wide angle lenses

I like my Sigma 8-16. There is nothing wider on a crop sensor. It's the equivalent of a 12-24 for full frame. I don't find the 4.5-5.6 aperture limiting at all. I tried shooting indoors in poor light and slow shutter/higher ISO fixes that problem. Even at 1/8 shutter speed handheld I couldn't tell any camera shake. Wide angle lenses can get away with slow shutter speed. You won't be shooting landscapes in shallow depth anyway.