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.