Nikon os Speedlight SB-102 - Manual (Page 21)

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Shooting Mode Selector ®
The shooting mode selector @ has five click-stop set­
tings. The shooting modes that can be used with specific
cameras are listed on page 28.
“TTL” position—TTL (through-the-iens) Automatic
Fiash Mode
This mode, which can be used only in conjunction with
the Nikonos-V camera, automatically controls the flash
exposure Through-The-Lens (TTL). In this mode, the
Nikonos-V’s SPD (silicon photodiode) reads the light
passing through the lens and automatically signals the
SB-102 to turn itself off when the exposure is correct.
Because the range of useable apertures is larger (from
f/2.8 to f/22 when using ASA/ISO 100 film) than with
non-TTL flash, you can shoot at a variety of flash-to-
subject distances. The farther the subject, the more
light emitted by the flash unit; the closer the subject,
the less light given off. In addition, the TTL mode makes
daylight fill-in fiash and close-up photography easier
than ever.
• The useable film speed range for TTL operation is from ASA/ISO 25 to
400. For information about the apertures that can be used at various
fiim speeds, see page 23.
• TTL operation is not possibie with the Nikonos IV-A or Hi or when the
Nikonos-V’s shutter speed/mode selector dial is set at M90 ( 1/90sec.)
or В (Bulb).
•Even if the Nikonos-V's shutter speed/mode selector dial is set from
1/30 to 1/IOOOsec., TTL operation is not possible when: the sync cord
is not securely connected, the ASA/ISO film speed is set beyond
ASA/ISO 400, or the batteries are completely exhausted.
“AUTO”—Non-TTL Automatic Flash Mode
When the optional Sensor Unit SU-101 is used, this
mode provides non-TTL automatic flash operation. In
this mode, the sensor unit reads the light reflected back
from the subject while the speedlight is firing and tells
the speedlight to turn itself off when the light output is
sufficient for correct exposure. The selector dial on the
back of the SU-101 allows one of two aperture settings
to be selected according to the flash-to-subject distance
and the shooting situation.
• In both the TTL and non-TTL automatic fiash modes, the SB-102 emits
amounts of tight sufficient for subiects having average reflectivity.
Therefore, correct exposure may not be obtainable if the subject's
reflectivity is extremely low or high.
“MFULL”, “M1/4” and “M1/16”-Manual Flash
Modes
Manual control is very convenient when the correct
exposure cannot be obtained through non-TTL auto­
matic operation. The SB-102 has three manual control
modes for selection according to the flash-to-subject
distance and the shooting situation. The guide numbers
are GN 32 (16) at the “MFULL” position, GN 16 (8) at
“M1/4,” and GN 8 (4) at “M1/16” (when using ASA/ISO
100 film. The guide numbers in parentheses are for
underwater photography). To determine the correct
aperture, use the exposure calculation dial or perform
the calculations yourself (see pages 25 to 26).
21