http://www.usa.canon.com/cusa/professional/products/professional_cameras/speedlite_flash_lineup/speedlite_transmitter_st_e3_rt?pageKeyCode=writeReviewPage
Speedlite Transmitter ST-E3-RT
24463

Overview
For sophisticated wireless flash setups, there's nothing like the new Speedlite Transmitter ST-E3-RT*. Facilitating radio controlled, two-way wireless transmission up to 98.4 feet, among up to five groups or fifteen individual Speedlites, the ST-E3-RT represents the next generation in wireless flash systems. With operational controls similar to the new Speedlite 600EX-RT, including diverse flash metering options, and a number of flash modes, the Speedlite Transmitter ST-E3-RT makes complex lighting setups simple. With a compact design and highly reliable construction, combined with a clearly laid-out information panel and buttons with back lighting and more, the Speedlite Transmitter ST-E3-RT is an indispensible tool for advanced, professional flash photography.
*Because it does not have an optical transmission function, the Speedlite Transmitter ST-E3-RT is not compatible with earlier Speedlite models such as 580EX II.
Speedlite Transmitter ST-E3-RT
4.3
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3
Great addition
Also have a single 600 flash. Wish they had an adaptor for my 580 flash. But great for getting rid of the cord for macro, hand pointing the flash, remote location of flash. I will be adding at least 1 more 600 flash to the arsenal.
October 11, 2012
So close
Canon had a winner with the older ST-E2 but is a bit short with the new radio transmitter ST-E2-RT. The omission of the focus assist light is major. My Canon 5D Mark II and Mark III cameras can focus well in daylight, but a dark room it is a challenge. The cameras just miss too much without a focus assist light. Canon omitted this feature and any other maker of radio transmitters also has no assist. So Canon has a great radio tool that may not deliver focus. As well it would have been better if we could integrate the ST-E3-RT with existing radio products. We have owned other radios for over 15 years. Some older receivers are built in our studio strobes. But the Canon will not talk to the current studio equipment.
It is unfortunate that the Canon product has been priced at level higher than we've paid for radios with no cross communication. And no focus assist at this escalated price. Canon acts like they invented radio transmitting, but really we've been fighting line of site for a decade. We bought the new 600 flash system, but it really talks about Canon not understanding the studio photographer's big picture.
May 21, 2012
State of the art finally arrived!!
Right out of the box, it performed exceptionally well. This is a long over due product that filled a gap that was provided by third party manufacturers, that tried to please everyone. This transmitter excels in the following points:
1-Controls the speedlites in both ETTL and M modes.
2-Controlls multiple flash groups, which opens the possibilities to infinite amount of combinations.
3-Eliminates the need to touch the remote flashes.
4-The most amazing mode of all is the stroboscopic, with multiple flashes on different group ratios.
5-Easy menu, with beautifully back-lit multi-function LCD, is located right on the top.
The Only Drawback is: It doesn't have built-in HOTSHOE!
that was a mini blunder! but i could live with that.
Enjoy shooting, and shoot hard!
April 13, 2012
