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 Post subject: Orion Mosaic
PostPosted: Wed Mar 06, 2013 3:40 pm 
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Hi folks,

A two panel mosaic covering the main part of the constellation of Orion:

    Image

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!

Bob.

_________________
Olympus OM-D E-M1 + M.Zuiko Digital ED 12-40mm f/2.8, Lumix 7-14mm f/4, Leica DG Summilux 15mm f/1.7 ASPH, M.Zuiko Digital 45mm 1:1.8, M.Zuiko Digital ED 75mm 1:1.8.
Leica D Vario-Elmar 14mm-150mm f/3.5 - f/5.6 ASPH.
OM-D E-M5, H-PS14042E, Gitzo GT1541T, Arca-Swiss Z1 DP ball-head.
Astrophotography: TEC 140 'scope, FLI ML16803 camera, ASA DDM60 Pro mount.


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 Post subject: Re: Orion Mosaic
PostPosted: Thu Mar 07, 2013 7:56 pm 
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Wonderful image Bob! I love your technique on stars to preserve their colours.

Some may think the image is a bit overly red due to the H-alpha element, but it sure does reveal the massive amount of nebulousity around Orion.

Nice work!

Gordon

PS - if you have a photo of the camera and Pentax lens in action, I'm sure I'm not the only one who'd find it interesting!


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 Post subject: Re: Orion Mosaic
PostPosted: Sat Mar 09, 2013 9:23 am 
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Joined: Sat Sep 30, 2006 4:30 pm
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Gordon Laing wrote:
PS - if you have a photo of the camera and Pentax lens in action, I'm sure I'm not the only one who'd find it interesting!


    Image

There you go, sans power and data cables of course! :)

I designed and had fabricated the U shaped adaptor which bolts to the dovetail plate and to which I can bolt the filter wheel. The filter wheel then supports both the lens and the camera. Since that photo was taken I've also added a power distribution and switching box.

Bob.

_________________
Olympus OM-D E-M1 + M.Zuiko Digital ED 12-40mm f/2.8, Lumix 7-14mm f/4, Leica DG Summilux 15mm f/1.7 ASPH, M.Zuiko Digital 45mm 1:1.8, M.Zuiko Digital ED 75mm 1:1.8.
Leica D Vario-Elmar 14mm-150mm f/3.5 - f/5.6 ASPH.
OM-D E-M5, H-PS14042E, Gitzo GT1541T, Arca-Swiss Z1 DP ball-head.
Astrophotography: TEC 140 'scope, FLI ML16803 camera, ASA DDM60 Pro mount.


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