Every winter I look forward to the return of the great Orion nebula. This year I captured I tried a few different approaches. First I captured a wide field view of the central Orion constellation using a short telephoto lens (see:
https://astrob.in/16f0kh/0/). Second, I went for a longer exposure than last year with my APO refractor taking advantage of newly developed skills in guided imaging. I worked on this one on and off from November 2019 through March 2020, ending up with about 8 hours of 6 minute subs that I used in conjunction with a series of 60 s subs to generate the final HDR image. I like this much more than last years attempt at this focal length (See:
https://astrob.in/387851/0/). This years version has much lower noise, better detail in the nebulocity, and I managed to capture the Trapezium with the improved HDR processing.
Imaged with WO GT81 at F4.7 (382 mm focal length) using Flat6A II field flattener/0.8x reducer, Optolong L-Enhance dual narrowband filter, and full spectrum modified Nikon D5300.
Long exposures: Total integration time of ~8 hours using 82 subs at ISO400x360 sec.
Short exposures: Total integration time of ~0.5 hours using 30 subs at ISO400x60 sec.
Pre-processed using PixInsight Batch Pre-Processing (BPP) script. Images calibrated using darks, flats, and flat darks. Extracted red/green/blue channels using BatchChannelExtraction script. R and G+B channels registered and stacked using StarAlighment and Integration.
R and G+B channels individually post-processed in Pixinsight: Cropped, gradient removal with ABE, HDRComposition (binarizing threshold = 0.8) to combine different exposure lengths, MLT for noise reduction, stretched using masked stretch, Curves Transformation, TGVDenoise for noise reduction, HDR transform, Local histogram transform, morphological transform to shrink stars.
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