Review by Klaus Schroiff, published June 2014

Introduction

Obviously Canon had to look for a place where to cut costs and it's mostly apparent in terms of build quality. Now please don't misunderstand me here because things are far from bad. Rather than made of metal, the lens body is simply made of good quality plastics down to the mount. However, everything is tightly assembled with no wobbling whatsoever. The zoom mechanism extends the lens just a little bit towards the wide- and long end of the range. The shortest physical length is reached around the 14mm setting. Both the zoom and focus rings operate smoothly. The front element does not rotate.

Canon's new STM ("Stepping motor") is optimized for silent and smooth operations and as such it is also usable for movies. It's pretty speedy, too. STM works "by wire" so you actually drive the focus motor by turning the focus ring. However, this is hardly noticeable and certainly one of the best implementations that we have seen so far. Even full time manual focusing is provided. The focus accuracy of the tested sample was excellent.
Interestingly Canon also implemented an image stabilizer with a claimed efficiency of up to 4 f-stops (expect a little less than that if you enjoy your coffee). Thus while it is slower than it's in-house cousin - the Canon EF-S 10-22mm f/3.5-4.5 USM, it has actually a better low light potential unless you have to deal with moving objects.