The Sigma 28-70mm f/2.8 DG DN Contemporary Lens for Sony E-Mount is a versatile wide-angle to portrait-length zoom characterized by its f/2.8 constant maximum aperture. The design suits working in available lighting conditions while affording increased control over depth of field. More lightweight and compact than similar 24-70mm lenses, it's optical design incorporates two FLD and two SLD low-dispersion elements plus three aspherical elements that reduce a variety of aberrations to achieve high sharpness, enhanced clarity, and improved color accuracy. It features just one lightweight focusing element, which keeps the AF unit small. This, along with a quiet and fast stepping motor, makes for responsive and near-silent autofocus performance, an ideal combination for filmmakers looking for a high-performance, lightweight, and easy-to-handle camera system that works well with a gimbal or other accessories. Each optical surface features Super Multi-Layer and Nano Porous coatings to improve contrast and color rendering by suppressing lens flare and ghosting for optimal light transmission, and an added water- and oil-repellent coating on the front optic helps keep the lens free from smudges and droplets. The weather-sealed design benefits working in trying environmental conditions, and a nine-blade rounded diaphragm contributes a pleasing bokeh quality when using wider apertures.