Eta Carinae Nebula is narrowband (SHO). Given the brightness of Eta C, I tried experimenting with this as a fast narrowband image using just 60 second subs: 29 x 60sec Ha, 25 x 60sec Oiii, and 25 x 60sec Sii. Taken with the ASI1600MM-C camera using Unity settings, at -25C. Scope was the TS 115mm APO, at f5.5. Processed in DSS and Photoshop CC.
This was my first attempt at Eta Carinae with this camera. The short subs were an attempt to avoid core blowout, unfortunately it also restricts the gathering of the fainter wider field gas data which shows up in long NB subs (like 300s +). At least it is not grainy.
Likely a layer mask approach is required for the core and I will return to this soon, with a longer sub version. Yes, my colour scheme is an acquired taste.
Astrobin details page here:
http://www.astrobin.com/274381/
Full screen here:
http://www.astrobin.com/full/274381/0/
Thumbnail is included here but in usual low quality form.