The Sigma Corporation is pleased to announce the new Sigma 17-50mm F2.8 EX DC OS HSM. This large aperture standard zoom lens is designed for digital SLR cameras and incorporates Sigma's efficient OS function. It is a compact lens with an overall length of just 3.6 inches. This lens covers a focal length from 17mm wide angle and offers a large aperture of F2.8 throughout the entire zoom range, making it ideal for many types of photography such as portraiture and landscapes. The OS (Optical Stabilizer) function offers the use of shutter speeds approximately 4 stops slower than would otherwise be possible. 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 image sensor shift anti-shake system. As compensation for camera shake is visible in the viewfinder, the photographer can easily check for accurate focus and ensure there is no subject movement. Two FLD ("F" Low Dispersion) glass elements, which have performance equal to fluorite glass, plus two glass mold and one hybrid aspherical lens, provide excellent correction for all type of aberrations. The Super Multi-Layer Coating reduces flare and ghost. This lens has superior peripheral brightness and provides sharp, high contrast images even at the maximum apertures. High image quality is assured throughout the entire zoom range. Incorporating HSM (Hyper Sonic Motor), the lens provides fast and quiet AF. The lens has a minimum focusing distance of 11 inches throughout the entire zoom range and a maximum magnification ratio of 1:5. The rounded 7 blade diaphragm creates an attractive blur to the out of focus images. The inner focusing system eliminates front lens rotation, making the lens particularly suitable for use with the supplied petal-type lens hood and circular polarizing filters.