Can I adapt Contax/Yashica Zeiss lenses to a Sony E or Nikon Z body?

Yes — plain mechanical C/Y-to-E, C/Y-to-Z, C/Y-to-RF, C/Y-to-X, and C/Y-to-MFT adapters are widely sold ($15-50 from Fotodiox, K&F Concept, Urth, and premium Novoflex builds). The 45.5 mm flange leaves 27.5 mm of clearance on a Sony α (18 mm) and 29.5 mm on a Nikon Z (16 mm), so infinity focus is preserved with no corrective glass. Focus is manual; aperture is set on the lens ring. The Zeiss Planar 50 mm f/1.4, Planar 85 mm f/1.4, Distagon 28 mm f/2.8, and Sonnar 135 mm f/2.8 are the most sought-after for this.

Are Contax/Yashica lenses the same as Contax G or modern Sony Zeiss lenses?

No — three different systems. Contax/Yashica (C/Y, 1975-2005) is the manual-focus SLR mount this page covers. Contax G (1994) is a separate autofocus rangefinder mount with no focus ring on the lens, which makes it awkward to adapt (manual-focus G adapters exist but are fiddly). Modern Sony/Zeiss optics (ZA, Loxia, Batis, the Otus/Milvus DSLR line) are entirely different native mounts. Only the C/Y Zeiss glass uses this 45.5 mm bayonet.

Will Contax/Yashica lenses focus to infinity on a Canon EF or Nikon F DSLR?

Not cleanly. C/Y's 45.5 mm flange sits only 1.5 mm above Canon EF (44.0 mm) — too thin for a reliable glassless infinity adapter, so a focal-reducer adapter with corrective glass is the practical route on EF. Nikon F (46.5 mm) and Pentax K (45.46 mm) are equal-to-longer than C/Y, so glassless infinity is physically impossible there; only corrective-glass adapters work, with some image-quality cost. Mirrorless bodies are the sensible adapting destination for C/Y glass.

Contax / Yashica · Legacy SLR mount

Contax/Yashica (C/Y) — flange distance, protocol, and adapter compatibility

The bayonet introduced on the 1975 Contax RTS, born from the Carl Zeiss / Yashica partnership and built by Kyocera through 2005. Its claim to fame is the glass: Carl Zeiss T* Planar, Sonnar, Distagon, and Tessar lenses — manufactured both in Oberkochen, Germany (AEG / MMG code) and in Japan under Zeiss licence (AEJ / MMJ code) — alongside the budget Yashica ML line that shares the exact mount. Pure mechanical interface: manual focus, an aperture ring on every lens, and no electrical contacts in any iteration. The 45.5 mm flange clears every mirrorless mount with a plain glassless adapter (infinity preserved), which is why C/Y Zeiss glass — the Planar 50 mm f/1.4, Planar 85 mm f/1.4, Distagon 28 mm f/2.8, and Sonnar 135 mm f/2.8 in particular — is among the most-adapted vintage glass on Sony α, Fujifilm X, Canon RF, and Nikon Z bodies.

Mount specifications

Flange focal distance: 45.5 mm
Throat diameter: 48 mm
Electronic protocol: Mechanical only (no electronic coupling)
Supported formats: full-frame, APS-C
Manufacturer: Contax / Yashica
Introduced: 1975 (discontinued)
Status: Discontinued

Contax/Yashica (C/Y) on the flange-distance axis

Contax/Yashica (C/Y) sits at 45.5 mm — highlighted in orange below. The flange-distance gap between the mirrorless and SLR clusters is the room a mechanical adapter occupies; that gap is why almost every SLR lens adapts onto every mirrorless body, and why the reverse is mechanically impossible.

Flange focal distance (mm)SLR / DSLRMirrorlessRangefinderMedium-format mirrorlessCinemaLegacy SLR

