Samsung Digimax GX-1S - Manual (Page 149)

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Using the Built-in Flash
ƈ A set criteria is necessary between the guide number, aperture and distance when shooting with the
flash. Calculate and adjust the shooting conditions if flash is not sufficient.
ƃ Built-in flash guide number
Sensitivity Built-in flash guide number
ISO 200 15.6
ISO 400 22
ISO 800 31
ISO 1600 44
ISO 3200 62
ƈ The following equation calculates the distance of the flash for aperture values.
Maximum flash distance L1 = Guide number ÷ Selected aperture
Minimum flash distance L2 = Maximum flash distance L1 ÷ 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 sensitivity is [ISO 200] and aperture value is F4
L1 = 15.6 ÷ 4 = approx. 3.9 (m)
L2 = 3.9 ÷ 5 = approx. 0.8 (m)
Therefore, the flash can be used in a range of about 0.8 m to 3.9 m.
The flash cannot be used when the distance is less than 0.7 m. When the flash is used at closer than
0.7 m, it causes vignetting in the picture corners, light is distributed unevenly and the picture may be
over-exposed.
Calculating Shooting Distance from Aperture Value
Distance and Aperture when Using the Built-in Flash