Product Description

Developed in conjunction with the Speedlite 550EX and the EOS-3 camera, this master control device for a wireless Speedlite flash system meets and exceeds professional and advanced amateur standards. Its dedicated transmitter controls an unlimited number of 420EX or 550EX Speedlites as slave units up to 33 feet away outdoors and 49.5 feet away indoors. It is mounted as a clip-on with shoe lock lever and locking pin. Compatible Cameras - Type A EOS cameras (E- TTL, autoflash); Type B EOS cameras (Manual flash) Type - 550EX-dedicated, clip-on Speedlite transmitter with direct contacts

Product Details

• Brand: Canon
• Model: ST-E2
• Dimensions: 2.60" h x 3.40" w x 5.00" l, .55 pounds

Features

• Wireless flash controller for the Canon EX420 and EX550
• Indoor transmission range of approximately 40 to 50 feet
• Outdoor transmission range of approximately 26 to 33 feet
• 1,500-transmission battery life
• Turns off after 90-second idle

Amazon.com Product Description
The Canon Speedlite Transmitter ST-E2 is compatible with Type A EOS cameras (E-TTL, auto flash) and Type B EOS cameras (manual flash). The ST-E2 is designed to control slaved Canon 550 EX flashes, enabling simultaneous flash use in professional settings. The wireless controller has a flash ratio control, allowing for several different A:B ratios, 1:8 to 8:1 in half-step increments, as well as slave confirmation via a test transmission button, which sets off slave A, followed by slave B, at 1/64 output.

Customer Reviews

works, but has its pros and cons
Does not work well in bright sun, but indoors, and when dark, the IR does well. I shoot weddings and local shows, and lighting is always changing, the Ettl is a must, and is also great as a auto-focus assist (really great in low light).

Very handy tool
I purchased this little item to aid in taking pictures at my first wedding. It worked nicely in a large worship center using both the 550ex and 430ex Speedlites and a 30D. I still haven't used it to its fullest but continue to learn. I'll add more to this in the future but just wanted to comment on this handy tool. A little pricy I guess but what in photography isn't?

Battery-less in ATL
this is probably a great item and there are plenty of reviews to provide that info. I just wanted to make it clear for others that the battery is NOT included. I have had a 380EX and now I have a 580EX. They did not come with batteries, but they take AA. All my cameras and other gear with oddball batteries come with one. Nowhere on the front page of Amazon does it say the battery is not included. You have to click for additional technical details. While running errands today, I went to two stores and each had some camera batteries, but not this one. I guess I need to go to a camera store (not too convenient) and pay their full retail ++ price because of this.
Just hoping to save someone else from that -
Not to mention the letdown from my pent-up excitement to try this out. With 3 kids aged 5 and under, I can't just go gallivanting all around town for a stupid battery. So here it sits next to my 5D and other gear... UGH!