The Sony E-mount 90mm f/2.8 DG DN Contemporary Lens from Sigma is a short-telephoto prime with the impressive optical performance. It is well-suited for portraiture and selective everyday shooting and offers a fast f/2.8 aperture for controlling the depth of field and working in less-than-ideal light. This lens includes an aspherical element and five special low dispersion elements to control a variety of aberrations and achieve notable sharpness and clarity. The lens incorporates a manual aperture ring for enhanced tactility, and also featured is a stepping motor for quick and quiet AF performance. A rounded nine-blade diaphragm lets you achieve pleasingly smooth bokeh, and the lens?s all-metal body is weather-sealed to suit working in inclement conditions. As part of the Contemporary line within Sigma?s Global Vision series, this lens is designed to achieve a balance between convenience and performance and meshes a compact, lightweight build and versatile handling with notable optical attributes. I-series lens emphasizes a sleek and stylish physical design that is built to the same operational standards of Sigma?s Cine lenses, including a mechanical aperture ring, knurled metal components, and various switches and tactile controls for intuitive operation. Short-telephoto 90mm lens is designed for full-frame Sony E-mount mirrorless cameras, however, can also be used with APS-C models where it provides a 135mm equivalent focal length. Five Special Low Dispersion (SLD) elements markedly reduce chromatic aberrations and color fringing for improved clarity and color accuracy. One aspherical element helps to control distortion and spherical aberrations for a high degree of sharpness and accurate rendering. Integrated stepping motor realizes smooth and quiet autofocus, which is further complemented by an internal focusing design to promote greater responsiveness. The manual aperture ring includes an ?A? position for camera-based aperture selection. The rounded nine-blade diaphragm contributes to a smooth and pleasing bokeh quality. Brass bayonet affords improved mounting accuracy and rigidity and rubber sealing is incorporated in the mount?s design to render it dust- and splash-resistant.