Adapting Contax/Yashica (C/Y) lenses onto other bodies

You own Contax/Yashica (C/Y) 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
Body mount Canon RF flange 20 mm	Mechanical MFno ISAp. ring	generic mechanical adapter ring (multiple vendors)	Mechanical adapter only — no electronic communication between Contax/Yashica (C/Y) lens and Canon RF body.
Body mount Canon FD flange 42 mm	Mechanical MFno ISAp. ring	generic mechanical adapter ring (multiple vendors)	Mechanical adapter only — no electronic communication between Contax/Yashica (C/Y) lens and Canon FD body.
Body mount Canon EF-M flange 18 mm	Mechanical MFno ISAp. ring1.5× crop	generic mechanical adapter ring (multiple vendors)	Mechanical adapter only — no electronic communication between Contax/Yashica (C/Y) lens and Canon EF-M body.
Body mount Nikon Z flange 16 mm	Mechanical MFno ISAp. ring	generic mechanical adapter ring (multiple vendors)	Mechanical adapter only — no electronic communication between Contax/Yashica (C/Y) lens and Nikon Z body.
Body mount Sony E (incl. FE) flange 18 mm	Mechanical MFno ISAp. ring	generic mechanical adapter ring (multiple vendors)	Mechanical adapter only — no electronic communication between Contax/Yashica (C/Y) lens and Sony E (incl. FE) body.
Body mount Fujifilm X flange 17.7 mm	Mechanical MFno ISAp. ring1.5× crop	generic mechanical adapter ring (multiple vendors)	Mechanical adapter only — no electronic communication between Contax/Yashica (C/Y) lens and Fujifilm X body.
Body mount Fujifilm GFX (G-mount) flange 26.7 mm	Mechanical MFno ISAp. ringvignettes	generic mechanical adapter ring (multiple vendors)	Mechanical adapter only — no electronic communication between Contax/Yashica (C/Y) lens and Fujifilm GFX (G-mount) body.
Body mount Micro Four Thirds flange 19.25 mm	Mechanical MFno ISAp. ring2× crop	generic mechanical adapter ring (multiple vendors)	Mechanical adapter only — no electronic communication between Contax/Yashica (C/Y) lens and Micro Four Thirds body.
Body mount L-Mount flange 20 mm	Mechanical MFno ISAp. ring	generic mechanical adapter ring (multiple vendors)	Mechanical adapter only — no electronic communication between Contax/Yashica (C/Y) lens and L-Mount body.
Body mount Leica M flange 27.8 mm	Mechanical MFno ISAp. ring	generic mechanical adapter ring (multiple vendors)	Mechanical adapter only — no electronic communication between Contax/Yashica (C/Y) lens and Leica M body.
Body mount Canon RF (cine) flange 20 mm	Mechanical MFno ISAp. ring	generic mechanical adapter ring (multiple vendors)	Mechanical adapter only — no electronic communication between Contax/Yashica (C/Y) lens and Canon RF (cine) body.
Body mount C-mount flange 17.526 mm	Mechanical MFno ISAp. ring2.7× crop	generic mechanical adapter ring (multiple vendors)	Mechanical adapter only — no electronic communication between Contax/Yashica (C/Y) lens and C-mount body.
Body mount Konica AR flange 40.5 mm	Mechanical MFno ISAp. ring	generic mechanical adapter ring (multiple vendors)	Mechanical adapter only — no electronic communication between Contax/Yashica (C/Y) lens and Konica AR body.
Body mount Minolta SR / MC / MD flange 43.5 mm	Mechanical MFno ISAp. ring	generic mechanical adapter ring (multiple vendors)	Mechanical adapter only — no electronic communication between Contax/Yashica (C/Y) lens and Minolta SR / MC / MD body.
Body mount Canon EF flange 44 mm	Speed booster MFIS lens-onlyAp. wheel	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.	Speed Booster equivalence calculator Plug in any Contax/Yashica (C/Y) lens and pick the focal-reducer family. The calc returns the effective focal length and aperture on a Canon EF (APS-C), plus the full-frame equivalent angle of view after the body's crop stacks on top. Lens focal length (mm)Max aperture (f/N)Focal-reducer family Effective focal length 35.5 mm 50.0 mm × 0.71 on the reducer. Effective aperture f/1.28 0.99 stops brighter than f/1.80. Full-frame equiv. angle of view 53.3 mm 35.5 mm × 1.5× (APS-C sensor crop). A focal reducer concentrates the lens's image circle, so both focal length and f-number scale by the same ratio (stops gained = `−2 · log₂(ratio)`). The body's crop factor still applies on top — the full-frame-equivalent angle-of-view multiplier is ratio × body crop. Calculator is informational; verify against the adapter vendor's per-lens compatibility chart before purchase.
Body mount Canon EF-S flange 44 mm	Speed booster MFIS lens-onlyAp. wheel1.5× crop	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.	Speed Booster equivalence calculator Plug in any Contax/Yashica (C/Y) lens and pick the focal-reducer family. The calc returns the effective focal length and aperture on a Canon EF-S (APS-C), plus the full-frame equivalent angle of view after the body's crop stacks on top. Lens focal length (mm)Max aperture (f/N)Focal-reducer family Effective focal length 35.5 mm 50.0 mm × 0.71 on the reducer. Effective aperture f/1.28 0.99 stops brighter than f/1.80. Full-frame equiv. angle of view 53.3 mm 35.5 mm × 1.5× (APS-C sensor crop). A focal reducer concentrates the lens's image circle, so both focal length and f-number scale by the same ratio (stops gained = `−2 · log₂(ratio)`). The body's crop factor still applies on top — the full-frame-equivalent angle-of-view multiplier is ratio × body crop. Calculator is informational; verify against the adapter vendor's per-lens compatibility chart before purchase.
