Sigma 24-105mm F4 DG OS HSM A Canon mount lens review: A new standard?By Kevin Carter - Monday December 16 2013 Lens Review
We were curious to see how the Sigma panned out against the new Canon EF 24-70mm f2.8 II USM and the newer stabilized Tamron equivalent, both state-of-the-art models. Surprisingly, the Sigma can match both in peak sharpness but not quite in terms of uniformity. Although only slightly lower, the Sigma’s peripheral sharpness isn’t quite a match for either model at f4 to f8 throughout the zoom range.
The Sigma also has higher barrel distortion than the Canon at 24mm and has more noticeable pincushion than either model, which develops quite early on in the zoom range and is evident at 35mm. On the plus side the challenger has better control of CA than the Canon at all focal lengths and it’s lower than the Tamron in the corners at its widest focal length (where it’s quite noticeable with that model).