So my brother's marching band championship event is this weekend, and i want to take some pictures. I don't have the money right now to buy a lense, as i just bought my xsi and my tattoo is sunday, so i am renting from canonlenserentals.com now the thing is, i'm thinking i will need the larger aperatures since its at night in a stadium and the fast shutter speeds will even it out. so i am considering the 70-200 2.8 is. however i am worried that the zoom won't be enough as i will be in the middle of the seats, maybe i can get down to the fence, not sure though. so basically i am debating between the 70-200 2.8 with the 2x converter or the 100-400 but its only 4-5.6. i am almost set on the 2.8 but anyone have any imput?