Body mount Nikon F flange 46.5 mm	Speed booster MFIS lens-onlyAp. wheel	Speed Booster / focal-reducer family	Flange clearance is only -1.0 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.	Speed Booster equivalence calculator Plug in any Contax/Yashica (C/Y) lens and pick the focal-reducer family. The calc returns the effective focal length and aperture on a Nikon F (APS-C), plus the full-frame equivalent angle of view after the body's crop stacks on top. Lens focal length (mm)Max aperture (f/N)Focal-reducer family Effective focal length 35.5 mm 50.0 mm × 0.71 on the reducer. Effective aperture f/1.28 0.99 stops brighter than f/1.80. Full-frame equiv. angle of view 53.3 mm 35.5 mm × 1.5× (APS-C sensor crop). A focal reducer concentrates the lens's image circle, so both focal length and f-number scale by the same ratio (stops gained = `−2 · log₂(ratio)`). The body's crop factor still applies on top — the full-frame-equivalent angle-of-view multiplier is ratio × body crop. Calculator is informational; verify against the adapter vendor's per-lens compatibility chart before purchase.
Body mount Sony A / Minolta A flange 44.5 mm	Speed booster MFIS lens-onlyAp. wheel	Speed Booster / focal-reducer family	Flange clearance is only 1.0 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.	Speed Booster equivalence calculator Plug in any Contax/Yashica (C/Y) lens and pick the focal-reducer family. The calc returns the effective focal length and aperture on a Sony A / Minolta A (APS-C), plus the full-frame equivalent angle of view after the body's crop stacks on top. Lens focal length (mm)Max aperture (f/N)Focal-reducer family Effective focal length 35.5 mm 50.0 mm × 0.71 on the reducer. Effective aperture f/1.28 0.99 stops brighter than f/1.80. Full-frame equiv. angle of view 53.3 mm 35.5 mm × 1.5× (APS-C sensor crop). A focal reducer concentrates the lens's image circle, so both focal length and f-number scale by the same ratio (stops gained = `−2 · log₂(ratio)`). The body's crop factor still applies on top — the full-frame-equivalent angle-of-view multiplier is ratio × body crop. Calculator is informational; verify against the adapter vendor's per-lens compatibility chart before purchase.
Body mount M42 (Pentax / Praktica screw mount) flange 45.46 mm	Speed booster MFIS lens-onlyAp. wheel	Speed Booster / focal-reducer family	Flange clearance is only 0.0 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.	Speed Booster equivalence calculator Plug in any Contax/Yashica (C/Y) lens and pick the focal-reducer family. The calc returns the effective focal length and aperture on a M42 (Pentax / Praktica screw mount) (APS-C), plus the full-frame equivalent angle of view after the body's crop stacks on top. Lens focal length (mm)Max aperture (f/N)Focal-reducer family Effective focal length 35.5 mm 50.0 mm × 0.71 on the reducer. Effective aperture f/1.28 0.99 stops brighter than f/1.80. Full-frame equiv. angle of view 53.3 mm 35.5 mm × 1.5× (APS-C sensor crop). A focal reducer concentrates the lens's image circle, so both focal length and f-number scale by the same ratio (stops gained = `−2 · log₂(ratio)`). The body's crop factor still applies on top — the full-frame-equivalent angle-of-view multiplier is ratio × body crop. Calculator is informational; verify against the adapter vendor's per-lens compatibility chart before purchase.
Body mount Pentax K flange 45.46 mm	Speed booster MFIS lens-onlyAp. wheel	Speed Booster / focal-reducer family	Flange clearance is only 0.0 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.	Speed Booster equivalence calculator Plug in any Contax/Yashica (C/Y) lens and pick the focal-reducer family. The calc returns the effective focal length and aperture on a Pentax K (APS-C), plus the full-frame equivalent angle of view after the body's crop stacks on top. Lens focal length (mm)Max aperture (f/N)Focal-reducer family Effective focal length 35.5 mm 50.0 mm × 0.71 on the reducer. Effective aperture f/1.28 0.99 stops brighter than f/1.80. Full-frame equiv. angle of view 53.3 mm 35.5 mm × 1.5× (APS-C sensor crop). A focal reducer concentrates the lens's image circle, so both focal length and f-number scale by the same ratio (stops gained = `−2 · log₂(ratio)`). The body's crop factor still applies on top — the full-frame-equivalent angle-of-view multiplier is ratio × body crop. Calculator is informational; verify against the adapter vendor's per-lens compatibility chart before purchase.
Body mount PL (Positive Lock) flange 52 mm	Speed booster MFIS lens-onlyAp. wheel	Speed Booster / focal-reducer family	Flange clearance is only -6.5 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.	Speed Booster equivalence calculator Plug in any Contax/Yashica (C/Y) lens and pick the focal-reducer family. The calc returns the effective focal length and aperture on a PL (Positive Lock) (APS-C), plus the full-frame equivalent angle of view after the body's crop stacks on top. Lens focal length (mm)Max aperture (f/N)Focal-reducer family Effective focal length 35.5 mm 50.0 mm × 0.71 on the reducer. Effective aperture f/1.28 0.99 stops brighter than f/1.80. Full-frame equiv. angle of view 53.3 mm 35.5 mm × 1.5× (APS-C sensor crop). A focal reducer concentrates the lens's image circle, so both focal length and f-number scale by the same ratio (stops gained = `−2 · log₂(ratio)`). The body's crop factor still applies on top — the full-frame-equivalent angle-of-view multiplier is ratio × body crop. Calculator is informational; verify against the adapter vendor's per-lens compatibility chart before purchase.
