I've been seriously thinking about getting one, but I wanted to hear from some people who've used it and the 1.8 alternative. Will I notice a large difference in quality/sharpness/speed compared to the 1.8? With the $500+ difference between the two lenses, I would hope the 1.4 is significantly better. I have a 50 1.8, though I rarely use it. I use my 70-200 2.8 the most out of my lenses, and I usually sit between 70-135 on it. I'd like to do more portrait/low light work, so I was considering the 85 1.4... thoughts? By the way, I shoot a d200 and plan on stepping up to the d3 later on.