, but existing light panel fit exactly on the front with removed hood and worked quite well in these initial tests. Stacked in DSS and further edited in CNX2. The first is a crop to about 75% of the frame.