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Computar · C-mount mount · Prime lens

Computar 12.5mm f/1.4 (C-mount) — adapter compatibility and body matches

The Computar 12.5mm f/1.4 (C-mount) sits on the C-mount flange geometry (17.526 mm) — below is every body mount it adapts onto, the autofocus / IS / aperture-control level you should expect, and the specific adapter SKUs that ship the path.

Lens specifications

Manufacturer
Computar
Lens mount
C-mount
Focal length
12.5mm
Aperture
f/1.4 – f/16
Lens type
Prime
Image stabilization
No
Weight
80 g
Filter thread
— (rear drop-in or no thread)
Released
1990

Background & adapter context

A workhorse machine-vision / industrial-inspection C-mount lens from Computar (CBC Group) — the kind of fast 12.5 mm standard that ships on factory-line and microscope cameras by the thousand. Compact and inexpensive on the used market, which made it a favourite for MFT shooters wanting a cheap fast near-normal with a distinct optical character (soft, glowy wide-open, swirling edges). Manual focus, continuous locking aperture. Covers MFT with noticeable corner vignetting; adapts to MFT / Sony E via a thin C-mount ring, no infinity on DSLRs.

Adapting the Computar 12.5 f/1.4 onto other bodies

Every feasible body-mount destination for a C-mount lens, sorted by adapter feasibility. Curated adapter SKUs (linked below) cover the specific lens-side → body-side pairing — pick the row matching the body you own, then click the SKU for the full teardown.

Body mountResultAdapter examplesCaveats

Body mount

Sony E (incl. FE)
flange 18 mm
Mechanical
MFno ISAp. 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.

Body mount

Fujifilm X
flange 17.7 mm
Mechanical
MFno ISAp. 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.

Body mount

Micro Four Thirds
flange 19.25 mm
Mechanical
MFno ISAp. 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.

Body mount

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.

Body mount

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.

Body mount

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.

Body mount

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.

Body mount

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.

Body mount

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.

Body mount

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.

About the C-mount mount

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.

See every adapter that touches the C-mount mount →

Common questions

What's the best body to adapt the Computar 12.5mm f/1.4 (C-mount) onto?
Two strong destinations. First choice: a Sony E (incl. FE) body via a Generic C-E rings (Fotodiox, Pixco, Rainbowimaging) preserves the most of the Computar 12.5 f/1.4's native behaviour (autofocus, in-lens IS where present, electronic aperture). Second choice: a Fujifilm X body via a Generic C-FX rings (Fotodiox, Kipon) — solid fallback when the first body family is unavailable. The /matrix and /picker pages let you compare every feasible adaptation side-by-side.
Will autofocus work when the Computar 12.5 f/1.4 is adapted onto another body?
No — adapters in our catalogue route the Computar 12.5 f/1.4 through a mechanical path on the best-supported body (Canon RF). Focus is fully manual; rely on the body's focus peaking and magnify-to-focus aids to nail focus.
Does the Computar 12.5 f/1.4's in-lens image stabilization still work through an adapter?
The Computar 12.5 f/1.4 has no in-lens IS / VR / OS unit — there's no in-lens stabilisation to pass through. Bodies with IBIS (most modern mirrorless) still stabilise the captured frame, but stabilisation is body-side only.

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