Pentax *ist Operating Manual page 124

122
USING EXTERNAL FLASH
Wireless flash control (P-TTL flash mode)
When the AF360FGZ is used for wireless flash, the following
process is executed between the built-in flash and AF360FGZ
before the flash is fired.
1. Press the shutter release button completely.
2. The built-in flash discharges a pre-flash (the camera's flash
mode is transmitted).
3. The external flash unit discharges a pre-flash (the subject's
lighting condition is checked).
4. The external flash unit discharges a pre-flash (the required
flash output is transmitted to the external flash).
If HS (high-speed sync) has also been set, the built-in flash will
discharge another pre-flash to transmit the flash duration time.
5. The AF360FGZ flash unit discharges the flash.
✍
MEMO
• You can select how the built-in flash is to be used: either as an
information controller for the external flash, or as a flash to affect the
exposure using the custom function number [CF8]. See pages 134 and
139.
Channel control
• For wireless control, channel (e.g. CH1) for the AF360FGZ
must be set on the camera. Attach the AF360FGZ to the
camera, turning on the camera and pressing the shutter
release button halfway down to set channel.
• The present channel is displayed for about 10 seconds when
flash mode or is set.