Finally gathered the courage to finish this one - my first attempt at narrowband imaging and processing with a mono camera, so it was quite the learning curve, but I'm very happy with this first result. The images were shot in May last year, at Greci, a small village near the Macin mountains. It was quite windy, and at one point I had to run to cover the telescope because unexpectedly it started raining.
Pre-processed using the LVA guide, then combination preparation using MaskedStretch and HistogramTransformation to equalize backgrounds and midpoints.
This is a bi-colour palette with synthetic green channel using only Hydrogen-alpha and O-III emission lines. I also have some S-II data, but I don't like how it looks, so I'll shoot again some time. The combination done in PixelMath is:
R=Ha, G=0.4xHa+0.6xOiii, B=Oiii
Then used BackgroundNeutralization, and some CurvesTransformation to balance the colors and saturation a bit. Post-processed in Photoshop to slightly increase contrast and bring out the oxygen envelope a little.
Thanks goes to
@stille for helping me with linear pre-processing of the Ha channel and showing me the advantages of different stretch methods.
Starless version here:
Crescent Nebula bicolour palette - Macin edition, starless
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