Roger Cicala of LensRentals.com has posted an interesting article about lens copy variation and the effects of ever-increasing resolution of digital sensors used in today’s digital SLRs. The article links to some other good outside resources as well, such as Diglloyd.com, etc.
It’s an unfortunate element of assembling a good camera kit these days, but I think that in some cases users are too quick to blame image weakness on camera gear (see almost any photography forum). Sure the gear plays a huge role in image quality, but not more than user skills during capture, post-processing and printing. Of course we don’t want our gear to be the weak link. Roger’s article highlights some good points to consider when buying gear.