I was wondering what people's thoughts on the Tokina 11-16 are... I'm possibly selling my Tamron 70-200mm f/2.8 (Don't need a zoom that is that wide open) for $600 to a friend, and I was gonna buy a wide angle lens for my camera. I've heard a lot of good about the 11-16, and I'd prefer to have the 2.8 aperture for star stuff. My price limit will be $500 for the lens, as I can get an 11016 for less than that on Amazon. Any thoughts? Other recommendations?