Various (cine / industrial standard) · Cinema mount

C-mount — flange distance, protocol, and adapter compatibility

1-inch × 32 TPI thread, 17.526 mm flange — originally introduced for 16 mm cinema cameras (Bell & Howell Filmo, Bolex H16) in 1926 and adopted as the de-facto industry standard for closed-circuit television, microscope, and machine-vision optics. Image circle is tiny (≈13 mm diagonal, sized for 16 mm cine film) so most C-mount lenses cover only the central crop of even a MFT sensor. A handful of fast cine primes (Cosmicar / Pentax 25mm f/1.4, Fujian 35mm f/1.7) cover MFT — most do not. Adapts onto MFT, X-mount, E-mount with thin mechanical rings, but heavy vignetting and an inability to focus at infinity are typical caveats on machine-vision and CCTV lenses.

Mount specifications

Flange focal distance: 17.526 mm
Throat diameter: 25.4 mm
Electronic protocol: Mechanical only (no electronic coupling)
Supported formats: 16mm-cine
Manufacturer: Various (cine / industrial standard)
Introduced: 1926
Status: Active production

Adapting C-mount lenses onto other bodies

You own C-mount glass and want to mount it on a body with a different lens mount. Rows are sorted by feasibility.

Body mount	Result	Adapter examples	Caveats
Sony E (incl. FE) flange 18 mm	Mechanical ——Ap. ringvignettes	Generic C-E rings (Fotodiox, Pixco, Rainbowimaging)	Full-frame E (FE) bodies see heavy vignetting; APS-C E (Sony α6000-series) bodies still vignette to a circle smaller than the sensor. C-mount flange is 0.474 mm below Sony E's — most lenses can't reach infinity focus through a standard thin adapter.
Fujifilm X flange 17.7 mm	Mechanical ——Ap. ringvignettes	Generic C-FX rings (Fotodiox, Kipon)	APS-C sensor (~28 mm diagonal) is more than 2× the C-mount image circle — heavy vignetting on every lens. Image is usable only with a heavy central crop. C-mount flange 17.526 mm vs X-mount 17.7 mm — clearance is fractional and most lenses cannot reach infinity focus on X-mount.
Micro Four Thirds flange 19.25 mm	Mechanical ——Ap. ringvignettes	Generic C-MFT thin spacer (Fotodiox, Rainbowimaging, Kipon)	C-mount flange is 17.526 mm vs MFT's 19.25 mm — adapter is a thin 1.7 mm spacer. Most C-mount lenses focus past infinity through such an adapter; check per-lens. Image circle is sized for 16 mm cine film (~13 mm diagonal). Only a handful of fast cine primes (Cosmicar / Pentax 25 mm f/1.4, Fujian 35 mm f/1.7) cover the MFT sensor; most others vignette into a tight central circle.
Canon RF flange 20 mm	Speed booster MFIS lens-onlyAp. wheelvignettes	Speed Booster / focal-reducer family	Flange clearance is only -2.5 mm — a plain mechanical adapter cannot reach infinity focus; a focal reducer (Speed Booster) with optical glass is required. Speed Boosters typically widen the effective focal length (~0.71×) and add ~1 stop of light, which can be desirable on crop bodies.
Canon EF-M flange 18 mm	Speed booster MFIS lens-onlyAp. wheelvignettes	Speed Booster / focal-reducer family	Flange clearance is only -0.5 mm — a plain mechanical adapter cannot reach infinity focus; a focal reducer (Speed Booster) with optical glass is required. Speed Boosters typically widen the effective focal length (~0.71×) and add ~1 stop of light, which can be desirable on crop bodies.
Nikon Z flange 16 mm	Speed booster MFIS lens-onlyAp. wheelvignettes	Speed Booster / focal-reducer family	Flange clearance is only 1.5 mm — a plain mechanical adapter cannot reach infinity focus; a focal reducer (Speed Booster) with optical glass is required. Speed Boosters typically widen the effective focal length (~0.71×) and add ~1 stop of light, which can be desirable on crop bodies.
Fujifilm GFX (G-mount) flange 26.7 mm	Speed booster MFIS lens-onlyAp. wheelvignettes	Speed Booster / focal-reducer family	Flange clearance is only -9.2 mm — a plain mechanical adapter cannot reach infinity focus; a focal reducer (Speed Booster) with optical glass is required. Speed Boosters typically widen the effective focal length (~0.71×) and add ~1 stop of light, which can be desirable on crop bodies.
L-Mount flange 20 mm	Speed booster MFIS lens-onlyAp. wheelvignettes	Speed Booster / focal-reducer family	Flange clearance is only -2.5 mm — a plain mechanical adapter cannot reach infinity focus; a focal reducer (Speed Booster) with optical glass is required. Speed Boosters typically widen the effective focal length (~0.71×) and add ~1 stop of light, which can be desirable on crop bodies.
Leica M flange 27.8 mm	Speed booster MFIS lens-onlyAp. wheelvignettes	Speed Booster / focal-reducer family	Flange clearance is only -10.3 mm — a plain mechanical adapter cannot reach infinity focus; a focal reducer (Speed Booster) with optical glass is required. Speed Boosters typically widen the effective focal length (~0.71×) and add ~1 stop of light, which can be desirable on crop bodies.
Canon RF (cine) flange 20 mm	Speed booster MFIS lens-onlyAp. wheelvignettes	Speed Booster / focal-reducer family	Flange clearance is only -2.5 mm — a plain mechanical adapter cannot reach infinity focus; a focal reducer (Speed Booster) with optical glass is required. Speed Boosters typically widen the effective focal length (~0.71×) and add ~1 stop of light, which can be desirable on crop bodies.

