70-200 f4 tested on Photozone

I actually don't put too much importance into any single test.  They are only indicators and do not address the various types of uses that a lens will be used for.  Most modern lenses produce good images, its more of the operators skill at capturing these images.  Also more to a lens than resolution, the same as there is more to a camera besides number of mp's..

Lenses do vary in quality control so two of the same lenses may produce slightly different results.

Larry