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Live stacking over multiple nights

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#1 glancey

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Posted 29 May 2020 - 05:39 PM

I was wondering if anyone has experience doing live stacking over multiple sessions of the same DSO? If so, is image detail and color significantly improved with combining the frames from each session? Also, if your mount is turned off and even moved after each session, what special alignment considerations have to be taken into account. Additionally, if the camera settings are changed, maybe due to seeing conditions, how would that affect the combined stacking and merging of dark frames and flats.

 

The reason I'm inquiring is I've seen some incredible images from people doing extremely long exposures by combining 100s of short exposures taken over a number of nights with fairly basic EAA imaging trains.

 

Some examples can be found here:

 

https://petapixel.co...d-after-photos/

 

 

 



#2 glancey

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Posted 29 May 2020 - 05:44 PM

Granted, the images from the link provided above are not strictly EAA, but involve post-processing. However, I'm curious if us EAA practitioners can get close to such jaw-dropping views, and how we might go about doing it.



#3 GaryShaw

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Posted 30 May 2020 - 07:26 AM

Hi Glancy

Dont lose sight of the difference between EAA and Astrophotography. EAA is all about observing and learning about our universe while AP concerns itself mainly with creating stunning processed images. Sounds like maybe you’re a bit more inclined towards AP. Just enjoy whichever aspect of the night skies that gives you pleasure and satisfaction - even the hybrid process you outlined.

Gary



#4 GazingOli

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Posted 30 May 2020 - 03:20 PM

Detecting events like a supernova is definitely reserved to astrophotography and always was. As soon as it was possible to use photographic techniques for astronomy, people did use it for that purpose. See words like plate solving coming exactly from that early techniques of exposing photographic plates to light in order to capture images in the 19th century.

 

Collecting exposures over several nights is definitely astrophotography and not EAA in my opinion.


Edited by GazingOli, 30 May 2020 - 03:26 PM.

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#5 chilldaddy

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Posted 30 May 2020 - 05:44 PM

Glancey,

 

It appears that the images linked aren't EAA at all since they are clearly captured data over many nights, stacked, and processed.  I don't know how you would live stack when you are no longer in a live session.  I guess you could try to pause your live stack, return to the object the next night (ideally not having moved the mount), re-center the target and see if the software identifies the same stars allowing you to restart the live stack, but to what end?  That really defeats the purpose of EAA, as Gary mentioned. 

 

If you want to observe with a camera and see far more than you could ever see visually, then EAA is the ticket.  If you want to produce jaw dropping results, I don't think you'll get there without hours of long sub exposures and post-processing.  Usually there is a point in live stacking of diminishing returns where noise is reduced and images look good but usually seem to stop improving noticeably after a while.  I would think that you would reach the limits of live stacking in one session.

 

Greg


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#6 Dwight J

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Posted 30 May 2020 - 08:03 PM

Well if you want to do it, software like Astro Toaster will allow you to do it.  I have not done it over successive nights but I have let a stack go for 2.5 hours on M51 to reveal the faint streamers of stars flung out from the close encounter of the two galaxies.  I considered it EAA as I watched the image build (one min exp) over time while I fiddled with the live adjustments.  I did a similar one with M31 but only 2 hours.  The rules of EAA only apply in this forum.  At home do whatever you like, even saving the image for further processing later...or picking it up again on another night and resuming stacking.  I assume SharpCap may also work to stack over several nights.  If you want to see dim objects like say, Abell 39 in Hercules, a short stack is not going to do it with the majority of cameras now being used.  


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