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Vignetting on ZWO6200mm with Chroma 2" mounted filter set

Astrophotography Equipment Optics Refractor Imaging
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#1 Hari Pyla

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Posted 23 June 2024 - 10:03 PM

Hi,

 

A quick question on identifying and understanding how to get around vignetting in my current setup. My setup is William optics FLT 132 --> Flat 7A (0.8x reducer) --> ZWO M68 tilt adapter --> ZWO OAG-L --> ZWO EFW (2" Chroma mounted filter set) --> ASI6200mm mono.  The Chroma 2" mounted filters fit perfectly into the 2" female filter thread EFW (https://www.zwoastro...inch-7-x-2inch/) and they are less 50.8 mm in diameter.  The ASI6200's sensor size is 36mm*24mm with the diagonal of 43.3mm which is less than the 50.8 mm. The clear aperture distance (CA) of a similar 2" Chroma filter SKU: CT-27101-2M, is 43 mm based on https://agenaastro.com/chroma-lgrb-imaging-filter-set-2-mounted.html. I could not find the exact specs for my SKU of Chroma filters other than the link below.

 

Is my understanding correct that given the filter's clear aperture is smaller 43mm than the sensor's diagonal of 43.3mm is the cause of vignetting? Any pointers on how to get rid of the vignetting?

 

Filter set:

LRGB (SKU: CF-LRGB-2M48 - https://optcorp.com/...rgb-filter-set)

 

Thanks a bunch!

 

 



#2 andysea

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Posted 23 June 2024 - 10:51 PM

Flats should correct for that.



#3 aabusara

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Posted 23 June 2024 - 11:19 PM

First thing is to determine if what you are seeing is indeed vignetting due to filter clear aperture, or simply due to expected light drop off. While manufacturers say it will illuminate a full frame sensor, it does not mean it will be 100% to the corners.  Either way most of these issues are easily correctable with flats. I had a similar problem with my focuser causing vignetting. I ended up fixing it with a bigger focuser. But you can see that my vignetting at f/5 with 50mm round filters is very minimal. 

 

https://www.cloudyni...ecommendations/


Edited by aabusara, 23 June 2024 - 11:20 PM.


#4 Hari Pyla

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Posted 23 June 2024 - 11:42 PM

Thank you Andysea and Aabusara. Truly appreciate it. Will check after taking the flats and will keep you posted. 




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