Ricoh GF-1 - Manual (Page 13)

EN -
Type R cameras
Set the shooting mode to Manual exposure or Aperture priority
mode. The correct exposure cannot be achieved in 5 mode,
Program shift mode or Shutter priority mode.
Also, when the ISO setting is set to AUTO, the flash unit will be
automatically adjusted to match the selected setting. If the ISO
setting is set to a certain value, please check the procedure for
cameras other than Type R.
* In movie, dynamic range (DR), interval shooting, or M-Cont
Plus (HI) mode, the flash will not fire.
Cameras other than Type R
The ISO setting on the camera is not linked with the flash unit.
Manually select the aperture value on the camera to match the ISO
setting, using the following table as reference.
Aperture
value on the
flash unit
ISO64 ISO80 ISO100 ISO200 ISO400
2.8 2.2 2.5 2.8 4 5.6
4 3.2 3.6 4 5.6 8
5.6 4.5 5 5.6 8 11
Manual flash
When you cannot get the exposure you intended using the TTL
auto or Ambient light auto mode, you can use manual flash to set
the desired flash output level.
1 Set the flash mode to NORMAL with the Mode select button
and the flash power level to FULL or 1/4 with the Flash power
level select button.
2 When using manual flash, use the following formula to select
the aperture value.
Aperture value = Guide No. ÷ Shooting distance
Example) If the guide No. is 20 and the shooting distance is 5
m, the appropriate aperture value is 20÷5=4, that is F4.
The flash unit’s output (guide No.) varies depending on the
zoom position. Refer to “Guide No. Table (ISO 100)“ on the
page EN - 18.
3 Set a shutter speed slower than 1/250 second.