5. Confirm wireless link. Confirm that the <LINK> lights on the 600 EX - RT’s are lit and green and that the AF- assist beam emitter on the receiver is blinking at 1-second intervals. Also confirm that the red flash ready light is lit on the sender unit.
Yet another Speedlite 600EX-RT and Speedlite Transmitter ST-E3- RT innovation is the ability to fire recent EOS cameras remotely, using either of these devices as a trigger. Remote control from your flash? Syl explains in this episode.
The EOS Speedlite Transmitter ST-E3- RT allows you to set up multiple Speedlite 600EX-RT flashes as “receivers”, which the ST-E3- RT will control and synchronize as the “sender” unit. The ST-E3-RT is exclusively designed for radio-based wireless flash control and cannot be used for traditional “optical” wireless flash control.
The Speedlite 220 EX AF- Assist beam is emitted automatically to enable precise autofocus under dim light and low contrast conditions. The AF-Assist beam is effective from 1 to 5 meters (3.3 to 16.4 feet)
If where you focus lack sufficient light or contrast, the Speedlite's AF- Assist beam is emitted automatically to help the camera autofocus. The AF-Assist beam is effective from 0.7 to 10 meters (2.3 to 33 feet) AF-Assist beam activation