The 28-70mm f/2.8 DG DN Contemporary Lens for Sony E-Mount from Sigma 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. E-Mount Lens/Full-Frame Format Aperture Range: f/2.8 to f/22 Two FLD Elements, Two SLD Elements Three Aspherical Elements Super Multi-Layer & Nano Porous Coatings Water- and Oil-Repellent Front Coating Stepping Motor AF System Rounded 9-Blade Diaphragm Dust- and Splash-Proof Design