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Figure 4-19.–Hand-held light meter.
A light meter can be either built into the camera or
a separate hand-held unit (fig. 4-19). Both types are
sensitive instruments and should be handled with care.
There is little maintenance, but they do require batteries.
When you think a light meter is not working properly,
have it checked by a qualified technician. Always be
sure to check your equipment before leaving on an
assignment. Like all camera equipment, careless
handling and excessive heat and moisture limit the life
of a light meter. A light meter must not be subjected to
high temperatures for prolonged periods of time. Unless
the light meter is designed for underwater photography,
it should be protected in inclement weather.
LIGHT METER READINGS
There are two methods of measuring light with
hand-held light meters. These two methods are the
incident-light method and the reflected-light method.
Incident-Light Method
This method requires the use of an incident-light
meter. An incident-light meter has a diffusing dome that
covers the photoelectric cell. When an incident-light
meter reading is taken, the meter is held at the position
of the subject with the photoelectric cell pointed toward
the camera. The meter measures the light falling upon
the scene. The incident-light method of measuring light
is used extensively in motion-media photography and
gives fast accurate results in all photography.
Most light meters are designed for use as either
incident-light or reflected-light meters. By removing the
diffusion dome from the photoelectric cell, you can use
the meter to measure reflected light.
Reflected-Light Method
When you are taking this type of light-meter
reading, the diffusing dome should be removed from the
photoelectric cell and the meter pointed toward the
subject.
A reflected-light meter receives and measures the
light reflected from a scene within the angle of
acceptance of the meter. The term angle of acceptance
compares to the term angle of view of a lens. Both are
predetermined during manufacturing. The angle of
acceptance and the distance between the meter and the
scene are the controlling factors as to how much of the
reflected light from the scene is measured by the meter.
When the angle of acceptance is greater than the angle
of view of a lens (when using a telephoto lens for
example), the meter should be moved closer to the
scene.
Light meters that are built into the camera are
reflected-light meters. When these meters are used, the
angle of acceptance is not greater than the angle of view
of the lens being used. The meter measures the light
from the scene as seen by the lens.
Some reflected-light meters have angles of
acceptance between 1 and 4 degrees. These meters can
be used from a distance to measure the reflected light
from specific objects within a scene. Exposure meters
with angles of reflectance this small are called spot
meters.
LIGHT METER OPERATION
You must understand the way light meters operate
to determine whether the information they provide is
accurate. No matter what type of light meter you use, it
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