Sigma 12-24 F4 DG HSM Art lens review vs Nikon 14-24 F2.8

Review of the new Sigma 12-24mm F4 Art lens compared to the Nikon 14-24 mm F2.8 lens. Canon version of the Sigma lens tested on a Sony A7R with the Sigma MC-11 adapter, Nikon lens tested on a Nikon D810. Between 12 and 14 mm the Sigma is a very good lens. Image quality decreases if you go to the longer end of the focal range but increases again at 24 mm.