The largest and brightest galaxy in this image is NGC7331, also known as the Deer Lick Galaxy. The Deer Lick Group includes the galaxies around NGC 7311, most of which are above and to the right of the main galaxy.

The galaxies in Stephen's Quintet are the small cluster of galaxies in the lower left side.

This picture certainly needs more exposure time. Currently there is almost 4 and a half hours in it and the dimmer, smaller galaxies are just beginning to show up.