Just a few questions on field curvature.
1) My take is that if it makes for unsharp corners or even edges in landscape shooting (where we often shoot at infinity) it is a bad thing. Correct?
2) If we stop down sufficiently, depth of focus will cover up field curvature, so we can live with it?
3) If we need to stop down to much we loose central sharpness due to diffraction, but that can be compensated to some degree with sharpening.
I'm very much interested to hear your take on the issue.
The C/N/AF version has pronounced field curvature. Many people notice this in part of their images and say "I got a bad sample". But if they conduct a careful test and the effect is radially symmetric, then it's just the design, not a particular bad copy. BTW stopping down reduces the impact of field curvature.