What’s Changed? There’s not much of a between this V3 and the previous V2 ST-E3-RT speedlite transmitters, however, this update is slightly lighter (0.14-ounces, to be exact). It maintains movement-focused Wireless Rear Curtain Synchronization, a 1/8192 minimum power range for low-light support, and FE memory to lock in exposure levels.

Flexibility. The ST-E3-RT V3 gives users the flexibility of line-of-sight-free shooting when coupled with the Canon Speedlite EL-1, 600EX II-RT, 600EX-RT, or 430EX III-RT. One V3 transmitter can control up to five groups or fifteen individual flashes, and with a range of 98.4 feet and the ability to adjust ratios and actual power settings from the transmitter itself, it greatly simplifies elaborate lighting setups.

Intuitive Controls. This transmitter features a detailed LCD with clearly laid out, backlit buttons for full control of settings. Since the transmitter uses a radio signal, it’s only compatible with the radio-signal based EL-1, 600EX II-RT, 600EX-RT, and 430EX III-RT. Despite this, the ST-E3-RT V3 transmitter still offers more control of its compatible Speedlite than any other trigger system out there.

Power. The V3, like its predecessor, is powered by two AA batteries (not included).

Adaptability. The Canon AD-E1 Multi-Function Shoe Adapter lets you use this transmitter on Canon cameras that feature the Canon Multi-Function Shoe, such as the Canon EOS R3.