yesterday I was playing around with my old 550 EX flash and my new Canon 7D and realized that if I place the flash on the shoe of the camera and set it to High Speed Sync, that I can get shutterspeeds higher than 1/250 - which is very cool.
However, if I remove the Flash Unit off the shoe and change it to a slave (using on board 7D flash as master), I immediately loose the ability to set it to High Speed (it goes into ETTL mode) and hence I can now no longer go above 1/250.
Is there any way of getting around this. I want to be able to position the 550EX on a stand and do not necessarily need it to be a slave of the 7D flash, but I would like to trigger it above 1/250. How would this be done? By using a sync cable? Wireless trigger?