Yeah, like I said, I was looking at a few lenses that get ultra-wide at 17mm, but could handle f/2.8. I've heard less than stellar remarks about the sigma. I've since been thinking about the Tamron 28-75/2.8. While it isn't near as wide as I'd like to go, it's still nearly double what I'm currently getting with my Canon 50/1.8, which of course is more like 80mm. Like I said, I'm doing concert stuff (you can see my photos
here), and I'm almost always in the front row, but I'd love to open up & get more than just the artist's face & guitar, you know?