>The idea of a 70-200 f/2 is intriguing, but just take a look >at the existing 200 f/2 to start imagining what a beast (and >how expensive) that lens would be.
I bet if it were a pound heavier and $1000 more, if it was just as sharp, I bet Nikon would hardly ever sell a prime 200. Of course chances of it being as sharp are pretty slim.
I'd really love to get a general 0.7x focal reducer for both the 70-200 and 200-400, to get F2 and F2.8 respectively out of them, even sacrificing some length. Too bad no one seems to build them (well, except for telescopes).