While multiple flash units increase creative
possibilities mixing primary flash with ambient natural light can produce very
good result. Using a single flash it’s important to keep the unit relatively close
to the subject so that it’s not operating at maximum capacity for each shot,
this will increase the range of exposure settings that can be set.
Where should I position the flash
The flash should be positioned opposite
the main light source, off camera at an angle of around 45 degree. This will
help to prevent red-eye as well as giving a more natural feel to the artificial
aspect of the source.
Five main aspects of flash systems to
consider
Power: quantity of light emitted by the
unit, referred to by its guide number. Guide number indicate its power output
in relation to a standard film speed on digital ISO setting. It’s important
when calculating flash exposure manually.
It indicate the maximum output of the flash,
with modern flash units it is possible to control output to levels below the
maximum.
Coverage: Refers to the spread of the
flash light from the point source. Ideally this should match the angle of view
of the lens used. Range are mostly between 28 and 135mm.
Recycling time: refers to the speed at
which the flash unit recharge after discharge.
Flexibility: not only its position
fixed.
Flash diffuser
over the flash head scatter emitted
light.
Flash extender
Are designed to be used with long focal length
lenses of 300 mm or longer when it’s impossible to get close enough to the
subject.
Off-camera shore cord
Acts to continue passing information
between the camera and the flash unit.
Flash bracket
Is used to support the flash unit
off-camera. Flash bracketing performs the same role as standard exposure
bracketing.
Front and back curtain
Modern camera have various settings for
flash fires at the shutter curtain opens at the beginning of the exposure, when
rear curtain sync mode is selected the flash fires at the end of the exposure. When
making long exposure and using flash creates the effect of motion blur
appearing behind the subjects.
The slow-sync flash mode
Can be used with the slow shutter speeds
to create interesting aesthetic effects.
High-speed flash-sync mode
Can be used with extremaly fast-moving
subjects to help freeze motion, when ambient light would otherwise cause an
amount of subject blur.
