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Orion and Running Man nebulae - with HDR sub-images (C&C welcome)

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#1 DivisionByZero

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Posted 06 December 2021 - 01:24 AM

I fixed it!  Last weekend or some-such I had attempted a serious swipe at this same subject, but was defeated by internal telescope reflections.  I managed to make some adjustments to the scope and an entirely new, fresh set of data.  The result is here:

 

get.jpg?insecure

 

This new one has 2 hours more luminance than the previous one, so I was able to push harder in some regions.

 

As part of this learning process, I was able to understand high-dynamic range (HDR) image creation much better.  I found myself somewhat mystified by it prior to embarking on this pair of images and I wanted to provide more information on my process for this image.  To that end, revision A and revision B of the above are the individual, processed images based on the two different subframe lengths.  Part of my process was to keep the same, approximate region of interest during stretching in StarTools.  This pushes the data in the two images to about the same contrast level and so it provides a comparison of a much longer integration time.  Other aspects of the processing is kept as close as possible, especially in the color processing.  

 

In the end, the two images are added to a single GIMP image as layers.  The 30s dataset is masked using some painted circles that are then subjected to a Gaussian blur in the range of 5-10 pixels.  The exact amount of blur depends on the region and I try to make the transition as seamless as possible.  There are really only a few areas from the 30s data set: the M42 core, few star cores in top right, and a couple star cores at the Running Man.  

 

At any rate, since I was confused by the HDR process, I hope that this set of images helps others with the same process.

 

C&C welcome.  I still need a coma corrector.  Thanks for looking!


Edited by DivisionByZero, 06 December 2021 - 01:38 AM.

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#2 ziggeman

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Posted 06 December 2021 - 01:53 AM

A beauty with color! Maybe I would have cropped it a little to get rid of coma and vinjetting but I would be very pleased if I managed to image like this. Very nice smile.gif


Edited by ziggeman, 06 December 2021 - 01:54 AM.


#3 Tim J Fowler

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Posted 06 December 2021 - 08:01 AM

Beautiful image. My only critique would be the whole image appears soft. Not out of focus soft, but processed as if there were a thin film of Vaseline on the image, if that makes sense. Still a very nice image.



#4 DivisionByZero

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Posted 06 December 2021 - 08:51 AM

Tim, thanks for the feedback. StarTools has a "Super Structure" tool and it has this effect. I have a love/hate relationship with it and turned it way down this time. Other times I don't use it at all. Maybe I'll go back to not using it - or more likely, read the documentation a lot more closely and figure out how to really use it correctly!

#5 DivisionByZero

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Posted 07 December 2021 - 12:54 AM



Beautiful image. My only critique would be the whole image appears soft. Not out of focus soft, but processed as if there were a thin film of Vaseline on the image, if that makes sense. Still a very nice image.

Tim - I took your comment and reprocessed the image making some adjustments to the Super Structure tool and then Noise Reduction settings.

get.jpg?insecure

 

Digging into super structure a bit, it works by constructing a "low-detail" version that finds the large-scale structures.  It then makes a new image by taking the original and the low-detail version and combining them in various methods.  Suffice it to say, for the presets I was using before, it layered the two together in a way that made the new image look like it had a big low-pass filter on it (I think "Vaseline" works as a description).  There are other presets though and I used, instead, the "Brighten" presets with some adjustments so that it brought out the darker clouds away from the noise floor.

 

On the Noise Reduction end, I tried to achieve a balance in scale settings and brightness detail loss that avoids looking overbaked, but still achieves some reduction in graininess.

 

I guess I should add that I followed the advice on the StarTools website to output the stacks as 32-bit files instead of 16-bit.  I don't know that that makes a big difference considering the number of subs I took and the bit-depth of the ASI1600MM.

 

Since there's not much noise in the core, I didn't bother re-processing the 30s data set - I just move the new image into the GIMP file as a layer and used that instead of the old one - easy!

 

Overall, I think I prefer this new version.


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#6 Tim J Fowler

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Posted 07 December 2021 - 07:25 AM

Tim - I took your comment and reprocessed the image making some adjustments to the Super Structure tool and then Noise Reduction settings.

get.jpg?insecure

 

Digging into super structure a bit, it works by constructing a "low-detail" version that finds the large-scale structures.  It then makes a new image by taking the original and the low-detail version and combining them in various methods.  Suffice it to say, for the presets I was using before, it layered the two together in a way that made the new image look like it had a big low-pass filter on it (I think "Vaseline" works as a description).  There are other presets though and I used, instead, the "Brighten" presets with some adjustments so that it brought out the darker clouds away from the noise floor.

