Canon POWERSHOT G9 User Manual page 246

2441 A ppendix
•
Speedlite 580EX II
• The maximum flash synchro shutter speed is 1/250 second.
• The flash will automatically adjust its output when [Flash
Mode] is set to [Auto].
• When [Flash Mode] is set to [Auto] the flash exposure
compensation can be adjusted. When [Flash Mode] is set to
[Manual], the flash output can be adjusted (pp. 149, 150).
• In M mode or when [Flash Mode] is set to [Manual], the
output of an externally mounted flash can be adjusted in the
flash output adjustment screen (p. 150). You can also adjust
the flash output from the flash. For the optimum aperture
values and tSO speeds for the distance to the subject, refer to
the guide number listed in the flash's user guide.
You can also adjust the flash output even when the camera is
set to the E-TTL automatic flash exposure compensation
mode by changing the flash exposure compensation setting.
• In M mode, you can set the flash output with the camera
even if the flash unit is set to E-TTL automatic flash exposure
compensation. [E-TTL] will display on the flash, but the flash
will fire manually.
• Other Canon Flashes
• Since other flashes fire at full strength, set the shutter speed
and aperture accordingly.
• The flash is charged when its pilot lamp lights up.