The Canon Speedlite Transmitter ST-E2 is an infrared flash controller that allows for simple control of wireless flash set-ups for up to 15 metres (indoors) and 10 metres (outdoors).

Who is it for?

If you’ve got one or more Speedlites that can be used as wireless slave units, the ST-E2 is for you. It provides a lightweight unit that controls the remote units by acting as a master flash unit.

Key features

• E-TTL II flash control
• Ratio control over two groups of flashguns
• High Speed Sync control
• Up to 10m range outside

When you don’t want to carry a dedicated master flash but you need wireless control of your flashguns, the ST-E2 is the answer. It attaches to the hotshoe of the camera and emits a controlling infrared signal to control remote flashguns.

It is not just for use in controlling flashguns though. In some locations flash is not allowed, but if the light levels are low, it can be hard to focus. If you can’t use a flashgun, then the ST-E2 provides the focusing beam grid to make autofocus faster and more accurate.

• Ratio control between flash heads

The ST-E2 can be used to control the ratio between two flash groups – group A and B. The unit provides from 1:8 to 8:1 control in half stop increments.

• High-speed sync

The ST-E2 allows for remote high-speed sync so flashguns can be synced at speeds higher than the maximum sync speed of the camera – up to 1/8000sec This can be used to obtain a faster shutter speed and therefore darken the ambient light captured in the image.