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Registering images taken through different filters so stars line up, yet stacking the images from the 2 different filters as completely separate stacks  

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(@davidharris11)
Brown Dwarf Customer
Joined: 6 months ago
Posts: 9
October 21, 2021 19:50  

I have dug through the various forums looking for the answer that will tell me how to do what I want to do here & I cannot find the specific answer I need. I have been using APP for a while & am pretty well-versed on the basics.

I know how to do exactly what I'm trying to do in deep sky stacker already, but since I'd rather do it in APP I'm asking here.

Here is specifically what I'm trying to do:
I have imaged the same object with OSC camera using two separate filters on different nights--the astronomik UHC filter & also the Optolong L-Extreme filter. I have multiple nights imaging with each of those filters, so this will need to be a multi-session integration of EACH of those filters.

I want to register ALL the lights from both filters to the same reference frame but to create 2 totally separate stacked images, one for the astronomik UHC only & another for the Optolong L-Extreme only. I need for all the stars & image scale for both stacks to align to each other, because I will later take each stacked image into photoshop and blend together using a method I like that gives me the most control. I do not intend to blend the two together in APP in this case.

I can always stack the astronomik UHC lights & the L-extreme lights completely independently & then take those into photoshop to do what I intend, but this has the potential problem of creating 2 stacked images with stars that are not aligned. Aligning these two in photoshop after the fact is possible, but a lot more tedious.

I can do what I need to in deepsky stacker by manually selecting one sub-frame from the lights to use as the reference frame by which all stars in all the different images will be aligned to & still produce two separate stacked imaged for the Astronomik UHC & L-Extreme, respectively.

I feel sure that many others here have done exactly what I'm describing above in APP. I would appreciate detail on how specifically to go about doing this. Thanks.


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(@wvreeven)
Quasar Admin
Joined: 3 years ago
Posts: 1226
October 21, 2021 20:19  

@davidharris11 This can be achieved in APP by making use of sessions. Simply load all UHC lights in session 1 and all L-eXtreme lights in session 2. Then go to tab 6 and click integrate without making any changes to the settings. This will result in two images: one for the UHC and one for the L-eXtreme filter and they will be aligned to each other.


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(@davidharris11)
Brown Dwarf Customer
Joined: 6 months ago
Posts: 9
October 21, 2021 20:39  
Posted by: @wvreeven

@davidharris11 This can be achieved in APP by making use of sessions. Simply load all UHC lights in session 1 and all L-eXtreme lights in session 2. Then go to tab 6 and click integrate without making any changes to the settings. This will result in two images: one for the UHC and one for the L-eXtreme filter and they will be aligned to each other.

I am well familiar with multi-session processing as I pretty much always stack multiple nights of data on the same object, but your suggestion will not work for me because I have multiple separate nights using the astronomik UHC filter & also multiple separate nights using the L-extreme, as I stated originally.

I'll give you an example. On the Crescent Nebula I did 2 nights with the UHC filter & another 2 nights with the L-Extreme filter, 4 nights total. I need 2 separate stacks from this but all registered to the same stars. This scenario I've described is a very common one for me. I normally spend several nights on an object & use two filters.

Obviously I can select a different filter that each of the 4 total sessions would apply to, but I am unclear if this will give me the result I want.

 

 

 


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(@wvreeven)
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Joined: 3 years ago
Posts: 1226
October 21, 2021 20:42  

@davidharris11 What is your rationale for loading the data from different nights into different sessions? You should be able to load all UHC data into one session.


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(@davidharris11)
Brown Dwarf Customer
Joined: 6 months ago
Posts: 9
October 21, 2021 20:46  
Posted by: @wvreeven

@davidharris11 What is your rationale for loading the data from different nights into different sessions? You should be able to load all UHC data into one session.

