| Tutorial....
Flash & Lighting
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Flash & Lighting - the basics
The most readily available form of light
is of course natural daylight. It is present everywhere
around us, although you should realize that its characteristics
can be very different depending on the time of day and
the position of the sun.
Midday sun is rather blue and creates dark harsh shadows
because it is right above you. Morning and evening light
are warmer in color and since the sun is lower in the
sky it creates lovely long shadows.
Sometimes however the available
light is not enough to create the image you are after,
and some form of artificial light will be needed.
The most readily available is of course
your in camera flash. Although it is rather limited
in its coverage as its guide number is usually only
enough to cover subjects of about three to four meters
away, it can be a very useful tool as a fill-in flash
to supplement available light and to lighten up dark
shadows in your subject. |
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Then we have studio flash which is usually
only available to professional photographers. These are
big flash units with very high guide numbers for use in
the studio. They are very versatile because their output
of light can be varied in ½ stops over a wide range.
The
Pitfalls
Most in-camera flashes lack the power to light
subjects more than 3 to 4 metres away, so a more
powerful off-camera flash unit will be required.
These automatically provide the correct amount of
light according to the aperture used. Make sure
to check voltage of older flash units before using
them.
To make full use of available flash power, always
wait for the flash-ready light before pressing the
shutter. |
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In-camera flash invariably causes red-eye
when photographing a person looking straight at the
camera, because the beam of light is too close to
the axis of the lens. Having the subject look away
from the camera or turning up the ambient room light
to narrow the eye's pupil, help in avoiding red-eye.
Alternatively some cameras can detect red-eye in an
image and correct it in-camera afterwards. Do not
pose subjects too close to the background or in front
of a window or mirror, as the flash will cause nasty
reflections or heavy shadows.
Using flashlight at concerts or stage shows in large
halls or venues is useless as even the more powerful
off-camera flash guns have a maximum working range
of about 10 to 15 meters, which is not enough to illuminate
the actors or musicians on stage. Try getting closer
to the stage or failing this, support your camera
firmly and use a slow shutter speed. |
Flash
Types
If some form of artificial light is needed, the
most convenient choice is of course your in-camera
flash. Its power is enough to light subjects up
to 3 or 4 meters away and it can be perfect for
filling in dark shadows when capturing images in
harsh sunlight.
It is less suited for direct flash however, because
it emits a hard direct light that could be softened
a little by taping a small piece of tracing paper
over it. |
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Some cameras have a hot shoe or
a synch socket to fit a portable flashgun. These
are available in several types, but some cameras
only work with dedicated "own-brand" flashguns.
If yours offers TTL (through the lens) flash metering,
this will be the most accurate flash illumination.
Most have some sort of automatic mode however. If
you set the camera's aperture on the flashgun it
will produce exactly enough light to ensure a perfect
exposure. The sensor on the front of the flashgun
measures the light reflected back from the subject,
cutting the output when sufficient light has been
emitted.
If your flashgun has a swivable head, it lets you
bounce light off a white ceiling or wall to give
a nice soft modeling light. For even more creative
effects, use the flashgun off camera and connect
it with a synch lead. If you don't have a hot shoe
or synch socket you could buy a slave flash unit
which fires when it senses the light from the in-camera
flash.
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Flash
Modes
Many digital cameras have a variety of flash modes.
They usually include flash on where the camera fires
the flash whenever the exposure system decides it
is necessary. The light is quite harsh, making the
subject stand out against a dark background.
Forced on always fires the flash when you press
the shutter, regardless of the amount of available
light present while flash off turns the flash off,
so you can capture an image with available light
without the flash firing. |
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Anti red-eye is used to reduce red-eye
when taking a picture of a person looking straight
at the camera. Red-eye is caused by the flash being
too close to the lens – as of course all built
in flashes are - reflecting the light off the retina
at the back of the eye. A pre-flash makes the eye's
pupil contract and lessens the red-eye effect. It
is not very effective though. A way of avoiding
red-eye completely is to make sure the subject is
not looking straight into the camera, which will
make for a more natural looking portrait anyway.
Slow synch or fill-in mode is the most versatile.
The camera will choose a shutter speed for the ambient
light plus a small dose of flash to lighten the
foreground. This will make for a balanced picture
as the subject will be lit by the flash while the
background will be recorded as well. Fill-in is
also very effective at lightening up dark shadows
in harsh sunlight.
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Flash
Output Compensation
Apart from the standard flash modes available,
some cameras also feature flash output compensation.
It is similar to exposure compensation in that it
allows you to manually adjust the value of the flash
output power.
Some enable you to vary compensation settings using
the familiar EV range by 1 or 2 stops either way
in 1/3 EV steps, while others have a “high,
normal and low” setting. |
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This feature is very useful in situations
where the camera's normal flash metering system
might struggle to achieve a correct exposure.
A typical scene would be where flashlight is used
to illuminate a small subject against a dominating
dark background. To avoid overexposure or bleaching
out of the subject, the flash would need compensating
by –1 to –2 stops.
Also when you need just that tiny bit of extra light
to soften shadows or to produce a catchlight in
a person's eyes when taking a portrait, this feature
allows you to fine tune flash exposure for a more
subtle effect than is possible with the standard
flash modes available on your camera. Since you
can see the result of any compensation used immediately
after capturing the image, it will be easy to obtain
the kind of effect you want by simply taking several
images at different settings.
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Special
Flash Units
Apart from your in-camera flash, there are several
other types of flash available. Probably the most
useful for digicam users is a portable flashgun
which fits to the hot shoe of your camera and has
a wider range than the built in flash. It has a
sensor, which measures the amount of light needed
for a correct exposure, and then adjusts flash duration
accordingly.
If you don't have a hot shoe, a slave flash would
be an alternative. |
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These fire the flash when they sense
another flash nearby going off. As most digicams
fire two flashes, the first to adjust white balance
and color settings and the second when the shutter
opens, you should make sure your slave has the possibility
to be triggered by the second flash.
A ring flash, which fits around the front of your
lens, gives a strong directional light without the
harsh shadows caused by in- or on-camera flash.
It is used mainly for fashion or advertising shots
although its shadowless light could be a real bonus
for macro shots.
Studio flash units are large mains powered flash
lights with variable power output for use in the
studio or on location. They can be fitted with all
sorts of accessories like softboxes, umbrellas or
"barndoors" to soften or direct the light.
Color temperature is exactly 5500 Kelvin, just like
midday sun, so there are no color casts such as
with tungsten light.
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