I just received my Canon EF 135mm f/2L back from Canon service and indeed Canon acknowledged and fixed an optical problem. Unbelievable really—an “L” lens ought to undergo the highest quality control (see Sept 15 entry). It’s not that the lens was way off, but it was showing astigmatism at the edges and corners, something the MTF curves suggest should not happen.
I’m also suspicious of my Canon EF 50mm f/1.2L, which is showing strong color fringing on one side. I just don’t understand why a $1000 or $1500 lens can’t work well out of the box.