Canon ST-E2 Speedlite Transmitter

The speedlite transmitter is a wireless flash controller. It can fire up to three slave groups, with variable output ratio up to 8:1. It is fully E-TTL II compliant, and can control 580EX (II), 550EX, 430EX (II), 420EX, MR-14EX, and MR-24EX flashes.

It uses IR pulses to trigger slaves, so unlike radio controlled triggers, all flashes must have line-of-sight. Direct line-of-sight isn’t strictly necessary indoors— the pulses bounce around pretty well, around corners, even through light modifiers like softboxes— but it’s a really good idea outdoors. Range decreases with the level of ambient IR, so trying to trigger a flash that’s sitting in direct sunlight is tricky at best.

While it provides wireless E-TTL II functions, it can also be used to simply trigger slave flashes, with the flashes set to manual power.

The ST-E2 also emits an AF-assist beam. It’s significantly smaller and lighter than a flash, so if you just need a focus assist, it’s a good choice.

Our units ship with one fully charged Lithium Ion battery. If you are going to shoot more than several hundred shots, you will want a 2CR5 battery for backup.