Photoguydon, I think what your saying is essentially correct: especially with zoom lenses it has been explained to me by technicians concerned that the problem is more an assembly issue than a glass issue, and there are limits to what one should expect with wide angle lenses at wide apertures. Also, it may true that roughly comparable Canon lenses are somewhat less costly than their Leica counterparts - if such comparisons can be made legitimately (I'm not sure - it's seldom an apples to apples comparison). But there is performance variation within the same model of an *L* lens, and it is noticeable, even within a range that Canon QA considers *acceptable*. They ARE doing the quality control - the issue is the range considered acceptable. Unless the lens falls outside that range, based on my experience dealing with them, Canon WILL NOT re-assemble your lens to get it to match the best of the range for that particular spec. Their philosophy is that once it's acceptable by their standards, its acceptable and if it's acceptable they don't tinker with it. What the customer thinks or wants is irrelevant.