Tamron 150-600mm f5-6.3 Di VC USD Canon mount lens review: New contenderBy Kevin Carter - Wednesday February 12 2014 Lens Review
However, there isn’t much between them. Peak sharpness is pretty much the same, though at 400mm the Tamron maintains the edge in sharpness (predominantly in the outer areas of the frame) that was seen on the Canon EOS 5D Mk III. Both the Tamron and Sigma have somewhat disappointing sharpness (at least compared to the Canon EOS 5D Mk III) at their maximum focal lengths, however the Canon’s sharpness at 400mm is still good, at least in the centers of the frame (the periphery is noticeably lower). The Canon also better control of CA than the Tamron when compared at 400mm, but it has slightly higher vignetting albeit not particularly noticeable.