M51

[kirkster501]

Have not got any Ha yet but here is 4 hours of luminance and an hour each of RGB - all 5 min subs.  TEC 140 (with flattener) and Atik 460.  Cropped about 50%.

I do like bright and cheerful renditions of objects, something I know I need to tone down a bit.  I may have slightly overdone the arcsin stretch leading to slightly red stars.  It is also a tad noisy so I may revisit. Anyway, putting out there for critique and commentary.

Steve

[Z3roCool]

Stunner

[vlaiv]

I would say that you probably went a bit too far with saturation?

 

[kirkster501]

40 minutes ago, vlaiv said:

I would say that you probably went a bit too far with saturation?

 

Yeah, maybe with arcsin stretch - have to be very careful with that tool.  I do like vibrant images but one can over do it.

[tomato]

I really like it, lots of detail captured. Maybe the colour is a little strong for some tastes, I agree the red channel is predominating as I view it on an iPad.

And imaged from the cloudy UK, nice one!👍

[kirkster501]

10 hours ago, tomato said:

I really like it, lots of detail captured. Maybe the colour is a little strong for some tastes, I agree the red channel is predominating as I view it on an iPad.

And imaged from the cloudy UK, nice one!👍

Thanks for the feedback.  Yes I will tone it down a bit and repost later, I think I need to do likewise with my M31 from the other day. 

I need to put a sign up on my desk saying "Steve, resist your urge to have very vibrant colours on your astro pictures"    !!!!!!!!!

[vlaiv]

5 minutes ago, kirkster501 said:

Thanks for the feedback.  Yes I will tone it down a bit and repost later, I think I need to do likewise with my M31 from the other day. 

I need to put a sign up on my desk saying "Steve, resist your urge to have very vibrant colours on your astro pictures"    !!!!!!!!!

This surely depends on one's taste, and that should not be discussed (as the old saying goes).

I'm starting to be in favor of "true color" approach. This is probably going to make my processing less likable since people are used to pronounced / stronger colors in astro images.

Here is a good "guide" that I found.

This is useful for objects of "stellar" origin - like clusters, galaxies, star fields (not nebulae). Two important things can be read from this table:

Most of stars are yellow / orange - more than 96%, with very few white and blue stars. Most bright stars are in fact white and blue, or rather orange ones tend to be very dim. This means that most of image should be pale yellow with a slight orange tint and very few bluish parts

 

[glowingturnip]

1 hour ago, kirkster501 said:

I need to put a sign up on my desk saying "Steve, resist your urge to have very vibrant colours on your astro pictures"    !!!!!!!!!

The last step in my processing workflow reads '24 hour eyeball filter'.  ie put it down, come back to it 24 hours later and see if I still like it before publishing.

All very well, but I almost always break that rule.

[Paul73]

Why resist? If colourful is your thing, go for it! Way too much for me, but definitely a very fine image.

Paul

[kirkster501]

Ok guys, I have dialled back the colour saturation a bit and added a bit of TGV Denoise. 

[alan potts]

There is a massive amount of data gone into that capture and I personally feel it looks much better toned down somewhat, I like punchy images which is probably why I got a bit of an orange caste into my M12 you looked at earlier. I would still try and tone the orange stars down a bit around M51 as for me they look a little overdone and I think it detracts from a superb centre-piece of the galaxy. In any case it's a super image which ever way you look at it and everything else is just personal taste. You have some wonderful scopes, as much as I could afford to have them I value my wife more, If I could pick one it would be the Tak.

Alan

[wimvb]

Going against the mainstream here, but I actually like the punchy first version better. The red halos around the stars can be toned down, but the vibrant blue in the galaxy is just great.

Have you done some sharpening on the Luminance? Deconvolution may give you better definition in the arms of the galaxy.

[kirkster501]

Yes Wim, I did deconvolution.  I overdid the arcsin stretch which is notorious for introducing these red stars.

@Alan, yes there is about 7 hours worth of data in this.  Very hard to get data in the UK I may add with our weather.  I want to get some Ha as well to make the Hii regions shine but will do that another day; so many more objects I want to image.

Thanks for the constructive feedback.  I will revisit again

Edited June 7, 2019 by kirkster501

[alan potts]

17 minutes ago, kirkster501 said:

Yes Wim, I did deconvolution.  I overdid the arcsin stretch which is notorious for introducing these red stars.

@Alan, yes there is about 7 hours worth of data in this.  Very hard to get data in the UK I may add with our weather.  I want to get some Ha as well to make the Hii regions shine but will do that another day; so many more objects I want to image.

