A two panel mosaic covering the main part of the constellation of Orion:
A half size version of the full mosaic is available here
. This one has been a bit of a 'mare to process using my new workflow, designed to protect the colour of the bright stars during stretching, because the focussing was not as tight as I would have liked on the blue subs. My Pentax 165mm f/2.8 was in use in front of the ML16803 and manually focussing it isn't easy, especially when using the blue filter. A normal histogram stretch tends to hide such errors but the V-stretch
workflow is quite brutal with such errors. In the end I chose a very low repair threshold (so lots of pixels were included) and a high repair radius. Not ideal and some of the stars still got away from where they should be but with Orion now out of view for me until next season I've had to work with what was available.
The bottom half of the mosaic was assembled from 3 x 40 second and 3 x 200 second subs in each of red, green and blue plus 3 x 1,000 second Ha subs. The top half was the same except no 40 second subs. The stars were generated by using "high repair" settings, as previously mentioned, and needed far too much processing to tidy up! The bright nebulosity was extracted using less extreme Repaired HSV Separation Script settings and the Ha nebulosity was "de-starred" before passing both through PI's HDR Multiscale Transform module. Ha colouration was chosen to match the colour of the Horsehead Nebula.
I look forward to returning to this subject to gather more and better subs in the future if I can motorise the lens focus in such a way as to allow FocusMax to work it's magic!