I have never had to deal with such a difficult image such as this. I tend to keep my scope pointed at northern objects since I am north of a city, but in the case of Orion it was slightly South. As a result, light pollution gradients and glow appeared in multiple corners of the image during the two nights I was imaging back on Thanksgiving weekend of 2016.

However, the benefits of the difficulty of this image were an exponential increase in my understanding of Photoshop techniques as well as an array of new tools to use in post processing. I have been using Star Tools thus far, but much of the light pollution glow was near enough to the Nebula's luminosity that large swaths of it were erased in Star Tools' Wipe module - I needed a more manual approach.

This is an HDR image, meaning I took longer exposures for the nebula, then layered in the shorter exposures over the Core to bring out the Trapezium details. I was fortunate to have forgotten to turn on my dew control for part of an imaging set - the accumulating dew further reduced the brightness of the trapezium during my shorter 30s exposures. I separated these and stacked them into their own Core stack which enabled me to separate 4 of the central stars.

This image is also the first of my autoguided attempts. While I was previously unable to open the shutter for more than 60 seconds (without trailed stars) at Orion's celestial latitude, with guidance I was able to push that to 2.5 minutes, though on my second night I backed off to two minutes to avoid having to delete any significant amount of frames. I probably would have had an easier time with the Core Exposures if I simply maintained the same ISO but reduced the exposure time. Looking back, reducing ISO to 200 yet increasing to 60s exposure makes no sense, but I had it in my head then that more exposure time means a better image. Next year I will try this again, choosing a darker site this time, but also gathering a less complicated set of data.

Special thanks to astropix.com and Carboni's Astronomy Tools, they were each a big help in post.


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2020 Re-edit: Addition of 300" 7nm Hα exposures via my ASI1600MM-P

The challenge was blending in the data when the 1600 images had been shot at a 45 degree angle to this image, so I pulled the Red channel and combined them using GradientMergeMosaic in PixInsight. As a result most of the brighter nebula benefits from H but a lot of the outer corners are more "stretched Red" than actual narrowband


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2022 Edit:

 - Crop
 - DBE
 - Hα blending (Ha image clipped to darken edges due to being shot at 45 degrees to color image)
 - Image Solver + SPCC
 - BlurXTerminator
 - Rista TGVD, MMT

 - ArcSinH + GHS
 - ANCDNR
 - Curves color/contrast tweaks
 - Bill's Star Reduction
 - HDRMT + Unsharp Mask
 - Annotation