I shoot kids sports using my 2 D50s. 95% of the time, I use my 300f4 AF ED. It's very sharp, and does pretty good shooting baseball. however, I do miss a few running shots because it can't focus fast enough. not that big of a problem with baseball, but soccer is coming up. and of course, the kids are always running. does anyone have any experience with both versions of this lens? will the motorized lens focus that much faster on a D50? Thanks.