Do Pentax K lenses autofocus on Sony with this adapter?

No — it's a dumb mechanical ring with no contacts, so even Pentax's own SDM/DC autofocus lenses can't be driven. Focus everything by hand with peaking; aperture is set on the lens ring.

My Pentax-A lens stays wide open on the adapter — why?

Take it off the 'A' (green) auto position. Left on A, the lens expects a camera to command the aperture; on a dumb adapter there's nothing to command it, so it sits wide open. Rotate off A and the aperture ring works normally.

Will it fit screw-mount Takumar lenses?

No — those are M42 screw mount, not the K bayonet. Use an M42-NEX adapter for screw Takumars. This ring fits only the K-bayonet SMC Pentax / SMC Takumar-K lenses from 1975 on.

K&F Concept · Pentax K → Sony E adapter

K&F Concept PK-NEX — Pentax K → Sony E adapter

Pentax K bayonet (SMC Pentax K / M / A glass and SMC Takumar-K) onto Sony E. Mechanical-only ring — no AF, no electronic aperture. K and M lenses set aperture directly on the ring; A-series lenses must be turned off the green 'A' position so the ring controls the diaphragm.

At a glance

Vendor: K&F Concept
Release year: 2016
Body-side contacts: None (purely mechanical)
Flags: firmware-updatable —weather-sealed —requires glass —

What this adapter preserves

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

Focus: Manual focus only
IS: Lens-only IS
Aperture: Adapter aperture wheel
Infinity focus: Reaches infinity

What it does

The 45.46 mm K flange clears Sony E's 18 mm by 27.46 mm — a flat glassless ring with infinity preserved. Fits the cult FA Limited primes (31/1.8, 43/1.9, 77/1.8) as readily as the cheap SMC-M classics.

Common questions

Do Pentax K lenses autofocus on Sony with this adapter?: No — it's a dumb mechanical ring with no contacts, so even Pentax's own SDM/DC autofocus lenses can't be driven. Focus everything by hand with peaking; aperture is set on the lens ring.
My Pentax-A lens stays wide open on the adapter — why?: Take it off the 'A' (green) auto position. Left on A, the lens expects a camera to command the aperture; on a dumb adapter there's nothing to command it, so it sits wide open. Rotate off A and the aperture ring works normally.
Will it fit screw-mount Takumar lenses?: No — those are M42 screw mount, not the K bayonet. Use an M42-NEX adapter for screw Takumars. This ring fits only the K-bayonet SMC Pentax / SMC Takumar-K lenses from 1975 on.

Mounts on either side

Lens side

Pentax K

Flange 45.46 mm · Pentax / Ricoh

Open mount page →

Body side

Sony E (incl. FE)

Flange 18 mm · Sony

Open mount page →

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