Sigma's 17-70mm f/2.8-4 DC Macro OS HSM lens is an upgrade to the AF 17-70mm f/2.8-4.5 DC Macro lens released in 2006. Designed for the smaller imaging circle of cameras with APS-C sized sensors, it is slightly larger and heavier than its predecessor and has a more complex optical construction.
You want an affordable general-purpose lens to replace a standard kit lens, You'd like a lens that requires no readjustment when you fit polarisers and graduated filters; Don't buy this lens if, You require a lens with excellent flatness of field and edge-to-edge sharpness, You need true macro...