Pentax K-X Operating Manual page 61

Combining two or more external flashes (AF540FGZ, AF360FGZ or
AF200FG) or using an external flash in combination with the built-in flash
allows multiple flash photography (contrast-control-sync flash
photography). This is based on the difference between the amounts of
light discharged from multiple units.
' The AF200FG must be Combined With the AF540FGZ or AF360FGZ.
, Do not combine with accessories that have a different number of Contacts,
such as a Hot Shoe Gdp, as a malfunction may occur.
Combining with flashes from other manufacturers may cause equipment
breakdown. We recommend using PENTAX automatic flashes.
1
Connect the external flash to the camera indirectly.
Refer to p.169.
2 Set the sync mode for the external flash to contrast-
control-sync mode.
3 Set the mode dial to P, Tv, Av or M.
Confirm that both the external flash and built-in flash are
fully charged and then take a picture.
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: when using two or more external flashes and the contrast-control-syncm0de
is set on the external master flash unit, the flash output ratio is 2 (master
unit) :1 (slave units). When an external flash is used in combination with the
built-in flash, the flash output ratio is 2 (external flash) ; 1 (built-in flash).
When using multiple external flashes or using an external flash with the built-
in flash, P-TTL is used for flash control.