Review by Klaus Schroiff, published June 2010

Introduction

Unlike the Nikkor 24-70, the Canon 24-70L and its older non-HSM sister the Sigma 24-70mm f/2.8 EX DG HSM is a more "traditional" zoom lens. It has its shortest physical length at the 24mm setting and the single inner lens tube extends towards the tele end - a probably preferred approach by most users actually. Size- and weight-wise there's not much of a difference. The Sigma lens is slightly shorter but more "fat". The build quality is excellent and really comparable to the genuine manufacturer lenses - except for the lack of weather sealing. There's no wobbling and the lens features the well known EX crinkle finish. The tested sample showed no signs of zoom creeping. The zoom and focus rings are somewhat damped and operate smoothly. Thanks to an IF (internal focusing) design the front element does not rotate so using a polarizer is no problem. However, because of a very large filter diameter (82 mm) a polarizer, especially a higher quality one, becomes a rather expensive accessory.

The 24-70mm f/2.8 EX features a silent-wave (ultrasonic) AF motor providing fast and near-silent AF operations and manual focus override at any time. The AF speed in Live-View mode is fairly slow - more so than e.g. on the EF 24-70mm f/2.8 USM L.