In all the HS and college games I've shot, I've never once seen a pro using a 100-400, FWIW. I once saw a pro using one at a HS soccer game, during mid-day, though. It's a perfectly decent lens, and not wanting to get into a battle over it, I think you'd be a lot happier with a 300 f2.8 and a 1.4TC. This way you'd be at 420mm f4.0, and would be a full stop faster than the 100-400 is at its max focal length, and as Billy said, you'll be a lot happier with the background blur, AKA bokeh.
Or, you could do what I do, go with a Sigma 120-300 f2.8
which gives you the flexibility of a zoom AND the speed of a constant f2.8 lens. FYI, I also tote a Canon 70-200 f2.8L on a second body for close-up action, though I don't use it nearly often enough 'cuz the Sigma is so flexible.
As for positioning, watch the other pros. You'll only be able to go on the sidelines from the goal line to the 25 (maybe the 30), then you'll hit the player's box. Shooting from the sidelines: use the following as a rough guide: 10 yards behind the line of scrimmage, shooting in the offensive backfield. Great for handoffs, QB shots (especially from the QB’s “open” side – the side showing his face) and QB sack shots. Also great for shooting backfield fumbles and defensinve tackles at or near the line of scrimmage. 10 yards beyond the line of scrimmage, shooting in the defensive backfield. Great way to catch big running plays just as they break past the line of scrimmage (like the shot below - a 50 yard TD run last Saturday, shot from about the 30 yard line - I was cheating a bit into the player's box on the visiting side of the field: you can't always get away with this, especially at NFL games), the QB preparing his throw downfield and catching the defense in their element.
The biggest challenges with shooting from the sidelines are:
a. Half of the plays will be on the other side of the field.
b. Many of the plays might be too close for you to catch, or too far away (depending on your lenses)
c. The action is “stacked up” and compressed, meaning that you are looking across 22 players, several officials, errant coaches, down boxes, ball boys, etc., all running right in front of you across maybe a 20 degree field of view. In other words, you’re shooting over, across, around, a lot of very big bodies, none of whom seem to want to cooperate with your desire to get “the shot”.
d. The backgrounds can be really, really messy, with all KINDS of stuff in the way (crowds, players, etc.), making the shots less appealing. Even with the background blur a good f2.8 lens gives you, the cluttered backgrounds can diminish the artistic merit of an otherwise great shot.
Once the play advances to the 35 yard line in the attacking zone (again, depending on your effective focal length - with a 400mm lens, you can do this from the 40 or longer, especially on a 1.6 crop body), head to the back of the end zone to get the running plays and the passes coming right at you.
You'll notice many pros hang out at the back of the end zone for most of the game, with their big (400, 500 and even 600) lenses 'cuz not only do you get great shots back there, but your background is usually a lot less cluttered when shooting from the back of the end zone. When you're shooting in the end zone and the action is coming right at you, literally, you have to stay alert, and be prepared to move out of the way! 500+ pounds of football players running at you under full heads of steam can do a lot of damage to you, not to mention your equipment (Which is worse? That’s your call).
Dennis
http://www.pbase.com/dmwierz45/sports_shots
HOSTED PHOTO
please log in to view hosted photos in full size.