Howdy
Decided to try for some very deep Hydrogen Alpha widefield images of the Gum Nebula area.
4x10 mins (40 mins total imaging time) ISO 200, 50mmF1.8 lens @F1.8, (hence the coma present)dark subtracted in IRIS, then red channel only used, finished off in Photoshop
Eta carina area, 2x 10 mins, same settings.
Shot with Baader 7 Nm Ha filter and Hutech uv/ir filter taped together, sitting on the 50mm lens, focus achieved by trial and error shooting 10 sec images then checking focus, till smallest star images obtained, then switching to ISO 200 and RAW image quality. No moon present.
I would have gotten less coma by stopping lens down but Id be there all night getting enough signal, as Brad Moore knows, narrow band filters cut the signal way down. Thought theres some coma theres no Chromatic abberation though, as only one colour is present
Scott