Body mount Canon EF (cine) flange 44 mm	Speed booster MFIS lens-onlyAp. wheel	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.	Speed Booster equivalence calculator Plug in any Contax/Yashica (C/Y) lens and pick the focal-reducer family. The calc returns the effective focal length and aperture on a Canon EF (cine) (APS-C), plus the full-frame equivalent angle of view after the body's crop stacks on top. Lens focal length (mm)Max aperture (f/N)Focal-reducer family Effective focal length 35.5 mm 50.0 mm × 0.71 on the reducer. Effective aperture f/1.28 0.99 stops brighter than f/1.80. Full-frame equiv. angle of view 53.3 mm 35.5 mm × 1.5× (APS-C sensor crop). A focal reducer concentrates the lens's image circle, so both focal length and f-number scale by the same ratio (stops gained = `−2 · log₂(ratio)`). The body's crop factor still applies on top — the full-frame-equivalent angle-of-view multiplier is ratio × body crop. Calculator is informational; verify against the adapter vendor's per-lens compatibility chart before purchase.
Body mount Exakta flange 44.7 mm	Speed booster MFIS lens-onlyAp. wheel	Speed Booster / focal-reducer family	Flange clearance is only 0.8 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.	Speed Booster equivalence calculator Plug in any Contax/Yashica (C/Y) lens and pick the focal-reducer family. The calc returns the effective focal length and aperture on a Exakta (APS-C), plus the full-frame equivalent angle of view after the body's crop stacks on top. Lens focal length (mm)Max aperture (f/N)Focal-reducer family Effective focal length 35.5 mm 50.0 mm × 0.71 on the reducer. Effective aperture f/1.28 0.99 stops brighter than f/1.80. Full-frame equiv. angle of view 53.3 mm 35.5 mm × 1.5× (APS-C sensor crop). A focal reducer concentrates the lens's image circle, so both focal length and f-number scale by the same ratio (stops gained = `−2 · log₂(ratio)`). The body's crop factor still applies on top — the full-frame-equivalent angle-of-view multiplier is ratio × body crop. Calculator is informational; verify against the adapter vendor's per-lens compatibility chart before purchase.
Body mount T-mount (T2) flange 55 mm	Speed booster MFIS lens-onlyAp. wheel	Speed Booster / focal-reducer family	Flange clearance is only -9.5 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.	Speed Booster equivalence calculator Plug in any Contax/Yashica (C/Y) lens and pick the focal-reducer family. The calc returns the effective focal length and aperture on a T-mount (T2) (APS-C), plus the full-frame equivalent angle of view after the body's crop stacks on top. Lens focal length (mm)Max aperture (f/N)Focal-reducer family Effective focal length 35.5 mm 50.0 mm × 0.71 on the reducer. Effective aperture f/1.28 0.99 stops brighter than f/1.80. Full-frame equiv. angle of view 53.3 mm 35.5 mm × 1.5× (APS-C sensor crop). A focal reducer concentrates the lens's image circle, so both focal length and f-number scale by the same ratio (stops gained = `−2 · log₂(ratio)`). The body's crop factor still applies on top — the full-frame-equivalent angle-of-view multiplier is ratio × body crop. Calculator is informational; verify against the adapter vendor's per-lens compatibility chart before purchase.
Body mount Praktica B flange 44.4 mm	Speed booster MFIS lens-onlyAp. wheel	Speed Booster / focal-reducer family	Flange clearance is only 1.1 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.	Speed Booster equivalence calculator Plug in any Contax/Yashica (C/Y) lens and pick the focal-reducer family. The calc returns the effective focal length and aperture on a Praktica B (APS-C), plus the full-frame equivalent angle of view after the body's crop stacks on top. Lens focal length (mm)Max aperture (f/N)Focal-reducer family Effective focal length 35.5 mm 50.0 mm × 0.71 on the reducer. Effective aperture f/1.28 0.99 stops brighter than f/1.80. Full-frame equiv. angle of view 53.3 mm 35.5 mm × 1.5× (APS-C sensor crop). A focal reducer concentrates the lens's image circle, so both focal length and f-number scale by the same ratio (stops gained = `−2 · log₂(ratio)`). The body's crop factor still applies on top — the full-frame-equivalent angle-of-view multiplier is ratio × body crop. Calculator is informational; verify against the adapter vendor's per-lens compatibility chart before purchase.
Body mount Olympus OM flange 46 mm	Speed booster MFIS lens-onlyAp. wheel	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.	Speed Booster equivalence calculator Plug in any Contax/Yashica (C/Y) lens and pick the focal-reducer family. The calc returns the effective focal length and aperture on a Olympus OM (APS-C), plus the full-frame equivalent angle of view after the body's crop stacks on top. Lens focal length (mm)Max aperture (f/N)Focal-reducer family Effective focal length 35.5 mm 50.0 mm × 0.71 on the reducer. Effective aperture f/1.28 0.99 stops brighter than f/1.80. Full-frame equiv. angle of view 53.3 mm 35.5 mm × 1.5× (APS-C sensor crop). A focal reducer concentrates the lens's image circle, so both focal length and f-number scale by the same ratio (stops gained = `−2 · log₂(ratio)`). The body's crop factor still applies on top — the full-frame-equivalent angle-of-view multiplier is ratio × body crop. Calculator is informational; verify against the adapter vendor's per-lens compatibility chart before purchase.

