Roger Cicala of LensRentals has written an article about lens and camera sample variation. The latest article builds on the several excellent pieces he's already written by subjecting a series of lenses to studio testing. As one of the few independent people in a position to test and assess sample variation with a reasonable sample size, it's well worth a read. As with all his posts, it does a good job of explaining and demonstrating the inherent variability and inconsistencies in lens behavior. It also addresses the reasonable desire (and sometimes unreasonable behavior) of photographers to get a 'good copy' of a lens.

Click here to read Roger Cicala's 'Notes on lens and camera variation'

And, for a little more background, we'd also recommend the articles that led up to this latest one:

'"This lens is soft" and other myths' - which looks at reasons why users may conclude their lens is faulty, even though it isn't.

'"This lens is soft" and other facts' - which looks at some of the reasons behind poor lens/camera results.