T hisultra-wide-angle zoom designed for APS-C format DSLRs is amazingly small for its type and is less than half the weight of most directly competing lenses. Its 67mm filter thread is also a lot smaller than usual, so filters are relatively inexpensive.
One weight-saving feature is that it has a plastic rather than metal mounting plate, but build qualit y feels robust nonetheless. Typical of many recent Canon lenses, it has an STM (Stepping Motor) autofocus system which is fast for stills, smooth for video capture and virtually silent in operation. The electronicallycoupled focus ring enables manual override of autofocus but, t y pically for an STM lens, there’s no focus distance scale.