Canon EF 17-40mm f4 L USM Features
Superb optical performance throughout the zoom range.
Fastest AF speed within its class (same as the EF16-35 f/2.8L USM)
Highly dust and moisture resistant
28cm minimum focusing distance at all focal lengths
While it is an excellent lens when used with an analogue SLR camera, the EF17-40mm f/4L USM is especially well suited for digital SLR cameras with an imaging sensor size smaller than the 35mm format. Indeed on such digital SLR cameras these focal lengths can give an angle of view approximately equivalent to that of a 28-70mm lens used on a 35mm camera, which makes it the ideal standard zoom lens.