4 hours exposure of the Horsehead Nebula, captured from a bortle 3 skies. I used an Svbony SV555 refractor to make this capture. Aperture: 54mm Focal Length: 243mm Focal Ratio: f/4.5 to f/22 Optics: Triplet Petzval APO Image Circle: 44mm Aperture Blades: 14 pieces Focus: Manual single speed Filter Diameter: 2” Total Weight: 4.4 lbs The image: 4 hours of processed light exposure from OSC cam, each sub was 10 minutes at 100 gain. Enjoy! #horseheadnebula