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.
DG Lens Design
DG Lens design corrects for various aberrations, with special coatings to improve color balance and reduce digital-sensor-based ghosting.
HSM (Hyper Sonic Motor)
Sigma's Hyper Sonic Motor provides smooth, silent AF with full-time manual focus override possible without needing to touch any switch.
ELD & SLD Elements
This lens uses three ELD (Extra-Low Dispersion) elements and two SLD (Special Low Dispersion) elements to correct chromatic aberration.
The rounded 9-blade diaphragm opening makes out-of-focus elements appear more natural.