Multi-channel/multi-session calibration question  

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(@pieterkoolen)
White Dwarf Customer
Joined: 1 year  ago
Posts: 14
October 29, 2018 22:36  

 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 Customer
Joined: 1 year  ago
Posts: 14
October 30, 2018 15:12  

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)
Neutron Star Moderator
Joined: 1 year  ago
Posts: 177
November 4, 2018 08:47  

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 Customer
Joined: 1 year  ago
Posts: 14
November 4, 2018 14:28  

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)
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Posts: 177
November 4, 2018 21:23  

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 Customer
Joined: 1 year  ago
Posts: 14
November 4, 2018 21:43  

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 Customer
Joined: 1 year  ago
Posts: 14
November 4, 2018 21:45  

combine RGB image SC mod St


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(@vincent-mod)
Neutron Star Moderator
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Posts: 177
November 4, 2018 22:58  

To which channels did you assign all colors?


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(@pieterkoolen)
White Dwarf Customer
Joined: 1 year  ago
Posts: 14
November 5, 2018 07:30  

SII - R/G

Ha - G

OIII - B/G


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(@vincent-mod)
Neutron Star Moderator
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Posts: 177
November 6, 2018 00:58  

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.

This post was modified 1 month  ago by Vincent Groenewold - Moderator

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(@vincent-mod)
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Joined: 1 year  ago
Posts: 177
November 6, 2018 01:09  

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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