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ZWO ASI294MC PRO 2" or 1,25" filters

ZWO ASI294MC Pro Optolong L-Pro Equipment CMOS Vignetting
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CVZ_Astrophotography avatar
CVZ_Astrophotography avatar
Hey friends,

I recently bought a ZWO ASI294MC PRO, and I'm using it on my Omegon Advanced 150/750 telescope. For the last month I've made a few photos of deepsky objects, but everytime I use it, I see a lot of vignetting. The camera came with a 1,25" nosepiece and the guy in the store gave me a 1,25" Optolong L-Pro filter extra.

So my question is as follows. Is the vignetting problem something I van resolve if i use a 2" nosepiece and filter?
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Konrad Krebs avatar
Konrad Krebs avatar
Good morning,

I also use my 294MC Pro with a Skywatcher 150/750 Newton telscope. I have a GPU comacorrector and use a 2" LPro Filter. I have no issues with strong vignetting. In all others scopes I habe no trouble with the 2" filters too.

For these cheap Newton telescopes it could also bei a problem with small secondary mirrors.
CVZ_Astrophotography avatar
CVZ_Astrophotography avatar
Konrad Krebs:
Good morning,

I also use my 294MC Pro with a Skywatcher 150/750 Newton telscope. I have a GPU comacorrector and use a 2" LPro Filter. I have no issues with strong vignetting. In all others scopes I habe no trouble with the 2" filters too.

For these cheap Newton telescopes it could also bei a problem with small secondary mirrors.

Oh alright, in that case I'm gonna give 2" without a filter a try, hope that it helps. Thanks for the advice!
Aris Pope avatar
Aris Pope avatar
Hey friends,

I recently bought a ZWO ASI294MC PRO, and I'm using it on my Omegon Advanced 150/750 telescope. For the last month I've made a few photos of deepsky objects, but everytime I use it, I see a lot of vignetting. The camera came with a 1,25" nosepiece and the guy in the store gave me a 1,25" Optolong L-Pro filter extra.

So my question is as follows. Is the vignetting problem something I van resolve if i use a 2" nosepiece and filter?

 I use the 294MC Pro and 2" L-Pro and L-Extreme with my GSO 6" Newtonian F/4 with the Starizona Nexus Coma Corrector. That being is down to F/3 and never had any issues with vignetting. I went with the 2" just to be sure.
Konrad Krebs avatar
Konrad Krebs avatar
Oh alright, in that case I'm gonna give 2" without a filter a try, hope that it helps. Thanks for the advice!


 I would recommend top use a UV/IR block filter instead of using nothing. Otherwise your stars may be not good.
I use a cheap SVBony one that is working without problems.
GalacticRAVE avatar
GalacticRAVE avatar
If the 1.25" filter is within some 20mm of the sensor, you should be fine (mounted 1.25" filter typically have a free aperture of some 27mm)

https://astronomy.tools/calculators/ccd_filter_size

If you screw your filter at the end of a 1.25" nose piece, you usually have considerably more than 20mm from filter to sensor - and get vignetting.
So changing the layout of your image train may be the cheapest version to solve the issue.

Matthias
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Ricky303 avatar
Ricky303 avatar
If you can afford go with the 2”. Always better to go bigger. If you’re really enjoying this hobby it’s only a matter of time before you go with a full frame smile