Canon EF 17-40mm f/4.0L USM Black

EF 17-40mm f/4.0L USM - 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.

Ultra wide lens for analogue EOS SLR cameras
The EF17-40mm f/4L USM is an ultra wide angle Canon EF zoom lens meant for professional and high amateur SLR EOS camera users.

Standard zoom lens for digital EOS SLR cameras
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.

Superior optical performance
The EF17-40mm f/4L USM has 12 lens elements arranged in 9 groups. Super Spectra Coating on the elements ensures excellent colour balance and minimises ghosting and flare. To provide superb image quality over a 17-40mm zoom range the lens uses three aspheric elements of two different types, while Super UD (Ultra-low Dispersion) glass is used to prevent the chromatic aberrations that often can degrade the subject edge clarity.