Lens mount compatibility, explained
The short checklist for avoiding the most expensive kind of accessory mistake.
The mount is the mechanical connection
Canon RF, Canon EF, Nikon Z, Nikon F, Sony E, Fujifilm X and other mounts are different systems. A lens must physically match the camera mount or use an adapter designed for that exact combination.
Adapters change more than fit
Some adapters preserve autofocus, aperture control and metadata; others are manual only. A speed booster or focal reducer also changes the optical behaviour. Check the manufacturer compatibility list rather than assuming every adapter supports every feature.
Sensor coverage matters
A full-frame lens can usually be used on a smaller sensor body, although the field of view changes. A lens designed only for a smaller sensor may vignette on a full-frame body. The listing should make the intended format clear; ask before buying when it does not.
Verify the whole setup
Check mount, sensor coverage, autofocus support, stabilisation, filter size and the physical clearance around the mount. Include the camera model, lens model and adapter model in a support question for a precise answer.