Help Please - HH & Flame (HaRGB) - but severe issues with huge halos.....

[geoflewis]

It's been a few years since I imaged this target and that was with the same scope but using a modified Canon 600D DSLR. I captured the Ha last month, since when I've struggled to find a clear sky to add the RGB data, but I got that a couple of nighyt ago, with a nearly 1st Qtr Moon close by. I almost wish that I hadn't bothered as the data from all 3 filters has large halos around the 2 belt stars, with the one around Alnitak a total nightmare. Here is the resultant image, which hasn't been fully processed, as until I can work out how, or even if it's even possible, to fix the halo around Alnitak, then I can't be bothered.....

The gear is:

• Scope - TSOAPO100Q (4" quad)
• Camera - QSI583wsg-5
• Filters - Astronomic Ha6nm and RGB Type 2.

FYI here are the stretched RGB channels.

Red

Green

Blue

I know I'm not the first person to have issues with Alnitak, but as you can see, the halos are double, triple or more for Altinak. I suspect the failure is a combination of back and forth reflections off the filters and the rear lens of the quad scope. I've tried a circluar, feathered raster over the halo in PS then adjusting levels to darken, which does a reasonable job for the interior of the halo, but it leaves a double ring where the edges of the 2 main halos sit. I've tried cloning those rings out, bit by bit, but it's an ugly process, with equaly ugly results. I've seen a tutorial for fixing these large halos in PixInsight, but I don't have that, so has anyone got a method that works, in either old version of PS (I have CS2), or Affinity Photo. I can probably fix the other bright star halos, or just live with them, but the one arond Alnitak is something else entirely.

Thanks for looking and even more thanks if someone can come to my (or this image's) rescue please...... 🤞

 

[peter shah]

Ah yes I see what you mean, I don't know what I was moaning about!!!....I do feel your pain Geof.....Alnitak is bitter sweet....its a pain but without it it just wouldn't be the same....Still a beautiful shot even with Alnitak's wrath.

Edited February 20, 2021 by peter shah
spelling

[peter shah]

I've only had a quick go, but with a bit of time you could get quite an accurate correction.......The damage in the area is already been done so its a case of repair and disguise. Its a difficult one as it has hard edges. This was all done in Photoshop with the colour range tool and and circle selection combined with colour balance to deal with the offending colour in the halo. I then layered the red channel with a circular feather and set it in Luminance mode to deal with the halo. 

On the second image I added some flare to disguise Alnitak.  

Its a long winded process but it can be fixed.

Hope this helps you a little.

[geoflewis]

49 minutes ago, peter shah said:

I've only had a quick go, but with a bit of time you could get quite an accurate correction.......The damage in the area is already been done so its a case of repair and disguise. Its a difficult one as it has hard edges. This was all done in Photoshop with the colour range tool and and circle selection combined with colour balance to deal with the offending colour in the halo. I then layered the red channel with a circular feather and set it in Luminance mode to deal with the halo. 

On the second image I added some flare to disguise Alnitak.  

Its a long winded process but it can be fixed.

Hope this helps you a little

Hi Peter, thanks for doing this. I've been playing with it for hours today, but didn't get close to either of those 2 versions, of which I think the first version looks the best. The attempts that I made always left 2 yellow/green rings where the outer edges of the halos were, but I'm not really much of a photoshop user so don't know what I'm doing......

I'll keep trying.....

[geoflewis]

After a very helpful discussion with @peter shah a couple of weeks ago and too many to count failed processing attempts to 'fix' or at least control the halo around Alnitak, I have finally managed to produce something that is just about passable to my low standards.

The post processing was done in Affinity Photo, comprising probably hundreds of small iterative colour adjustments to the double rind at the halos edges together with brightness & contrast adjustments to the main core of the halo. Lastly I used the red channel as a 50% luminance mask, which further helped to mask (no pun intended) the worst of the many rather crude adjustments that I'd applied. Clearly the halo around Alnitak is still very visible, but I've taken it as far as my limited skills allow, so hopefully it doesn't dominate the image quite as badly as it before.

I have also ordered a set of Chroma LRGB filters (~3 weeks back order), in the hope (🤞) that they will perform better on bright stars, than my existing Astronomic Type 2c LRGB set.

[tooth_dr]

1 hour ago, geoflewis said:

After a very helpful discussion with @peter shah a couple of weeks ago and too many to count failed processing attempts to 'fix' or at least control the halo around Alnitak, I have finally managed to produce something that is just about passable to my low standards.

The post processing was done in Affinity Photo, comprising probably hundreds of small iterative colour adjustments to the double rind at the halos edges together with brightness & contrast adjustments to the main core of the halo. Lastly I used the red channel as a 50% luminance mask, which further helped to mask (no pun intended) the worst of the many rather crude adjustments that I'd applied. Clearly the halo around Alnitak is still very visible, but I've taken it as far as my limited skills allow, so hopefully it doesn't dominate the image quite as badly as it before.

I have also ordered a set of Chroma LRGB filters (~3 weeks back order), in the hope (🤞) that they will perform better on bright stars, than my existing Astronomic Type 2c LRGB set.

That’s a remarkable result Geoff.  Totally acceptable level of halo that does not detract at all from the image. 

[peter shah]

very well repaired Geof

[CraigT82]

Excellent work Geof, well worth the effort.