The lens experts at LensRentals.com have put together a very interesting chart showing the variations between individual wide angle zoom lenses of the same model to show the differences in manfuacturing tolerances from lens to lens.
So, to summarise very briefly what they say:
The EF 16-35 f/2.8L II USM has more variation than other zooms, which as they say is hardly a surprise as it’s the oldest of those tested (they didn’t test the EF 17-40 f/4L USM but claim that 17-40 fanboys will be upset at the variation!)
The real news is how astonishingly consistent the EF 11-24 f/4L USM lenses are with very little variation.
The Canon 11-24 f/4 though was just shockingly good. We did not expect anything like those numbers. It’s by far the most consistent zoom we’ve tested; far better than many prime lenses. I have no idea what Canon is doing or how they are doing it, but the copy-to-copy variation in most of their new lenses is minimal. I know people love to think that better inspection or QA procedures would accomplish this, but that’s not really the case. A lot of it has to do with designing the lens so that tolerances are not so critical. Put another way, that means that a tiny movement of an element doesn’t cause a huge change in the optics.
Read the full article here.