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Multi-channel/multi-session calibration question

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(@pieterkoolen)
White Dwarf
Joined: 6 years ago
Posts: 14
Topic starter  

 Hi Vincent,

I ran across the following.

I am executing a multi-channel and a multi-session operation in one run.

Three channels (OIII, SII and Ha) and 3 session days (every day the same three channel acquisition scheme).

All Ha and SII frames of all sessions are properly calibrated (specifically no vignetting visible anymore).

However the OIII frame calibration is somewhat peculiar.

OIII frames from one of the sessions are properly calibrated. The other two sessions are not, as strong vignetting is still visible. 

I executed the calibration process several times already with a repeating outcome.

BTW the file list indicates that the appropriate calibration files have been assigned to all the lights.

How could I figure out what is going wrong?

 


   
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(@pieterkoolen)
White Dwarf
Joined: 6 years ago
Posts: 14
Topic starter  

Hi Vincent,

I have been digging in the console log.

APP is assigning master flats to all lights.

It remains strange that for the OIII runs in two out of the three sessions calibration does not eliminate the vignetting properly.

 


   
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(@vincent-mod)
Universe Admin
Joined: 7 years ago
Posts: 5707
 

Hi again Pieter, sorry for the delay..

Yes that is strange, but also sounds a bit like the data from the two other nights might be a bit different in some way, could this be the case if you look at the subs without any calibration?


   
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(@pieterkoolen)
White Dwarf
Joined: 6 years ago
Posts: 14
Topic starter  

Hi Vincent,

I calibrated in PI as well. Same problem. Must be something wrong with the flats. I will shoot new ones on a rainy day as my image train remained unchanged.

I tried the remove vignetting option. But that did not work well enough. A crop and remove light pollution bypassed the problem.


   
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(@vincent-mod)
Universe Admin
Joined: 7 years ago
Posts: 5707
 

Ah yes that can very well be. Every though about getting a flat-panel? Personally I love it as you can then take the flats at any time and in a very controlled manner.


   
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(@pieterkoolen)
White Dwarf
Joined: 6 years ago
Posts: 14
Topic starter  

Hi Vincent,

I just finished my first narrow band image ever. As well as my first APP processing.

I attached my result so far.

How can I remove the greenish color.

Pls feel free to forward your recommendations.


   
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(@pieterkoolen)
White Dwarf
Joined: 6 years ago
Posts: 14
Topic starter  
combine RGB image SC mod St

   
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(@vincent-mod)
Universe Admin
Joined: 7 years ago
Posts: 5707
 

To which channels did you assign all colors?


   
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(@pieterkoolen)
White Dwarf
Joined: 6 years ago
Posts: 14
Topic starter  

SII - R/G

Ha - G

OIII - B/G


   
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(@vincent-mod)
Universe Admin
Joined: 7 years ago
Posts: 5707
 

So the main component of this nebula is Ha, which is green in your pallet. Or are you talking about a more general cast?

You can try HSL selective color and select green. Then using the saturation slider, go down a bit and slide the G->M (green to magenta) a bit to the right. Which should reduce the green.


   
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(@vincent-mod)
Universe Admin
Joined: 7 years ago
Posts: 5707
 

I tried a few little things on the jpeg you posted here (so not optimal). I did some light pollution correction and selective color, reducing the green a bit. Most will still be green ofcourse. 🙂

1566 combine RGB image SC mod St SC

   
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