Nebulousity around M45 - 7 hours data

[tooth_dr]

Firstly - I now don't think that the Atik sensor and the ED80 is a good size for the seven sisters, it's too cramped, not enough space around the cluster.

Secondly I'm struggling to properly combine the data, and I'm sure I overexposed it subs too.   I would like advice or comments or anything I can work on please.

Data details:

41 x 300s ISO1600 Canon 40d (No filters) = just under 3.5 hours

41 x 300s Atik 383L+ (Luminance filter) =  just under 3.5 hours

Total data = 6 hours and 50 minutes 

Atik data stacked in APP.

40d data stacked in APP, and registered with a subframe from the Atik.

The stacked were lined up in PS, and combined by creating a lum layer for the atik data and merging it down onto the RBG data in increments of 20% approx. at a time, repeating with a copy of the original lum layer until it 'looked' ok.  This is how I think Richard @Allinthehead suggested doing it, but I may have picked that up wrong!  I've attached a sharper and differently colour balanced version.

 

Anyway thanks for looking.

Adam

 

[jjosefsen]

I quite like it to be honest!

The framing is tight, but I think it just fits, and you captured some lovely nebulosity/dust.

It will be hard not to over expose stars as bright as those.. In PI it is possible to do a HDR composite, where you combine images of different exposure lengths (example: master of x number of 5s subs, master of x number of 30s subs, master of x number of 300s subs), I don't know if this is possible in APP..

The result would be a 64bit image with high dynamic range.

[alexbb]

The lum looks excellent. Perhaps the background is a bit too brown?

Anyway, really good!

[teoria_del_big_bang]

Adam,

Nice image. Like most people on this forum you are too self-critical. Thanks for sharing the image 

Steve

[jjosefsen]

1 minute ago, moise212 said:

The lum looks excellent. Perhaps the background is a bit too brown?

Anyway, really good!

Good point.

It could use a little noise reduction in general, mostly in the background.

[tooth_dr]

14 minutes ago, jjosefsen said:

Good point.

It could use a little noise reduction in general, mostly in the background.

Its is a technique I don’t know how to do! I have seen people say/do this before but I’m not sure how to go about it. 

[jjosefsen]

1 minute ago, tooth_dr said:

Its is a technique I don’t know how to do! I have seen people say/do this before but I’m not sure how to go about it. 

You use APP and Photoshop right?

[tooth_dr]

Just now, jjosefsen said:

You use APP and Photoshop right?

Yes ?? 

[jjosefsen]

7 minutes ago, tooth_dr said:

Yes ?? 

I don't use Photoshop, so hopefully someone else can help you.

BUT I did remember bookmarking some videos before I decided to bite the bullet and get PixInsight.

 

https://photographingspace.com/noise-reduction-photoshop/

https://www.davemorrowphotography.com/NoiseReduction-for-NightSkyPhotography

He mentions a photographing space action pack for PS, which contains some NR tools, maybe it would be easier to use that pack instead of doing it manually.

[alexbb]

Something really simple: invert the luminance, stretch it. Duplicate the final RGB, apply the stretched inverted luminance as layer mask. Apply noise reduction. This will let only the noise reduced dark areas to pass into the final image.

[newbie alert]

Stunning Adam..i like it as it is.. great star colour.. personally I like a bit of background colour..adds more to the image..

[tooth_dr]

Thanks guys. Thanks so much for comments and advice. I take all this onboard, and actually regularly screenshot these posts on my phone for future reference, as these tips are invaluable. 

[Xiga]

Adam i know you feel like you still have much to learn, but honestly you're about 90% of the way towards a truly great image here. The data itself looks really good and you're processing above is also very close to being the finished article, so keep it going!

You're on the lookout for some advice so i'll try and offer some if i may. 

The main thing the image needs is a very simple adjustment in PS that takes less than a minute to do. The R G B channels simply haven't been balanced properly, this is why the background and overall colour scheme seems a bit off. If you raise the black point of the Red channel by about 16 and the Green Channel by about 8, then the humps of the histograms will roughly match up and the background becomes more neutral rather than the reddish tone it currently has. This alone will make a massive difference to the overall look of the image. 

Secondly, it could, perhaps, have a smidge of a green tone about it? It's very subtle so not a big deal at all. But if you run HLVG on a duplicated Layer (set to blend mode Color) and then re-merge then you will see a slight reduction in green throughout the image. 

Thirdly, you say you don't really know how to do Noise Reduction properly. Alex has described perfectly above how to go about this. But a picture says a thousand words so i've attached a pic below of how this should look. Basically, you duplicate your layer, then create  a layer mask on the new layer (tip - click the small square with a circle in it near the bottom-right), then copy the image from the new layer (Ctrl-A, Ctrl-C), then Alt-Click on the Layer Mask (this should now show a white screen), then paste the image into the Layer Mask (Ctrl-V). You will now see the mask showing as a mono copy of the image itself. But when it comes to doing NR you mainly only want to do it on the dark areas and not the bright areas (remember in a mask, White Reveals and Black Conceals) so you need to Invert the Mask, you do this by pressing Ctrl-I. All that's left to do now is stretch the mask so that the areas of nebulosity are nice and dark, and as you gradually move away to the areas of dark sky background the mask should gradually become white. Once you've done this, all that's left to do is click back on the image rather than the mask, and then run your favourite NR action/routine. You could try Carboni's Space Noise Reduction for example, or even PS's own one under the Camera Raw filter. If the effect isn't enough, then check how White the mask is around the areas of low signal in the image. If the mask is not White enough then it won't be letting enough of the NR through, so you might need to tweak the mask a bit with Levels or Curves.

