Canon 550EX Speedlite

• The 550EX is capable of covering the area of an 17mm lens by the use of its built-in diffuser panel.
• The flash head can tilt down -7 degrees for better coverage of close-up subjects.
• AF assist when used with the EOS 3 is multi-point.
• AF assist range is 0.6 - 15 meters center point, 0.6 - 5 meters outer points (EOS 3).
• Rapid fire capability is available with external HV power.
• Wireless control capable (IR) with the ST-E2.
• Multi-flash E-TTL capable with other 550ex units and ST-E2.
• Has "modeling flash" function (199Hz) in DOF preview mode (EOS 3).
• Flash exposure bracketing (FEB) capability with the EOS 3.
• 6 custom functions:
1. FEB cancellation after completion (enabled or disabled)
2. FEB sequence (0-+ or -0+)
3. Flash metering system (E-TTL or TTL)
4. Slave unit SE mode activation (after 60 minutes non-operation or 10 minutes)
5. Slave unit SE mode cancellation (by master unit for 1 hour or 8 hours)
6. Modeling flash (enabled or disabled)
• The power switch has 3 positions:
1. Off
2. SE (On with save energy function)
3. On (On without save energy function)

Official Canon USA page:
http://consumer.usa.canon.com/ir/controller?act=SupportDetailAct&fcategoryid=217&modelid=7270