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■Guide Number (GN)
Guide numbers indicate flash light intensity. The larger
the number, the farther you can reach with your flash.
From the guide number, you can easily obtain the
proper aperture setting required for an optimum
exposure.
●
Depending on the camera and lens you are using,
the effective flash range may be displayed. (Refer to
page 81.)
Guide Number Table *With the wide-angle panel attached
Aperture (f/stop) =
GN/flash-to-subject distance (m)
ISO
Flash
light
intensity
Camera format
Zoom position
35mm 85mm 70mm 50mm 35mm 28mm 24mm *20mm
645 150mm 135mm 100mm 70mm 55mm 45mm *35mm
67 190mm 180mm 120mm 90mm 70mm 60mm *55mm
DIGITAL 58mm 48mm 34mm 24mm 19mm 16mm *13mm
645D 106mm 87mm 62mm 43mm 35mm 30mm *25mm
ISO100
1/1 54504539353221
1/2 38 35 32 27.5 24.5 22.5 14.5
1/4 27 24.5 22.5 19.5 17 16 10
1/8 19 17 1613.512 11 7
1/16 13.5 12 11 9.5 8.5 7.5 5
1/32 9.5 8.5 8 6.5 6 5 3.5
1/64 6.7 6 5.6 4.6 4.2 3.5 2.4