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M51 LRGB - nearly there!


Whippy
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It took ages to for the skies to clear here, but when they did I was happy enough to grab the colour data for the M51 I started about a month ago. I will add some Ha for this at some point, one more clear night before SGL6 please!

Total exposure time is 8 hours 40 mins (luminence 5 hours 40 mins (34 x 10 mins) and an hour each of Red, Green & Blue (12 x 5 mins) ). Taken with an Atik 16hr, Baader RGB, IR cut and Hutech IDAS filters through an ED120. Guided with a QHY5 and WO ZS66, PHD doing the hard work :) and an EQ6 making sure it sitting abouve the mud. Stacked in DSS and played about with in photoshop.

Tony..

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Very fine M51. Sharp ad deep.

On the colour it looks to me as if the greens are a bit out. I always used to moan that green held the balance of power in RGB but I now use a PixInsight filter which zaps rogue greens in a single click. In fact Pix has a very good colour calbration tool which works on galaxies or starfields to set the balance.

Olly

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Cheers guys :), have to say I'm happy with the way this one is turning out!

Very fine M51. Sharp ad deep.

On the colour it looks to me as if the greens are a bit out. I always used to moan that green held the balance of power in RGB but I now use a PixInsight filter which zaps rogue greens in a single click. In fact Pix has a very good colour calbration tool which works on galaxies or starfields to set the balance.

Olly

I was going to say Olly that I wasn't sure where you was coming from until I just has another quick peek and I can see it's a bit green around the outer dust. I was umming and ahhing all day before I posted this and I also ran it past my wife (who doesn't have issues with colour like me) and she said it was alright, I wonder if it's suffered being Jpegged and reduced? I'll take another look later :(.

Tony..

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Don't get me wrong, it's good. But for me the outer dust and gas is more green than yellowish white, which is where I think it should be. I don't speak from experience because I don't have a respectable M51 so what do I know?

The Pix filter for saying goodbye to green has the typically Pix name of SCNR. I mean, what's wrong with that for a name? Obvious, eh? Get rid of green imbalance with a filter called SCNR! I mean if you called it the green imbalance filter nobody would guess what it was for... (Don't worry, I'm just trying to wind Harry up!!!)

Olly

Edited by ollypenrice
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Don't get me wrong, it's good. But for me the outer dust and gas is more green than yellowish white, which is where I think it should be. I don't speak from experience because I don't have a respectable M51 so what do I know?

The Pix filter for saying goodbye to green has the typically Pix name of SCNR. I mean, what's wrong with that for a name? Obvious, eh? Get rid of green imbalance with a filter called SCNR! I mean if you called it the green imbalance filter nobody would guess what it was for... (Don't worry, I'm just trying to wind Harry up!!!)

Olly

No worries Olly, I see what you're saying and I'm not offended in the slightest! I'm very aware that my RGB efforts are hit & miss because I am slightly colour blind and that plus my not great RGB filters means that I probably have to work a bit harder at getting the colour right than some. Hence I normally run my colour images past L'Missus for a second opinion before I post the up. Even then, I'll most likely do a second (or third, fourth....) go anyway! So all criticisms and pointers are most welcome :).

Mmm Pixinsight. I like the idea of it, what does worry me is I'll download the trial, end up loving it and then not being able to pay for it!

Tony..

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Don't get me wrong, it's good. But for me the outer dust and gas is more green than yellowish white, which is where I think it should be. I don't speak from experience because I don't have a respectable M51 so what do I know?

The Pix filter for saying goodbye to green has the typically Pix name of SCNR. I mean, what's wrong with that for a name? Obvious, eh? Get rid of green imbalance with a filter called SCNR! I mean if you called it the green imbalance filter nobody would guess what it was for... (Don't worry, I'm just trying to wind Harry up!!!)

Olly

Ah Mr Olly

What you probabley don't know is that SCNR can remove any colour Red Green Or Blue sometimes handy if you have any colour inbalance :)

harry

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I did use PixInsight to adjust the green just to try it out. You can do similar in PS using selective colour, replace colour or adjusting hue and saturation but the SCNR tool is quick and easy.

I then did my standard galaxy colour correction in PS - under highlights give a little boost to red and yellow and then a little boost the blue in mid tones.

With all that signal you can afford to do a bit more sharpening and with a target like this the high pass filter works nicely - first make a protective star layer. Then create a duplicate of the background. Select overlay as the blend mode for the background copy. Then under filters select other/high pass. Play around with the slider, the further over to the right the coarser the adjustment. I think I went for a value of 2.5 (this value varies quite a bit depending on target). This filter acts as an edge enhancer. Then layer/layer mask/hide all. Now the background copy as a little layer mask symbol beside it and the effect of the high pass mask is completely er masked. Make sure the foreground palate is set to white and select a brush and adjust to an appropriate size. Then draw over the areas you want to sharpen. Do this at quite high magnification to make sure you aren't just generating lots of noise. It works really well on dust features in M51. You have almost infinite control of this process, you can adjust the opacity of the brush or the layer. You can do different layers using different values for the high pass filter. Usually I keep it pretty simple though

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Usually I keep it pretty simple though

:( You lost me after about half a sentence! I'll v e r y s l o w l y run through what you do later on tonight when I have a bit more time. I'm still very much on the 'smooth the background & sharpen the details' vibe ;). We have much to discusss at SGL6!

That has to be your best to date?

Thanks Ant :(. I still want to get some Ha in there so I'll reserve judgement until that's done. I've never added Ha into a colour image before so who knows how it'll turn out :).

Tony..

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