Yongnuo speedlite transmitter ST-E2

Description

Yongnuo speedlite transmitter ST-Yongnuo ST-E2 is a speedlite transmitter very similar to the original Canon ST-E2. Yongnuo improved features of the Canon’s model and added some new functions.
The Canon ST-E2 is an infrared-based flash controller mounted on the camera’s hot-shoe that allows the user to control multiple off-camera slave flashes sorted in channels and groups. The ST-E2 allows you to retain E-TTL flash metering as well as high-speed sync and ratio-based output even when flashes are placed away from the camera wirelessly.
The Yongnuo ST-E2 also sports a high-output auto-focus assist beam to use in low-light, particularly for cameras without a built-in flash/AF assist beam.
The Yongnuo ST-E2, as mentioned, uses IR beams for communication. Unlike radio triggers, the ST-E2 requires line-of-sight for the flashes to receive the signal of the controller. However, line-of-sight is less critical when in an indoor environment as nearby walls and ceilings aid the IR beam patterns even without line-of-sight.
Yongnuo’s model has some advantages over Canon‘s:
AA-powered (no more 2xCR5 batteries)
Greater range – very important
Swivels 135 degrees
Thus it can control flashes behind the camera