Disc Brake -- Canon 20D & Carl Zeiss Vario-Sonnar 35-70mm f3.4
I bought this lens along with the Zeiss S-Planar 60mm f2.8 Makro. I have kept the S-Planar, but not the Vario-Sonnar 35-70mm. It's clear that was a mistake. It was one of the few zoom lenses that were very sharp, but I think it was just too difficult to focus on the 20D. I have learned my lesson and now take my time to use the lens before deciding to sell it or not, especially the better lenses.