Canon PowerShot G9 - Manual (Page 250)

Appendix 248
z The following functions can be used with a Speedlite 220EX,
430EX or 580EX II*.
- Auto Exposure (Use the E-TTL mode with a 430EX or
580EX II)
- FE Lock (Not available in mode or when [Flash Mode] is
[Manual])
- Shutter Sync. (1st-curtain/2nd-curtain) (2nd-curtain priority
with Speedlite 430EX)
- Slow Synchro
- Flash Exp. Comp
- Auto Zoom (Not available with the 220EX)
- Manual flash
- High-speed sync
* You can also use 380EX, 420EX, 550EX and 580EX.