56
3
n
Calculating the Flash Effective Range
When setting the lens to manual F/stop, calculate the guide
number at full flash with the use of flash’s zoom position and
ISO. Divide the resulting guide number by the aperture in use.
Thus, the maximum distance is obtained. The minimum
distance is obtained in dividing this max. distance by approx.
10. However, if the minimum distance obtained is 0.7 m or less,
the minimum distance will be 0.7 m. Refer to page 58 for the
guide number table.
3. Appendix
Flash Effective Range
Example:
With an 85 mm lens at F/4 and sensitivity at ISO100
1
For the zoom position 58mm and sensitivity at ISO100,
the guide number is 54.
2
54 (guide number) /4 (aperture) = 13.5m (max. distance)
3
13.5m (max. distance) /10 = 1.35m (min. distance) Thus,
flash effective range is approx. 1.35m - 13.5m.
* The numbers used in this example are for K series (APS-C).
AF360FZ_540FGZ.book Page 56 Friday, December 20, 2013 6:11 PM