- 17-40mm ultra-wide-angle zoom lens with f/4 maximum aperture for Canon SLR cameras
- 3 aspherical lens elements and super UD glass element create superior optics in all conditions
- Powerful ring-type ultra-sonic monitor (USM) produces fast and silent autofocusing
- Focuses as close as 11 inches; supports screw-in 77mm filters or up to 3 gel filters
- Suitable for Wedding/Nature Photography, Weather-resistant construction; measures 3.3 inches in diameter; 1-year warranty
The EF 17-40mm f/4L USM Lens from Canon is a high quality "L" series wide angle zoom lens for full frame and APS-C size DSLR cameras. It combines one high-precision molded glass aspherical element and two replica aspherical lenses to achieve the extended zoom range, while also correcting for common aberrations that arise during zooming. A Super UD (Ultra-low Dispersion) glass element minimizes the chromatic aberration of magnification which tends to occur with wide-angle lenses, to help eliminate color bleed along the edges of the subject and achieve high image contrast and resolution.