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Anyone with experience fixing a stuck aperture (25mm SOM Berthiot C-mount)

madmaxmedia

New member
Hi all,

I just received a 25mm f/1.9 Lytar on EBay. Focus ring is smooth, but aperture ring is absolutely stuck at f/4.

Is there something I'm missing with the C-mount (like perhaps there is some pin that needs to be pushed down to change aperture?) I don't have my c-mount adapter yet so haven't mounted the lens to my G1.

Has anyone ever taken apart such a lens (or similar) to fix this? The aperture ring is near the base of the lens, so I'm hoping that's the right path.

I got it for pretty cheap, so would much rather fix it than return for refund (I have contacted the seller to hopefully get a partial refund though.) I guess I could also try to find a shop to fix it, its amazing in this 'disposable' age such an idea seems quaint.

Thanks for any pointers.
 
I

Irwell

Guest
Hi all,

I just received a 25mm f/1.9 Lytar on EBay. Focus ring is smooth, but aperture ring is absolutely stuck at f/4.

Is there something I'm missing with the C-mount (like perhaps there is some pin that needs to be pushed down to change aperture?) I don't have my c-mount adapter yet so haven't mounted the lens to my G1.

Has anyone ever taken apart such a lens (or similar) to fix this? The aperture ring is near the base of the lens, so I'm hoping that's the right path.

I got it for pretty cheap, so would much rather fix it than return for refund (I have contacted the seller to hopefully get a partial refund though.) I guess I could also try to find a shop to fix it, its amazing in this 'disposable' age such an idea seems quaint.

Thanks for any pointers.
Can you post a picture(s) of the lens,
maybe someone can help you,
 

madmaxmedia

New member
LOL, my greater issue is that this does not seem to be a C-mount lens? (as it is unthreaded)

Does anyone know what this is? If so, do you know if the lens has to be mounted for the aperture to be adjusted?
 

madmaxmedia

New member
Okay, from looking at other pictures of the same lens, it looks like my lens is literally missing the mount piece. I'm guessing that someone tried to fix the lens, but then gave up and forgot to put the last piece back on.

I've arranged a refund with the seller. Thanks!
 
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