Puppy Face , May 15, 2010; 12:09 p.m.
The 7D flash sync speed is selected to “Auto” in AV mode, and I am shooting in AV mode.
If you need to select faster shutter speeds, Tv or M mode is better for high speed sync than Av. In Av mode the shutter speed is set automatically by the camera and out of your control. I've used my ST-E2 with my 7D extensively and it works fine (greatly preferred over the popup). However, I avoid high speed sync since the range is so limited.