Be careful when buying a C-mount adapter for M4/3 and Nikon 1

I must confess that I was naive when I bought my first set of C-mount adapters for my Nikon 1 V1 and Olympus OM-D E-M10. I assumed that it was very easy to make a so called “dumb adapter” – meaning an adapter that doesn’t pass through electrical signals from the camera to the lens and vice versa. Boy was I wrong! As it turns out it is quite a challenge to get the design right, in order to ensure compatibility with as many lenses as possible. At least it seems to be a challenge for manufacturers like “Kiwi”. I posted a couple of images down below, so you can identify the adapters in question.

C-mount to Nikon 1

C-mount to Micro Four Thirds

Both the C-mount to Nikon 1 and C-mount to M4/3 adapter work fine in conjunction with less wide C-mount lenses – wide in regard to the width of the base around the mount, not in regard to focal length. One such lens is the no-name 25mm f/1.4 CCTV C-mount lens (read my review of the lens here, if you are interested) you can get at amazon and other online shops for less than 30 bucks.

Lenses with a wider base around the mount, like the no-name 50mm f/1.4 CCTV C-mount lens (you can read my review of that lens here), can’t be screwed all the way in or can’t be screwed in at all. The former was the case with the C-mount to Nikon 1 adapter and the latter with the C-mount to M4/3 adapter. What made it impossible to screw the lens all the way in or at all was the inner ring-shaped protrusion, which serves no purpose at all.

What I ended up doing was looking for a machine shop willing to shave off a millimeter off of the inner ring. This increased the longest distance to which the 50mm f/1.4 lens could be focused on the V1 and made it possible to use the lens on the OM-D E-M10. This is what the adapters look like now, after the “treatment”.

C-mount to Nikon 1

C-mount to Micro Four Thirds

Keep in mind, that any such modification involves the danger of destroying the adapter, if you shave off too much. It goes without saying that if you decide to do it, you will be doing it at your own risk.

Now, I can’t really tell you which is the best C-mount adapter for each of the two systems, since I only have the two adapters shown in this post. But I’ve discussed this topic with the dpreview user walter g1, who seems knowledgable in regard to lens adaptation. According to him adapters without the inner circle should work even in conjunction with lenses like the 50mm f/1.4 CCTV C-mount lens. He even uploaded an image of his C-mount to M4/3 adapter, which according to him allows focus to be set all the way to infinity.

© walter g1

While I wasn’t able to find a “big-is” adapter this one seems to be identical. Sadly there doesn’t seem to be a C-mount to Nikon 1 adapter, which looks even remotely similar. Does such an adapter even exist? If anyone knows of a C-mount to Nikon 1 adapter that can focus to infinity with the 50mm f/1.4 and other wider C-mount lenses, please post a photo or a link to a shop where I and other people who are interested can buy it. Thanks!

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