"C" Mount Lenses

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Mark Day

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"C" Mount Lenses

PostWed Feb 21, 2018 3:57 pm

Anyone ever use "C" mount, M-39, or M-42 lenses on their BMCC? Just curious.
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Denny Smith

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Re: "C" Mount Lenses

PostWed Feb 21, 2018 6:50 pm

Most of the C mont lenses were designed for 16 and S16 film formats, and do not project an image circle wide enough for the BMCC. Search “Vintage Lenses on BMCC” for previous discussions on this.
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Anatoly Mashanov

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Re: "C" Mount Lenses

PostThu Feb 22, 2018 1:45 am

1. C-mount lenses would vignette. The possible exclusions are 1" lenses such as Fujinon C-series zooms (C6x17.5) and Canon V-series zooms (V6x16). They need machining to fit into MFT adapter. "Possible" because BMCC sensor is bigger than BMPCC). If your camera is EF then you are out of luck since you cannot adapt C to EF.

2. M42 is OK for both EF and MFT versions with corresponding adapter. It's too long focus for BMCC but for MFT you can use some speedbooster. For EF the speedbooster is not applicable.

3. There are different versions of M39, so beware. At least there are lenses for reflex and range meter cameras. Be warned that some M39 lenses protrude too deep into the camera and could damage it.
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Uli Plank

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Re: "C" Mount Lenses

PostThu Feb 22, 2018 8:21 am

M39 has a far shorter flange distance and can't be fit to EF without optical elements, which normally degrade image quality. The rule is simple: You can always fit a lens from a longer flange distance to a shorter one, but not the other way round.
The only cameras in the line-up which can take all of these lenses are the BMPCC and the BMMCC, due to the short flange distance of MFT. Some may vignette, though, in particular the wider ones. A wide one that works is the Schneider Cinegon 10mm f1.8, but only the one with the larger filter thread (55mm). Due to this fact and it's excellent optical quality, it's very sought after.
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Alain Bourassa

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Re: "C" Mount Lenses

PostWed Feb 28, 2018 6:30 pm

I tried some old c mount
the first problem is the focal dept, smaller than MFT, making the c-mount adapter fitting INSIDE the lens hole
that makes the lens hard to manipulate
and of all the c mount they had had some vigneting
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Anatoly Mashanov

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Re: "C" Mount Lenses

PostThu Mar 01, 2018 2:43 am

1. There are at least 3 types of M39 lenses I've seen personally, and even more according to Wikipedia. I mean range finder camera lenses (which have a special mechanism to transfer range to finder), reflex camera lenses and half frame camera lenses. And they have different FFD and need different adapters, so beware.

2. Since C to MFT mount adapter has a recess which covers part of lens controls it was needed to make a special wrench to rotate a focal ring. Hope it helps.

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