The Canon EF-M 18-55mm f3.5-5.6 IS STM ($299.99 direct) is the standard zoom lens for the EOS M compact interchangeable lens camera. You can buy the EOS M bundled with it or the EF-M 22mm f/2 STM, so buying it separately to supplement the prime lens is not out of the question. It features a 3x zoom ratio that covers a 29-88mm (35mm equivalent) field of view. The lens has an all-metal design, so it feels impressively sturdy.
The lens is bigger than its 22mm prime counterpart, adding quite a bit of depth to the svelte EOS M. It measures 2.4 by 2.4 inches (HD), weighs 7.4 ounces, and has a standard 52mm filter thread. The lens can focus as close as 9.8 inches through its zoom range. Despite a narrow f/3.5-5.6 aperture range—it’s f/3.5 at 18mm, but narrows to f/5.6 at 55mm—you can still create a good amount of background blur when working close to your subject. There is a manual focus ring, but it utilizes an electronic focus design. Moving it activates the focus motor rather than physically moving the glass. This results in a noticeable delay when adjusting focus manually.
The lens is optically stabilized, which will help you get sharper photos at longer shutter speeds, assuming that your subject is cooperative and remains still for the photo op. There’s no lens hood included, but Canon will sell you one for an additional $29. Using a hood can help reduce the chance of lens flare and increase the contrast of your photos by eliminating stray light coming in from odd angles.
Imatest shows that the lens is quite sharp throughout its zoom range when paired with the EOS M. At 18mm f/3.5 the lens hits 2,314 lines per picture height, noticeably better than the 1,800 lines we used to define a sharp photo. Zooming to 35mm limits the maximum aperture to f/5, and the lens manages 2,268 lines there. At its maximum 55mm focal length the lens notches 2,285 lines at f/5.6. Sharpness is excellent, but the lens does show a good bit of distortion.
At 18mm there is 2.7 percent barrel distortion, which causes straight lines to curve outward. As you zoom the barrel distortion gives way to pincushion distortion, where straight lines curve in. At 35mm it shows a mere 0.6 percent of this type of distortion, but that increases to 1.1 percent at 55m. You can correct for distortion in software like Lightroom, but other cameras have profiles to perform those corrections in-camera when shooting JPGs. The Sony Alpha NEX-6 ships with a 16-50mm Retractable Zoom Lens that shows an incredible amount of distortion, but if you shoot in JPG you’ll never know it. On the other side of the spectrum, the collapsible 14-42mm zoom lens that Olympus offers with its PEN cameras is smaller, also quite sharp, and shows very little distortion.
If you bought the EOS M with the 22mm f/2 STM lens and feel limited by a single focal length, the EF-M 18-55mm f3.5-5.6 IS STM is your only current option with which to supplement it. The zoom is impressively sharp, but has a small aperture. This limits your ability to use it in lower light, even with its optical stabilization system—the EOS M does not have a built-in flash. The lens also shows a good deal of barrel distortion at wider angles, which you’ll have to correct in software if straight lines are important in your photography. Overall, it’s a good example of an 18-55mm zoom, but a slightly faster aperture or a smaller design would go a long way to make it more useful with the compact EOS M.
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