Tips for Dark Nebula Processing - LRGB [Deep Sky] Processing techniques · Megsgallery · ... · 10 · 612 · 3

You are right about more data being what is needed for you to get a better result. Unfortunately, there is no post-processing cure for a lack of data when shooting broadband targets. You mentioned you shot that on a moonlit night which is another big problem. I personally don't shoot broadband when the moon is above the horizon. 

I see two things in your images - noise, and gradient issues. You can help reduce noise by reducing the amount you stretch your image and by also running NoiseXterminator. I wouldn't drizzle your subs (if you did) if you don't have that many of them. My only other suggestion for decreasing noise is to generate a synthetic luminance sub by combining your RGB subs with your L sub to get all the luminance data into one sub, then follow some tutorials on LRGB combination strategies; this will help pull the most signal out of your data as possible. PixInsight has a great tutorial for this on their youtube channel. Here is part 1 https://www.youtube.com/watch?v=eciH4yn3r0Q. Actually I think this just focuses on LRGB combination as opposed to the RGB+L strategy I mentioned, but that is a two part step. Part 1 is create the RGB+L luminance sub and Part 2 is to follow the tutorial linked above. 

As for the gradient, it looks like you have something strange going on - like an improper gradient removal. When dealing with an image that has a lot of stars and a lot of nebulosity, it can help to remove the stars first before doing your gradient correction. There are a number of gradient removal tools but I am mostly familiar with DBE. Remove the stars using whatever script you like - I use StarXterminator, for example. Then on the starless image, set your DBE sample points, targeting areas that have no, or as little nebulosity as possible. The more sample points, the better (in general), but experiment with the number of and placement of sample points. 

You mention you used SPCC but your colors look very off. Lots of green and purple which you should not have. SPCC should be one of the first things you run - either right before or after DBE. You should then run a linked STF stretch and see good looking star colors. Ensure you are running SPCC correctly.

I agree with both posts here! I shot this a while back and in all honesty I really should reprocess it as I’m sure I could process it better now. Its about 5.5hrs of data in bortle 4 skies with my esprit 100 and 2600mc pro.
https://www.astrobin.com/ci9phg/

1st I’d try to reprocess the data because as last 2 posters commented its got a wierd look to it, however Moonlite can do things like this in my experience.

If your kinda at your best go with it, and you want to take what you have and do 2 things to this variation then I suggest the following.

1) I’d run the “Gradiant Corrretion” process at even just default settings but you can tweak them and get things better but it’s a good start. With this process DBE and ABE are pretty much absolete now.
2) run SCNR to remove the green appearance.
3) then run the script “CorrectMagentaStars”. These 2 steps with help out with the color issue you have.
4) as mentioned you need to run some sort of noise reduction. If you don’t have NXT then use one of the NR tools in PI.

Once you get this done I think it will help get you closer to what your looking for but I will add that more data especially in dark moonless skies will  help you out a ton!

Dale

Here is the thread for the "gradient" that wasn't. 

https://www.astrobin.com/forum/c/astrophotography/deep-sky/anyone-know-whats-going-on-with-this-image/

This video was so helpful!  Thank you!

I was applying luminance using the wrong settings in LRGB channel combo, and I was also not making sure my luminance data “matched” the brightness of my RGB master.   I think that was a huge part of what I was doing wrong (among other things). 

Thanks for sending this!   Way easier to follow (and faster) than the Block tutorials.  I love Adam’s videos, but sometimes it’s just …. Too much (and yet not enough).  

Jeff Nibler:
You are right about more data being what is needed for you to get a better result. Unfortunately, there is no post-processing cure for a lack of data when shooting broadband targets. You mentioned you shot that on a moonlit night which is another big problem. I personally don't shoot broadband when the moon is above the horizon. 

I see two things in your images - noise, and gradient issues. You can help reduce noise by reducing the amount you stretch your image and by also running NoiseXterminator. I wouldn't drizzle your subs (if you did) if you don't have that many of them. My only other suggestion for decreasing noise is to generate a synthetic luminance sub by combining your RGB subs with your L sub to get all the luminance data into one sub, then follow some tutorials on LRGB combination strategies; this will help pull the most signal out of your data as possible. PixInsight has a great tutorial for this on their youtube channel. Here is part 1 https://www.youtube.com/watch?v=eciH4yn3r0Q. Actually I think this just focuses on LRGB combination as opposed to the RGB+L strategy I mentioned, but that is a two part step. Part 1 is create the RGB+L luminance sub and Part 2 is to follow the tutorial linked above. 

As for the gradient, it looks like you have something strange going on - like an improper gradient removal. When dealing with an image that has a lot of stars and a lot of nebulosity, it can help to remove the stars first before doing your gradient correction. There are a number of gradient removal tools but I am mostly familiar with DBE. Remove the stars using whatever script you like - I use StarXterminator, for example. Then on the starless image, set your DBE sample points, targeting areas that have no, or as little nebulosity as possible. The more sample points, the better (in general), but experiment with the number of and placement of sample points. 

You mention you used SPCC but your colors look very off. Lots of green and purple which you should not have. SPCC should be one of the first things you run - either right before or after DBE. You should then run a linked STF stretch and see good looking star colors. Ensure you are running SPCC correctly.

Thanks to everyone who has replied already!   Such a great help!

1.  Yes, even though it was a Bortle 1 sky, I do think the moon compromised my luminance data.  By the time I got to RGB, the moon had already set, which helped, but not enough.

I have the same scope that you used, the Stellarvue SVX-102T (amongst others) and I shoot from Bortle 1.

I shoot in OSC, with a 2600MC,  and dont use any filters at all.

I also dont bother shooting when the moon is up. the Moon makes my Bortle 1 site more like a bortle 8/9 and destroys the Subs.

Good Luck with the Data, and hope things work out.