Mounted on a high-resolution full-frame camera, the Canon EOS 1Ds Mark III, this lens offers a pretty good resolution of 50 lp/mm. At such a focal length, distortion is never really a problem, so it is not surprising that its distortion score is very low.
The DxOMark score map also tells us that this lens achieves an acceptable level of quality under low-light conditions up until 200mm at f/5.6. Overall, however, its quite low DxOMark score of 12 shows that this lens is not a great performer even when mounted on the excellent Canon 1Ds Mark III.
The measurements for the Nikon version are close; see the full results for this lens mounted on a Nikon D3x.
Canon mount vs Nikon Mount
If we compare the two versions of the Sigma 70-300mm DG OS on a Nikon D3x and on a Canon EOS 1Ds Mark III, we note that the Nikon mount achieves slightly better DxOMark scores, but this difference is mainly due to the better noise behavior of the Nikon D3x. See the sensor comparison: Nikon D3x vs Canon EOS 1Ds Mark III.
Sigma 70-300mm DG OS vs its predecessor
- The comparison of the two Sigma 70-300mm DG Canon versions, mounted on a Canon EOS 5D Mark II.
- The same comparison for the Nikon versions, mounted on a Nikon D3x.
These results show that the resolution of the previous version is slightly better, but the stabilization offered by the new lens should make it so much easier to use that we would still advise to choose the new model.