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Combining images from different cameras - an easier way?

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#1 RJF-Astro

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Posted 17 January 2020 - 04:34 AM

Last month I had collected data from M42 with to different setups. One is a mirrorless Fuji OSC with a 72ED scope, the other an ASI1600 mono on an 130mm F5 newt, with H-alpha filter. I liked both images. One because of the color, the other because of the detail.

 

That's when I thought: why not try to combine both images? And it actually worked! However it took some fiddling in Photoshop with rotating and scaling. Once I got them close, I could use PixInsight for star alignment and dynamic crop.

 

My question: is there a way to automate or calculate the amount of scaling that is required to be able to fit them? I noticed star aligment did not work before the rescaling. I figured image scale can be a key figure, but I cannot get my head around the 'how'.

 

Here are the separate images and the result of the merger. I also like how the Ha-layer makes the stars smaller. Unfortunately the Fuji creates some strange color artifacts around the stars, maybe in combination with limited color correction from the ED-scope.

 

20191030 M42 def.jpg

 

20201101 M42 1,3 uur tdl.jpg

 

_20191030_M42_merge_def.jpg


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#2 AKHalea

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Posted 17 January 2020 - 07:44 AM

I use the Software APP (Astro Pixel Processor) for combining images from different set-ups (OTA, diff filters, diff cameras and different sensor sizes). It does the scaling, rotation and integration etc all in a few easy steps. Great software to combine images and get more SNR & better overall images  ...... Anil 


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#3 kathyastro

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Posted 17 January 2020 - 08:04 AM

If you are going to use PixInsight anyway, it should handle it for you.  Star Alignment will do all the rotation and scaling for you.



#4 RJF-Astro

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Posted 17 January 2020 - 08:38 AM

Thanks for the tip Anil! I do not have APP and would assume PI and PS would get me there too, but I will keep it in mind.

 

Kathy: I have tried using Star Alignment with the initial images, but that did not work. It makes 18 attempts and then gives an error '*** Error: Unable to find an initial set of putative star pair matches.' That is when I decided to get them closer together in Photoshop. SA did work in the end, but I had to do a lot of scaling and rotating manually first.



#5 AKHalea

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Posted 17 January 2020 - 08:56 AM

I had tried other methods beofre using APP and most of the times it did not work without a lot of pre-work. But as soon as I got APP, it worked beautifully. Just as an example, I have managed to combine a real widefield image of the IC 405/410 & 417 area captured with a 200mm lens and combined that very successfully with individual images of IC405, IC 410 and IC 417 taken with an 80mm scope (560mm focal length vs 200mm FL of the camera lens). These were combined into wide nice wide field image of the whole complex. It was a breeze to do that in APP. You can check out the result here. It was super easy getting this done in APP! ...... Anil


Edited by AKHalea, 17 January 2020 - 04:25 PM.

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#6 AhBok

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Posted 17 January 2020 - 02:58 PM

This may not help the OP, but I must add that I also use APP to combine images taken with different OTA, different cameras and different angles. All you do is load them, analyze the stars, register and normalize them—then combine. Super easy!

#7 FiremanDan

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Posted 17 January 2020 - 04:16 PM

I have done this a few times and until recently it usually worked with very minimal fiddling. 
Combining my 80mm and 8in RC (380 vs 1186mm FLs) worked fine. It seems adding a preview of on the shorter FL image around the scale/FOV of the longer FL image helps with star alignment. It tells PI “Look here for matches” as I understand it. 
I did have old data from the same setup that was rotated and star alignment couldn’t figure it out. It was only a few 1200s subs so I just went in and manually rotated them and everything worked. 
But anyways, nice image and combining short FL color data and long FL Lum data works pretty well in my experience.


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#8 pfile

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Posted 17 January 2020 - 04:33 PM

that's the key - you need a preview to restrict the wide-field image so PI doesn't get distracted by all the stars outside of the FOV of the narrow image.


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#9 RJF-Astro

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Posted 19 January 2020 - 04:37 AM

Alright, so that did the trick. A preview of roughly the same size get's it done in PixInsight. Thanks!


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