Obviously when it comes to doing sharpening (ie the opposite of NR, and which should be done Before NR) then the only thing you need to do differently is NOT invert the mask. The problem with this is, the stars will also be white, along with the areas of nebulosity that you do want to sharpen. So for this you could try removing the stars from a duplicated version of the image (if you have Annie's Actions then there is one in there that, although a bit crude, will do the job just fine for this). Clean it up a bit with the spot-healing brush (it doesn't need to be perfect) and then use this as the image that you copy into the Layer Mask. Then when you use Levels or Curves to really darken it (don't be afraid of white or black clipping a layer mask, it might actually be necessary!) the stars should be gone and won't be sharpened (and neither will the sky background either). 

Hopefully that helps you a bit. I've attached below what i did in 10 mins in PS using just the adjustments mentioned above on your Jpg. The image has a lot more potential within it so keep going! And always remember to do things in small increments instead of making any one big change in a single go. 

ps - I also rotated it 180 degrees, as for whatever reason (probably OCD, lol) it looked upside-down to me the other way ?

Edit - I've just spotted what looks like a tiny edge-on galaxy at the very top-middle of the image. Very cool! ?

[Xiga]

Just remembered something else. At this point you have plenty of colour data. If you want the image to be less noisy then what you really need is more luminance. The good news is, you actually have lot more luminance than you realise.

You can convert the DSLR data to grayscale, then create a super luminance from both it and the 383L+ data, by layering the DSLR data on top in Screen blend mode at the appropriate opacity. This could really boost your Luminance before combining it with the DSLR colour data. 

Ps - You should check out Scott Rosen's DSLR LLRGB approach in the video below. Not all of it will necessarily apply to you, but a lot of it will, and wouldn't you know it it's also of M45 too! ? It's over 2 hrs long, but we'll worth it. 

http://www.astronomersdoitinthedark.com/dslr_llrgb_tutorial.php

 

[tooth_dr]

@Xiga I genuinely can’t think you enough for this info. This will take me up a notch in terms of processing the data and well as work flow.

[jjosefsen]

Outstanding post @Xiga! ?

[souls33k3r]

Very nice. You even managed to capture UGC2838 too 

[tooth_dr]

1 minute ago, souls33k3r said:

Very nice. You even managed to capture UGC2838 too 

Ugg looks bad zoomed in lol!

Thanks for labelling it. I spotted it last night and was pleasantly surprised ??

[tooth_dr]

4 minutes ago, souls33k3r said:

Very nice. You even managed to capture UGC2838 too 

And 300 million lights years away ?

[souls33k3r]

4 minutes ago, tooth_dr said:

Ugg looks bad zoomed in lol!

Thanks for labelling it. I spotted it last night and was pleasantly surprised ??

Hahahah mate don’t sweat it. It looks perfect. I was just reading through the comments and noticed that @Xiga beat me to it  nonetheless it’s  great finding these little buggers in the image.

[jjosefsen]

I love when an image reveals something unexpected like that..

300 million lightyears away.. Think about it, when those photons were emitted there wasn't even really dinosaurs on earth yet, reptiles had just started to walk the earth. ?

 

[Allinthehead]

15 hours ago, tooth_dr said:

The stacked were lined up in PS, and combined by creating a lum layer for the atik data and merging it down onto the RBG data in increments of 20% approx. at a time, repeating with a copy of the original lum layer until it 'looked' ok.  This is how I think Richard @Allinthehead suggested doing it, but I may have picked that up wrong!

That looks really good and with the tips from Alex and Ciarán you should be able to clean up that background.

This was a tip i got from Olly and it goes like this.

Add in your lum as a layer with luminosity selected. This significantly weakens the colour and makes it look pale. Reduce the opacity of the lum layer until the colour starts to fade. Increase the saturation to taste. Blur the image then flatten. Repeat these steps until the image can take the luminance at 100% opacity. Don't blur the final image obviously. 

[tooth_dr]

1 hour ago, Allinthehead said:

That looks really good and with the tips from Alex and Ciarán you should be able to clean up that background.

This was a tip i got from Olly and it goes like this.

Add in your lum as a layer with luminosity selected. This significantly weakens the colour and makes it look pale. Reduce the opacity of the lum layer until the colour starts to fade. Increase the saturation to taste. Blur the image then flatten. Repeat these steps until the image can take the luminance at 100% opacity. Don't blur the final image obviously. 

Thanks Richard. Oh I forgot the blur! Gaussian and how much? Is it possible to quantify the fading of coulour to a certain measurable level?

[Allinthehead]

33 minutes ago, tooth_dr said:

Thanks Richard. Oh I forgot the blur! Gaussian and how much? Is it possible to quantify the fading of coulour to a certain measurable level?

Maybe there's a way to quantify but i don't know it sorry. I just go by eye and when i feel the saturation needs a lift i stop adding luminance, lift the saturation and then blur. I just use filter/blur/blur.

A great way to increase saturation is to make 3 copy layers of the image. Set the first copy to luminosity, the second to soft light, leave the third as normal.  

[tooth_dr]

Just now, Allinthehead said:

Maybe there's a way to quantify but i don't know it sorry. I just go by eye and when i feel the saturation needs a lift i stop adding luminance, lift the saturation and then blur. I just use filter/blur/blur.

A great way to increase saturation is to make 3 copy layers of the image. Set the first copy to luminosity, the second to soft light, leave the third as normal.  

Thanks Richard, yet again incredibly useful info.  The ability to judge by eye is something I will just have to work on!