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Are these Images processable?

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#1 IanK

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Posted 16 April 2021 - 04:54 PM

This is a link to a dropbox with 4 images being the luminance and RGB frames.

 

https://www.dropbox....WNkToJ8exa?dl=0

 

Yes I know there's collimation and coma problems. I can't afford a coma corrector and was very tight on time so couldn't really collimated precisely. But besides those issues the color images are 20 stacked frames at 150 seconds each and the luminance being 40 150 seconds taken with a f/4 refractor with a QHY183 monochrome camera. I cannot afford pixinsight so I did some histogram and levels adjustments in gimp as well as combined the color channels and I feel like for over 4 hours of exposure the amount of detail and color is severely lacking. All photos were taken at a gain of 11 because light pollution and cooled to -30 C. I know images immediately stacked are not supposed to look amazing, but even after some stretches' and curve adjustments I still feel like the detail and color is not what it should be given the camera and the integration time. Are these images actually useless or is gimp just not very good at precise image processing. I can get detail from black and white only, but when dealing with color it gets funky and feels like I'm wasting my time and should move onto a different hobby.

 



#2 Alex McConahay

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Posted 16 April 2021 - 05:38 PM

Ten minutes in Pixinsight produced the following on the luminance. SO, they are processable. 

 

With enough cropping, and displayed on a cell phone (so they remain small), you could have something to show off. 

 

Yes, as  you know, you have problems with star shape. And more skilled processors, or more time from somebody with my limited skills, might produce better.

 

I would, if I were you, process away.  I doubt you will get anything you can be proud of forever because of the problem with the optical aberrations. But, you will learn as you go. 

 

But, it is time to reshoot if you can, also. 

 

Alex

 

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#3 Alex McConahay

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Posted 16 April 2021 - 05:46 PM

Looking at the R, G, B, I think the same thing can be said......

 

Have you registered the whole pile (regardless of filter) to the same master?

 

Or did you register each filter's worth to that filter?

 

Alex



#4 dswtan

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Posted 16 April 2021 - 05:47 PM

I spent less time on it than Alex ;-), but yes, can confirm. You should proceed. But maybe fix that coma! But I would also say I didn't see much color either. It's not a very colorful target though remember!

 

See: https://www.astrobin.../search/?q=m101

 

Image13

 



#5 cybermayberry

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Posted 16 April 2021 - 07:10 PM

Did you do flats?

Don't give up, they very worth processing.

Start saving for the coma corrector smile.gif



#6 BQ Octantis

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Posted 17 April 2021 - 03:39 AM

Yes…most definitely processable.

 

LRGB (Click for full size @ ~29% scale)

gallery_273658_12412_43011.jpg

 

Luminosity (Click for full size @ ~29% scale)

gallery_273658_12412_40857.jpg

 

RGB (Click for full size @ ~29% scale)

gallery_273658_12412_68725.jpg

 

This was all in Photoshop CS5 w/Astronomy Tools 1.6 & Annie's Astro Actions 7.0.

 

Cheers,

 

BQ


Edited by BQ Octantis, 17 April 2021 - 05:48 AM.

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#7 BQ Octantis

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Posted 17 April 2021 - 07:09 PM

I thought I'd mention, if you're not going to spend on a coma corrector, to get the biggest bang for the buck out of this setup you need to invest the time on collimation and calibration—especially if you're going to invest 4 hours+ on capture. The luminosity channel illustrates this nicely—these are the things that limit the quality of what you can get from this setup:

 

(Click for full size.)

gallery_273658_12412_380776.jpg

 

I have a Celestron C5/750 (6-in 750mm f/6 SCT) built in ~1973 that has barely enough backfocus to capture an image. So its performance is what it is, edge coma and all. That doesn't stop me from pushing it to its limits—which requires good collimation and calibration:

 

(Click for full size.)

post-273658-0-94838400-1595855035.jpg

 

Cheers,

 

BQ


Edited by BQ Octantis, 17 April 2021 - 07:11 PM.



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