Canon provides two different means to wirelessly control your remote Speedlites today. The first is to use a 580EX II Speedlite as a “master” and the second is to use Canon’s Speedlite Transmitter ST-E2.
There are some distinct advantages and disadvantages to using the Canon Speedlite Transmitter ST-E2. The biggest advantage is it’s size and weight. The ST-E2 weighs less than 6 oz with it’s 2CR5 6v battery installed. Its very small compared to the 580EX II and mounts on your DSLR’s hot shoe or on the Canon off-camera shoe cord OC-E3. The size and weight savings can be a real advantage when shooting on location.
Both the ST-E2 and the 580EX II master will allow flash output ratios to be adjusted between the channels they control with the ST-E2 allowing ratios from 8:1 to 1:1 to 1:8 to be selected in 1/2 stop increments. And while both the Canon Speedlite Transmitter ST-E2 and the 580EX II will support any number of remote flashes, the ST-E2 controls only 2 channels while the 580EX II will control all three. Another big advantage to using a 580EX II as a master is the effective range. The ST-E2’s effective range is only about 40 feet indoors and 30 feet when used outdoors. The range of the 580EX II master is more than twice that. However, the biggest disadvantage to using the Canon Speedlite Transmitter ST-E2 is that is does NOT support manual flash output and for many Strobists, this is a deal killer!
Although I may get flamed by other “strobists”, for me the ST-E2 is a great accessory. At only $220 (USD) it’s less expensive than using one of my 580EX II’s as a master and it’s way (WAY) less expensive than buying a set of PocketWizards. I’ve never found “line-of-sight” to be a problem when used indoors and I’m rarely placing my strobes more than 10 to 20 feet away from my camera.
I’m not really a flash “purest” and like the ease of use that Canon’s E-TTL II brings to flash. I’ve found that Canon’s thru-the-lens metering technology is damn smart when it comes to exposure and if I need to tweak it a little, the ST-E2 and my 50D provide all the extra control I need through FEC (flash exposure compensation) and flash ratios. Best of all, I can do this all from my camera’s LCD and the back of the ST-E2 transmitter.
Given how well Nikon’s i-TTL wireless CLS stuff works for Joe McNally, taking a look at Canon’s offering makes perfect sense to a frugal (cheap) Irishman like me.