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 depth of field and working in less-than-ideal light. 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 a pleasingly smooth bokeh, and the lens's all-metal body is weather-sealed to suit working in inclement conditions. 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. Five Special Low Dispersion (SLD) elements markedly reduce chromatic aberrations and color fringing for improved clarity and color accuracy. The integrated stepping motor realizes smooth and quiet autofocus, which is further complemented by an internal focusing design to promote greater responsiveness. 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.