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3h M92

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#26 the Elf

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Posted 12 June 2021 - 03:30 PM

 

Still, I would think your 8 inch RC might also be helping with its resolving power?

I don't think so. I might be wrong. The RCs tend to produce soft stars due to the central obstruction and because collimation is critical and perfect collimation is difficult to achieve. Here is a thread dealing with the topic:

https://www.cloudyni...or-unavoidable/

 

To answer the question we have to ask Freddy if he is friendly enough to upload the stack and I process the data in the way I processed my globs. I guess conditions are very similar as we are almost neighbors (some 200 miles I guess).


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#27 F.Meiresonne

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Posted 13 June 2021 - 02:56 AM

I don't think so. I might be wrong. The RCs tend to produce soft stars due to the central obstruction and because collimation is critical and perfect collimation is difficult to achieve. Here is a thread dealing with the topic:

https://www.cloudyni...or-unavoidable/

 

To answer the question we have to ask Freddy if he is friendly enough to upload the stack and I process the data in the way I processed my globs. I guess conditions are very similar as we are almost neighbors (some 200 miles I guess).

Here you go

 

https://www.dropbox....zz/M92.fts?dl=0

 

I leave rather near the sea guess about 25 miles....from it...The Elf more land inworth but i guess to that the conditions are pretty much thesame



#28 the Elf

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Posted 13 June 2021 - 05:35 AM

I'm at the foot of the low mountain range Egge mountains. So the air is troubled when passing by. Most of the time the wind is alongside the mountains and not crossing the range.

Downloading your data. Going to process them later, now that the sun is out I want to spend some time in the pool if it is not too cold.


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#29 F.Meiresonne

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Posted 13 June 2021 - 06:51 AM

I'm at the foot of the low mountain range Egge mountains. So the air is troubled when passing by. Most of the time the wind is alongside the mountains and not crossing the range.

Downloading your data. Going to process them later, now that the sun is out I want to spend some time in the pool if it is not too cold.

 

absolutely.

 

Hope you have 'access' to a good cold Belgian beer, goes great with a the pool or just after the pool...

 

lol.gif



#30 F.Meiresonne

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Posted 13 June 2021 - 10:07 AM

'Egge gebirge' ..? hmm never heard of that sofar, elevation about 400 m over seal level...

 

A range of hills...

 

Eeklo in Belgium is at about 3-4 m above sea level...



#31 vidrazor

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Posted 13 June 2021 - 12:28 PM

I'm at the foot of the low mountain range Egge mountains. So the air is troubled when passing by. Most of the time the wind is alongside the mountains and not crossing the range.

Downloading your data. Going to process them later, now that the sun is out I want to spend some time in the pool if it is not too cold.

Have you heard of this? It's mostly Chinese to me at the moment, but it may be of help in optimizing your rig for your location and seeing conditions.
https://smallstarspot.com/metaguide/
 



#32 Helvetios

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Posted 13 June 2021 - 12:28 PM

Here is a version of M92 that I did recently.  This came out much better than a previous attempt, which had a burned out core, due mainly to using a ZWO EAF with auto focus every hour and temperature change of > 1C, and then using the ArcsinhStretch in PixInsight with a factor of 600.  I like this approach on star clusters as it preserves color and maintains the core stars pretty well.  It does result in an image that is too warm in color and too dim (i.e., not stretched enough), so I then stretched it further using CurvesTransformation and then a bunch of other tweaks in DXO PhotoLab, including the tint slider to get the color where it seems it should be based on HST images of globular clusters.

 

https://www.astrobin...cq52l4/?nc=user



#33 vidrazor

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Posted 13 June 2021 - 02:55 PM

Here is a version of M92 that I did recently.  This came out much better than a previous attempt, which had a burned out core, due mainly to using a ZWO EAF with auto focus every hour and temperature change of > 1C, and then using the ArcsinhStretch in PixInsight with a factor of 600.  I like this approach on star clusters as it preserves color and maintains the core stars pretty well.  It does result in an image that is too warm in color and too dim (i.e., not stretched enough), so I then stretched it further using CurvesTransformation and then a bunch of other tweaks in DXO PhotoLab, including the tint slider to get the color where it seems it should be based on HST images of globular clusters.

Very nice! You might want to check out Topaz Sharpen AI. I ran your full res image through and it did a nice job of "focusing" the stars. The actual "focus" operator in the app, while it wasn't bad, did not look as good as what the "stabilize" operator did. The Topaz apps are hit-n-miss affairs, but they are handy tools to have I think.

 

Have a look. Below are 100% crops embedded into the image res limit here on CN (and hopefully not too chewed up in the transfer, click to view full size), I also brought the white point just before clipping in PS in your original image. What do you think?

