Deep widefield Ha images, Gum and Eta Car. Nebs

[tornado33]

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

[davidpretorius]

nice work as always scott

[seeker372011]

scott, this may be a silly question but why the uv/ir filter in addition to H alpha? shouldnt the narrow band filter out all other wavelengths?

[tornado33]

No its a fair question. I dont think the HA filter blocks oud the deeper infra red, as it was designed in assumption the imaging gear would have an IR cutoff filter. Note the graph, infra red below 1100 gets through. When taking High ISO test images without the uv/ir filter I was getting a reddish light background that I assume was some of this IR light getting through.
Scott

[seeker372011]

OIC

(oh I see)

[astroboy]

Great shot of the Gum Neb' Scott:thumbsup:
Be a good full moon night project to stop the lens down and expose for a couple of hours.

zane

[Mick]

Nice images Scott, there is a H-alpha image of the Gum nebular on APOD today.