IC 4756 is an open cluster in Serpens constellation. 9x30s exposures at f/5.6, IS=6400 with Nikon D5 DSLR, Nikkor 300mm 2.8GVR2 lens, IDAS LPS D1 QRO filter, Avalon Linear mount, MGEN3 guider.
Nikon 70-200 2.8E FL lens at 170mm and f/4, Nikon D5 DSLR, 15x80s, ISO1600, Avalon Linear mount, MGEN3 autoguider. Targets were only 20° over the horizon.
