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Guide number (ISO 100, m/ft)
Flash output
Zoom-head position (mm)
level
14* 24 28 35 50 70 85
M1/1 14.0/45.9 26.0/85.3 28.0/91.9 30.0/98.4 36.0/118.1 38.0/124.7 40.0/131.2
M1/2 9.9/32.5 18.4/60.4 19.8/65.0 21.2/69.6 25.5/83.7 26.9/88.3 28.3/92.8
M1/4 7.0/23.0 13.0/42.7 14.0/45.9 15.0/49.2 18.0/59.1 19.0/62.3 20.0/65.6
M1/8 4.9/16.1 9.2/30.2 9.9/32.5 10.6/34.8 12.7/41.7 13.4/44.0 14.1/46.3
M1/16 3.5/11.5 6.5/21.3 7.0/23.0 7.5/24.6 9.0/29.5 9.5/31.2 10.0/32.8
M1/32 2.5/8.2 4.6/15.1 4.9/16.1 5.3/17.4 6.4/21.0 6.7/22.0 7.1/23.3
M1/64 1.8/5.9 3.3/10.8 3.5/11.5 3.8/12.5 4.5/14.8 4.8/15.7 5.0/16.4
* With the wide-flash adapter in place
ISO sensitivity factors
For sensitivities other than ISO 100, multiply the guide number by the factors
shown in the table below.
ISO 25 50 100 200 400 800 1600
Factors x0.5 x0.71 x1 x1.4 x2 x2.8 x4
To calculate the correct aperture
Calculate the correct aperture by using this equation and the guide number
table, according to the ISO sensitivity, shooting distance, flash output level and
zoom-head position that are set:
For example, for the ISO sensitivity of 400 (or ISO sensitivity factor: 2), with the
zoom-head position adjusted to 28mm, and the flash output level set to M1/1:
• Referring to the guide number table, determine the guide number as 28/91.9 (m/ft.).
When the shooting distance is 3.5m (11.5 ft.), the correct aperture value is:
28/91.9 (GN at ISO 100, m/ft) × 2 (ISO sensitivity factor for ISO 400) ÷ 3.5/11.5 (shooting
distance; m/ft.) = 16 (aperture)
• Set the aperture value 16 on both the SB-600 and the camera or lens.
To obtain the correct flash output level
Calculate the guide number (GN at ISO 100; m/ft.) by using this equation,
according to the shooting distance and aperture required.
Referring to the guide number table, determine an appropriate flash output
level corresponding to the guide number obtained above, then set the same
value on the SB-600.
For example, for the ISO sensitivity of 400 (or ISO sensitivity factor: 2) and the
shooting distance of 3.5m (11.5 ft) with an aperture of f/8:
3.5/11.5 (shooting distance; m/ft.) × 8 (aperture value)
÷2 (ISO sensitivity factor of ISO 400) = 14/45.9 (GN at ISO 100; m/ft.)
Guide number (GN at ISO 100; m/ft.) = Shooting distance (m/ft) × Aperture (f/) ÷ ISO sensitivity factor
f/stop (aperture) = Guide number (GN at ISO 100; m/ft.) × ISO sensitivity factor ÷ Shooting distance (m/ft)
Detailed operation