The Sigma 85mm f/1.4 DG DN is an Art-series prime characterized by its advanced and updated optical design, sleek profile, and bright design. The optical layout incorporates a series of low dispersion, aspherical, and high refractive index elements and its large-diameter design achieves a notable degree of clarity and sharpness with well-controlled distortion and aberrations. For autofocus, a stepping motor is used that maintains a lightweight and compact design while promoting fast and near-silent focusing performance for both stills and video applications. As part of the Art line within Sigma's Global Vision series, this lens is designed to achieve truly notable optical performance and is ideally suited for creative and artistic applications. Bright f/1.4 maximum aperture is particularly well-suited for working in available light conditions and provides extensive control over depth of field for isolating subject matter with selective focus. One aspherical element and four high refractive index glass elements control spherical aberrations and distortion for increased sharpness and accurate rendering. The integrated stepping motor realizes quick and quiet autofocus, which is further complemented by an optimized AF algorithm to produce a smoother focusing performance. Built-in Autofocus-Lock (AFL) button which can be assigned additional functions widens the range of operations available on the lens.