I reported on the field curvature of the Oympus 60mm f/2.8 ED macro at 1:25 focusing range a few days ago.
Following up with field shots, I now confirm and document detailed examination of field curvature of the Olympus 60mm f/2.8 ED macro as a pronounced sharpness handicap on real images in the field, including additional supporting examples. Also added is a visualization of the affected zone at ƒ/4 and ƒ/5.6.
One can see a lot just by looking.
For more on field curvature, see Making Sharp Images.