20D and focus question
I am gonna be taking some pics of a group of runners as they run through out the day. It's a 52 mile course that benefits St Judes Childrens Hospital. I drive a RV for the runners to rest but want to take pics for them too. I did last year and most of the pics came out where just a few of the runners were in focus. Just wondering, there might be anywhere from from 5 to 45 runners at a time. How do I manage to get them all in focus? I will be using the Canon 20D and the 18-200 IS. Thanks.