I currently have an extra $200 on my hands that I would like to spend on something photographic. I could either upgrade my D70s to a D200, upgrade my 50mm F1.8 for an F1.4, or put it towards a lens that I haven't thought of yet. I really like the look of the 50mm F1.4, and have seen some amazing pictures taken with it, portrait and other. But is it worth double the price of the F1.8? Besides aperture and price, what does the F1.4 give you that the F1.8 doesn't?