For any one wondering how the third copy faired. (+ a few more to B&H for exchanging this so many times)

The third copy of the 24-70mm f/2.8 L II showed up today, and I have had some time to check it out.

It is sharper than the first two. It is comparable to the 24mm f/1.4L II at 24mm, slightly sharper in the center and seems to be the close to the same on the edges. The vignetting of the lens detracts a bit of the IQ in the corners when comparing to the 24mm f/1.4L.

At 35mm it is a shave sharper than my 35mm f/1.4L, and at 70mm it is the same in comparison to my 70-200mm f/2.8L II.

Very much in line with some other reports I have read.

For those wanting to replace their 24mm and 35mm L with this lens. The lens will not replace my two primes, the fact that the primes have less distortion and vignetting make them superior at that particular length. Any resolution that is better than the primes is fractional and in the real world not noticeable.

The 24-70mm II has substantially better IQ than my copy of the 16-35mm f/2.8L which is a great copy itself.

When using focal I ran an aperture sharpness test. The first copies didn't perform as this third copy does. The first two copies would move up the chart to about f/3.2 or so then the IQ score would drop at f/2.8. This is very consistent of the other lenses I own, stop down just a bit and it gets sharper. Not the case with this copy of the 24-70 f/2.8L II. It spikes up at f/2.8 and gets its highest score at f/2.8. I think this is a good thing, the numbers that it is spiking at are higher than the previous two copies achieved.

Now for the AF, it checked out on the 5D II -3 @ 24mm, -2 @ 35mm, 0 @ 50mm and -3 @ 70mm. A bit erratic but I think I can live with that.

But it gets strange, this copy didn't play well with my 1D IV tonight. It was more than a bit erratic, +4 at 24mm, -2 at 35mm, +5 at 50mm and -1 at 70mm. I got irritated at the results, so put my gear up and will try again later in the week. Possibly it was my set up tonight. (hoping anyway) If not I may just pack this one up and send to Canon with my two camera bodies, this lens is so sharp I hate to send it back.