

A radio frequency flash trigger for professional photographers using external flash.
Trigger compatible Speedlites from up to 30m away. Radio frequency control allows for reliable operation even without direct line of sight.
Reliable external flash control
You can control compatible Speedlites from up to 30m away. 2.4GHz radio frequency triggering works reliably even outdoors and without direct line of sight.
Photography with multiple flashes
Create multi-flash lighting systems and trigger up to 15 Speedlites with a single on-camera Speedlite Transmitter ST-E3-RT. E-TTL II flash metering makes exposure control easy.
Remote camera control
You can trigger an EOS camera equipped with the Speedlite Transmitter ST-E3-RT with another unit or a compatible Speedlite flash such as the Speedlite 600EX-RT. You can also trigger up to 15 cameras simultaneously and shoot in sync.
Easy to use
Like EOS cameras and L-series lenses, the Speedlite Transmitter ST-E3-RT is dust and moisture resistant, has a clear backlit LCD display, and is powered by two AA/LR6 batteries.