OK, first things first. I contacted KEH about the inventory error. I
was thanked for my honesty and told to enjoy the upgrade. (unless I
REALLY wanted to return it--yeah right).
Secondly, regarding the corner darkening, it appears to be related to
one of the lenses under a limited circumstance. More testing to
follow. But it did not appear with other combinations.
Thirdly, some of the lenses experience rather severe vignetting wide
open. It's partially the lens, and partially the sensor's microlenses.
I am finding that the falloff is smooth enough that the Lightroom
vignetting correction tool works really well.
Themed Olympus Photo Exhibition: http://www.tope.nl/