Playing with the ISO 12233 charts and the 24-70 f/4 IS has made me appreciate primes that much more....

Here it is compared to the 24 mm f/2.8 IS, 35 mm f/2 IS, 50 mm f/1.4, and 85 mm f/1.8. Not even getting into the L glass, but at f/4, the non-L is awfully close.

Granted, different camera bodies, but also against my EFS 15-85 at 24 mm, 35 mm, 50 mm, and 70 mm. It may be odd to compare these two, but optically I'd call the 24-70 f/4 IS on a 1DsIII just a little better than an EFS 15-85 on a 50D, mostly at 24 mm and 70 mm. Of course, I really like the EFS 15-85 on my 7D and thus I think the 24-70 f/4 IS will be a great walk around lens on FF. But it seems that the 24-70 f/4 IS doesn't take full advantage of the bump up to FF that I typically expect.

Rick and Eldar. Great to hear such positive reports on the 24-70 f/2.8 II.