Pencil Nebula in (mainly) narrowband

DiscoDuck (Paul) · #1 22-03-2015, 11:01 AM

I've been trying to get to grips with combining Ha and OIII into a synthetic colour image.

Attached is the pencil nebula with about 3 hours each of Ha and OIII. The stars seemed a bit unrealistic looking, so I threw in the stars from about 20 mins of RGB data I had (couple of practise shots the other week whilst waiting for the Leo Triplet to come up high enough!).

Comments/advice appreciated. The technique I used was based on http://lightvortexastronomy.blogspot...guide-for.html though I used a blend in the blue channel (about 75% OIII and 25% Ha). Obviously more data would help. Also the res is quite low as this is from a OSC camera (QHY8) mounted on an RC8 scope.

Paul

rustigsmed (Russell) · #2 24-03-2015, 07:23 PM

I can't offer any advice Paul but I know it's a difficult target.
Thanks for sharing!

Rusty

gregbradley · #3 24-03-2015, 07:47 PM

Nice image. A bit green. The Ray is more bluish and pink. See Steve's recent version. The colour on that one is very accurate.

Usually in bicolour its Ha red + ((Ha+(2 x O111))/2 green and O111 blue.

Greg.

Stevec35 (Steve) · #4 24-03-2015, 10:27 PM

You're getting there Paul. OIII is nearer blue than green so if you follow Greg's instructions you are pretty close. Noel Carboni's suite of photoshop actions has one that simulates the green channel if you supply red and blue. I use it sometimes and it works pretty well.

Cheers

Steve

DiscoDuck (Paul) · #5 25-03-2015, 07:29 PM

Thanks for the advice guys.

A quick reprocess attached. Hopefully this is closer to the true colour balance. (This one is purely narrowband - the stars didn't look too bad this second time!). More data needed - especially when viewed next to Steve's amazing image

Paul

P.S. A friend punned that I should be using some sharpening tools given it's the Pencil Nebula

Stevec35 (Steve) · #6 25-03-2015, 08:14 PM

Thanks for the comment about my image Paul. I think you've pretty well nailed the colour balance this time. It's a bit noisy though which of course just emphasizes the fact that you need a lot of exposure to pick up the faint stuff with this one.

Cheers

Steve