Caution, I important – Nikon 58-104 User Manual
Page 44
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In manual mode, you can determine the correct f/stop using the following
equation:
f/stop =
guide number
flash-to-subject distance
See table below for the guide number at various film speed.
Guide number at various film speed
m (ft)
Light
Underwater shooting
output
ISO 25
50
64
100
200
400
800
1000
M Full
8(26)
11 (36)
12(39)
16(53)
22 (72) 32(105) 45 (148) 50(164)
u 1/4
4(13)
5.6(18)
6(20)
8(26)
11 (36) 16(53)
22 (72)
25 (82)
M 1/16
2(7)
2.8 (9)
3(10)
4(13)
5.6(18)
8(26)
11 (36)
12(39)
m(ft)
Light
On-land shooting
output
ISO 25
50
64
100
200
400
800
1000
M Full
16(52)
22 (72)
25 (82) 32(105) 45 (148) 64 (210) 90 (295) 101 (331)
U 1/4
8(26)
11 (36)
12(39)
16(52)
22 (72)
32(105) 45(148) 50(164)
M 1/16
4(13)
5.6(18)
6(20)
8(26)
11 (36)
16(52)
22 (72)
25 (82)
• Caution
•Guide numbers under water vary according to water conditions.
•When aiming the Speedlight diagonally, open the aperture 1/2 to 1
step wider (smaller f-number) than the aperture value obtained in the
above equation to compensate for the different angle of reflection.
•When taking photographs with the arm removed from the bracket,
Nikon recommends you to take various pictures with different
apertures by adjusting the camera-to-subject distance.
I Important
If the camera-to-subject distance is actually measured underwater,
multiply the measured distance by 3/4 to get the estimated distance
undenwater.
For example, if the actual camera-to-subject distance is 1.33 meters
(4.3 feet), set the lens distance scale to 1 meter (3.3 feet), and read the
"1 meter” column on the exposure calculation chart.
44