The Canon EF-M 22mm f/2 STM ($249.99 direct) is one of the two lenses that launched along with Canon's EOS M compact interchangeable lens camera. The EOS M uses an APS-C sensor, so the 22mm focal length delivers a 35mm equivalent field of view when compared to full-frame cameras. The lens doesn't feature optical stabilization, but its f/2 aperture will help in low-light shooting.

The lens is impressively small. It measures 0.9 by 2.4 inches (HD) and weighs only 3.7 ounces. Standard 43mm filters are supported, and the lens can focus on objects as close as half a foot away from the camera. There is a manual focus ring, but it's a focus by wire design—moving it simply tells the camera to adjust the focus, rather than physically moving the glass. Because of this, there's a delay when adjusting focus manually. A lens hood is not included, but is available for $29.

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I used Imatest to check the sharpness of the lens when paired with the EOS M. It exceeds 1,800 lines per picture height, the figure that we use as a cutoff for an acceptably sharp photo, at every tested aperture. At f/2 it records 2,294 lines, and increases only marginally to 2,331 lines at f/2.8. Resolution peaks at f/5.6, where it notches 2,362 lines. Distortion is completely negligible. The only other lens available for the EOS M, the EF-M 18-55mm f3.5-5.6 IS STM, is also quite sharp, but shows a lot of distortion at wider angles.

Chances are that you'll only be in the market for this lens if you bought the EOS M along with the 18-55mm zoom. The EF-M 22mm f/2 STM limits you to a single focal length, but it captures almost three times as much light, allowing you to shoot in dim conditions and to create a shallow depth of field. It also makes the EOS M a practical camera to slide into your pocket, which just isn't possible when the comparatively large zoom lens is attached.