Lens tests, how to spot a dud?

Hi,

With a lot of us buying a whole set of new lenses for their BMCC, how does one test that lenses received are within manufacturers specifications/tolerances?

I've been reading stories about how the same lens model can come off the production line with quite different qualities; softer than expected or other problems. What tests to perform that can help distinguish whether you have a good lens or a dud? Obviously if tests fail then we'd want to seek a replacement/refund giving the reasons.


Thanks for any advice,
Jules