I'm awaiting my eBay Canon 20D, and wondering if it's possible to save a lot of money by using older flash units with it - units from film cameras. There are plenty around! I'd want to use the flashes (at least two, which might be different), with some kind of cheap remote control kit, with the flashes off-camera on stands. Is this technically possible? Am I right in saying that a flash hotshoe, for basic connections, is universal? How far does the connection date back?