 

On the Noise Reduction end, I tried to achieve a balance in scale settings and brightness detail loss that avoids looking overbaked, but still achieves some reduction in graininess.

 

I guess I should add that I followed the advice on the StarTools website to output the stacks as 32-bit files instead of 16-bit.  I don't know that that makes a big difference considering the number of subs I took and the bit-depth of the ASI1600MM.

 

Since there's not much noise in the core, I didn't bother re-processing the 30s data set - I just move the new image into the GIMP file as a layer and used that instead of the old one - easy!

 

Overall, I think I prefer this new version.

Agreed, I like your second version better. I was thinking maybe create a starless version and a stars only version. After you have the starless version, you could process the nebulosity with the super structure feature, then just blend a stars only version back in so the stars should remain pin point. I know nothing about StarTools, so you might have to use starnett++ to create the starless version. Your new process looks good though. I'd love to try processing your stacked TIF or FIT file myself just to see what I could get out of it. That's a crazy amount of detail you captured! Well done.



#7 DivisionByZero

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Posted 07 December 2021 - 11:49 PM

Tim: have at it!

 

https://drive.google...P-9?usp=sharing

 

The technical card on A-bin is accurate for the most part.  Everything is calibrated with bias, matched darks, and flats

30s data set:

L: 15m actual integration time

R: 13m 30s

G: 8m 14s

B: 10m 21s

 

240s data set:

L: 4hr

R: 52m

G: 32m 30s

B: 39m

 

The varying integration times for the colors were determined by a G2V calibration.  The ratios are pretty close to the theoretical values based on the QE curve of the camera and filter bands.  They compare favorably to a set of single subframes from a shot on HD210211.

 

I'd love to see how it goes - you've got me curious about starnet++!


Edited by DivisionByZero, 07 December 2021 - 11:53 PM.

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#8 DivisionByZero

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Posted 07 December 2021 - 11:57 PM

Also: I don't know where else to put this, but I inadvertently posted that Orion Nebula picture, almost 6-years to the day that I posted my first, ever, M42!

 

I like comparisons so here is one.

Attached Thumbnails

  • M42-comparison_2015v2021.jpg

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#9 Mike in Rancho

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Posted 08 December 2021 - 04:53 AM

I saw 4 hours L on M42 and had to give it a try.  smile.gif  Great amount of surrounding dusty stuff you picked up.

 

I only used the 240s set, usually no need to blend exposures when you have the HDR module.  But at 240s, the deep core is saturated and so are the big stars.  I think it still worked though.  Composited just as L, RGB.  I thought about trying to undo the unbalanced RGB by setting the exposure times, but that just affects the Synth L so not sure it would have done much.  In Color I just went with star sampling and it seemed okay so left it at that.  I suppose I could have tried to bump up the dynamic range in SVD also to see if more of the core could be recovered, but if saturated at acquisition that may not have worked anyway.

 

I kept things fairly mild on the swirls, and then didn't like the SS result - made this data too soft in my opinion and pushed back too many stars.  So canceled that and just did default NR.

 

As you noted, there's some coma going on as you near the corners.  And the dust detail also gets pretty ragged on both far sides.  Uncertain if that's the same effect?

 

Still, lots of fun, and no crazy arches to try to heal out either! tongue2.gif  Thanks for posting.

 

gallery_345094_15786_18179.jpg


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#10 Tim J Fowler

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Posted 08 December 2021 - 05:06 AM

Thanks for posting! I downloaded everything, but it's going to be Saturday before I can give processing a whirl (work heavy days). This will be fun! I'm used to RGB data, so a learning experience for me grin.gif .


Edited by Tim J Fowler, 08 December 2021 - 05:10 AM.

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#11 DivisionByZero

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Posted 08 December 2021 - 07:41 AM

I saw 4 hours L on M42 and had to give it a try. smile.gif Great amount of surrounding dusty stuff you picked up.

I'm glad you did! I feel like I'm only now getting a better grip on post processing and seeing others' choices and comparing has been helping a lot.

