550EX-dedicated, clip-on Speedlite transmitter with direct contacts
Type A EOS cameras (E- TTL, autoflash); Type B EOS cameras (Manual flash)
High-Speed Sync (FP flash): Enabled with high-speed sync mode
Flash Exposure Confirmation
1. Before flash fires during FE lock Adequate flash exposure indicated by the flash exposure level icon lit in the viewfinder. Insufficient flash exposure indicated by the flash exposure level icon blinking in the viewfinder. 2. After flash fires ST-E2's flash confirmation lamp lights in green for 3 sec.
AF Assist Beam
Compatible with EOS-3's 45-point Area AF and 28mm and longer lens focal lengths Effective Range: Approx. 0.6 to 10m/2.0 to 16.5 ft along the periphery (in total darkness).