Canon EF 17-40mm f/4L USM Ultra Wide Angle Zoom Lens for SLR Cameras
From the Manufacturer: Broaden your perspective with the Canon EF 17-40mm ultra-wide-angle zoom lens. Ideal for both film and digital SLR cameras, the lens offers three aspherical lens elements in addition to a Super UD (ultra-low dispersion) glass element, creating superior optics in all conditions.