Cocoon and B168 Dark Nebula

[Bonamy]

This has been one of the trickiest images I have had to process to date.  The main struggle has been balancing the intense star field whilst trying to pull out the Ha data whilst maintaining the detail in the dark dust clouds.

Aquisition was with a Tak 85FSQ on and SkyWatcher AZ6EQ6GT (recently upgraded with StellarDrive), approximately 4 hours of each L,R,G, and B with 8hours of Ha.

I used Pixinsight to calibrate, and process each channel (DBE, BlurX, RGB combination, NoiseX, and StarX and GHS). I struggled to get the combination of Ha, Lum and RGB  right in Pixinsight, so switched to Photoshop and used non destructive layers to get a blend I was reasonably happy with.

Lovely part of the sky, with so much going on.

 

[Sunshine]

Beautiful, so rich with stars!

[carastro]

Lovely image but there is something not right with the colour.  

[peter shah]

Lovely job, It's a very tricky object to process

[Bonamy]

1 hour ago, carastro said:

Lovely image but there is something not right with the colour.  

Thank you. 

I've been going round in circles with the colour blending. It's really tricky to find true background in the RGB to get a clean set of samples for DBE, and I came to the conclusion that here is quite a bit of variation caused by the dust and the Ha.

I struggled to bring out the Ha in particular, so boosted the Red channel with the Ha as well as a combined Luminance layer. I suspect that may have caused some of the issues.

This is the RGB after stretching, background extraction (as best I could), and star removal. Very blotchy! 

 

[Bonamy]

10 hours ago, peter shah said:

Lovely job, It's a very tricky object to process

Thank you. 

[simmo39]

Lovely image and even if the colour is not to everyones taste it looks good to me.

[ollypenrice]

The image is essentially great, to my eye, but that dusky magenta for the Ha doesn't sit well for me. Did you use a heavy dose of SCNR green? That would slew the hue towards magenta.

However, I think it will be more to do with how you blended the Ha. I keep it very simple and add Ha to red in Blend Mode Lighten. I prefer not to add it to luminance but, if I do, it is only at a very low opacity - 10% max. It can also be useful to boost Ha signal at any time in Ps by going to Selective Colour, Reds, and dropping the cyans in red.

Edit: I don't think your RGB is blotchy but it does show a mild trace of the tile pattern which sometimes arises from StarXterminator. Sometimes I don't get this at all and sometimes it's awful and takes a lot of fixing.

Olly

Edited August 30, 2023 by ollypenrice