All-new optical design with significant improvements in peripheral brightness. High-performance standard zoom lens with constant f/4L aperture and a broad angle of view covering from wide angle to mid-telephoto. Air Sphere Coating (ASC) helps to significantly reduce flare and ghosting. Diagonal Angle of View:84°00' - 23° 20' Image Stabilizer performance at up to 4 stops* of shake correction helps capture sharp images. Lens Construction: 17 elements in 12 groups Circular Aperture (10 blades) helps deliver beautiful, soft backgrounds.