|
|
|
|
|
<
Product
Resources
INTRODUCTION:
LIGHT METERS
Contents:
Light Meters
The
majority of cameras have built-in exposure meters, and yet many
people who have such cameras feel the need for separate exposure
meters.
Built-in
exposure meters are almost exclusively limited to reading the
light reflected. In some instances the resulting photograph
may be satisfactory. But very frequently this "Average" light
measurement is inappropriate. Unlike the handheld meter, built-in
meters often fail to compensate for scenes with high or low
contrasts.
Proper exposure
control is the key to accurate and creative photography. Suppose
pictures are being taken at a sunny beach or in bright snow
- both intense light situations. The built-in reflected meter
will tend to be overly effected by the light reflected from
the sand or snow, resulting in an underexposed photograph. In
such a case, a hand-held incident light exposure meter can be
relied upon to give you the correct reading for beautiful pictures.
The incident meter which measures the light falling on the subject,
is suitable for photography work in studios, such as shooting
models and commercial products and for copy-work where precise
illumination balance and color reproduction are necessary, while
the reflected light types which measure the light reflected
from all parts of a scene to the camera are more suitable where
the subject is rather far away and unapproachable.
For a long
time, handheld exposure meters were simple instruments that
did simple chores, namely measure ambient light. Newer meters
added a new dimension to light measuring capability - reading
short pulses of light from electronic flash units. But the mechanism
of the meter is still mechanical: An electrically charged coiled-galvanometer
movement responds to light reaching a photocell and this reading,
in arbitrary light value units or EVs (Exposure Value), is transferred
to a calculator dial to arrive at a combination of aperture
and shutter speed. With flash-reading devices, the shutter speed
is a fixed value, namely 1/60th second for X-sync. Other meters
may have the galvanometer movement and calculator dial in one
function.
Microchip
The
incorporation of microchip control into meter design effectively
overcomes the meter's mechanical limitations to an appreciable
degree, and, at the same time, broadens its capabilities. A microchip
is nothing more than a miniaturized integrated-circuit board.
It is up to the user to redefine those parameters in daily use.
The photographer merely enters data that corresponds to the mode
of operation or specific light-measurement needed.
Microminiaturization
permits cosmetic as well as functional changes. It made the
meter sleek in design, smaller in size, and lighter in weight.
A typical microprocessor based meter features an LCD (liquid-crystal-display)
panel situated below the rotating head, and buttons. There are
slider controls that let you enter the operating mode/measurement
function and buttons for selecting film speed, shutter speed,
EV scale, and possibly more. The digital readout displays one
set of data at any given time. With a calculator dial, on the
other hand, you simply have to visually line up any combination
you want, back and forth, from combination to combination, to
your heart's content.
There is
an advantage to digital. Having gotten the hang of it, the easier
to read display allows for faster decisions. The numbers are
more legible. And most important, the readings obtained are
fast and direct - there is no need to transfer data from a needle
reading to a calculator dial. And for those who require exposure
readings made to the nearest 1/10 stop, the digital display
provides that information.
Spot Metering
Selective-area
reflected light measurement with a spot meter is an approach favored
by many photographers. Used with a neutral gray card, the spot
meter simulates an incident light meter. With microprocessor technology,
spotmeters are available with electronic flash as well as with
ambient light.
Back
to Top
|
|
