Metered Manual Mode - Pentax *ist Operating Manual

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ADVANCED OPERATION FOR THE BUILT-IN FLASH

4.Metered Manual Mode

• When using the built-in flash in the Metered Manual Mode,
any combination of aperture and shutter speed 1/125 or
slower can be set. In this mode, the exposure of the
background can be controlled by the manual exposure to
take a flash photograph.
1. Calculating the flash effective range according to the camera-
to-subject distance.
Maximum flash distance = Guide Number ÷ Selected aperture
Minimum flash distance = Maximum flash distance ÷ 5*
*The value 5 used in the formula above is a fixed value applied to the
built-in flash in this camera.
✍
MEMO
• When the distance to the subject is less than 0.7m (2.3ft), the flash
cannot be used. If the flash is used within 0.7m, it causes vignetting in
the picture corners, light is distributed unevenly and the picture may be
over exposed.
The guide number (GN) depends upon the film speed used as
shown below.
ISO25
ISO50
ISO100
GN5.5 ISO200
GN7.8 ISO400
GN11
GN15.6
GN22