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M20 Processing - Request for the feedback

ZWO ASI662MC Pleiades Astrophoto PixInsight CMOS Processing Request for feedback Deep Sky Emission Nebula M20 Messier Objects Nebula
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Interactive Sky avatar
Interactive Sky avatar

This summer, I’ve done the 2-night project, shooting the M20 aka. Trifid Nebula. I captured it with my Celestron SLT130 (Alt-Az) and ZWO ASI662MC camera.

After I stacked it in WBPP and processed it in PixInsight. Here’s my result:

📷 The_Final.jpgThe_Final.jpgI wonder if the processing could be done better. So, any criticism and advice are welcome, and also here’s the link to the original file; I would be interested in what more experienced astrophotographers could do with it. https://filebin.net/qre4ec55x52cnytk

Clear Skies!

Well written Respectful Engaging
andrea tasselli avatar
andrea tasselli avatar

Not bad but you should always use an good UVIR filter to avoid stars blooming and colour shift. Obviously an Alt-Az mount without a derotator isn’t a good proposition to start with, coupled with the smallish sensor..

Not a lot better but gives a hint.

📷 image.pngimage.png

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andrea tasselli · Jul 23, 2026, 07:57 PM

Not bad but you should always use an good UVIR filter to avoid stars blooming and colour shift. Obviously an Alt-Az mount without a derotator isn’t a good proposition to start with, coupled with the smallish sensor..

Not a lot better but gives a hint.

📷 image.pngimage.png

Hi Andrea,

Thank you for your comment, and I will take a look at the UVIR filter.

By the way, I like how your processing turned out.

Can you tell me what steps you use during the processing, if you are okay with that?

Thanks and clear skies!

Well written Respectful Supportive
andrea tasselli avatar
andrea tasselli avatar

I can’t recall all the steps exactly but essentially:

Linear ABE then cropping the sides a bit, Graxpert (both flattening and denoising) , then BXT and CC. MsAS after that and extraction of the stars. Slight ASinhStretch to boost colours and then shifting of the background into the shadows via HS. Creation of luminance mask, inverted and applied to give a saturation boost to the nebula (but not the background). Back to stars-only and HS again to lower their brightness so as not to be too intrusive. Screen the stars back into the image and further cropping of the sides.

Concise
andrea tasselli avatar
andrea tasselli avatar

Although on a second thought is best to avoid Graxpert and use DBE with carefully chosen sample points for the background, as I shall show shortly(ish)…

📷 image.pngimage.png