[lputman]

You have to bump your ISO, the 50D can handle it. Additionally, most photogs run their night game images through a noise reduction program. Bumping up the exposure in post is going to exploit noise also. Granted, this is taken with a 5DII but it was also using a 70-300 f/4-5.6 lens. This is a cropped photo.

Camera: Canon EOS 5D Mark II
Exposure: 0.006 sec (1/160)
Aperture: f/5.6
Focal Length: 300 mm
ISO Speed: 6400

I've seen outstanding night shots with the combination that you have. Here's a quote from a photog on a different forum that uses your same combination...

Thanks. No, I didn't use a flash. This is a brand new high school (first year in the new building / on the new field). I was able to get 1/800 at f/2.8 and ISO 3200. The field I normally shoot on requires ISO 6400 for 1/800 @ f/2.8.

BTW, I use the 50D too.

Here's the website of the person I quoted, he does excellent work...http://www.midtnsportsphotos.com/