I tried to shoot my son's speedskating tonight with my newly acquired E-M1. I'm blown away by the ISO performance (I shot some shots at 6400! with my E-3 I would just have put the camera away. I couldn't shoot past 800). However I had problems trying to get AF to lock (lighting wasn't great but at times I was around f3.5, 1/350s, ISO 2000). I'm wondering what the optimal settings are to get the best from the camera's AF system. Any tips and tricks would be greatly appreciated.