Adapting other lenses onto a Contax/Yashica (C/Y) body

You own a Contax/Yashica (C/Y) 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
Lens mount PL (Positive Lock) flange 52 mm	Mechanical MFno ISAp. ring	generic mechanical adapter ring (multiple vendors)	Mechanical adapter only — no electronic communication between PL (Positive Lock) lens and Contax/Yashica (C/Y) body.
Lens mount T-mount (T2) flange 55 mm	Mechanical MFno ISAp. ring	generic mechanical adapter ring (multiple vendors)	Mechanical adapter only — no electronic communication between T-mount (T2) lens and Contax/Yashica (C/Y) body.
Lens mount Canon EF flange 44 mm	Speed booster MFIS lens-onlyAp. wheel	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.
Lens mount Canon EF-S flange 44 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.
Lens mount Canon FD flange 42 mm	Speed booster MFIS lens-onlyAp. wheel	Speed Booster / focal-reducer family	Flange clearance is only -3.5 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.
Lens mount Nikon F flange 46.5 mm	Speed booster MFIS lens-onlyAp. wheel	Speed Booster / focal-reducer family	Flange clearance is only 1.0 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.
Lens mount Sony A / Minolta A flange 44.5 mm	Speed booster MFIS lens-onlyAp. wheel	Speed Booster / focal-reducer family	Flange clearance is only -1.0 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.
Lens mount M42 (Pentax / Praktica screw mount) flange 45.46 mm	Speed booster MFIS lens-onlyAp. wheel	Speed Booster / focal-reducer family	Flange clearance is only -0.0 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.
Lens mount Pentax K flange 45.46 mm	Speed booster MFIS lens-onlyAp. wheel	Speed Booster / focal-reducer family	Flange clearance is only -0.0 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.
Lens mount Canon EF (cine) flange 44 mm	Speed booster MFIS lens-onlyAp. wheel	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.
Lens mount Exakta flange 44.7 mm	Speed booster MFIS lens-onlyAp. wheel	Speed Booster / focal-reducer family	Flange clearance is only -0.8 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.
Lens mount Praktica B flange 44.4 mm	Speed booster MFIS lens-onlyAp. wheel	Speed Booster / focal-reducer family	Flange clearance is only -1.1 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.
Lens mount Konica AR flange 40.5 mm	Speed booster MFIS lens-onlyAp. wheel	Speed Booster / focal-reducer family	Flange clearance is only -5.0 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.
Lens mount Minolta SR / MC / MD flange 43.5 mm	Speed booster MFIS lens-onlyAp. wheel	Speed Booster / focal-reducer family	Flange clearance is only -2.0 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.
Lens mount Olympus OM flange 46 mm	Speed booster MFIS lens-onlyAp. wheel	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.

