I'm looking for some help regarding the best lens for landscape photography. I have a Canon 40D DSLR, and my walk around lens is a Canon 17-85 mm f/4.0-5.6 IS USM. It's a great lens for most purposes, but I've been a little dissapointed with some of my landscapes with some "soft" focus, and not great color saturation. I don't use the auto mode very often, and I usually shoot in daytime with the smallest apeture available. Not matter how much I experiment with ISO, aperture size, etc., many of my landscapes aren't as crisp as I'd like them to be. Any advice on a lens would be greatly appreciated.