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Orion Nebula critique required.


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Hi All,

Put your critical hats on please. I have spent quite a bit of time processing this in PixInsight, trying to do HDRCompositions and all manner of similar sounding mathematical loveliness, and I have spent more time and care on each step than any other image by quite some distance, so I am at the point of not being able to see the wood for the trees. I just think it is lacking something, or has too much of something, but I need someone to tell me their opinions as maybe I am too critical, or maybe not enough, I have exhausted my critical faculties on this one at the moment.

SkyWatcher ED80, HEQ5, ST80 guiding, modded 450D.

24x10minute subs with a stack of 20sec subs for the core. darks, flats (mostly ok),  bias as well.

2187f7afa2a326ab111aee739e9dea73.1824x0_

Thanks as ever.

Matt

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Hi Matt,

It is a very nice image but there are a couple of things wrong with it. It has a green cast, the background is clipped in the blue and the histogram is not lined up. I have done a quick round in PS just to highlight the issues, hope that you don't mind.

Regards,

A.G

post-28808-0-78153500-1422394688_thumb.j

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Don't mind at all, exactly the kind of thing I need to hear and see, thank-you very much. I'll have another crack at it after some sleep. Have been fiddling around with all sorts of complex things and I have neglected some basics!

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post-40997-0-72361700-1422405294_thumb.j

I'm new at this but LOVE processing images! I've logged well over 500hrs in the last 3 months doing so. It is an awesome image! I just got started doing the actual imaging part and aspire to do ones like this. I couldn't help fiddling with it and hope you don't mind. Didn't do much but visually darken the background and adjusted the blue (2%) and green (1%). I like the rare green in this nebula. Used AA5.

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Hi All,

Put your critical hats on please. I have spent quite a bit of time processing this in PixInsight, trying to do HDRCompositions and all manner of similar sounding mathematical loveliness, and I have spent more time and care on each step than any other image by quite some distance, so I am at the point of not being able to see the wood for the trees. I just think it is lacking something, or has too much of something, but I need someone to tell me their opinions as maybe I am too critical, or maybe not enough, I have exhausted my critical faculties on this one at the moment.

SkyWatcher ED80, HEQ5, ST80 guiding, modded 450D.

24x10minute subs with a stack of 20sec subs for the core. darks, flats (mostly ok),  bias as well.

....

Matt

Matt

I hope you don't mind comments from a rank (in all senses of the word) beginner.  

It's a terrific image.  It's sharp and has plenty of detail.  

As already mentioned, it has a green cast, and the downloaded jpg (when examined in Photoshop) does show that the blue channel is clipped.  It shouldn't take too long to fix these issues.  Did you use Colour Calibration in PixInsight?  An issue I had was finding a patch of 'clear' background, that is, a bit of the sky that didn't have some of the nebula in it.  My background preview ended up being quite small (it was roughly in the top left hand corner of your image).  If you fix the colour balance whilst the image is still 'linear' (before stretching), I suspect that the blue clipping will take care of itself.  zcdawson's effort is very dramatic, but the black levels have been clipped too far in my view with the result that some of the fainter parts of the nebula (those bits surrounding the dramatic core) have been lost altogether.  Perhaps, there is a little bit too much clipping in your original image too, although it is difficult to tell with the green cast. 

Regards

Steve

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Matt, lovely image so well done. Might be worth taking a copy of the original stack and using the MaskedStretch process to try and get some colour in the stars. Then tweak the saturation curve. Finally use a star mask and pixel math to blend the stars back in to this version. Has worked quite well on some of my DSLR images.

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You guys are great. A sleep and some retracing of my steps (mindful of what you suggest) gives the below image, in which I have tried to tease out the brown dust clouds which I clipped out before. The main difference though was doing the core in Photoshop after processing both short and long exposure images in PI, using the layer mask and blending them together, rather than HDRComposition at the linear stage in PixInsight. Will keep plugging away with PI and see if I can work out why I struggled so badly.

Also, zcdawson, if you want to practice processing, I can upload the original calibrated tiff file somewhere, which will be much more educational to practice with than a clipped, shrunk and compressed jpeg file.

ee724b02a9a13090c7aff0ae36802f17.1824x0_

edit - Just seen your post Ian - will have to give that masked stretch a go, as you are right, the stars do look a bit white and washed out. That process is also something that sounds well worth practicing.

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You guys are great. A sleep and some retracing of my steps (mindful of what you suggest) gives the below image, in which I have tried to tease out the brown dust clouds which I clipped out before. The main difference though was doing the core in Photoshop after processing both short and long exposure images in PI, using the layer mask and blending them together, rather than HDRComposition at the linear stage in PixInsight. Will keep plugging away with PI and see if I can work out why I struggled so badly.

Also, zcdawson, if you want to practice processing, I can upload the original calibrated tiff file somewhere, which will be much more educational to practice with than a clipped, shrunk and compressed jpeg file.

...

edit - Just seen your post Ian - will have to give that masked stretch a go, as you are right, the stars do look a bit white and washed out. That process is also something that sounds well worth practicing.

Matt

To my eye that's much better.  Have you tried that technique of extracting a luminance layer then doing a LRGB combination (ticking only the extracted luminance layer) to boost saturation?

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