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GUIDENUMBER------------~~
~~~~~~~~~
In
manual flash and Repeating-Flash modes, apart from checking the shooting
distance
in
the
LCD
panel, you can also determine the correct flstop using the
following equation.
fl
t _ guide number
s op - flash-to-subject-distance
See table for the guide numbers at various film speeds.
Guide
number
at
various
film
speeds
meters (feet) at
ISO
100
~
24mm 28mm 35mm 50mm 70mm 85mm
Light output
1/1
30(98)
32(105) 36(118)
42
(138)
47
(154)
50 (164)
1/2
21
(69) 22 (72)
25 (82) 30 (98) 33 (108)
36 (118)
1/4
15
(49)
16
(52)
18
(59)
21
(69) 23 (75) 25 (82)
1/8
10
.5 (34)
11
(36)
12
.5 (41)
15
(49)
16
.5 (54)
18
(59)
1/16
7.5(25)
8 (26)
9(29)
10.5 (34)
11
.5 (38)
12
.5 (41)
..
For film other than
ISO
100,
multiply the above figures by the
follOWing
magnifications:
ISO
25
xO.5
50
xO.71
200
x1.4
400
x2
800
x2.8
1600
x4
81