The invention of portable flash had a tremendous
impact on photography: it opened the night world
to the camera, with compact, easily carried
equipment. Today, electronic flash is standard to all
compact digital cameras, found on many cell phone
cameras, and fitted to the majority of dSLRs.
However, the position of the fitted flash is just about
the worst possible, in terms of the quality of lighting.
Accessory lighting units are a necessity for versatile
and attractive lighting.
Power and recycling
A further problem is that flash built into a camera
relies on the camera’s own batteries for power. To
curb their hunger for energy, built-in flashes are
designed to be low-powered—usually sufficient to
light to a distance of 3–7ft (1–2m) but little further.
In addition, the recycling rates—how quickly the
flash can be fired in sequence—is also limited.
Flash power
Portable, or accessory, flash units overcome the
limitations of built-in flash by carrying their own
power and circuitry; this makes the units much
larger than compact cameras. Accessory flash units
also offer more control over flash power, direction
of flash, and angle of coverage.
Accessory flashes fit onto the hot shoe, which
combines electrical contacts with a slot that “mates”
with a corresponding, locking part on the bottom
of the flash unit. While the majority of cameras use
a standard hot-shoe design, the contacts may be
specific to the camera producer, and some
manufacturers—such as Sony—use proprietary hot-
shoe designs.
Adjustable angle
Many portable flash units place the flash on a
swiveling turret so that it can be directed to the
sides, or even backward, according to the nearest
surface for bounce flash (see pp. 82–9). Some offer
a tilting head so that you can point the flash upward,
or downward for close-up work. A fully adjustable
head increases flexibility, so is a must for wedding
and paparazzi photography.
Adjustable coverage
On many flash units you can also adjust the
coverage, or the angle over which light is spread.
This ensures that when you use a wide-angle lens or
Small supplementary flash
Units like this can augment the power
of built-in flash units. It is triggered by
the camera’s own flash, so it does not
need a hot shoe, and adds its output
to that of the camera’s unit. It is an
inexpensive solution to lighting
problems, but control is limited.
Slave flash unit
Slave units can add to the power of
built-in flash units. This unit synchs
with the on-camera flash for the
most accurate exposure, after which
operation is fully automatic. Position
it to one side of the camera to
improve modeling effects.
Powerful on-camera flash
Accessory flash mounted on a
camera’s hot shoe can be sufficiently
powerful forall normal needs,
offering a tilt-and-swivel head for
bounce, multiple-exposure facilities,
and focusing aids for working in
complete darkness.

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