High performance, large aperture medium telephoto macro lens with OS (Optical Stabilizer). SLD glass provides good control of aberration and the floating inner focus system ensures high rendering throughout the focusing range. By using Sigma's APO Tele Converter, it is possible to take photos at greater than 1:1 magnification. HSM ensures a quiet and high speed AF as well as full-time manual focus override. This lens has a rounded 9 blades diaphragm which creates an attractive blur to the out of focus areas.