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144
NIKON D5300
4
›
Guide Numbers
The Guide Number (GN) is a measure
of the power of a flash. In the past,
photographers used GNs constantly to
calculate flash exposures and working
range. With modern flash metering, like
Nikon’s i-TTL system (see below), such
computations are rarely needed. However,
the GN does help us to compare different
flashguns. For instance, the GN for the
built-in flash is 12 (meters, ISO 100); for the
Nikon SB-910 it is 34, indicating almost
three times the power. This allows shooting
at three times the distance, at a lower ISO,
or with a smaller aperture.
Tip
GNs are specifi ed in feet and/or
meters and usually for an ISO rating
of 100. When comparing diff erent
units, be sure that both GNs are stated
in the same terms.
Flash, as the name implies, is virtually
instantaneous, lasting just a few
milliseconds. If the flash is to cover the
whole image frame it must be fired when
the shutter is fully open, but at faster
shutter speeds DSLRs like the D5300 do not
FLASH MODE SETTING IN THE ACTIVE
INFORMATION DISPLAY
Standard flash mode
(front-curtain sync)
This is the default flash mode in most
exposure modes. However, the flash mode
item in the Active Information Display
labels it “Fill-flash” when using P, S, A, and
M exposure modes and “Auto flash” in
other modes.
In standard flash operation, the flash
fires as soon as the shutter is fully open, i.e.
as soon as possible after the shutter-release
button is pressed. This gives a fast response
›
Flash synchronization
and flash modes
in fact expose the whole frame at once. In
the case of the D5300, the fastest shutter
speed which can be used with flash is
1/200 sec. This is therefore known as the
sync (for synchronization) speed.
Flash modes are distinguished by how
they regulate synchronization and shutter
speed. Choose a flash mode by pressing
and rotating the Command Dial, or using
the Active Information Display.
Nikon D5300 Ch4 138-157 P2 RY.indd 144Nikon D5300 Ch4 138-157 P2 RY.indd 144 19/02/2014 16:4919/02/2014 16:49