I realize this is the review page, however, I am very disturbed whenever I read any review of an L lens where someone bought a bad copy or in the case of one recent reviewer, two bads before finally getting a good one. I wrote to Canon about this since any L lens is relatively expensive and considered professional and that I expect it to come out of the box, perfect and ready to shoot. Here is the response I received from Canon.
Please note, various things can happen to a lens from the time it is
manufactured, and the time it reaches a dealer or customer that may
require the lens to have some minor adjustments made to obtain full
In our newer camera models, there is a new feature called AF
Microadjustment. This allows you to make fine adjustments of the AF's
point of focus. It can be adjusted in ±20 steps (-: Forward / +:
You may set the same adjustment amount to be applied to all of your
lenses, or an adjustment can be set individually for any particular
lens. Adjustments for up to 20 lenses can be registered in the camera.
Unfortunately, this new feature is only available in our newer camera
models (currently the EOS 1D Mark III and EOS 1Ds Mark III).
SAY WHAT? "various things can happen to a lens from the time it is
manufactured, and the time it reaches a dealer or customer" What the hell is going on here? Do they employ monkeys to package and ship their products to store? Even if they did, I would expect any lens of this caliber to hold up to some abuse. Canon needs to clean up their act and do something about their apparent lack of quality control. I have a 70-200 2.8 L IS that I assume is a "good" copy since I haven't seen anything to the contrary but I'm having second thoughts about getting a Canon 24-70 or any other L lens