Consensus on 24-70/2.8 II field curvature at infinity focus?

This one comes closer to proving your point, although I'd rather see test shots of something that was truly flat (in a plane) and farther off, if the complaint is about the curvature of the infinity focal plane (and not just the thinness of the DOF, or soft edges in general). Not saying the problem doesn't exist. Just it would be good to truly isolate field curvature from other effects.

What I'm thinking of is taking a picture of a row of objects off in the distance that are known to be in the same plane, and you are shooting perpendicular to that plane. Shoot one shot where the center is in optimum focus, and presumably the edges will be out of focus due to the curvature. Then manually adjust focus so that the edges are sharp and the center is out of focus. How much you can turn the focus ring to make that adjustment is a measure of how much the focal plane is curved.  If you can't make that adjustment, and the edges never get sharp, then you are seeing some other problem, like soft edges in general.

You also have to separate field curvature from the fact that the DOF is surprisingly thin with a full-frame camera if you are pixel-peeping, even at moderately long distances.  So if the objects you are taking a picture of are not in the same plane to begin with, you have to wonder if it is field curvature, or just the fact that they are nearer or farther than the focal plane.

You guys will have to carry on without me. I'll be in Yosemite this weekend. Maybe I can find something flat there to do some tests on.