Attached Thumbnails

  • m92 Helvetios.jpg

Edited by vidrazor, 13 June 2021 - 03:05 PM.

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#34 the Elf

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Posted 13 June 2021 - 03:23 PM

Actually I do not drink any beer. Have a nice Italian red wine instead. I have a swimming tray for the pool with little pockets to put glasses in....

 

Back to the topic. Here is my go on Freddy's data.

Processed to 4k, downsampled for the upload:

 

M92_Freddy_low.jpg

 

100% crop of the center:

 

M92_Freddy_crop.jpg

 

actually I find this better than my own data. It shows less stars but also less artifacts. Nice data!

 


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#35 F.Meiresonne

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Posted 13 June 2021 - 03:42 PM

Wow, that is one heck of a crop...very well done...


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#36 F.Meiresonne

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Posted 13 June 2021 - 04:07 PM

Actually I do not drink any beer. Have a nice Italian red wine instead. I have a swimming tray for the pool with little pockets to put glasses in....

 

Back to the topic. Here is my go on Freddy's data.

Processed to 4k, downsampled for the upload:

 

attachicon.gifM92_Freddy_low.jpg

 

100% crop of the center:

 

attachicon.gifM92_Freddy_crop.jpg

 

actually I find this better than my own data. It shows less stars but also less artifacts. Nice data!

Do you think the artifacts of which you speak are caused by the central obstruction of the RC?



#37 Helvetios

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Posted 13 June 2021 - 04:44 PM

Very nice! You might want to check out Topaz Sharpen AI. I ran your full res image through and it did a nice job of "focusing" the stars. The actual "focus" operator in the app, while it wasn't bad, did not look as good as what the "stabilize" operator did. The Topaz apps are hit-n-miss affairs, but they are handy tools to have I think.

 

Have a look. Below are 100% crops embedded into the image res limit here on CN (and hopefully not too chewed up in the transfer, click to view full size), I also brought the white point just before clipping in PS in your original image. What do you think?

Thanks very much.  I do have this app and have found that it sometimes messes up stars.  But what you got looks very good.  I'll have a go at it.


Edited by Helvetios, 13 June 2021 - 08:11 PM.


#38 Mike in Rancho

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Posted 13 June 2021 - 06:04 PM

I'm at the foot of the low mountain range Egge mountains. So the air is troubled when passing by. Most of the time the wind is alongside the mountains and not crossing the range.

Downloading your data. Going to process them later, now that the sun is out I want to spend some time in the pool if it is not too cold.

 

I tried Wikipedia, it says "Lower Saxon Hills."  Wow, that sounds very historic (at least to an American lol).

 

However, in the picture I can't say I saw anything that looked like much of a hill.

 

 

Actually I do not drink any beer. Have a nice Italian red wine instead. I have a swimming tray for the pool with little pockets to put glasses in....

 

Back to the topic. Here is my go on Freddy's data.

Processed to 4k, downsampled for the upload:

 

 

 

100% crop of the center:

 

 

 

actually I find this better than my own data. It shows less stars but also less artifacts. Nice data!

I think we will need one of your famous side-by-side's, Elf.  Though I would imagine you are again being too self-critical of your own data, I'm curious what the artifacts are that you speak of.  Maybe a zoom with some arrows?

 

I'm also wondering about resolving when it comes to these RC's vs. refractors, though Freddy does have a decent aperture at 130.

 

The star halos have a particular color pattern to them, almost like prismatic dispersion.  I have been getting quite a bit of that myself lately.  I expect it low on the horizon, like with Omega Centauri, but I'm going to have to do a test to see if it follows my objective lens orientation to rule out an optical problem.  That said mine are generally half and half as to blue and red edges.  Freddy's data looks more like 3/4.

 

RGB align in the stacker helps fix most of it on my data.



#39 vidrazor

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Posted 14 June 2021 - 12:10 AM

Thanks very much.  I do have this app and have found that it sometimes messes up stars.  But what you got looks very good.  I'll have a go at it.

Yes, all the Topaz apps can be a double edge sword, but when they work they can spare you a lot of reprocessing or alternate/additional processing. Sometimes I use parts of a process, like DeNoise for skies, but original stars dropped in through alphas, or Denoise on a Starnet++ data, which tends to work well more often than not. Like I said, they can be hit-n-miss affairs, but they are still tools to have in the toolbox.
 



#40 vidrazor

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Posted 14 June 2021 - 01:49 AM

I took a stab at your file and, not surprisingly, wound up somewhere else. smile.gif For some reason I always start these projects just before going to bed, and before I know it, it's 2:45 AM LOL!

