My worst lens from the film time was the Pentax 28-70f4. It was unusable at apertures larger than f8. This lens was recommended by a couple of lens testers, so I learned to be sceptical to lens tests. Maybe the lens was decentered, but I had never heard about that.
The worst lens from the last years is the Panaleica 15/f1.7. I tried two samples and both had severe decentering.
The worst lens from the last years is the Panaleica 15/f1.7. I tried two samples and both had severe decentering.