Sigma 120-300mm f2.8 EX DG OS HSM S Canon and Nikon mount lens review: Prime image quality in a zoom?By Kevin Carter - Friday October 25 2013 Lens Review
With a high DxOMark lens score of 29 points, the Sigma lens shows that it’s a match for Canon and off-brand rivals in image quality. It has a very high sharpness score at 20P-Mpix and performance doesn’t fall off at 300mm, as it does with some lesser models. Transmission is excellent and while there’s some pincushion at the longer end it’s generally well controlled. Vignetting is more noticeable at 300mm as well but it’s less important now with software correction and few people can argue that it doesn’t help with the look of some images. Chromatic aberration is low generally, appearing at the shorter end of the zoom range at full-aperture mostly, rather than at 300mm.