I'm interested in mainly getting the 50mm f1.4 ZF for a 5D, when I eventually replace my backup camera. I'll have to get a Nikon to Eos adapter, but I'm wondering if it'll really be that much better for portraits and some street photography than a Canon 50mm f1.4. I'm mainly interested in the ZF lens b/c of the price and the ability to get them as new vs. used.