How to get rid of Alnitaks blodge?

Thanks a lot for the tipp - and the insight that the Askar might have caused it.
Its somehow escalated during GHS stretching and was too tough to fix it with clonestamp process or colormod script.
StarXTerminator also is already in use - so I might be scratching the barrel :-)

BTW: Do you understand, why some filter create stronger blodges than others?

Arny

Arny:
Thanks a lot for the tipp - and the insight that the Askar might have caused it.
Its somehow escalated during GHS stretching and was too tough to fix it with clonestamp process or colormod script.
StarXTerminator also is already in use - so I might be scratching the barrel :-)

BTW: Do you understand, why some filter create stronger blodges than others?

Arny

https://www.researchgate.net/publication/377357274_Understanding_Filter_Induced_Star_Halos Thinis the most detailed explanation I’ve come across. Filter off band blocking performance, reflections within the filter, filter thickness

Andrea posted a link to their tutorial. That’s probably going to be you’re best solution. I’m not aware of anything that will work better.

Arny:
I took this image of FlameNebula and Alnitak, but can't get rid of the incredible blodge around Alnitak, which stems from the filters used.

Any idea how to get rid of this artefact in Pixinsight?

Image was taken on an 11" EdgeHD with L-Enhance OH and Askar OS dualband filters on an ASI2600mc OSC.
Integration time 2h15, flats taken that night.

https://www.astrobin.com/8869xz/

Despite what everyone else is saying about filters, ontop of those, that's just the internal reflections from the EdgeHD optical design. To get rid of these from this point on, you'll need to either flock the telescope with flocking paper, or buy some vantablack paint to coat the insides of the tube & the T-Adapter/baffle with. This is an issue with all SCT's when dealing with bright stars, that reflections can occur.

Alternatively (wouldn't be my pick) you can sell the 11 and go for a similar optical system that does not use a Schmidt Corrector Plate.

I definitely agree that the Edge HD optical system can be prone to those issues. I have had them with my Edge 11 myself with running the Hyperstar config (my understanding is that faster optics are also going to have a greater impact) with an Antila highspeed filter which was absolute trash. Not only did it have harsh haloing, but also caused internal reflections. This issue was eliminated by swapping it out for an IDAS UHS filter and haloing was minimal. Results may vary.

Precisely, IDAS UHS is a really good filter. I'm wanting to get one myself, but I don't really see the benefit in Bortle 3.

If you have a Hyperstar / OSC, then the IDAS UHS would be my goto recommendation. If you’re imaging at f7 or f10 then I’d look at a mono camera and 3nm bandpass NB filters. (I use a OSC and Optolong Extreme.) I believe the extreme in 5-7nm but don’t remember. I’m in a Bortle 7 | SQM about 18+.

Although the IDAS isn’t going to be as effective as a 3nm it should be drastically better than nothing or a standard LP broadband filter when used on emission nebulae.

On the lower end, I think Optolong recently came out with the l-ultimates that have a 3nm bandpass in Ha an Oiii. They claim that it has virtually no haloing on 52 Cyg / Witches broom, but I don’t have any 1st hand experience.

Ideally we’d all have Chroma filters.

I use the same OSC. Great pixel matching at f10/7 imo. Looking at 6200MC or MM for Hyperstar and my ES 152 APO.

What do you mean by, 6200 doesn’t some close to the numbers…? I thought that the 6200 would be better for lower FLs, has higher resolution and bit depth. It has lower full well than the 100k e, but that’s due to pixel size. I thought the only downsides were price, large file size, and fullwell depth.