The Whirlpool (M51)
The Whirlpool is the object that got me into imaging and I just keep coming back to it. It is a grand design spiral galaxy that is undergoing an interaction with the accompanying galaxy. The pair are located about 25 million light-years away. Astrophotographers talk a lot about 'deep images' at times. Using the NASA Extragalactic Database I picked out a few of the brighter background galaxies (for example SDSS J132940.44+471440.3) down to magnitude 20.5, so given that there a quite a few fainter ones scattered about this is a fairly 'deep image.'
This is three hours and twenty-five minutes of five minute exposures captured with a 6D at iso 1600 through a Meade 14"SCT @f10. The image was calibrated with darks flats and bias frames, and stacked/processed in Pixinsight.