I know there are hundreds of threads about lenses, and I just did some quick searches, and I could read forever and still not really know what I'm looking for. I'm wondering if there are any good books on the basics of lenses. I'm starting to research my next lens purchase and want to make sure I get something I'm happy with. I was looking on Canon's website and the different variety of lenses can be confusing...for example, what's the difference between an ultra-wide zoom and standard zoom? I didn't know a wide-angle lens could also be a zoom lens! So I want a good book on just lenses. Are there any?