This telephoto zoom lens incorporates Sigma's original OS (Optical Stabilizer) function and is housed in a compact construction. The OS function offers the use of shutter speeds approximately 4 stops slower than would otherwise be possible. It makes telephoto shooting easy for many types of photography such as sport and nature. For Sony and Pentax mount, the built-in OS function of this lens can be used even if the camera body is equipped with an anti-shake function. As compensation for camera shake is visible in the view finder, the photographer can easily check for accurate focus and ensure there is no subject movement. The SLD (Special Low Dispersion) glass element provides excellent correction for all type of aberrations. The Super Multi-Layer Coating reduces flare and ghosting and provides high contrast images throughout the focal range. The lens has an overall length of 126mm (5.0), maximum diameter of 76.5mm (3.0) and weight of just 610g/21.5oz. Its compact construction makes it convenient for travel and hand held telephoto photography. This lens rounded 9 blade diaphragm creates an attractive blur to the out of focus areas of the photograph. This lens has a minimum focusing distance of 150cm (59.1) throughout the entire zoom range and a maximum magnification ratio of 1:3.9, making it ideal for close-up photography.