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Firstly, you have some wonderful data there. The Ha loops are well defined and nice tight round stars. Well done. You're at first base.
As Alex and Marc have pointed out Ha blending is tricky business.
I myself am doing this exact same object and I have done this sort of thing a lot. But I got to the end and wasn't happy with it so I am also back to the drawing board.
I even started watching Adam Block's Ha blending tutorial (his tutorials are usually great but this one is very poorly done, very tedious and unclear).
There are basically 2 or 3 approaches to Ha. Marcus here is very good at the lum + Ha approach and Ha + red layer approach. This is Rob Gendler and Adam Block approach.
You basically make a blend of Ha and Lum and also Ha and red. It is not as simple as that though. It is beyond a short post here and I suggest if you want to use that technique have a look at Rob Gendlers site where he details it. Adam Block I believe has extended that technique further and is quite detailed and he has an educational DVD on his processing techniques which is very good.
Also I might add manually aligning all your subs sounds like very very hard work. Try a free trial of CCDstack for that sort of work. It does that hack work very well.
A simple yet powerful approach to Ha is:
1. Do your LRGB image as usual. Get it as nice as you would normally.
You could pump up the saturation a tad as it will eventually get washed a tad by the Ha as luminance.
2. Make a new layer call it Ha red.
3. Open your processed Ha image (get it to the point you would post it by itself). Copy it and paste it to the new layer. That is control A, control C click on the new layer to make it active then control V.
One point with Ha, I would tend to make the background of the Ha a little bit dark as you don't want your final image to have red background everywhere which it can easily so darken the background of Ha a tad using levels. Running a noise filter on Ha can also be good as you don't want little red dots in your final image either.
4. Set the new layer to lighten mode. Lighten mode means only those pixels below it that are lighter than the ones above it show through. You want this. This means the dimmer Ha stars which are awful won't wreck your lovely LRGB stars (or so the theory goes).
5. Duplicate this Ha red layer 2 times. Call one Ha blue and one Ha luminance.
6. Now make the Ha red laye active (click on the layer and it goes blue in the layers dialogue box).
7. Click on channels. Hold down the shift key and click on green and blue. Now control A and hit delete. You just deleted the green and red channel and left only red. Set opacity to suit the image. Perhaps 50%, perhaps 100%.
Now if you use curves and the curve is positive in shape then you boost the red and it goes above the LRGB image brightness and shows through. So now you have control over how much red will shine through - nice eh?
8. Do the same for the Ha blue layer except delete red and green.
Set opacity on the blue layer to only about 10% as you are only adding a small amount of blue to match the H beta content of the nebula and I am told its about 105 or thereabouts.
9. Set the Ha luminance layer to luminosity blend mode. Here adjust to suit and this you tend to only use a small amount of as it will create the salmon colours if done too hard. So perhaps only 20% opacity otherwise you're back to what you already posted - Ha luminace washing out your LRGB and creating a false salmon coloured look.
This is exactly what I do almost all the time with Ha and it usually works really well. This is essentially the Tony Hallas technique and I like it as it is simple and you have control over the reds, you don't have the horrible red stars (usually but a few seem to get through and you clean them up with the healing tool or clone tool).
It does assume a good Ha image to start with which is detailed and low in noise.
Good luck with it.
Greg.
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