K&F Concept M42-FX – M42 Lens to Fujifilm X Mount Adapter

The K&F Concept M42-FX adapter lets you mount M42 screw-mount lenses on Fujifilm X mount cameras. A brass mount and a metal body hold the lens firmly with no play. It is a purely mechanical adapter without electronic contacts: focusing is manual, the aperture is set with the ring on the lens, and infinity focus is retained.

Which lenses and cameras

On the lens side it takes M42 screw-mount lenses. On the body side it fits Fujifilm X mount cameras, such as the X-Pro1, X-Pro2, X-T1, X-T2, X-T10, X-T20, X-E1, X-E2, X-A1 to X-A3 and X-M1.

Build and mounting

The mount is brass and the body aluminium alloy, so the adapter sits firmly, without play or twisting. The mount does not deform even after 100,000 mounting cycles. A red dot makes mounting easy: screw the lens into the adapter, then align the dots and turn the adapter on the body until it clicks.

Manual operation

The adapter has no electronic contacts, so the camera does not recognise the lens and neither autofocus nor automatic aperture control works. Focusing is manual and the aperture is set with the aperture ring of the lens. Infinity focus is retained. Before first use, enable shutter release without a lens in the camera menu (e.g. “Release w/o Lens” – the name varies by model), otherwise the camera will not fire.

Tips for use

• On telephoto lenses the infinity mark (∞) is deliberately offset slightly to allow for thermal expansion, so check infinity focus in the viewfinder or on the screen.
• On a body with an APS-C sensor the focal length is multiplied by roughly 1.5×, and a full-frame lens uses its sharp centre.