L-series ultra-wide-angle zoom lens that s ideal for both film and digital SLRs. Superior optics by the use of three Aspherical lens elements in addition to a Super UD (Ultra-low Dispersion) glass element. Optical coatings are optimized for use with digital cameras. This lens focuses as close as 11 inches (0.28m) and offers both Canon s full-time manual focus and a powerful ring-type USM for fast and silent AF. It has a constant f/4 maximum aperture and offers the choice of screw-in 77mm filters or a holder in the rear of the lens for up to three gel filters. Finally it offers weather-resistant construction.