Wireless master function (optical) allows multiple flash units to be controlled for creative lighting effects
For a number of advanced lighting setups, the Speedlite 90EX can be used as a master transmitter to control multiple flash units - wirelessly! Through 4 channel optical light pulse transmission, the Speedlite 90EX can control up to three groups of slave-enabled flashes, controlling power from 8:1 to 1:8 in 1/2 stop increments. It can transmit up to approximately 16.4 ft. indoors, up to 23 ft. outdoors. With the Speedlite 90EX controlling each light source according to the specific parameters of a shot, the creative possibilities are endless!
I ended up buying this flash after buying the EOS M. The "M" doesn't have a flash and there are many situations where you need one. The 90E was made for the "M" and really should have some with it. I bought it based on the size, but Canon sells other more powerful flashes for less money reducing the value of this flash. Functionally it does the job and plays nicely with other flashes.
January 21, 2013
Prices and specifications subject to change without notice. Actual prices are determined by individual dealers and may vary.