Does the K&F Contax/Yashica adapter preserve infinity focus on Sony?

Yes — the 45.5 mm C/Y flange is far longer than Sony E's 18 mm, so a thin glassless ring reaches infinity comfortably with margin to spare. No corrective glass is involved, so optical quality is entirely the lens's own.

Will it autofocus the Zeiss Planar 85 mm f/1.4?

No — C/Y is a purely mechanical mount with no electrical contacts, so no adapter can autofocus it. Focus the Planar by hand with Sony focus peaking and magnify; it's a deliberate, manual-focus portrait experience and the aperture is set on the lens's own ring.

C/Y-NEX from K&F or the Urth equivalent — does it matter?

Mechanically they're comparable OEM-grade builds; both reach infinity and fit the C/Y bayonet the same. K&F is usually cheaper; Urth adds a recycled-aluminum finish, plastic-free packaging, and a tree-planting commitment. For premium daily use with German AEG/MMG Zeiss glass, a Novoflex C/Y-NEX has tighter tolerances at 3-4× the price.

K&F Concept · Contax → Sony E adapter

K&F Concept C/Y-NEX — Contax → Sony E adapter

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.

At a glance

Vendor: K&F Concept
Release year: 2018
Body-side contacts: None (purely mechanical)
Flags: firmware-updatable —weather-sealed —requires glass —

What this adapter preserves

Compatibility for Contax lens on a Sony E body (computed from the lensmount dataset — open the Contax to Sony E adapter page for the full verdict, flange clearance, and adapter caveats).

Focus: Manual focus only
IS: No IS
Aperture: Manual aperture ring
Infinity focus: Reaches infinity

What it does

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.

Common questions

Does the K&F Contax/Yashica adapter preserve infinity focus on Sony?: Yes — the 45.5 mm C/Y flange is far longer than Sony E's 18 mm, so a thin glassless ring reaches infinity comfortably with margin to spare. No corrective glass is involved, so optical quality is entirely the lens's own.
Will it autofocus the Zeiss Planar 85 mm f/1.4?: No — C/Y is a purely mechanical mount with no electrical contacts, so no adapter can autofocus it. Focus the Planar by hand with Sony focus peaking and magnify; it's a deliberate, manual-focus portrait experience and the aperture is set on the lens's own ring.
C/Y-NEX from K&F or the Urth equivalent — does it matter?: Mechanically they're comparable OEM-grade builds; both reach infinity and fit the C/Y bayonet the same. K&F is usually cheaper; Urth adds a recycled-aluminum finish, plastic-free packaging, and a tree-planting commitment. For premium daily use with German AEG/MMG Zeiss glass, a Novoflex C/Y-NEX has tighter tolerances at 3-4× the price.

Mounts on either side

Lens side

Contax/Yashica (C/Y)

Flange 45.5 mm · Contax / Yashica

Open mount page →

Body side

Sony E (incl. FE)

Flange 18 mm · Sony

Open mount page →

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