So this is your specialist lens for fluffy things.

I've just been going through a lot of photos I took with my last-but-one DSLR, which had a ridiculously sharp lens; it's amazing what difference going from a decent to a superb lens has for fur.

Presumably at f/2 the autofocus is very fast and precise. I have committed the cardinal sin of reading lots of reviews of new not-quite-unaffordable cameras and now I find the autofocus on my D100 slow and error-prone.