Hey, all. Here's my setup: Canon 30D 70-200 f/2.8L IS 550 EX (as master) 2x 430EX (as slaves). I have the master directly on the camera; I have the slaves on stands. I am using flash umbrellas. In my home environment, I had no problem configuring the flashes to do what I wanted - using the master for metering only, using a ratio on the slaves, etc. ... all seemed well. I got to my 'real' shoot yesterday, and had no end of problems getting the flashes to communicate. I just stuck in fresh batteries, and was about 15 feet away from each slave. It seemed as though the angle that the slave was oriented was a real picky point. I haven't confirmed this, but I gather that ETTL is not RF, and so orientation of the slaves is critical. But half the time, the slave would not fire. I'd move the master by half a foot in one direction, and the left-hand slave would fire, but the right-hand one would not. Eventually, I had to give up, as I was not getting reliable results in this room. I pulled the flash off, opened up my lens all the way (f/ 2.8 - yay), set my ISO to 1000, and got reasonably decent hand-held results with no flash. Question - what the heck is going on here? It's almost as if when you use umbrellas on these slaves, you have a teeny angle of useable orientation where the slave sensor is visible to the master, but is not blocked by the umbrella! And then, I flipped the camera to portrait orientation - the lens was completely blocking the signal between the master and the right-hand slave. It was ludicrous. I see two possible options here: 1: put my master on a stand (having found it's 'sweet spot', and connect the body to it with a off-shoe cord; and 2: buy one of those dedicated flash triggers. Maybe that has more power to the signal or something. Can anyone offer any suggestions here? Am I completely out to lunch with respect to what I was seeing with the flashes' behavior? Thanks for all wisdom!! BD
