Canon Speedlite 420EX TTL-Shoe Mount Flash Features

• Maximum Guide Number 138 (ISO 100, feet) at 105mm setting; G.N. 101 at 35mm setting
• Approximately 1 / 2-stop less powerful than 550EX
• Full E-TTL flash operation with "Type-A" bodies (EOS-1v, EOS-3, Elan 7 / 7E, Rebel 2000, Elan II/IIE, and Rebel G; EOS IX and IX Lite; and digital EOS D2000 and D30 bodies.)
• E-TTL features include high-speed FP sync mode, and FE Lock (spot / partial flash metering)
• Fully compatible as an affordable Wireless "slave" flash, with EOS-1v, EOS-3, Elan 7 / 7E, & D30
• Taller than previous 380EX flash, but head is 30% smaller, and both width & depth are smaller
• Powered by four AA-size batteries (alkaline, lithium, Ni-Cd, or Ni-MH)
• Totally TTL-compatible with all "Type B" EOS cameras, and the manual-focus T90 SLR body.