I only used the 240s set, usually no need to blend exposures when you have the HDR module. But at 240s, the deep core is saturated and so are the big stars. I think it still worked though. Composited just as L, RGB. I thought about trying to undo the unbalanced RGB by setting the exposure times, but that just affects the Synth L so not sure it would have done much. In Color I just went with star sampling and it seemed okay so left it at that. I suppose I could have tried to bump up the dynamic range in SVD also to see if more of the core could be recovered, but if saturated at acquisition that may not have worked anyway.

Knowing I had the 30s data set definitely had me worrying less about the core. There was an analogy when processing the 30s: I only worried about the core in that one. I had used a L+synthetic L and RGB when I composites. That helped reduce the saturation in the stars and core just a bit.

I guess color is a funny thing, really. There are so many images with one white balance that when it is different, we really notice. It was the one with the arcs where I decided to trust the G2V calibration. I set the biases to 1.0 and then only cap green if I have to. My M45 needed a little extra of adjustment, but I've tried to keep it close to the theory. I don't know what's real.

I kept things fairly mild on the swirls, and then didn't like the SS result - made this data too soft in my opinion and pushed back too many stars. So canceled that and just did default NR.

As you noted, there's some coma going on as you near the corners. And the dust detail also gets pretty ragged on both far sides. Uncertain if that's the same effect?

I'm positive they are the same effect. Coma is a loss of contrast so all the contrast goes to pot out there. Some day I'll get my new gear including the CC...

Still, lots of fun, and no crazy arches to try to heal out either! tongue2.gif Thanks for posting.

gallery_345094_15786_18179.jpg


Thank you for the example!
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#12 Tim J Fowler

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Posted 11 December 2021 - 09:51 AM

Okay, I finally got a chance to give your data a try. This was only using the 240 sec data. Keep in mind that I have no idea what I'm doing with LRGB data, especially the "L" part. I did this on my laptop, so I'm sure my colors are a bit wonky. I used Siril and GIMP and a lot of trial and error. Mostly error. After the CN needed downsizing, my stars look a bit soft to me. Also, I did no star removal, and very little in the way of noise reduction. This was mostly a trial run to try a figure out how to handle the separate channels. I will try to do a better processing run now that I have a better idea what I'm doing. Thanks for posting your data!

 

I am curious, when I stretched the 30 sec red channel, there was some kind of grid pattern. What causes this? I attached an example.

Attached Thumbnails

  • M42 Siril GIMP edit small.jpg
  • 2021-12-11T14.55.jpg

Edited by Tim J Fowler, 11 December 2021 - 09:58 AM.

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#13 F.Meiresonne

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Posted 11 December 2021 - 12:48 PM

Interesting data. This is the 30 s stack.

 

I noticed in the original stretch 2 strange patters are visible. There is a circular one, not good visible and also a strange vertical lining of some kind. Looks like walking noise but it is not.

 

I could get some stunning core detail (always like that, can't help)

But i messed the stars a bit up...

 

@Mike Rancho, how do you get to stars to good, what do do you do?

 

background a bit dark cause of that strange vertical banding of some kind..

 

Still nice to process, great shot!

Attached Thumbnails

  • M42Short2.jpg


#14 F.Meiresonne

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Posted 11 December 2021 - 01:26 PM

This stack was better 240".

Vertical ligning was not there, i did not see the circular artifacts either.

More data, seemed cleaner .

 

Came out nice, one of the few i did not touch in GIMP afterwards. Well only to make a jpg and png for it .

 

 

And the  jpg does not do it justice so here a link to a better png

 

https://www.cloudyni...911_4173934.png

Attached Thumbnails

  • M42_240_ST_500kb.jpg

Edited by F.Meiresonne, 11 December 2021 - 01:30 PM.

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#15 Mike in Rancho

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Posted 11 December 2021 - 02:42 PM

Yes, I hadn't looked at the 30s files earlier, but indeed that waffle pattern in the red is weird.  All the files have a slight vertical streaking, really not enough to cause any trouble, but that 30s red almost looks like a debayer gone wrong but still stacked?  I've had cross-hatching from using spiral dithering, but it wasn't like that.

 

But how it would happen with a mono file, unless the stacker mistakenly thought it was OSC...?

 

Freddy, I dunno!  tongue2.gif  Other than a big HDR to tame the core, I think this was my fairly quick and routine workflow.

Attached File  StarTools DivByZero M42 1.txt   6.02KB   3 downloads


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#16 fewayne

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Posted 11 December 2021 - 03:11 PM

I guess I should add that I followed the advice on the StarTools website to output the stacks as 32-bit files instead of 16-bit.  I don't know that that makes a big difference considering the number of subs I took and the bit-depth of the ASI1600MM.

