Canon RF 28mm F2.8 STM

Reviewers agree the centre is excellent from f/2.8. One lab measured the outer field as very good to excellent wide open and called it sharper than Canon's larger 24mm and 35mm f/1.8 primes; a real-world test found the edges noticeably softer than the centre, at their best from f/4 to f/11. Lateral colour is low and longitudinal fringing is limited to f/2.8 and f/4. The lens leans heavily on software: raw files show around 4% barrel distortion and more than 3 stops of vignetting at f/2.8, and the camera will not let you switch distortion correction off.

Autofocus is quick and accurate with very little hunting, though the STM hums and manual focus by wire is noisy and the thin ring is fiddly. Bokeh is smoother than expected for a 28mm f/2.8 at close range, but subject isolation is limited. Flare results were mixed, with one test showing rainbow artefacts around the sun and another finding it well controlled. Build is plastic over a metal mount and feels solid for the price.

Owners use it as an always-on walk-around lens and like how small it makes bodies from the R50 to the R5. They describe image quality as sharp, clean and well above what the price suggests, with quick, consistent focus, and several say it has become their most-used lens for travel and everyday shooting.

The few reservations are the f/2.8 aperture, which some owners call slow, and its limits for video without extra stabilisation. Few owner reviews report any faults.