Allen Walker , Dec 29, 2006; 01:18 a.m.
Traditionally, product photography is done using a view camera, as the controls give one command of perspective and the location of the plane of best focus.
If you want to use the 5D, you could consider the three tilt-shift lenses that Canon offers. They have a small subset of the controls of a view camera. Which focal length you choose for a shot will be determined by the kind of perspective you want -- or what the agency's art director wants.