Nikon announced a new AF-S version of their 50mm f/1.4 lens at the back end of 2008, but when we went shopping we decided we preferred this Sigma. It's surprisingly chunky for a lens of this specification - check out that 77mm filter thread, compared to 49-58mm for all the other 50mm f/1.4 lenses on the market! - and it feels reassuringly well built. But the real reason we're offering it is performance. The test data we've seen suggest that the Nikon seems to be a tad sharper around f/8, but this one is clearly the better performer wide open. And let's face it, you don't hire an f/1.4 lens to use it at f/8, do you?