I guess DBZ knows what's going on here, but since this is the beginning deep-sky forum it's worth pointing out: Regardless of the number of bits your camera's analog-to-digital converter puts out, stacking will increase that bit depth very considerably since the averaging interpolates between values. If your camera had a one-byte output (256 possible values), two adjacent pixels in a nebula might have values of, say, 142 and 143 in a single sub. No way to determine from that what the "real" values were -- since they're adjacent, the actual (unknowable) brightness probably differs by less than 1 part in 256.

 

But as you take more subs, the means get more and more precise. Just as a random example, you shoot 8 subs and you get 3 142s, a 143, and 4 141s. The mean of those values is 141.625, that is to say you're now down to eighths of the original steps, as if you'd added 3 more bits to the ADC.

 

Now, whether DBZ's 12-bit ADC is "enhanced" enough by his number of subs to be worth using 32-bit stacking output instead of 16-bit is left as an exercise for the reader. Seems pretty likely though.


Edited by fewayne, 11 December 2021 - 03:13 PM.


#17 F.Meiresonne

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Posted 11 December 2021 - 04:36 PM

Yes, I hadn't looked at the 30s files earlier, but indeed that waffle pattern in the red is weird.  All the files have a slight vertical streaking, really not enough to cause any trouble, but that 30s red almost looks like a debayer gone wrong but still stacked?  I've had cross-hatching from using spiral dithering, but it wasn't like that.

 

But how it would happen with a mono file, unless the stacker mistakenly thought it was OSC...?

 

Freddy, I dunno!  tongue2.gif  Other than a big HDR to tame the core, I think this was my fairly quick and routine workflow.

attachicon.gifStarTools DivByZero M42 1.txt

Thanks Mike for the log...some examination to dolaugh.gif


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#18 DivisionByZero

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Posted 12 December 2021 - 05:56 PM

Ah - it's helpful and I know how to pull it out, so I'm attaching my process log for the 240s image.  I want to compare notes.. or maybe someone else can compare and let us all know what was different - I'm stuck fixing a dishwasher today!

 

As for the waffle pattern: wow - I didn't notice it ever before!  That said, I had to stretch my levels down to the very bottom of the signal range to see it at all.  When I processed the 30s set, I concentrated my attention on the core and didn't need to get nearly as aggressive elsewhere.

 

I'm going to guess that this is a flat artifact - both the waffle and the circular pattern.  I can't find the waffle in my light frame when I stretch it about the same.  My flats are taken as follows:

I have a tracing pad that provides "uniform" illumination.  That is placed against a white T-shirt (single layer).  This is spaced about 2.5" away from a single sheet of white printer paper.  The white printer paper (the last diffuser) is very close to the end aperture of the telescope opening.  It's possible that the paper has a pattern, though I kind of find this far-fetched, it's about the only thing I can think of.

 

I'm uploading, a stretched master flat for my red channel.  There's apparently a lot of dust on my filters!  However, I can also make out a little bit of pattern in the image!  I'll be considering frosted acrylic instead of the T-shirt/printer paper options, I think.

 

Seeing all these alternate processes is great, by the way!

 

Ok... back to a dishwasher problem with me...

Attached Thumbnails

  • MasterFlat_RED-Gain0.jpg

Attached Files



#19 Mike in Rancho

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Posted 12 December 2021 - 10:52 PM

Hope your dishes are now clean!  tongue2.gif

 

I just gave your log a cursory read, will have to follow through later maybe.  But, you might consider trying out 1.8 too.  There's a bit of a learning curve again with some new modules, but one of those is HDR and is more powerful.  It needs a bit of CPU power and can take time to churn through the first iteration, but there are tips on the ST forums on ways to deal with that.  But, tailor-made for something like this with the strong core.

 

I tried stretching your master flat even more, and am really not seeing the same thing.  Some vertical banding, fairly mild, but no waffle.  What do you use for stacking?  Might take some more investigation if you are looking to see what's up the 30 second set and what the source of the grid pattern is.

