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M42 - Layered and masked (Ha)


Uranium235
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Hiya,

After being inspired by Peters AG12 spanking of M42, it gave me an idea of the kind of exposures needed to get more of the outer nebulosity. Tricky, given that the core of M42 is so bright, so this was my first time using layers and masks in photoshop. Theres a bit noise creeping into the corners (something that could be fixed with more data), but it seems to have worked(ish).

The weather was clear all night (bar midnight when we had a bit of cloud), and a slight breeze which wrecked a couple of subs from M101. I stayed out as long as I could (3.30am) so I got more data from the Rosette and M101 (will process that later on).

Next step will be to colourise it, but when we're going to get any more clear sky is anybodys guess :rolleyes:

M42: Orion Nebula

ED80, Atik 314L+, 50mm finderguider

4x1200(Ha), 10x60(Ha, for the core)

No calib

Guiding hassles = Zero

Thanks for looking :eek:

attachment.php?attachmentid=52049&stc=1&d=1298810494

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Edited by Uranium235
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Woaaa, I'm really really amazed by the amount of detail using "just" a ED80 & 314, tight stars & superb processing, I like the natural mix of long & short exposures, no obvious sign of the mask, you did a great job!

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Thanks Rob :( I wasnt quite sure if i'd got it right because the tutorial I was following probably wasnt for CS2, I couldnt find the "view / new view" option so it was impossible to preview the final image as I made the adjustments to the mask layer.

Ive just noticed too that the noise in the top and bottom right and isnt as noticeable in the TIFF version, I might have jpegd it a bit too much.

Hmmm.... I'll go and stack it on the PC to see if I can improve it.

"I may be gone for some time" :)

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The easiest way I find to composite two images together is with the layer mask tool.

Basically copy the new core into your overall image and add a layer mask to that new layer.

Next I tend to fill the mask black so the new core disappears then, using a white coloured brush, 'paint' back the core building it up until if looks right. The beauty with layer masks is that shades of grey can be used to partially mask parts.

Hope that makes sense, but it looks like you've got the hang of it anyway :)

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Cheers Digz :( Ive been using the layers tool (using a blur on the mask), and figured out how to preview the changes you make. But for the past 2 hours ive been trying to better it on the PC, but I just cant seem to get it to save right as a jpg... it keeps the main part of the nebula ok, but then loses the subtle detail in the corners (even with lowest compression). Its fine in the tiff though.

More data is needed i think. So I'll grab a few more 20min subs when Im out next time.

Funny... more often than not you can re-stack 10 times, and still not have something better than your first effort....lol. :)

Edit: Im going to have a go a bypassing DSS, and try doing the curves in PS.

Edited by Uranium235
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Do you flatten everything PS before saving to JPEG?

I tend to make all edits on non destructible layers. Save a master PSD file. Merge everything down. Convert to sRGB. Resize and then save as a JPEG. There is also a save to web option but I dont use that anymore.

Funny... more often than not you can re-stack 10 times, and still not have something better than your first effort....lol. :)

I hear that. I've been playing about with my M42 today and I ended up posting my original stack from DSS!!

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Do you flatten everything PS before saving to JPEG?

Yep, done that. Ive stacked it another 3 times and still not beaten my first attempt! I'll need to get a sledgehammer to crack this nut (lots more subs) :)

My war against noise starts here!

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Hey Digz, I cracked it! :)

All i did was go back to my original stack on the laptop and combine those in PS. The outer edge is a lot less noisy now, but at the expense of some feint nebulosity... cant have it all I guess :(

It will be interesting when I get some OIII on this becuase its going to complicate the processing somewhat. But it looks like tonight is off, so I think I will take another look at my Rosette data.

Oh btw, you can do Ha with a DSLR. It wont be as fast or sensitive as a CCD but im pretty sure you can get Ha clip filters (Astronomik).

attachment.php?attachmentid=52217&stc=1&d=1298916726

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Hey that looks a hell of a lot better.

When you say you went back to the original stack and combined in PS what exactly do you mean?

That sounds interesting about the Ha clip filters for DSLR, however it sounds like a canon thing and I have a Nikon :)

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Sorry dude :) what I meant is that I went back to the original DSS output files and layered/masked them in PS a little better (applied some more curves to the long exposure), and saved any noise reduction for the final image - rather than applying NR to both the long and short exposure before combining.

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Nice one, I get it now. Certainly done the trick!

Another trick I have found is that you can apply adjustment layers to an image and then make it a clipping mask so it only affects the layer directly below it.

For example you may have copied in a short exposure for the core, masked off what you need, but want to apply some curves to that layer only. Do it as an adjustment layer and right click and click 'make clipping mask'. All the adjustments to that adjustment layer will only then affect the layer it is 'clipping'

Hope that makes sense? and a bit of food for thought :)

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