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
As you might expect, the Nikon version performs similarly to the Canon mount. That said, given the 36-Mpix sensor of the D800, sharpness levels are high but they’re not quite as lofty as we expected. Set to full aperture, the centers are noticeably sharper than the periphery throughout the zoom range. And, the performance across the field isn’t quite has high at 300mm as it is at 120mm.
Not only that but transmission is slightly lower at 3.1TStops,
However, on the plus side, vignetting is lower, as is chromatic aberration but in real world use the difference is negligible between the two versions.