I started in Siril, where I miraculously was able to get it to do a photometric color calibration, which rarely happens for me. I have to say the color always looks off to me when I do that, I should have tried a manual calibration I think. Then I did a gradient removal. From there I did some initial stretches with it's histogram tool, then did an asinh stetch, followed by the deconvolver set at default. While I liked what the deconvolver did to the stars, it wreaked havoc on the sky, I had to do noise reduction in DeNoise for the skies, and continued stretching Photoshop where I also removed black level color noise and brought up star color. I don't know if it will get hacked up uploading here, but here's your core area at 100%. smile.gif

Attached Thumbnails

  • M92F.Meiresonne.jpg

Edited by vidrazor, 14 June 2021 - 01:52 AM.

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#41 F.Meiresonne

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Posted 14 June 2021 - 05:45 AM

This too looks impressive...

 

EDIT : this is stunning! forgot to open the jpg...you are sure this is my stack lol.gif ? I am very surprised that is cropped that much but still producings pretty fine sparkling stars....

 

Deconvulation seem to have done  a great thing here..

Personaly i would apply a bit less saturation perhaps, cause the blue stars showing some blue halo. Still i noticed that too about 10 o'clock on the stars..wich is probably a atmosferic issue. The glob was not that high up.

 

Still this is awesome..!

 

Seems my processing still can be better...seems that for some reason, the capturing of objects in most cases goes very good, but my processing still needs tinkering...hmm.gif


Edited by F.Meiresonne, 14 June 2021 - 05:58 AM.


#42 vidrazor

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Posted 14 June 2021 - 09:33 AM

This too looks impressive...

EDIT : this is stunning! forgot to open the jpg...you are sure this is my stack lol.gif ? I am very surprised that is cropped that much but still producings pretty fine sparkling stars....

Deconvulation seem to have done  a great thing here..

Personaly i would apply a bit less saturation perhaps, cause the blue stars showing some blue halo. Still i noticed that too about 10 o'clock on the stars..wich is probably a atmosferic issue. The glob was not that high up.

Still this is awesome..!

Seems my processing still can be better...seems that for some reason, the capturing of objects in most cases goes very good, but my processing still needs tinkering...hmm.gif

Yeah, I really wasn't happy with the color balance, so the color saturation was an act of desperation at 2:45 AM LOL! Maybe later I'll redo it and do manual color calibration in Siril instead of photometric to try and get a better color balance. The deconvolution worked really nice on the stars but the skies were frightening! I had to jump some hoops With Topaz DeNoise and Photoshop to tame both the luminosity and color noise that shot through the roof at the black levels.

I appreciate when people put up their stacks so I can practice post production, because I haven't been able to get out to good skies to shoot. I'm actually finalizing setting up a rig I started last year, been doing some tests in my Bortle 9 skies, and I think I'm just gonna start shooting here in astrophotography hell (I live right across from Manhattan) and finish honing in the setup. This summer I hope to get out to some good skies to shoot, but in the meantime I play with everyone else's stacks. smile.gif

 

EDIT: I did some channel processes to the existing render to try and wrangle that color. It looks a little better I think. I brought some of the core density/color back as well. Core density is something you really need to address at the 32 bit stage but this render was already at 16 bit, but I managed a little bit of an eek out of it. Overall it looks better to me although the color is still not where it should be I think.

Attached Thumbnails

  • M92F.Meiresonne-16b.jpg

Edited by vidrazor, 14 June 2021 - 10:17 AM.


#43 the Elf

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Posted 14 June 2021 - 01:00 PM

Do you think the artifacts of which you speak are caused by the central obstruction of the RC?

Yes and no. I think they are caused by too much deconvolution and I do it with the actual PSF picked from the image. Maybe this sort of procedure enhances the problem. My globs:

 

Globs.jpg

 

In M5 and M92 stars look like little droplets. In M3 some stick together like little worms. M13 is fine in my eyes. It is the only one take with true L from my mono. The others are OSC only. This might tell it is the debayer. Otoh M13 was shot with the scope out of collimation. All stars have sort of a belly towards the same direction. This is fixed now.

For the time being I won't do anything here. They look much better then the first attempt and they look quite good in full screen on fullHD. I have worse images in my gallery that need care more urgent. For example stupid Elf forgets the Semi-Apo filter (fringe killer) in the box and shoots a blueberry Elephant trunk.

https://www.elf-of-l...Obj_IC1396.html

Definitely want to capture new data here.


Edited by the Elf, 14 June 2021 - 01:03 PM.

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#44 F.Meiresonne

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Posted 14 June 2021 - 02:08 PM

Well, if you it makes you feel better, i once forgot my Bahtinov mask....would you believe that....

 

The thing is a Bahtinov easily falls off the scope ....that particular evening it refused to do so and stayed on the scope , bravely ,the whole session ...



