Turns out that in most indoor 25 yard pools shooting from the bleachers, 300mm is a good length. The 200 f2.0 on a D300 with DX crop was exactly that. Then for light reasons and better high ISO, I upgraded to D700 and it became a 200 again. Drat. The 300 2.8 VR costs a bomb, so I added a cheap 1.4 tele, losing one stop, and made a 280 2.8 which does the job just nicely. Fall back to f2.0 if there just isn't light is a quick thing too.