The Sigma 16-28mm f/2.8 DG DN Contemporary Lens is a compact, high-performance ultrawide zoom meant to compliment a photographer's arsenal by providing a versatile range of focal lengths in a small and lightweight package, without compromising on optical quality. A fast f/2.8 constant aperture allows for the use of faster shutter speeds in low light scenarios as well as being especially useful for closeup shots thanks to its shallow depth of field.This lens utilizes a complex arrangement of specialized aspherical and low dispersion glass elements to effectively suppress chromatic aberrations for improved clarity and color accuracy. Super Multi-Layer and Nano Porous Coatings have also been applied to improve contrast and color rendering by reducing lens flare and ghosting when working in strong lighting conditions. The inner zoom & focus mechanism keeps the dimensions of the lens constant throughout the zoom range and at all focus distances. This design feature allows for almost no balance point shift and a fixed front element, making it an ideal instrument for videography, travel, and landscape photography. Constant f/2.8 maximum aperture is well-suited for working in available lighting conditions. Two large-diameter aspherical elements control spherical aberrations and distortion for increased sharpness and accurate rendering. Rounded nine-blade diaphragm contributes to a smooth and pleasing bokeh quality. 72mm front filter thread allows for the use of common screw-in filters instead of specialized setups. A stepping AF motor benefits both photographers and videographers with its fast, precise, and near-silent performance. Full-time manual focus control can also be selected. Weather-resistant construction with a brass bayonet that affords improved mounting accuracy and rigidity.