Given that the lens reviewed is the Canon version the most appropriate comparisons are with other 70-200 f2.8 lenses with Canon mounts. There are two others in the market at the moment that have been tested by DxOMark: Canon’s EF 70-200 f2.8L IS II USM and Sigma’s 70-200 f2.8 EX DG APO OS HSM. The specifications for these three lenses are almost interchangeable: the Tamron is fractionally shorter, the Sigma is fractionally lighter but the numbers are very close. The biggest single difference is not unexpected: the Canon lens has an indicative price significantly higher than either the Sigma or the Tamron, seeming to position it apart from the two independent lenses.
The measurements for these three lenses are all pretty good but the lens that is set apart from the others this time is the Sigma, because it doesn’t quite match up. The Canon has a DxOMark score of 24, close to the 25 of the Tamron, while the Sigma has a score of 20. When you break the Sigma’s scores down further none of the individual measures is best, Sharpness at 14P-Mpix being the worst. The Canon and the Tamron are close in all measures except for Chromatic aberration where the Tamron and Sigma are good at 7µm while the Canon is exceptionally good at 3µm.
In the tests for transmission, distortion, vignetting and chromatic aberration the scores for each of the lenses are predominantly good. It is only when you start to compare them that one looks weaker than the others. In vignetting for instance, individually the lenses look OK but side by side the Sigma is relatively poor compared to the Canon
A comparison with the equivalent lenses from other makers: Nikon and Sony gives a much more clear-cut picture. Again the specifications are very similar, even the prices are closer, but the Nikon AF-S VR Zoom-Nikkor 70-200mm f/2.8G IF-ED which has been on the market since 2002 and the Sony 70-200mm F2.8 G since 2006 and both fall well short of the Tamron in performance. The big disappointment is in sharpness: the Nikkor scores 13 P-Mpix and the Sony 13 P-Mpix. As sensor resolutions get bigger this is quite a sacrifice to be making. Nikon has a newer version of this lens too – the Nikon AF-S NIKKOR 70-200mm f/2.8G ED VR II – which will be reviewed soon. Maybe Nikon will have made improvements that will change these findings.
Tamron is not new to having a 70-200mm f2.8 lens, its previous version, the SP AF 70-200mm F/2.8 Di LD (IF) MACRO Canon has been on the market for 5 years. It isn’t a bad lens and it does have a macro facility that, for some people will still make it preferable, it is also much cheaper. However, it isn’t as sharp, and has no image stabilisation, two of the things that make the new lens so good.