Streetcar -- NEX-5N & Tokina RMC 17mm f3.5.
I heard/read that Tokina was founded by ex-Nikon employees. Not sure if this was true. The early Tokina lenses were pretty good. I have had the 17mm f3.5 for some time, but haven't really used it much. It's got a Canon FD mount, hence I can only use it on my NEX-5N or the Panasonic G1. Naturally, I use it on the NEX-5N. It's a wide angle lens after all, because the focal length would be equivalent to 34mm on the G1, but on the NEX-5N, the focal length is 25.5mm; still pretty wide.
Table for two -- NEX-5N & Tokina RMC 17mm f3.5.
Ultra wide angles and very long telephoto lenses have same problem: they are very hard to focus. The Peaking Level feature on the NEX-5N helps tremendously in both cases, making it much easier to focus. I used this feature extensively today and it was great. When properly focused, the 17mm lens is actually VERY sharp when stopped down a couple of clicks. The edge is very good, though I am sure on full frame it's still a bit soft, but on the NEX-5N, it much better than the kit lens. I have grown to like it, although I am not really a very wide angle guy.
Found a Vivitar wide angle hood for it (come to think of it, I believe Vivitar has its own version of this lens, made by Tokina, essentially the same lens). The metal hood fits perfectly; makes the lens look very nice and more "professional".
In all, I think it's a very decent lens. Well built, focus very smoothly, and reasonably sharp for an ultra wide angle lens.
John and King Sts -- NEX-5N & Tokina RMC 17mm f3.5