 
This post was modified 1 month ago by David Harris

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(@davidharris11)
Brown Dwarf Customer
Joined: 6 months ago
Posts: 9
October 21, 2021 21:26  
Posted by: @wvreeven

@davidharris11 What is your rationale for loading the data from different nights into different sessions? You should be able to load all UHC data into one session.

I take a new set of flat frames at every imaging session, so I must load each individual session separately so that only the flats from that session are applied to that session. This approach is necessary & I’m sure quite common. You can't mix flats that were not actually for that session.

 

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(@vincent-mod)
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Joined: 4 years ago
Posts: 3961
October 21, 2021 21:31  

@davidharris11 If I may... that's correct. I think the best way forward in your case is to treat these filters separately. You can then save the calibrated frames (tab 2, all the way down) for both filters. Then reset APP and load them in as Wouter pointed out and continue the integration.


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(@davidharris11)
Brown Dwarf Customer
Joined: 6 months ago
Posts: 9
October 21, 2021 21:48  
Posted by: @vincent-mod

@davidharris11 If I may... that's correct. I think the best way forward in your case is to treat these filters separately. You can then save the calibrated frames (tab 2, all the way down) for both filters. Then reset APP and load them in as Wouter pointed out and continue the integration.

Ok, that idea is starting to make sense to me. Help me with some clarity though. I have never stopped at this stage and simply saved the calibrated frames. If my understand is correct, if I run each filter separately through APP & stop and save the calibrated frames I will end up with all the same subframes I loaded to begin with simply calibrated against the calibration frames that would apply to them. I would like clarification on this point here because I tend to integrate many hours of imaging data on a routine basis. In the crescent nebula example I mentioned above I have 106 exposures with the UHC filter & 24 exposure with the L-extreme. Saving the calibrated frames here is going to require a good bit of additional hard drive space. I can do that if needed, but just need to understand completely.

 

Then I would start over with all the calibrated frames from each of my filters in a new session of APP then load the calibrated UHC frames as session 1, then the calibrated L-extreme frames as session 2 and go on from there.

 


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(@vincent-mod)
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October 21, 2021 21:53  

Correct. You could also simply go all the way up to integrating the UHC data, same for L-Extreme as separate workflows and then load the resulting integrations back in and register to each other and then save the registered frames. That would bypass having to save the calibrated frames, having separate frames gives you a bit more control as to what you'd want to do maybe.


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(@davidharris11)
Brown Dwarf Customer
Joined: 6 months ago
Posts: 9
October 21, 2021 22:13  
Posted by: @vincent-mod

Correct. You could also simply go all the way up to integrating the UHC data, same for L-Extreme as separate workflows and then load the resulting integrations back in and register to each other and then save the registered frames. That would bypass having to save the calibrated frames, having separate frames gives you a bit more control as to what you'd want to do maybe.

Ok, can you explain a bit more on this last part. Let's say that I did fully integrate all the UHC data on its own, then separately do the same for the L-extreme data, then load these two back into APP, register to each other & save the registered frames--this would fully align the stars in these two images with each other but as still separate, independent frames? This seems possibly the ticket for me.

 


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(@vincent-mod)
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Joined: 4 years ago
Posts: 3961
October 21, 2021 22:17  

Also correct. The two would then be aligned.


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(@davidharris11)
Brown Dwarf Customer
Joined: 6 months ago
Posts: 9
October 21, 2021 22:21  
Posted by: @vincent-mod

Also correct. The two would then be aligned.

Excellent. Thanks for your help.

 


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(@vincent-mod)
Universe Admin
Joined: 4 years ago
Posts: 3961
October 21, 2021 22:22  

If anything is not clear after this, just let us know. Good luck! 🙂


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(@davidharris11)
Brown Dwarf Customer
Joined: 6 months ago
Posts: 9
October 21, 2021 23:03  
Posted by: @vincent-mod

If anything is not clear after this, just let us know. Good luck! 🙂

Thanks. Thanks for the quick responses to my questions.

 


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