Originally Posted by HiFiGuy1
I have a 40D and a 300 f/2.8 and have shot some high school football. A 1.4x is really not needed, in fact I find the 300 to be a bit too much sometimes and switch over to a 70-200 trying to follow the action. I do seem to spend quite a bit of time moving around to get a shot (fast paced games) and wind up in the end zone to get a clear view of the action with the 300. In less than perfect field lighting conditions (like at many high school football venues) The 300 f/2.8 is almost too slow, the 1.4x would make it even worse.