I'll be going to the World Cup of Snowmobile Grass Drags once again this summer. It's usually in August and very bright. What I'm wondering, is there a formula for calculating shutter speeds to freeze objects travelling at certain speeds. I fully understand how it affects exposure, but wondering if there is a guideline to follow. Last year I shot @ 1/500th and they were blurred. These sleds reach speeds of 110+mph in 500'. Any help is appreciated.