Operation Manual

224
Using the Flash
9
The following equation calculates the effective distance of the flash for
aperture values.
Maximum flash distance L1 = Guide number ÷ Aperture value
Minimum flash distance L2 = Maximum flash distance ÷ 5 *
* The value 5 used in the formula above is a fixed value
which applies only when using the built-in flash alone.
Example:
When the sensitivity is ISO 200 and the aperture value is F5.6:
L1 = 17 ÷ 5.6 = approx. 3 (m)
L2 = 3 ÷ 5 = approx. 0.6 (m)
Therefore, the flash can be used in a range of about 0.6 m to 3 m.
However, the built-in flash in this camera cannot be used when the
distance is 0.7 m or less. When the flash is used at distances closer
than 0.7 m, it causes vignetting in the picture corners, light is
distributed unevenly and the picture may be overexposed.
The following equation calculates the aperture value for shooting distances.
Aperture value F = Guide number ÷ Shooting distance
Example:
When the sensitivity is ISO 200 and the shooting distance is 4 m,
the aperture value is:
F = 17 ÷ 4 = approx. 4.2
If the resulting number (4.2, in the above example) is not available
as a lens aperture, a smaller number that is closest (4.0, in the
above example) is generally used.
Calculating Shooting Distance from Aperture Value
Calculating Aperture Value from Shooting Distance
K-01_OPM_ENG.book Page 224 Wednesday, February 22, 2012 2:08 PM