Very interesting test done by DxOMark. They measured and ranked 85 lenses with the Canon EOS 5D Mark III [shoplink 2431](price & specs)[/shoplink], DxOMark:

[…] measured 47 primes ranging in focal length from 14mm to 300mm. Breaking that down further, 17 are wide or ultra-wide angle including the new optically excellent Sigma 35mm f/1.4DG HSM A and Canon EF 35mm f/2 IS USM, the Canon EF 28mm f/2.8 IS USM and the exquisite but pricey Carl Zeiss Distagon T* 2,8/15 (15mm f/2.8) ZE. Standard and short telephoto lenses account for another 25 lenses, while a further 5 are telephotos (including 3 Canon models, two of those being exotic, pro-grade f/2.8 types).

Results are surprisingly high in comparison with the Nikon D800 [shoplink 4853](price & specs)[/shoplink], which has 36Mp compared to the 22Mp of the 5D mark III:

While the Nikon D800 is capable of getting the best from any lens that’s fitted, it is essential to select lenses specifically to maximise the potential resolution of the sensor. If you’re trading in a Nikon D3X, for example, you may want to confirm that your existing lenses are capable of meeting (or maybe even exceeding) your expectations.

While that same principle of choosing the best glass also applies to the Canon, it’s not quite as crucial. In financial terms alone, this may be an important consideration if you have already invested in a sizeable range of lenses. Lenses on the Canon EOS 5D Mark III are without doubt very efficient.

Despite the Nikon D800’s 60% extra pixels, the measures reveal that the EOS 5D Mark III is capable of similar sharpness and of achieving a close DxOMark camera/lens score when compared to the D800. In the conclusion they write:

Given the somewhat lowly-looking pixel count of the Canon EOS 5D Mark III the potential sharpness is, surprisingly, one feature where the camera exceeds expectations. Providing the camera is matched to specific lens models, sharpness can even exceed the Nikon D800 under certain circumstances (when that camera is used with lesser capable lenses). This is great news if you’re looking to invest in one or own one already. If you’re a Canon user and are looking to upgrade, or maybe even switch because of the sensor’s perceived lowly capabilities then this should put your mind at rest. Please look out for next part of this review, where we’ll look at the finer points of the results for camera and lens combinations to choose from and those lenses that you may want to avoid.

They just added the second part part of the review, which deals with standard lenses and measures these on the EOS 5D Mark III. Don’t miss this review by DxOMark.

Canon EOS 5D Mark III price check: [shopcountry 2431]