ReVisited - HaLRGB with ASI1600 and Samyang 135mm - Andromeda Galaxy M31

[bdlbug]

I revisited this after a week break, also managed to get significantly more imaging time in last Monday and Tuesday nights

I got a lot of great advice from my original post,

I used a new tool as I couldn't get GradX to work effectively on the high gradients I get from light pollution in my location so I downloaded AstroFlat Pro plugin for PS  http://www.prodigitalsoftware.com/AstroFlatPro1_News.html

AstroFlat Pro worked really well on L, mergedRGB and Ha removing gradient that was on my original post

So below is the result of a lot more data and different processing, I tried two different methods to add in Ha, one replacing  the RED channel with a mix of R + Ha and one that put the Ha as a RED channel layer

Below is a Ha included as  Red channel layer with a Lighten blend (http://bf-astro.com/tutorial/addHa.htm)

L - 1.5hr , R,G,B 1hr each, Ha (7nm) - 2.5hr

L,R,G,B taken in 30s subs, Ha in 60s subs

The resulting image  seems quite a  'warm' , so I don't think I have got the Ha blend on red channel quite right yet, image is cropped as I didnt quite match the framing across my sessions,

Appreciate comments and advice

Bryan

 

[celestron8g8]

I like that bottom image best . It's more realistic to me except there seems to be too much red in a lot of the stars . However the first one is really nice also !

[bdlbug]

Yes - that's where my beginners processing  knowledge is missing. I am using different techniques referenced on SGL and internet searches but blending Ha has many different methods and clearly the one I chose is definitely making my image too red overall and impacting the star colour.

Bryan

[bdlbug]

tried out a re-blend of Ha using Rob Gendler description http://www.robgendlerastropics.com/HARGB.html

I think this version has much less red on the stars but does enhance the Ha in the galaxy spiral arms

 

Bryan

[ziofrancotto]

I prefer the first version because it's warmer.

[ollypenrice]

My own method for adding Ha to (L)RGB comes, from memory, from Rob Gendler - who is a very nice guy. I'm afraid I can't remember the original link but here's my view.

1) Ha is deep red so it belongs in the red channel, not in the luminance.

2) If you add it to red in Ps using Blend Mode Lighten it will only appear in the red channel where it is brighter than the red channel, so stars should be unaffected. If they are affected go back a step and run some star reduction routines on the Ha. (Noel's Actions.)

3) While adding Ha to red in blend mode lighten you can blink the Ha top layer on and off to see what it's doing. If it's affecting your stars, see stage 2. If it's lifting the background sky in red use Levels to black clip it slightly so it doesn't raise the background. If it's affecting the image in a place you don't like, just use the eraser.

4) Remember that when you are adding Ha to red you are not neessarily trying to add a nice Ha image. I frequently add absolutely horrible Ha images to red, knowing that only the brightest parts will appear in the final result. In galaxies this is often, quite honestly, just a few diffuse red 'blobs' of star formation.

5) You cannot replace red with Ha because the Ha stars are far smaller and because not all red comes from Ha.

6) When you have made an HaLRGB from your LRGB you can always paste it on top of the LRGB and erase what hasn't worked.

Olly

[bdlbug]

Olly,thank you I have revisited this image this evening and used a 'lighter' touch in blending the Ha into the Red channel still using Rob Gendler 's process as you outlined. The stars don't have the red shift that my other processing efforts produced I didn't have to use Noels actions to reduce Ha stars. So three weeks from first data capture and many hours of reading, learning new PS skills and applying new techniques my first 'real' HaLRGB image using my new ASI1600 : M31 Andromeda Galaxy - August 2017

thanks everyone, Bryan

[ollypenrice]

That's a very good image. The whole charm of this game is that you can go on improving, but you'll need increasing amounts of learning to produce decreasing amounts of improvement! Tell me about it...

Olly