A fantastic object and one of my favorites: this is the large hydrogen bubble in Cepheus. I imaged it from several locations and with varying focal lenghts: 135mm, 180mm, 420mm, and now with the new Esprit 120mm F/7 at a focal length of 840mm.
The image was taken from my backyard in Hoegaarden, Belgium, under an average sky (SQM readings 20,40-20,70), during the night of August 15-16 2018. Camera was the Nikon D750, only a lightpollution filter was used (no narrowband filters).
420mm (TS APO 420 Quadruplet):
Focal length 180mm. (Nikon 180mm F2.8 ED) from Hoegaarden