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Eagle Nebula (M16) SHO


glowingturnip
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Here's my last one from my summer crop - it actually turned into a year-long project, I took the Ha in August 2017, the OIII in July this year and the SII in August.

LRGB_crop1_desat3.thumb.png.09e486cc47625507224fc2e463e3b3c1.png

 

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10 each x900s Ha, OIII and SII, darks flats and bias, equipment as per sig, taken in southern Spain, PI processing.

 

Just for fun, here's a side-by-side comparison of my Pillars of Creation vs Nasa's, can you guess which is which ?  

nasa_comparison.PNG.437e8c8c63cdb4930b686b3f912db6a1.PNG

Ok, not much of a contest really, but then their telescope is a bit more expensive than mine is !  Quite interesting to have a close look though, there are a number of features in common that I have managed to pick up that aren't apparent at first glance.

 

I'd be happy to receive feedback on what you think, feel free to be honest since I'm not quite sure how I feel about it, especially the colours.  Comments and cc welcome.

 

Hope you enjoy,

 

Stuart

 

[edited to fix Flickr link}

Edited by glowingturnip
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You have a very good image Stuart and your patience to collect has ensured a smooth image with a great level of detail.  It is framed well and there are no residual gradients - well done on a fine image.

For constructive feedback to enhance an already very good image, I do wonder if you tried to deconvolve the Ha data?  I think this would help with star control and to tighten up small scale detail?  A touch os star reduction would also be of benefit in helping concentrate the viewers. Equally this target can withstand a little more colour which ideally wouyld come from a longer integartion, however, PI's curves or colour saturation combined with a colour mask will help give some greater depth.

HTH.

Barry

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thanks all for the great remarks  ?

 

@Barry, thanks very much for your comments, some things there to think about.

Regarding the colour, getting the balance right was my big concern, but actually I had the opposite problem to not enough - the colours I had coming through during the final stretches and whatnot were very strong even without any enhancement, so that to my tastes it was coming across as a little garish, a little 'Disney'.   So actually my final act was to de-saturate it a little bit (I know, a first for me !), but looking at it again with fresh eyes this evening I wonder if I've gone a little too pastel.

I'll put it to the vote, do you prefer...

Full Disney: 

LRGB_crop1_disney.thumb.png.c8bf725eaeaf5f52b8b0378418461024.png

 

or pastel shades:

LRGB_crop1_desat3.thumb.png.972ec122bfbb42efa621d4fe01a6b04b.png

Probably somewhere in-between I guess.

 

Re the star sizes, I did think about applying some (the Morph transform is a great tool), but in the end figured I'd keep it as it was, I wanted to convey something of the open cluster in the middle.  The stars are actually from the Ha only - the OIII and SII stars were much more bloated, especially with the strong stretch on the SII, but I merged them with the tonemap method.

Deconvolution yes, I did it on all three channels actually, though it didn't add much to the OIII and SII.

 

Cheers,

Stuart

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Your 'full Disney' does look a little red, so you could try adjusting the histogram, selcting the red channel.  Or create a blend of the two images using Pixelmath.  Colour Masks are very useful for isolating a specific colour for processing too.  NB data can w ithstand a little more of a bold approach over and above LRGB imaging: afterall one is trying to show structure from the different emissions.

There is no practical benefit in deconvolving anything other than the Ha channel and even afterwards, depending on the subject and nebula details, you have the option of using MultiScaleLinearTransform and its 'Bias' settings to sharpen selectively and gently (using a nebula mask to protect stars and background sky).  Local Histogram Equalisation is also a great tool when used gently to tweak contrast and gain a sense of depth.

You have a great image Stuart and your tastes are what matter - I am just gently encouraging you to help you get the most from your data with going 'Full Disney'.

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On 17/11/2018 at 14:49, glowingturnip said:

Ok, not much of a contest really, but then their telescope is a bit more expensive than mine i

You say not that much of a contest but i say not that far away. That's astonishing what can be achieved with amateur equipment. Great image.

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As someone who is a decade or two away from being able to do this, I like them both, but see why you chose to lighted up the colours a bit.  The top right 'quadrant' loses out a little in the pastel image as the detail is finer but the remainder of the image looks slightly better balanced.
That said, post either anywhere astrophotographers gather and you'll get nothing but praise ?

All the best

Michael

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14 hours ago, Synchronicity said:

The top right 'quadrant' loses out a little in the pastel image as the detail is finer but the remainder of the image looks slightly better balanced.

Actually that's a good point, yes that bar that leads off to the right goes from being finely tinted in the first image to looking like greyscale lum with not enough rgb behind it in the second.

I'll have another go, masking for only the most saturated bits and addressing the reds.  I think the blues can probably be allowed to stay. 

 

I'll be back  ?

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it's been a busy week, but I finally got round to tweaking the colour on these - what do you think ?

LRGB_crop1_rydesat_bluesat_scnr.thumb.png.d6a79a48b3c7a6f9365292ba60d4f25a.png

 

LRGB_crop2_CTHT_rydesat_bsat_scnr.thumb.png.faf4e37c92f2956d0437dd017745e365.png

 

I came up with doing the idea of a ChannelExtract of the c channel (saturation) from Lch, blurring and stretching that to use as a saturation mask, then multiplying it by a red+yellow mask from the ColorMask script then doing specific red+yellow desaturation with the ColorSaturation tool.  I gave the blue a bit of a nudge higher too.  Quite like how it's taken the fizz out of the reddish areas but left the delicate areas with a nice tinge.

What do you think, am I on the right track ?

 

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  • 1 month later...

Just looking through SHO images as it's my next attempt. That's an amazing comparison to the Hubble image!! There's really not that much in it considering the kit you use versus Nasa's budget! If I got a result like that it would be a crowning achievement in my eyes! Fantastic, well done!???

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I love this one! It´s one of those objects that are almost possible to image from my location but still not. I can do a few minutes of Ha in late summer but when it´s dark enough for the rest, it´s below my imaging view.

Really like your processing and as far as colours go, there really is no truth when it comes to narrowband combination, right? ?

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19 hours ago, Stub Mandrel said:

That's an amazing image.

I tried a bit of crude deconvolution on it to see if it would go a bit closer to the Hubble image, I hope you don't mind, but it suggests using deconvolution on your original data may well be worth doing:

 

Wow, surprised you managed to make such a difference ! 

I did deconvolve all three channels as a very first step, but didn't get it making that much of a difference.  Maybe I should have another go - mind you, I'm not sure I want to go through all the processing steps again, it did take ages !  Although I suppose I only have to do it for the lum...

Mind sharing what deconv settings you used ?  Obviously they'd be different for the raw linear data.

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28 minutes ago, glowingturnip said:

Mind sharing what deconv settings you used ?

It does seem to have 'crisped it up' nicely, although I can't see extra detail.

I use Astra Image.

I used my rough 'base' settings which I generally use first before 'tuning':

Deconvolution for sharpening, Lucy-Richardson, Lorentzian, 10 iterations, blur kernel about 1.6, deconvolution strength about 1.5,  aggressive and reduce haloes not checked.

My temptation would be to create a mono version, deconvolute it, then add it over your best colour version as a luminance layer and play with the opacity to get teh best result - that minimises any extra processing and keeps the fine tuning of colour you have done.

Edited by Stub Mandrel
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