Canon EF 40mm f/2.8 STM £200/$180

Canon’s ‘pancake lens’ is a bit of a pocket rocket

While the flexibility to fit the ‘right’ lens for the job gives DSLRS supreme versatility, nobody enjoys lugging around a big bag of heavy lenses. This pancake lens is remarkably flat in its design, extending just 23mm from the host camera. It’s slim enough to slip into a spare pocket and, at 130g, weighs less than an eighth of the Sigma 85mm lens on test.

Despite its incredibly small design, the EF 40mm is compatible with full-frame as well as APS-C format DSLRS, and features a metal rather than plastic mounting plate. The inner barrel of the lens physically extends at shorter focus distances, but the 52mm filter thread doesn’t rotate during focusing. The optional ES-52 lens hood adds only a little extra length.

Typical of Canon’s latest small-build lenses, the autofocus system is ‘gear type’ STM (Stepping Motor), which is neither as fast nor as quiet as Canon’s regular STM system. The additional helical gears that drive autofocus are clearly audible, but the advantages of smooth transitions during movie capture, and manual focus override via an electronically coupled ‘fly-by-wire’ focus ring, are retained.

Performance

With its focal length of 40mm being the widest on test and a relatively ‘slow’ aperture rating of f/2.8, this is the worst lens in the group for getting a tight depth of field (see over the page). In other respects, image quality is very pleasing, with good centresharpness even at f/2.8, and corner-sharpness becoming very good at f/5.6. Colour fringing and distortion are also well-controlled, making the little pancake lens worth considering for portraiture on an APS-C format body.