Full-Frame | f/2.8 to f/22 | Ultrawide Prime Lens | Linear Stepping Motor Autofocus System | 1 HR, 3 ED & 1 ASPH. Elements | 8 Elements in 7 Groups | 7-Bladed Diaphragm
EF-Mount Lens/Full-Frame Format | Aperture Range: f/2.8 to f/22 | One Extra-Low Dispersion Element | Ultra Multi-Coating | Autofocus, AF/MF Switch | Weather-Sealed Construction