Sigma APO 17-50mm F2.8 EX DC OS HSM

Constant aperture of f/2.8, Smooth zooming action, Delivers excellent results

Manual focus ring is fiddly, All-plastic outer construction, Resolution tails off above f/11

noticeable chromatic aberration at the shortest focal length,, a bit too high vignetting,, significant coma at 17 mm,, too simplified manual focus ring,, image quality at the maximum aperture, at the edge of the frame for shorter focal lengths could...

The Sigma AF 17-50mm f/2.8 EX DC HSM OS is a highly competitive APS-C standard zoom lens and Sigma's best product in this class so far. It's not a flawless lens, though, but none really is. Its biggest weakness is the performance at f/2.8 - the...