Im new to this wireless flash stuff. What is a slave, and what is a master?
A2: A wireless Master is any of the above mentioned Canon flash units. It is the device that the camera uses to transmit flash trigger information via pulses of light to the other flash heads, so that a group of Canon flash units will work as one. There is just ONE wireless master in any given flash setup, and it is the device attached to the camera hot shoe (or alternately, on a flash bracket, connected to the camera via a hot shoe extension cable). A wireless slave is a Canon flash that can read these pulses of light sent out by the master, and use them to fire the flash tube at just the right moment, with the correct level of light output, anywhere from 1:1 all the way down to 1:128. Currently there is just one Canon flash device that can be a Wireless Master, and a Wireless Slave, and this is the extremely versatile 550EX. While often overlooked, both of the new Canon Macro flash units can be used as wireless master devices. Some great, dramatic results can be obtained by adding on
