$849 for a new version of a pretty good existing lens? Sure this one should be a long way better than ver. 1. But what they can improve? In mine 1.4 CA is quite good (OK, not perfect, but eliminated with one click in PP), sharpness - too, USM is quite accurate and fast enough. Well, build quality is so-so, but for 500$ more? Thank you, but... thank you!