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Some Basic Imaging and Processing Questions

astrophotography beginner Orion
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#1 Seaquel47

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Posted 22 January 2020 - 12:58 PM

Up to now, most of my efforts have been focused on putting together a decent starter Astrophotography setup and working out the kinks and challenges of my imaging workflow.  Having worked through focusing, guiding, image framing (remembering to remove the bahtinov mask, lol), everything finally when well shooting the Andromeda galaxy last night.  I even did my first full set of calibration frames.  So as I try to decide how to begin processing this I have several unrelated questions:

 

I took 50, 2 minute light frames and afterwards I see a reddish cast to the second half of them.  I'm assuming it is from light pollution as Andromeda got lower in the sky.  Should I try to remove the cast from individual frames before stacking?

 

I just purchased the Adobe photography suite and I have Sequator, DSS and a trial version of APP.  I have both a Mac and a Windows 10 machine.  My first attempt with APP was disappointing (albeit with limited data) whereas Sequator did a better job with it.  Any suggestions on where to find a good processing workflow to try?  I am open to try other programs.

 

With the Orion nebula so prominent, I would like to gather data now for later processing.  Because of the dynamic range, should I shoot it using different exposure times to get both the nebulosity and the bright inner core?  I gather there are ways to combine these data to get a better image.  Are there other ways to accomplish this without using different exposures?

 

I read where folks keep adding lights to previous sessions to improve the results.  Am I right in assuming that all of the lights are shot with the same image train?  How are different exposures and ISO's added together?

 

Thanks in advance for your thoughts.

 


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#2 georgian82

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Posted 22 January 2020 - 02:38 PM

I suggest you also look into PixInsight for pre and post processing. It is expensive and has a relatively big learning curve BUT for me has been the best astrophotography purchase so far. I believe PixInsight offers a 45-day free trial...Tons of people use it and there is a PixInsight forum as well as other people that have tons of tutorials to share. 

 

https://pixinsight.com/

 

https://pixinsight.com/forum/index.php

 

https://www.lightvor.../tutorials.html

 

It is hard to know what's going on with your light frames without you attaching an example. 

 

Lastly, yes...if you want to shoot the Orion Nebula, the best way to do it is to do two sets of light frames, one at longer exposure and one at shorter exposure and combine in post processing. Here is an example of one I did a while back...

 

https://www.astrobin...336090/?nc=user

 

Hope this helps and good luck!


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#3 jerahian

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Posted 22 January 2020 - 02:42 PM

I will try to help where I can...

 

I took 50, 2 minute light frames and afterwards I see a reddish cast to the second half of them.  I'm assuming it is from light pollution as Andromeda got lower in the sky.  Should I try to remove the cast from individual frames before stacking?

No, normally the gradients are removed after the frames are stacked.  Here is a tutorial with a video on how to do so with Photoshop:  https://astrobackyar...ents-photoshop/

 

 

I just purchased the Adobe photography suite and I have Sequator, DSS and a trial version of APP.  I have both a Mac and a Windows 10 machine.  My first attempt with APP was disappointing (albeit with limited data) whereas Sequator did a better job with it.  Any suggestions on where to find a good processing workflow to try?  I am open to try other programs.

If you haven't already done so, you should get this book:  The Deep-sky Imaging Primer, Second Edition 2nd Edition by Charles Bracken.  It discusses the main steps of a processing workflow using the two main processing software solutions many imagers use:  PixInsight and Photoshop.

 

 

With the Orion nebula so prominent, I would like to gather data now for later processing.  Because of the dynamic range, should I shoot it using different exposure times to get both the nebulosity and the bright inner core?  I gather there are ways to combine these data to get a better image.  Are there other ways to accomplish this without using different exposures?

 

I read where folks keep adding lights to previous sessions to improve the results.  Am I right in assuming that all of the lights are shot with the same image train?  How are different exposures and ISO's added together?

 

Thanks in advance for your thoughts.

Different exposures is a good way to address the saturation you would experience from the nebula core.  Here is a site which describes doing just that for Orion using Photoshop:  http://www.astropix....it/laymask.html

 

GL&CS!


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#4 Seaquel47

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Posted 22 January 2020 - 03:01 PM

Thanks for the suggestions.  I've been hesitant to tackle Pixinsight but I think I will try my dataset with the trial version.

 

These are 2 minute subs at ISO 800 using a Zenithstar 61 with the WO flattener and a Nikon 5600.  The white balance is set to daylight.

 

Here is a beginning light frame

 

DSC_0010.jpg

 

And the last one

DSC_0059.jpg

 

 



#5 Seaquel47

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Posted 22 January 2020 - 03:04 PM

Thanks Jerahain, I do have that book, it is excellent!  This is another push to PI.



#6 georgian82

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Posted 22 January 2020 - 03:09 PM

Thanks for the suggestions. I've been hesitant to tackle Pixinsight but I think I will try my dataset with the trial version.

These are 2 minute subs at ISO 800 using a Zenithstar 61 with the WO flattener and a Nikon 5600. The white balance is set to daylight.

Here is a beginning light frame

DSC_0010.jpg

And the last one
DSC_0059.jpg

Yeah it looks like it could be light pollution as you mentioned. You will be able to remove the cast in post processing so don’t worry 😉

If you decide to try out PixInsight, PM me and I can give you some pointers for pre processing the data that’s going to save you a lot of time and headache the first time.

Sebastian

Edited by georgian82, 22 January 2020 - 03:32 PM.

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#7 jerahian

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Posted 22 January 2020 - 03:16 PM

Oh yah, that gradient is nothin' to process out.  You pretty much will always have a gradient :(  The important thing is your stars look great, so all your effort is paying off!!


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