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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.
Aperture (f/stop) =
GN/flash-to-subject distance (m)
Guide Number Table
Camera format
Flash
ISO
light
intensity
ISO100
1/16
1/32
1/64
82
35mm
85mm
645
150mm 135mm 100mm
67
190mm 180mm 120mm
DIGITAL
58mm
1/1
54
1/2
38
1/4
27
1/8
19
13.5
9.5
6.7
Depending on the camera and lens you are using,
the effective flash range may be displayed. (Refer to
page 81.)
*With the wide-angle panel attached
Zoom position
70mm
50mm
35mm
70mm
90mm
48mm
34mm
24mm
50
45
39
35
32
27.5
24.5
22.5
19.5
17
16
13.5
12
11
9.5
8.5
8
6.5
6
5.6
4.6
28mm
24mm
*20mm
55mm
45mm
*35mm
70mm
60mm
*55mm
19mm
16mm
*13mm
35
32
21
24.5
22.5
14.5
17
16
10
12
11
7
8.5
7.5
5
6
5
3.5
4.2
3.5
2.4
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