 

240s seems awfully long for Orion though.  This wasn't filtered data was it?  I may take a run at M42 later on, depending on what I think of the moon and my tolerance for chilly temps.  tongue2.gif   And if I feel okay with my latest collimation practice test.  But when I first tried it, even 30 seconds at ISO100 was blowing the cores of the brightest stars.  Granted, quite a few bright ones here.  But if you're using ST, I would just find a good exposure limiting any left and right side clipping, and go with it.  I really don't think old school manual HDR by blending short subs is a concern. smile.gif 



#20 Look at the sky 101

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Posted 12 December 2021 - 10:55 PM

Also: I don't know where else to put this, but I inadvertently posted that Orion Nebula picture, almost 6-years to the day that I posted my first, ever, M42!

 

I like comparisons so here is one.

Remarkable progress in your work. 


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#21 DivisionByZero

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Posted 12 December 2021 - 11:40 PM

Hope your dishes are now clean!  tongue2.gif

 

I just gave your log a cursory read, will have to follow through later maybe.  But, you might consider trying out 1.8 too.  There's a bit of a learning curve again with some new modules, but one of those is HDR and is more powerful.  It needs a bit of CPU power and can take time to churn through the first iteration, but there are tips on the ST forums on ways to deal with that.  But, tailor-made for something like this with the strong core.

 

I tried stretching your master flat even more, and am really not seeing the same thing.  Some vertical banding, fairly mild, but no waffle.  What do you use for stacking?  Might take some more investigation if you are looking to see what's up the 30 second set and what the source of the grid pattern is.

 

240s seems awfully long for Orion though.  This wasn't filtered data was it?  I may take a run at M42 later on, depending on what I think of the moon and my tolerance for chilly temps.  tongue2.gif   And if I feel okay with my latest collimation practice test.  But when I first tried it, even 30 seconds at ISO100 was blowing the cores of the brightest stars.  Granted, quite a few bright ones here.  But if you're using ST, I would just find a good exposure limiting any left and right side clipping, and go with it.  I really don't think old school manual HDR by blending short subs is a concern. smile.gif

Man - I didn't even know ST 1.8 was out!  I'll check it out at some point, for sure.  I find that once I started understanding what the modules were doing (e.g. super structure) I was much better at getting good results out of them.  Deconvolution is magical, for instance.  I imagine the new version improves further.

 

For stacking I use DSS.  If it doesn't show up in the 240s data (or the other short subs), I don't think it's as systemic as my stacking software would be, but I guess I can't be sure.  It's a bit of a mystery, for sure.

 

The filters are just broadband LRGBs, but 4 minutes was a conscious choice.  I'm not a fan of transferring (and inspecting!) a lot of sub-frames and I knew I wanted to get more than 5 hours on this target.  Once I committed to an HDR process I didn't worry about blowing things out, just getting the dim stuff.  It was really liberating, actually.  But even at 30s I'm letting some of those star cores saturate (my 1s sub set didn't stack properly so I left it away).  If I had just used 30s subs, I would have been up to 480 subframes, just for 4 hours of luminance!  It's just too much, in my opinion.  Since my mount was handling it ok, I think it works out in the end.



#22 unimatrix0

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Posted 12 December 2021 - 11:42 PM

 

Imaging Scope: Modified Celestron Astromaster 114 (448mm f.l., f/5 effective)

Great stuff, especially from a 114mm Astromaster! 
 

Any insight how you modified this telescope? 



#23 DivisionByZero

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Posted 12 December 2021 - 11:56 PM

Great stuff, especially from a 114mm Astromaster! 
 

Any insight how you modified this telescope? 

I chopped about 3 inches off the back to move the primary up and forced the Bird-Jones corrector out of the draw-tube base.  These both allowed prime imaging onto a DSLR sensor, which is what I started with.  I've added a hood and some more flocking/baffles here and there.  A few years ago it all looked like this:

get.jpg?insecure

Now I have an ASI1600 and filter wheel instead of the DSLR.  I still source the 12V TEC on the ASI with that P/S below the scope, though.  Also: I don't live where there's grass any longer.  At any rate, I think I used metal shears to do the cutting on the tube, but I was careful enough that any tilt from hand-cutting the metal was within range of the primary mirror cell.  There's a bit of light-loss in the 1.25" draw-tube and it's still the original secondary which is sized for the original mirror position.  Between those two it ends up being stopped down slightly, hence the note about an "effective" f/#.

 

My biggest problem is that there are no-where in existence, coma correctors for a 1.25" draw-tube.  I would have to make much stronger modifications for a 2" focuser to go in that direction with this scope.  Instead, I've been eyeing a proper 6" imaging newt, but supply chains are thwarting my efforts.




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