Found some unprocessed M42 subs

[Space Oddities]

So many clouds lately, I haven't been able to image anything since end of September... so I looked into my hard drive for something to work on, maybe reprocess one, and I found some subs of the Orion nebula that I never used. Data is from February 2022, I was testing the back focus of my small Omegon 72ED refactor, and the stars weren't great in the corners.

Now that I'm not afraid of PixInsight anymore, I thought I'd give it a try and improve my processing technique at the same time. I didn't think I'd manage something good out of this data, but I'm quite pleased actually!   You've got to love what modern sensors and software can do in 2022!

This is what I started with, a stack of 20 x 5min subs, taken with the ZWO ASI2600MC and an Omegon 72ED f/5.5 APO doublet. I believe I used the Antlia ALP-T dual band filter.

As you can see the back spacing needed some work...

The process I used, as far as I can remember:

• Cropped the image to get rid of the most distorted stars
• Realigned the channels
• Removed the stars using StarsXTerminator... which ran for maybe 5 minutes! The new algorithm works really well, but damn, it is slow... The funny thing is that it left 1 star, the bright one in the Running Man... oh well, good enough!
• When autostretched the core is really blown out, so I used Bill Blanshan's stretch script, that worked well to keep the core from saturating
• Used a range mask to select the nebulosity and exclude the core, and used this mask to add some slight curves modifications to the rest of the nebula
• I wanted to sharpen the fine details of the nebula, so I used the Unsharp process to do this. It also added some noise of course...
• ... which I took care of with a first pass of NoiseXTerminator. As always, it did an amazing job!
• The colors needed some work, so I balanced it the best I could. Made the blue pop a bit more, the red as well, and of course removed some of the green that's always there. I kind of like the slight orange tint, which is there because I don't know how to remove it... so I thought I'd keep it!
• Before adding the stars back, I added some saturations to them, and put them back in the main image using Pixelmath. I like that part of the processing, it feels the final image is coming to life!
• I ran a bit of deconvolution to enhance the stars, but a side effect I didn't expect is that it also enhances the details in the nebulosity... So I tweaked the settings to find the right balance
• A last touch of noise reduction, a last touch of color balancing, another crop to center the nebula... and voilà!  

Let me know what you think or what I could improve! I still have so much to learn in Pixinsight, so every tip helps

 

 

[The Lazy Astronomer]

That is looking nice, good detail in there, and I like the colour too!

Just looking at your processing summary: deconvolution should be done when the image is still linear - it's one of the first things l do (after cropping and background extraction). The idea behind deconvolution is to reverse some of the blurring caused by the atmosphere, and in order for the algorithm to function properly, it needs a measurement of the point spread function (PSF), which you can think of as essentially the amount of blurring that has been caused to a point source of light. As stars are point sources of light, you can measure them to derive the PSF, but crucially, the image needs to be linear to get a proper measurement.

[Space Oddities]

Thank you, that's very helpful! I'll keep that in mind next time   Learning something new everyday!