Adapting other lenses onto a C-mount body

You own a C-mount body and want to mount glass from other systems. Mirrorless-lens-onto-DSLR-body combinations are omitted (rear element collides with the mirror box).

Lens mount	Result	Adapter examples	Caveats
Canon EF flange 44 mm	Mechanical MFIS lens-onlyAp. wheel2.7× crop	generic mechanical adapter ring (multiple vendors)	Mechanical adapter only — no electronic communication between Canon EF lens and C-mount body. Lens has no aperture ring; choose an adapter with a built-in aperture-control wheel.
Canon EF-S flange 44 mm	Mechanical MFIS lens-onlyAp. wheel1.8× crop	generic mechanical adapter ring (multiple vendors)	Mechanical adapter only — no electronic communication between Canon EF-S lens and C-mount body. Lens has no aperture ring; choose an adapter with a built-in aperture-control wheel.
Canon RF flange 20 mm	Mechanical MFIS lens-onlyAp. wheel2.7× crop	generic mechanical adapter ring (multiple vendors)	Mechanical adapter only — no electronic communication between Canon RF lens and C-mount body. Lens has no aperture ring; choose an adapter with a built-in aperture-control wheel.
Nikon F flange 46.5 mm	Mechanical MFIS lens-onlyAp. wheel2.7× crop	generic mechanical adapter ring (multiple vendors)	Mechanical adapter only — no electronic communication between Nikon F lens and C-mount body. Lens has no aperture ring; choose an adapter with a built-in aperture-control wheel.
Sony A / Minolta A flange 44.5 mm	Mechanical MFIS lens-onlyAp. wheel2.7× crop	generic mechanical adapter ring (multiple vendors)	Mechanical adapter only — no electronic communication between Sony A / Minolta A lens and C-mount body. Lens has no aperture ring; choose an adapter with a built-in aperture-control wheel.
Fujifilm GFX (G-mount) flange 26.7 mm	Mechanical MFIS lens-onlyAp. wheel3.42× crop	generic mechanical adapter ring (multiple vendors)	Mechanical adapter only — no electronic communication between Fujifilm GFX (G-mount) lens and C-mount body. Lens has no aperture ring; choose an adapter with a built-in aperture-control wheel.
L-Mount flange 20 mm	Mechanical MFIS lens-onlyAp. wheel2.7× crop	generic mechanical adapter ring (multiple vendors)	Mechanical adapter only — no electronic communication between L-Mount lens and C-mount body. Lens has no aperture ring; choose an adapter with a built-in aperture-control wheel.
M42 (Pentax / Praktica screw mount) flange 45.46 mm	Mechanical MFIS lens-onlyAp. ring2.7× crop	generic mechanical adapter ring (multiple vendors)	Mechanical adapter only — no electronic communication between M42 (Pentax / Praktica screw mount) lens and C-mount body.
Leica M flange 27.8 mm	Mechanical MFIS lens-onlyAp. ring2.7× crop	generic mechanical adapter ring (multiple vendors)	Mechanical adapter only — no electronic communication between Leica M lens and C-mount body.
Pentax K flange 45.46 mm	Mechanical MFIS lens-onlyAp. wheel2.7× crop	generic mechanical adapter ring (multiple vendors)	Mechanical adapter only — no electronic communication between Pentax K lens and C-mount body. Lens has no aperture ring; choose an adapter with a built-in aperture-control wheel.
PL (Positive Lock) flange 52 mm	Mechanical MFIS lens-onlyAp. ring2.7× crop	generic mechanical adapter ring (multiple vendors)	Mechanical adapter only — no electronic communication between PL (Positive Lock) lens and C-mount body.
Canon EF (cine) flange 44 mm	Mechanical MFIS lens-onlyAp. wheel2.7× crop	generic mechanical adapter ring (multiple vendors)	Mechanical adapter only — no electronic communication between Canon EF (cine) lens and C-mount body. Lens has no aperture ring; choose an adapter with a built-in aperture-control wheel.
Canon RF (cine) flange 20 mm	Mechanical MFIS lens-onlyAp. wheel2.7× crop	generic mechanical adapter ring (multiple vendors)	Mechanical adapter only — no electronic communication between Canon RF (cine) lens and C-mount body. Lens has no aperture ring; choose an adapter with a built-in aperture-control wheel.
Exakta flange 44.7 mm	Mechanical MFIS lens-onlyAp. ring2.7× crop	generic mechanical adapter ring (multiple vendors)	Mechanical adapter only — no electronic communication between Exakta lens and C-mount body.
T-mount (T2) flange 55 mm	Mechanical MFIS lens-onlyAp. ring2.7× crop	generic mechanical adapter ring (multiple vendors)	Mechanical adapter only — no electronic communication between T-mount (T2) lens and C-mount body.
Praktica B flange 44.4 mm	Mechanical MFIS lens-onlyAp. ring2.7× crop	generic mechanical adapter ring (multiple vendors)	Mechanical adapter only — no electronic communication between Praktica B lens and C-mount body.
Konica AR flange 40.5 mm	Mechanical MFIS lens-onlyAp. ring2.7× crop	generic mechanical adapter ring (multiple vendors)	Mechanical adapter only — no electronic communication between Konica AR lens and C-mount body.
Minolta SR / MC / MD flange 43.5 mm	Mechanical MFIS lens-onlyAp. ring2.7× crop	generic mechanical adapter ring (multiple vendors)	Mechanical adapter only — no electronic communication between Minolta SR / MC / MD lens and C-mount body.

C-mount — flange distance, protocol, and adapter compatibility

Mount specifications

Adapting C-mount lenses onto other bodies

Adapting other lenses onto a C-mount body

References

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