Welcome to the forum, Ed!
If you're using a 300mm lens or greater, try the "Better Beamer". It's inexpensive, breaks down to a small package and does a nice job.
Here's a link to one at Adorama: http://www.adorama.com/FAFX4.html?searc ... ter+beamer
This shot was taken with a Canon 30D, a Canon 100-400 at 400, a 1.4x teleconverter and a Canon 580EX flash with a Better Beamer.
1/250s f/8.0 at 560.0mm iso400