The Canon Speedlite 600EX-RT is a powerful (LZ 60) system flash for Canon cameras. It supports TTL and can be grouped with similar devices and triggered simultaneously. As transmitter, you need a Speedlite transmitter ST-E3-RT wireless trigger or a 600EX-RT mounted on the camera. Radio trigger with 30 m range Up to 15 flash units can be used together Integrated optical receiver Camera Remote Shutter Release Rotatable flash reflector with 20-200mm zoom function Guide number 60 (m, ISO 100, at 200 mm) White balance correction filter Quick and quiet charging E-TTL-II Flash metering Whether the Speedlite 600EX-RT is used on the camera or as an external flash unit, Canon's E-TTL II flash metering ensures precise exposure at all times. The Speedlite 600EX-RT can also be used to trigger an EOS camera from a distance of up to 30 metres. To do this, the camera only needs to be equipped with a Speedlite Transmitter ST-E3-RT wireless trigger or another 600EX-RT flash unit and the path to particularly interesting and unusual viewing angles is paved. Up to 15 cameras can be triggered together. Further technical data: Zoom reflector: yes focal length: 20 - 200 mm Wide angle cover: 14 mm Automatic zoom for sensor size: yes BLITZMODI Automatic exposure control: E-TTL II/E-TTL/TTL FP short time synchronization: a Manual/output settings: yes - 1/1-1/128 Manual steps: 1/3 steps Strobe/output settings: yes - 1/4-1/128 Frequency: 1-500 Hz (199 Hz when using the optical slave function)