Vignetting correcti...
 
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Vignetting correction  

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(@plicciar)
White Dwarf Customer
Joined: 4 months ago
Posts: 11
June 15, 2021 17:14  

Hi all, 

I'm trying, without success, to exploit the "vignetting correction" tool, following the tutoria but the result is completely unusable so I'm surely doing something wrong.

I provide the screenshots before and after so that you can eventually provide some suggestions

Schermata 2021 06 15 alle 17.12.41
Schermata 2021 06 15 alle 17.11.43

 


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(@cwm2col)
Red Giant Customer
Joined: 7 months ago
Posts: 52
June 15, 2021 20:36  

@plicciar

Hi,

I also have severe vignetting in my Intes MN56 with a very small (28 mm) secondary. I find this tool rarely works effectively, but the light pollution removal tool is so good it negates the need for the vignetting tool.

Maybe you can try the light pollution removal tool to balance gradients. It works very well for me - just a thought/suggestion.


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(@vincent-mod)
Universe Admin
Joined: 4 years ago
Posts: 3550
June 15, 2021 21:48  

Yes that tool can be a bit tricky.

Here's an answer Mabula gave in the past and works for me. Though it's always preferred to use real flats to correct vignetting;

On all lights if you make an artificial master flat, select "create artificial flat". This will save the correction model as an artificial Master Flat. You can then use this Master Flat, just like an original master flat to correct the vignetting.

To get the most accurate result, first calibrate the lights with a master dark or master bias (create masters & assign to lights button, tab 2). Save these calibrated files (tab 2 all the way down). Then clear APP or reload APP and make the artificial flat using one of the calibrated frames (load in 1 of the calibrated lights). Then load in all the calibrated lights and add the artificial flat, calibrate again and see if that works.


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(@nicholas64)
Main Sequence Star Customer
Joined: 2 years ago
Posts: 27
June 20, 2021 02:24  

@vincent-mod

Hey vincent is there a video on this? I'm not very adept at these instructions.

Cheers


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(@vincent-mod)
Universe Admin
Joined: 4 years ago
Posts: 3550
June 21, 2021 10:35  

Unfortunately not. But to break it down a bit better;

1. Calibrate your lights with your darks and bias frames.

2. Save the calibrated frames (tab 2, all the way down)

3. Load 1 of the calibrated subs (just one).

4. Create the artificial flat using that sub and save that artificial flat

5. Load all data you have in APP, add the artifical flat and process like you normally do.

This is how it works best usually, of course it's a bit of a workaround for not having actual flats and it won't remove dust etc.


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(@nicholas64)
Main Sequence Star Customer
Joined: 2 years ago
Posts: 27
June 21, 2021 11:46  

you say create the artificial flat using that sub, how exactly do you create the flat? how do you do that step?


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(@vincent-mod)
Universe Admin
Joined: 4 years ago
Posts: 3550
June 21, 2021 12:08  

For that step you go to the tools tab, select "correct vignetting" and in there you also select "create artificial flat". You create 8 boxes around the image in the background and press "calculate". If that looks ok, you can save the resulting masterflat and use it for your data. It doesn't always work nicely, that will depend on proper data and calibration.


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