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uneven brightness ?

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#1 ccvle

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Posted 25 January 2021 - 06:27 PM

Any idea why one side of the image is brighter (not sure if this the right technical term) than the other side ? Not sure if it my processing or something wrong with the camera. I did stack flats but didn't help at all.

Any feedback would be greatly appreciated.


Processed:

https://astrob.in/lv4pha/0/



original stacked image before processing:

https://astrob.in/tgvefn/0/

#2 imtl

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Posted 25 January 2021 - 06:36 PM

Welcome to the world of light pollution (or moon light pollution). May the force be with you. Or preferably a tank of gas to drive to a dark site.


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#3 Wei

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Posted 25 January 2021 - 07:21 PM

Is there moon when you took the shots?


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#4 Dynan

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Posted 25 January 2021 - 07:23 PM

Can you upload and link the final integrated, unprocessed image? We can take a look.



#5 ccvle

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Posted 26 January 2021 - 08:25 AM

Is there moon when you took the shots?

 
Yes. I thought about that too, but would that really explains it ?

 

Can you upload and link the final integrated, unprocessed image? We can take a look.


Let me know if you can download it.

https://cdn.astrobin...074c9a0ffaf.TIF

#6 Dynan

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Posted 26 January 2021 - 08:45 AM

Can you upload the file as a .fit? The .tif format doesn't include some information.



#7 ccvle

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Posted 26 January 2021 - 09:25 AM

Does Astrobin not support Fits ? I got an error message that fts extenson is not supported.

#8 imtl

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Posted 26 January 2021 - 09:28 AM

Upload your file to google drive or dropbox or something like that. Not to Abin


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#9 ccvle

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Posted 26 January 2021 - 09:38 AM

Here. Thanks.

https://drive.google...iew?usp=sharing

#10 imtl

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Posted 26 January 2021 - 09:41 AM

I managed to remove your gradient easily with ABE in pixinsight.


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#11 Wei

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Posted 27 January 2021 - 10:07 AM

If you shoot under bright moon and if your exposure is long that would affect the shot. You will get uneven brightness and accentuate vignettes. I avoid bright moon if I can. If you use large aperture scope I believe it would be more obvious.

Light pollution filters don’t help. Perhaps you can get away by doing narrowband photography.

#12 ccvle

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Posted 27 January 2021 - 11:41 AM

I managed to remove your gradient easily with ABE in pixinsight.


Thanks for pointing that out. I reprocessed the image and it came out much better.

https://cdn.astrobin...4fe34dc5afb.jpg

#13 Wei

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Posted 27 January 2021 - 12:03 PM

But you do lost a lot of data

 

Thanks for pointing that out. I reprocessed the image and it came out much better.

https://cdn.astrobin...4fe34dc5afb.jpg

But you did lost a lot of data when you do it this way.


Edited by Wei, 27 January 2021 - 12:03 PM.


#14 ccvle

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Posted 27 January 2021 - 01:40 PM

But you do lost a lot of data
 
But you did lost a lot of data when you do it this way.



Any other alternatives ? btw, I did have a narrowband filter on at the time.

#15 Noobulosity

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Posted 27 January 2021 - 01:48 PM

Any other alternatives ? btw, I did have a narrowband filter on at the time.

Can you share exactly what filter you used?


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#16 ccvle

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Posted 27 January 2021 - 09:21 PM

Can you share exactly what filter you used?


I used the triad quad band filter

#17 Noobulosity

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Posted 28 January 2021 - 12:22 PM

Do you know if there were any light sources off to that side of your setup?  Have you noticed anything similar with that same camera?  Perhaps there's some amp glow or another light source?  Is the camera astro-modified or full-spectrum?  What type of camera are you using?



#18 ccvle

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Posted 29 January 2021 - 05:21 PM

Do you know if there were any light sources off to that side of your setup?  Have you noticed anything similar with that same camera?  Perhaps there's some amp glow or another light source?  Is the camera astro-modified or full-spectrum?  What type of camera are you using?


There was the moon but I don't know if that would explain it. It is not like I was shooting ultra wide with one side next to the moon and the other side that is on the other side of the sky.

I was using the ASI2600MC. It is not supposed to have amp glow I think, unless it is defective.

If I can make it out to the freezing cold this weekend I can try again and perhaps with different targets.

Thanks!

Edited by ccvle, 29 January 2021 - 05:23 PM.



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