Messier 51/The Whirlpool long exposure
This is a combined image that I captured on two separate nights with two separate cameras. It consists of three hours and forty minutes of five minute exposures through a Meade 14" SCT at f10, and one hour and fifty-five minutes of five minute exposures through a QSI 583c at -20 with the same telescope. It totals out at five hours and 35 minutes of exposure. Everything is calibrated with flats darks and bias frames, and was stacked/processed in Pixinsight.
I tried quite hard to bring out details in the core, so that was my main focus, but I have measured and confirmed a background galaxy down to magnitude 21.8, so happy days given the light pollution around here!