Samsung GX10 User Manual (ENGLISH) - Page 211

Using the Built-in Flash Distance and Aperture when 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 ISO 100 ISO 200 ISO 400 ISO 800 ISO 1600 Built-in flash guide number 11 15.6 22 31 44 Calculating Shooting Distance from Aperture Value 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. ŝ210Ş