Originally Posted by devsalvi
If you don't use the ST-E2, you'll have to have one of the 580EX II's on the camera (or use an off-camera cord, but that's only about 3' long). One advantage of fixed off-camera strobes is that the light doesn't depend upon the camera position. You can move around for various angles and the lighting stays the same. With an on-camera flash, the light will change when you move. You're also limited in the direction of the light, unless you bounce the light indoors. If you're going to use on-camera flash, consider a flash bracket that will elevate the flash above the usual position. That will help reduce redeye and shadows.