Thanks for the constructive feedback.  I will revisit again

We have had terrible weather through May and the beginning of June, we have just had 4 days of no rain where 102mm of rain fell, thats forecasters for you. last night was the first clear I have had with no cloud for over a month. I know you struggle in the England with weather but if helps I am genuinely concerned and always wish you all well, when I was over in late July and early August it was lovely, maybe I need to come over more often.

I have never done more than 2 hours so far on an image but galaxies do really need it, my trouble is I am up very early every morning so don't stop out that late, looks clear for tonight so maybe have a go at M10 or 14.

I don't know what arcsin stretch is can you enlarge on it, I would like to red up my stars a bit😀.

Alan

[kirkster501]

Had another go.  Took out the arcsin stretch and used masked stretch instead on the RGB to create the chrominance master before blending with the stretched luminance, which had deconvolution applied to it.  Usual sharpening with MLT and Histogram Equalisation followed by TGV Denoise.  Then applied Morphological transformation.  Only used a bit of saturation.  This time left the subject in native FoV for the TEC and Atik 460.

Edited June 7, 2019 by kirkster501

[sloz1664]

That's looking great Steve, glad to see you are using Pixinsight to it's potential. As a retired Engineer well versed in statistical analysis, it's right up my street

Steve

[DaveS]

Haven't commented up till now, but I think that's the best of the three.

[wimvb]

2 hours ago, alan potts said:

I don't know what arcsin stretch is can you enlarge on it, I would like to red up my stars a bit😀

arcsinh stretch is a stretching method developed by SGL member Mark Shelley (@sharkmelley). Unlike levels and curves, where colours get washed out in the brighter regions, arcsinh stretch preserves or even boosts colour in these regions. It is available in PixInsight and in PhotoShop.

Here's his original post on the matter

 

[alan potts]

Thank you for that Wim, all I need to do now is go outside and take an image good enough to use it on, looks long and involved but I will sit and have a go at it, like anything in PS there are 10 ways to do the same or similar, I tend to try and keep it simple even though I am half decent using it, that's only because I've used it for years with normal photography. The trick I always wanted to pull off was Urainum35's control of Alnitak on the HH, I have watched his video about 50 times and I still can't see what he does, Olly gave me a good half measure though which I'm happy with, one day I will suss it.

Alan

[gorann]

Nice inage in many ways! I think it was too much yellow centrally in the galaxies and too much red in the stars of the original version, but your reduced colour in later version made it a bit too tame. The blue was great so do not tune that down at all and you could bring a bit back of the original red/yellow. In my humble oppinion.

[Allinthehead]

That's a great image. I like the more toned down background of the last version with maybe a blend of that version and the first for the galaxy itself. As always saturation is a tricky one and should come down to whatever you like yourself.

[MarsG76]

On 07/06/2019 at 01:13, kirkster501 said:

Have not got any Ha yet but here is 4 hours of luminance and an hour each of RGB - all 5 min subs.  TEC 140 (with flattener) and Atik 460.  Cropped about 50%.

I do like bright and cheerful renditions of objects, something I know I need to tone down a bit.  I may have slightly overdone the arcsin stretch leading to slightly red stars.  It is also a tad noisy so I may revisit. Anyway, putting out there for critique and commentary.

Steve

Great detail.. a little yellow but looks good.

 

[MarsG76]

20 hours ago, kirkster501 said:

Had another go.  Took out the arcsin stretch and used masked stretch instead on the RGB to create the chrominance master before blending with the stretched luminance, which had deconvolution applied to it.  Usual sharpening with MLT and Histogram Equalisation followed by TGV Denoise.  Then applied Morphological transformation.  Only used a bit of saturation.  This time left the subject in native FoV for the TEC and Atik 460.

Thats what I'm talking about.. now its a masterpiece.. love it.

 

[alan potts]

Those TEC140 are great scopes, Olly swears by his, It is a scope I would consider very strongly if I were to go up in APO size but I also keep looking at the 150mm Espirit which is also very decent. Lovely image now in my books but some will want more saturation🙂.

Alan

[kirkster501]

Yes the TEC140 is superb and it's my best and favourite 'scope.  If I had a gun against my head and told I could only keep one, this is the one to keep.   Not surprising as it is by far the most expensive and hardest to come by too - Yuri's waiting list is a year.    It is a superb 'scope for AP and for visual.  OK, no great shakes in terms of aperture, and won't win any contests in splitting doubles,  although a 5.5 inch refractor is respectable size.  My views through this scope on open clusters and on The Moon with a Nagler 17mm EP are out of this world.

Would love a TEC180 but that is getting silly in terms of size and also cost - over £20000 landed in the UK.  I may get one with a retirement lump sum in six years maybe and then flog the 140.