Mixing a useful zoom range with a sophisticated design, the Sigma SA-mount Sigma 17-70mm f/2.8-4 DC Macro OS HSM is a Contemporary-series lens, also characterized by its compact, lightweight profile. The bright f/2.8-4 maximum aperture range pairs with the wide-angle to short-telephoto zoom range to create an ideal travel and everyday lens. The optical design uses a series of low dispersion and aspherical elements to control color fringing and distortion in order to realize high clarity and sharpness. A Super Multi-Layer Coating has also been applied to suppress flare and surface reflections for improved contrast in bright conditions. Also, this zoom sports a high 1:2.8 maximum magnification and 8.7″ minimum focusing distance to suit working with close-up subjects.
In terms of handling, a Hyper Sonic Motor is incorporated in the design to provide fast, quiet, and precise autofocus performance along with full-time manual focus override. An Optical Stabilizer also minimizes the appearance of camera shake for sharper handheld shooting. Additionally, the 17-70mm f/2.8-4 features a rounded seven-blade diaphragm for smooth bokeh quality and it is compatible with the optional USB Dock for fine-tuning focusing characteristics and updating its firmware.