This is the ugliest imaginable lens... Sorry, but had to say that and get it off my chest. It just looks ghastly on my Nikon F5 and on the F100 too. Oh, well, now that I said it, I should add that it's a very good, reliable tool. Where does one get a wide-angle this wide Nowhere!
Speed, size and relatively discreet look (if it wasn't for that front element that's downright bulbous); Nice range of focal lengths
Maybe it's ugliness, along with that the front element is so weird looking and doesn't allow for filters of any type; Other than that, it's not a lens to use with flash 'cuz it vignettes like mad, especially at 12mm (and what's the fun of using a flash at 24mm with this lens None.