On our optical bench in the Popular Photography Test Lab, the lens garnered excellent SQF results for sharpness and contrast at all focal lengths. Comparisons are difficult, given its speed and focal-length range, but it outpaced full-frame f/2.8 wide-angle zooms, edging out Canon's EF 16–35mm f/2.8L II at 24mm and Nikon's older 17–35mm f/2.8D at 28mm. More surprising was how well it did against prime lenses in its range, especially at maximum aperture, where sharpness is often an issue. While Sigma's own 24mm f/1.4 logged a better SQF score at f/2 at our highest magnification of 20x24 (it's one of the sharpest lenses we've ever tested), at 35mm this new zoom lens did slightly better than Sigma's 35mm f/1.4. It also outshone Canon and Nikon's 24mm f/1.4 models as well as Canon's 35mm f/2.