Designed For Automatic Operation Only, The 220ex Flash Unit Excels At Providing Natural-looking Balanced Flash Exposures. When Attached To The Eos Ix, Eos Elan II/elan IIe/IIe, Or Eos Rebel G, The 220ex Incorporates The Superior Technology Of Canons Unique E-ttl Evaluative Pre-stored Flash Exposure Control System, Fe Lock For A New Dimension Of Creative Control And Fp Flash(high Speed Sync) For Flash Photography Up To Maximum Shutter Speed. When Used With Other Eos Cameras, Or The T90, It Operates As A Ttl Autoflash (off-the-film Flash Metering).