Sigma 17-50mm f/2.8 EX DC HSM Lens for Pentax

This large aperture standard zoom lens is designed for digital SLR cameras and covers a focal length from 17mm wide angle. It is a compact lens with an overall length of just 91.8mm (3.6"). This lens 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. Two FLD ("F" Low Dispersion) glass elements, which have performance equal to fluorite glass, compensate for color aberration. Two glass mold and one hybrid aspherical lens, provide excellent correction for field curvature and astigmatism. 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 28cm (11") 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.