Camera: Canon 1D Mark II, Flashes: 2x 580 EX II + 1x 550 EX. As expected - 550 EX can only be fired in Manual mode, not ETTL, and adjustment of power is on the flash. Essentially - the Yongnuo gizmos work as wireless trigger. Both 580EX II work fine in Manual mode, adjustments of power in groups A and B works fine. However - ETTL mode seems to be completely out...huge overexposure, by more than 3 stops. Looks like the flashes are firing at full power. Question: would that be the fault of the camera - which seems to be unable to communicate ETTL settings to the transmitter ? Does anyone have experience with the above Youngnuo devices on 1D Mk II ? The transmitter has the latest firmware upgrade, BTW.