Pentax K-5 Operating Manual page 12

Using an optional external flash AF540FGZ, AF360FGZ, AF200FG or
AF160FC enables a variety of flash modes, such as P-TTL auto flash
mode, depending on the external flash being used. See the chart below for
details.
(_/ Available #: Restricted x: Not available)
Red-eye reduction flash _/ _/ _/
Auto flash discharge _/ _/ _/
After the flash is charged, the camera
automatically switches to the flash sync _/ _/ _/
speed.
Aperture value is automatically set in P
mode and Tv mode. *_/ *_/ *_/
P-TTL auto flash (appropriate sensitivity: _/'1 ,_/'1 ,_/'1
ISO 100 to 3200)
Slow-speed Sync _/ _/ _/
Flash exposure compensation _/ _/ _/
AF assist light of external flash x _/ x
Trailing Curtain Sync *2 _/ _/ x
Contrast-control-sync flash mode #*3 _/ #*4
Slave flash x ,_/ x
High-speed flash sync x ,_/ x
Wireless flash #*4 ,_/'5 x
"1 Available only when using a DA, DA L, D FA, FA J, FA, F or A lens.
*2 Shutter speed of 1/90 sec. or slower.
*3 When combined with the AF540FGZ or AF360FGZ, 1/3 of the flash discharge can be
output by the built-in flash and 2/3 can be output by the external flash.
*4 Available only when combined with the AF540FGZ or AF360FGZ.
*5 Multiple AF540FGZ or AF360FGZ units, or a combination of an AF540FGZ or AF360FGZ
unit and the built-in flash is required.
Flashes with reversed polarity (the center contact on the hot shoe is minus)
cannot be used due tothe risk of damaging the camera and flash: