|Focal Length & Maximum Aperture||17 - 40mm; 1:4|
|Lens Construction||12 elements in 9 groups|
|Diagonal Angle of View||104° - 57° 30'|
|Focus Adjustment||Inner focusing system with USM|
|Closest Focusing Distance||0.28m / 0.9 ft.|
|Zoom System||Rotating type|
|Max. Diameter x Length, Weight||3.3" x 3.8", 1.1 lb. / 83.5 x 96.8mm, 500g|
A new and affordable L-series ultra-wide-angle zoom lens that's ideal for both film and digital SLRs. Superior optics are assured 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 similar to other high-end L-series lenses.