The Sigma 24-70mm f/2.8 IF EX DG HSM Lens is a large aperture standard zoom lens that's ideal for photojournalism and general professional photography. It provides (in 35mm terms) the equivalent of a 38-112mm f/2.8 lens upon current Pentax digital SLR cameras. The lens provides a bright viewfinder, speedy AF, and full-time manual focus override at any time without having to change the focusing switch position.
The Hyper Sonic Motor (HSM) ensures silent, high-speed AF function, and this is the first 24-70mm f/2.8 for Pentax cameras that can boast of this feature. The 24-70mm f/2.8 IF EX DG HSM features a Super Multi Layer Coating which reduces flare and ghosting. "DG" is a designation Sigma uses upon lenses featuring optical systems designed to meet the performance characteristics of digital SLR cameras.