This has been an interesting read. I got my 24-70 II a few weeks back and the results it has given me has been outstanding. I did not buy the version I, because I thought it was too big and heavy, so my basis for comparison has primarily been the 24-105mm f4.0L. But I also upgraded to the 1DX at the same time, so in all fairness, I have not done a very thorough quality control on the lens.

Having read your experience H, I became a bit worried and decided to give it a more dedicated check. I have verified it against the 24 mm f2.4L II, 50mm f1.2L, 24-105mm f4.0L IS and the 70-200mm f2.8L IS II. I do not have the expensive charts either, so I had to create scenarios I believed would show any weaknesses. I checked focusing with a LensAlign MkII and concluded on an even -1 throughout the zoom range. I shot enough images with it to conclude that AF is both very fast, stable and accurate from very low to very high temperatures.

Color is a bit more difficult to be totally objective about, but it looks good to me on my iMac 27". CA is also very well controlled. The main problem in my view is vignetting. It falls off a bit more than I like, but when required, I fix it in Lightroom or Photoshop.

Sharpness and resolution is then left, and what I have seen from my copy of the lens is very good. Center is as good or better than any of the lenses I compared to, throughout the zoom range. corners are slightly behind the 24mm, but not much. It competes very well with the others. The 70-200 is sharper, but then that lens is just incredible. Compared to the 50mm, IŽd have to conclude that the 24-70 is better.

I hope Canon is reading your posts here. When charging USD2300 for this lens, you should certainly expect and get both first class and consistent quality.

Good luck with No.3!