Adapter SKU teardown

Curated adapter SKUs that involve the Contax/Yashica (C/Y) mount on either side, with the operational specifics — body-side electronic contact count, firmware-update path, weather sealing, and whether optical glass is in the path.

K&F Concept C/Y-NEX
released 2018
Contax/Yashica (C/Y) lens → Sony E (incl. FE) body
- no firmware updates
- not weather sealed
- no glass — pass-through
- Contax/Yashica (C/Y) bayonet — Carl Zeiss T* Planar / Distagon / Sonnar / Tessar and the budget Yashica ML line — onto Sony E. Mechanical-only: no electronics, no AF, no aperture coupling; focus by hand, set aperture on the lens's own ring.
- The 45.5 mm C/Y flange clears Sony E's 18 mm by 27.5 mm, so this is a flat glassless ring with infinity focus preserved (no focal reducer needed, unlike adapting C/Y to Canon EF). Matte-black interior helps suppress flare from bright vintage elements.
Urth Contax/Yashica to Sony E
released 2020
Contax/Yashica (C/Y) lens → Sony E (incl. FE) body
- no firmware updates
- not weather sealed
- no glass — pass-through
- Contax/Yashica (C/Y) bayonet onto Sony E with an anodised recycled-aluminum body and plastic-free packaging; one tree planted per product. Mechanical-only — no AF, no electronic aperture; focus by hand, aperture on the lens ring.
- Flat glassless ring: the 45.5 mm C/Y flange clears Sony E's 18 mm by 27.5 mm, so infinity focus is preserved without corrective optics. Mechanically equivalent to K&F's Pro-line internals at a finish / sustainability premium.

References

Common questions

Can I adapt Contax/Yashica Zeiss lenses to a Sony E or Nikon Z body?: Yes — plain mechanical C/Y-to-E, C/Y-to-Z, C/Y-to-RF, C/Y-to-X, and C/Y-to-MFT adapters are widely sold ($15-50 from Fotodiox, K&F Concept, Urth, and premium Novoflex builds). The 45.5 mm flange leaves 27.5 mm of clearance on a Sony α (18 mm) and 29.5 mm on a Nikon Z (16 mm), so infinity focus is preserved with no corrective glass. Focus is manual; aperture is set on the lens ring. The Zeiss Planar 50 mm f/1.4, Planar 85 mm f/1.4, Distagon 28 mm f/2.8, and Sonnar 135 mm f/2.8 are the most sought-after for this.
Are Contax/Yashica lenses the same as Contax G or modern Sony Zeiss lenses?: No — three different systems. Contax/Yashica (C/Y, 1975-2005) is the manual-focus SLR mount this page covers. Contax G (1994) is a separate autofocus rangefinder mount with no focus ring on the lens, which makes it awkward to adapt (manual-focus G adapters exist but are fiddly). Modern Sony/Zeiss optics (ZA, Loxia, Batis, the Otus/Milvus DSLR line) are entirely different native mounts. Only the C/Y Zeiss glass uses this 45.5 mm bayonet.
Will Contax/Yashica lenses focus to infinity on a Canon EF or Nikon F DSLR?: Not cleanly. C/Y's 45.5 mm flange sits only 1.5 mm above Canon EF (44.0 mm) — too thin for a reliable glassless infinity adapter, so a focal-reducer adapter with corrective glass is the practical route on EF. Nikon F (46.5 mm) and Pentax K (45.46 mm) are equal-to-longer than C/Y, so glassless infinity is physically impossible there; only corrective-glass adapters work, with some image-quality cost. Mirrorless bodies are the sensible adapting destination for C/Y glass.