What do you guys think about getting a UWA lens for a 6D? Rokinon 14mm F2.8 seems to get all the attention around here, but how does it feature besides landscape photography? Have anyone tried using it for a function or portrait purposes? How does the Tokina 16-28mm F2.8 hold up to it? Is it a versatile lens, or a very specific usage lens? How does the Tokina perform? Any other lens to recommend besides Canon 16-35mm F2.8, since as far as I've heard for that price it kinds of suck, compared to Nikkor 14-24mm F2.8? (It's simply too expensive anyway :-X).