Canon 580EX II Flash 2x with ST-E2 Transmitter Kit
Ooooooooo, nice combo. Pricey, but what isn't in the whole Canon line? The 580EX II is their ultimate flash, and the transmitter unit allows you to place the flash almost anywhere you like. Having the flash on top of the camera really limits creative lighting, this kit will allow you all sorts of flexibility.
The ST-E2 is small and light, much more so than any Speedlite. It weights 100 g (3.5 oz) and is 62H x 51H x 80D mm. The power source, a 2CR5 lithium battery, is extremely light, especially when compared to AA batteries. Thus, it balances well on the Elan 7 with a small lens and BP-300 grip. I really can't feel a difference in weight with the ST-E2 attached to my Rebel XTi. Although light, it appears well built, perhaps a little more beefy than the 420EX Speedlite. The oversized near infrared AF assist light is powerful and projects a pattern of horizontal lines about 34 feet in total darkness.