I like my 18-55mm kit lens that came with my D40 but I'm looking to upgrade a bit. I've heard the Nikon 50mm f/1.8D is a great lens and very affordable too. But the only problem with it is it won't autofocus on my D40. I've never tried working with manual focus. Is it difficult to learn? Will there be a lens like the 50mm f1.8D WITH autofocus built-in coming out anytime soon? If not, what is the best, sharpest, and highest quality prime lense I can get for an affordable price? How about one from Sigma or Tamron? Do they have any great prime lenses?