> Set lower switch on 420 to Slave, and on 550 to Master. This automatically > sets the 550 to group A. Turn 550EX ON at main switch. > Press SEL/SET repeatedly until Ratio blinks. Press + or - until A:B appears > plus a ratio scale. Now press + or - until desired ratio is set. Probably > 1:2 or 1:4 will be OK for getting the 550EX to act as a fill-in. > Check that both guns are set to same channel; (set similarly to above) 1 is > probably best if the 420 doesn't have this as an option. > (Incidentally, if you want to adjust settings on the Slave mode gun, press > the MODE switch for > 2 seconds.)
It is very important that the 420EX be explicitly set to GROUP B. Otherwise it will fire (together with the 550EX as GROUP A), but you will get an underexposure warning (no light detected from GROUP B). Additionally, you will not get the expected flash ratio except if you accidentally have the flash-to-subject distance exactly correct. Note that the 420EX has pushbuttons for CHANNEL and GROUP. There is no MODE button, like on the 550EX. Even if using a remote 550EX Speedlite, pushing MODE for 2 seconds allows switching to MANUAL mode, where flash is unmetered, and the flash ratio setting will not be respected. This could defeat the whole purpose of setting a flash ratio. It is better to make adjustments on the MASTER unit. More details are at eosdoc. http://eosdoc.com/manuals.asp?q=ETTLRx Cheers Julian Loke * **** ******* *********************************************************** * For list instructions, including unsubscribe, see: * http://www.a1.nl/phomepag/markerink/eos_list.htm ***********************************************************
