Introduction The Sigma 17-70 f2.8-4 DC Macro OS HSM C Canon is a “standard” zoom lens for APS-C cameras, in this case Canon. It is also available for Nikon and Sigma APS-C bodies. It covers the range 17mm to 70mm, the relative focal length for full frame 35mm would be 27.2mm to 112mm. This type of lens is aimed at photographers looking for a single, all purpose lens that will at the same time be compact enough to carry around. This particular lens is also equipped with a Macro setting allowing focussing down to 22cm giving