I shoot huge amount of pictures with 17-40L on 30D, and it is basicaly my walkaround lens in general. It is f/4, but it's WA, therefore intended for shooting at smaller apertures, so no problem here, plus it's superior in build and picture quality, also can be used not only on crop sensor cameras...

Rick Hunter: I'm one of those neophytes that need help from you pros. I have a Canon digital Rebel that is several years old and 3 Tokina "Pro"f 2.8 lenses---16-35mm, 28-70mm, 70-200mm. I'm looking to upgrade to the Canon L lenses and would like to know what would be recommended for...