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IC 1396 in SHO

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#1 Astro_Sholo

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Posted 14 August 2019 - 06:41 PM

Anyone have any idea on how I can get that washed grey look out of this image? Or do you think this is this images limit?  I think I need to take another stab at processing.  I use photoshop + DSS.  I captured this on Aug 9-10 under bortle 6 skies.  I should mention that my Sii data is a tiny bit out of focus.  (electronic focuser on its way) 
 
-20C on ASI1600mm-p 
Sii - 11 x 420s
Ha - 22 x 360s
Oiii - 19 x 420s
darks and flats applied
 
The uneven amount of subs per filter has to do with my unexpected clouds as well as the learning curve with SGP and trying to figure out how to do a meridian flip with my CEM25P (which I haven't figure out yet)
 
Anyway, thanks for taking a look
 
 
IC 1369

Edited by Astro_Sholo, 14 August 2019 - 06:43 PM.

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#2 Kevin Ross

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Posted 14 August 2019 - 06:48 PM

Raise the black point, that will improve the contrast.

Nice image, BTW
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#3 rkinnett

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Posted 14 August 2019 - 07:17 PM

This stack looks surprisingly grainy, given the amount of integration time you put into it.  It looks like you have great data though.  Must be something off in your processing.  

 

Here's my shot of the same target, same weekend, same camera, 2x focal length and 1/3 the integration time.

 

Try processing your images with the same workflow that Trevor at AstroBackyard shows here, along with this tutorial for combining your S/H/O frames into Hubble palette.  Trevor provides some great tips for initial levels adjustments, noise reduction (using Camera Raw filter), star reduction, etc.



#4 the Elf

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Posted 15 August 2019 - 01:04 PM

You can also use a curves tool and lower the left part while pusing up the right part. This is the usual contrast enhancement S-curve.

Do you have Charles Bracken's book The Deep Sky Imaging Primer? Strongly recommended!



#5 rkinnett

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Posted 15 August 2019 - 09:06 PM

Levels and curves will indeed improve global contrast but it will also blow up the noise. You have to get that under control before deep stretching. With this camera and that amount of exposure time, I doubt this amount of pixel-level noise is present in the raw DSS output frames. Unless maybe the source frames were captured in 8 bit? If the source frames are good, you can still end up with discretized pixel-level noise if you apply too many levels, curves, vibrance, etc in 16 bit mode. You want to get your black and white points and gamma dialed in 32 bit mode before switching to 16 bit, and then be conservative in further levels and curves. 2 or 3 curves adjustments are fine if you’re careful not to saturate anything, but half a dozen curve stretches will discretize your color and chop up your histogram into a spiny mess. I’m betting that’s what’s going on here and that another levels or curves adjustment won’t make the image any more printable.

I would be interested to see the DSS output frames with just levels adjustments and one curve stretch.

#6 Astro_Sholo

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Posted 17 August 2019 - 12:16 AM

Levels and curves will indeed improve global contrast but it will also blow up the noise. You have to get that under control before deep stretching. With this camera and that amount of exposure time, I doubt this amount of pixel-level noise is present in the raw DSS output frames. Unless maybe the source frames were captured in 8 bit? If the source frames are good, you can still end up with discretized pixel-level noise if you apply too many levels, curves, vibrance, etc in 16 bit mode. You want to get your black and white points and gamma dialed in 32 bit mode before switching to 16 bit, and then be conservative in further levels and curves. 2 or 3 curves adjustments are fine if you’re careful not to saturate anything, but half a dozen curve stretches will discretize your color and chop up your histogram into a spiny mess. I’m betting that’s what’s going on here and that another levels or curves adjustment won’t make the image any more printable.

I would be interested to see the DSS output frames with just levels adjustments and one curve stretch.

 

 

You can also use a curves tool and lower the left part while pusing up the right part. This is the usual contrast enhancement S-curve.

Do you have Charles Bracken's book The Deep Sky Imaging Primer? Strongly recommended!

 

I decided to try and take another stab at this completely from scratch while using both the youtube tutorial and Deep Sky Imaging Primer and this is what I was able to come up with.  I think it's an improvement from what I previously had as there is not as much noise and the image looks much more pleasing than before.  What do you guys think?

In the future I'm realizing I'm going to have to be much more patient and timid with my processing techniques to yield better results.  

Thanks guys laugh.gif

 

 

IC 1396 Revised

 

 

 

 

 

get.jpg?insecure


Edited by Astro_Sholo, 17 August 2019 - 12:22 AM.

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#7 rkinnett

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Posted 17 August 2019 - 12:32 AM

Love it!


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#8 terry59

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Posted 17 August 2019 - 06:39 AM

I really like your new version. Green, to me, is excellent in SHO images

 

waytogo.gif 


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