Guide Number - Nikon Autofocus Speedlight SB-22 Instruction Manual

Guide Number

In M or MD mode, without referring to the aperture se-
lection/shooting distance range panel, you can de­
termine the f/stop by using the following equation:
,,
f/stop =--------------------------------- - —
See the table for guide numbers at various film
speeds.
Guide number at various film speeds
Mode
selector
1600 100(328)
800
400
o
200
too
50
25
guide number
flash-to-subject distance
Normal
M (manual)
70(230)
50(164)
36(118)
25 (82)
18(59)
12.5(41)
MD
M (manual)
32(105) 70(230)
22 (72) 50(164)
16(52) 35(115)
11 (36) 25 (82)
8(26)
5,6(18)12.5(41)
4(13)
Unit; m (ft)
With wide-flash
adapter
22 (72)
18(59) 5.6(18)
9(30)
MD
16(52)
11 (36)
8(26)
4(13)
2.8 (9)