K&F Concept PK-FX Pro – Pentax K Lens to Fujifilm X Mount Adapter

The K&F Concept PK-FX Pro adapter mounts lenses with the Pentax K mount on cameras with the Fujifilm X mount. It is purely mechanical, with no electronic contacts: focusing is done by hand on the lens and the aperture is set with the lens aperture ring, while infinity focus is retained. The all-metal adapter is precisely machined and coated inside with matte anti-reflection paint.

Pentax K lenses on Fujifilm X bodies

With the PK-FX Pro adapter, Pentax K lenses can be used on a modern Fujifilm X body with everything it offers – a viewfinder with magnification for precise manual focusing, sensor stabilisation if the body has it, and current recording formats. The length of the adapter matches the difference in flange distance between the two systems, so the lens focuses across its whole range, all the way to infinity.

Solid metal construction

The adapter is all-metal, made of hardened anodised aluminium. Precise machining ensures a firm connection without play. The interior is coated with matte paint that absorbs stray light and reduces reflections and flare. A red dot shows how to align the adapter with the mount, making mounting and removal quick and accurate.

Manual focus and aperture

The adapter has no electronic contacts and the camera does not recognise the lens – autofocus, aperture control from the body and lens data in EXIF do not work. Focus with the ring on the lens; magnification or focus peaking in the viewfinder makes precise focusing easier. The aperture is set with the aperture ring on the lens; lenses without an aperture ring cannot be stopped down with this adapter.

First use

Before the first shot, enable shutter release without a lens in the camera menu (on Sony “Release w/o Lens”, a similar option on other brands). Otherwise the body will not treat the adapter without contacts as an attached lens and will not release the shutter.

Infinity with telephoto lenses

On telephoto lenses the ∞ mark on the scale is often set slightly beyond true infinity so that the lens can still focus when heat expansion occurs. Focus on distant subjects using the viewfinder, not the scale.

Sensor format

A full-frame lens on a body with a smaller sensor uses only the centre of its image circle, where it is sharpest, and the angle of view narrows (1.5× on APS-C, 2× on Micro 4/3). Conversely, an APS-C lens on a full-frame body may vignette; some bodies solve this with an APS-C crop mode.

Compatible cameras

Fujifilm X-Pro1, X-Pro2, X-T1, X-T2, X-T10, X-T20, X-E1, X-E2, X-E2S, X-A1, X-A2, X-A3, X-A10, X-M1 and other bodies with the Fujifilm X mount.