Flash modes – Nikon SB-28 User Manual
Page 57
57
For film speeds other than ISO 100, multiply the guide numbers by the factors shown
in the above table.
For example, if the film speed in the previous example was ISO 400 rather than ISO
100, the guide number is 72 (36 x 2).
ƒ
and
"
flash modes
Adjustment factors for other ISO film speeds
ISO film speed
Factor
25
50
200
400
800
1600
x 0.5
x 0.71
x 1.4
x 2
x 2.8
x 4