Canon EF 40mm f/2.8 STM

It’s virtually the same as the Canon EF-S 24mm lens, but built for full-frame cameras

without reading the numbers printed on the barrel, it’s hard to tell the EF-S 24mm and EF 40mm pancake lenses apart. Both have the same physical dimensions and the 40mm lens’s weight gain of 5g goes unnoticed. Both have the same filter thread and optional ES-52 hood. Even the viewing angles are similar, at 57 degrees for the 24mm on an APS-C camera, and 59 degrees for the 40mm on a full-frame body.

The gear-type autofocus system is the same as the one we described in the 24mm lens review. Again, manual focusing can only be applied when the camera is switched on, as the tiny focus ring is electronically, coupled. Conventional zone focusing or accurately setting the hyperfocal distance are impossible, due to the lack of a focus distance scale or depth of field markers.

One difference between the lenses is that the 24mm has a shorter minimum focus distance than the 40mm, at just 0.16m compared with 0.3m. This enables a larger maximum magnification ratio at the shortest focus setting, of 0.27x instead of 0.18x. Even so, the 40mm can get you close enough to pretty much any subject for street photography.

Performance

Given the overwhelming similarities between Canon’s two pancake lenses, it’s hardly surprising that they have almost identical performance. Image quality is almost identical, except that extreme corner-sharpness isn’t as good in the 40mm lens when shooting wide-open at f/2.8. The 40mm also has slightly less barrel distortion.