#45 F.Meiresonne

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Posted 14 June 2021 - 03:12 PM

M3 looks the best to me.M13 a little bit more fuzzy...guess different opinions....



#46 the Elf

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Posted 15 June 2021 - 01:31 AM

Hermannsdenkmal_Teutoburger_Wald.jpg

 

https://en.wikipedia...Hermannsdenkmal

(the image shown is in the German wikipedia)

This is what I see from my garden, well not from the bird perspective of course. The monument is at 368m elevation, my garden is at 130m. I think it is this difference in height that troubles the air when the wind is in the wrong direction. It looks a lot different today. We suffered from a severe drought 2 years ago and the Bark Beetle wiped out all spruces you can see in the image. Now this looks mostly like a desert, only the hardwoods are left. Spruces are not a natural vegetation for this region. They have been imported for timber business generations ago because they grow so fast. Now nature has shown that the plan did not work.

 

Fun fact: in Detmold city center there is a copy of one foot in original size in the city center. Several persons can easily sit on it.


Edited by the Elf, 15 June 2021 - 01:45 AM.

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#47 the Elf

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Posted 15 June 2021 - 01:40 AM

I forgot the Bahtinov mask, too. The list of foolish mistakes is long. As a beginner I took the wrong star for polaris and was not able to align the mount. There is no cap that fits the rear thread of my photo back of the RC8. So I attach a 10mm extension I have a cap for when storing the scope. The correct procedure is to unbox the scope, remove the extension that holds the cap and put the T-ring there. One night I pulled of the cap and put the T-Ring there. The focuser had enough travel to compensate but there was absolutely nothing in the guide camera at the OAG. Since that day I know that the focuser supposed to be at 15mm for a sharp image and 15 is marked with a red felt pen. I also tried a wide field with a camera lens and left image stabilization turned on. Good news is, so far I have never broken any glass and nothing went up in smoke. Knock on wood.

My theory: going to work every day causes severe brain damage.


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#48 Mike in Rancho

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Posted 15 June 2021 - 02:24 AM

There's some good purple in that Elephant Trunk, Elf.  I approve!  lol.gif

 

And what a beautiful green photo, seems a nice forested area to be in.  laugh.gif  Looks to be a few dying trees there already, hopefully the drought damage wasn't as bad as you say?

 

Seriously I can see Hobbits living there.  Or maybe a witch in a gingerbread house? tongue2.gif

 

The glob comparisons are interesting.  For Freddy's, I'm wondering how much of that is legit and how much is Topaz?  From a distance it practically looks like Hubble level small detail.  But lean in close and things start looking weird.  The sharp edges everywhere don't look like what I'm used to from deconvolution either.

 

But, it does seem very sparkly.



#49 vidrazor

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Posted 15 June 2021 - 08:04 AM

For Freddy's, I'm wondering how much of that is legit and how much is Topaz?  From a distance it practically looks like Hubble level small detail.  But lean in close and things start looking weird.  The sharp edges everywhere don't look like what I'm used to from deconvolution either.

 

But, it does seem very sparkly.

Actually that "weirdness" you're seeing is probably mostly me hammering the crap out of the image with levels LOL. It actually is mostly deconvolving although DeNoise did contribute to sharpening, especially at the core. A combination of the two, if you will. Topaz DeNoise worked out pretty well on this image I think, but I do wish you could shut sharpening all off if you wanted to. I could've softened things up with a Gaussian blur, but I like what did overall. Below are 100% crops of before and after DeNoise. You can see all the chroma noise and luma "lumpiness" I still had to contend with in the blacks. I think if I had just started with better color correction in Siril I could've had a better time of it in Photoshop.

 

Considering what we're looking at tho, how weird is weird? grin.gif

Attached Thumbnails

  • nr sample.jpg

Edited by vidrazor, 15 June 2021 - 08:58 AM.


#50 F.Meiresonne

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Posted 15 June 2021 - 08:18 AM

Hermannsdenkmal_Teutoburger_Wald.jpg

 

https://en.wikipedia...Hermannsdenkmal

(the image shown is in the German wikipedia)

This is what I see from my garden, well not from the bird perspective of course. The monument is at 368m elevation, my garden is at 130m. I think it is this difference in height that troubles the air when the wind is in the wrong direction. It looks a lot different today. We suffered from a severe drought 2 years ago and the Bark Beetle wiped out all spruces you can see in the image. Now this looks mostly like a desert, only the hardwoods are left. Spruces are not a natural vegetation for this region. They have been imported for timber business generations ago because they grow so fast. Now nature has shown that the plan did not work.

 

Fun fact: in Detmold city center there is a copy of one foot in original size in the city center. Several persons can easily sit on it.

Wow, what a view...i envie you...




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