The large angle of view (122 degrees super wide angle of view at 12mm along the diagonal axis) on Sigma's 12-24mm f/4.5-5.6 EX DG Aspherical Lens is ideal for shootings indoor as well as landscape photography. It has a variable angle of view from 122 degrees at 84.1 degrees. Four Special Low Dispersion (SLD) glass elements are provided for effective compensation of color aberration, which is a common problem with super-wide angle lenses. Two pieces of Glass Mold and one-piece hybrid aspherical lenses offer excellent correction for distortion as well as all types of aberration. By effective arrangement of lens elements and advanced technology this lens has Super Compact dimensions of 3.9 inches full-length, and 3.4 inches maximum diameter. The 12-24mm f/4.5-5.6 EX DG Aspherical lens is equipped with Inner focusing system that will keep the length of the lens unchanged while controlling aberration. The models, which are equipped with HSM (Hyper Sonic Motor, available for Sigma, Canon and Nikon camera mount lens) system offer Full Time Manual Focusing. It has a minimum focusing distance of 11 inches (28cm) at all focal lengths. This lens is equipped with an integral Petal-type hood to block out extraneous light.