Canon EF 17-40mm f/4L USM lens review: Popular high-performance optionBy Kevin Carter - Monday January 13 2014 Lens Review
Although overshadowed by its more glamorous sibling, as a moderately priced, highly portable ultra-wide zoom, the EF 17-40mm f/4L USM is a hugely popular model. Read on to find out how well it performs in our labs.
Introduced in 2003 the EF 17-40 f/4L USM was one of the first of the lightweight pro-level L-series zooms from the firm adopting a constant f4 aperture. Not only does that make the lens relatively small and more portable compared with the f2.8 varients, but it also helps keep it moderately priced. This full-frame lens is also popular with users when mounted on APS-C cameras where it’s the equivalent to a 27-64mm. Like other L-series lenses from the company, the EF 17-40mm f/4L has a high grade optical construction consisting of three aspherical lens elements and even adopts a Super-UD glass element, an expensive glass type usually resevered for more esoteric lenses in the range. The 12-element 9-group construction allows a closer than usual minimum focusing distance of 11.02” (0.28m). It weighes 1.05 lb (475g) and measures 3.81” (96.8mm) in length, and is available now for $839