Many functions can be controlled effortlessly through the camera's menu system, such as the AF assist beam (used to ensure accurate AF in low light situations), Canon's amazing E-TTL II flash metering, FE lock and flash exposure compensation. Even color temperature information can be transmitted back to the camera.
A wireless master function (optical) is built-in that allows multiple flash units to be controlled for creative lighting effects. Through 4-channel optical light pulse transmission, the 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. Best of all, the 90EX has a standard Canon hot shoe mount that makes it compatible with all Canon EOS SLR cameras.
|Guide Number||30' (9.14 m) ISO100 at 50 mm position|
|Maximum Recycle Time||Approximately 0.1 seconds - 5.5 seconds|
|Zoom Range||Covers 24mm Wide-Angle Lens (35mm Terms)|
|Cordless Ttl Control||4 Channels, 3 Groups|
|Power Source||2x AAA Alkaline, Lithium, Rechargeable Ni-MH Batteries|
|Weight||1.8 oz / 51 g|