The Sigma 12-24mm F4 DG HSM Art is a premium full frame wide angle zoom designed to have minimal distortion in its wide angle imagery. Part of the Art line, the Sigma 12-24mm F4 DG HSM Art was created from decades of experience manufacturing wide-angle lenses. FLD glass elements, with performance equal to fluorite, provide for exceptional image quality while an updated Hyper Sonic Motor (HSM) uses 1.3X the torque for quick AF. A constant F4 aperture through the entire zoom range allows for greater ability in low light compared to previous models and the use of the largest aspherical element in the industry controls distortion, ghosting and flaring. An emphasis on edge to edge performance brings stunningly sharp and contrasty images to life. Ideal for many types of photography, the 12-24mm F4 Art is perfect for landscape photography, architecture photography, interior photography and much more. SPECIFICATIONS Lens Construction 16 Elements in 11 Groups Angle of View 122.0?-84.1? Number of Diaphragm Blades 9 (Rounded Diaphragm) Minimum Aperture F22 Minimum Focusing Distance 24cm* / 9.4in. *At 24mm end of the zoom range Maximum Magnifications 1:4.9 Dimensions(Diameter x Length) 4.0in. ? 5.2in. Weight 40.6oz