Metering For Correct Exposure - Lastolite School of Photography

Monthly Tips & Tutorials from Lastolite
Lesson One
Metering For Correct Exposure
Getting exposure right in camera will maintain more detail in the image.
A correct exposure is determined by a combination of
the amount of light reaching the cameras sensor
through the lens (aperture) and the length of time the
shutter (speed) is left open. This combination will also
be effected by the sensitivity of the sensor to light,
which we set via the ISO setting on camera.
Metering can be difficult in a dramatic scene, especially when there is
a domination of light or dark. Avoid auto metering modes to capture
the detail you want to record, not what the camera averages.
Correct Exposure
This will give detail in the highlights as well as in the
shadow areas of an image with a subtle transition
through the general tonal range in a scene. An image
may contain brighter or darker areas in the
photograph, however the main subject area will
contain detail with little or no loss.
Correct Exposure - captures important detail, especially in
the highlight and shadow areas.
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Over Exposure
This occurs when too much light is allowed to effect
the sensor causing lost detail in the highlight areas of
the image. The overexposure will give either a subtle
loss or a more dramatic loss of detail in the highlight
areas; the result will depend on how much extra light
is allowed to hit the cameras sensor.
Check - ISO setting, Aperture Setting, Shutter Speed
Over Exposure - Loses detail in the highlight areas.
Under Exposure
This occurs when too little light is allowed to affect
the cameras sensor, causing lost detail in the mid tone
and shadow areas. Under exposure will give either a
totally black image if the setting is less than 4 stops
lower than the ambient light or an overall dark image
depending on the difference from a correct exposure.
Check - ISO setting, Aperture Setting, Shutter Speed
Under Exposure - Loses detail and contrast

Monthly Tips & Tutorials from Lastolite
Lesson One
Key Points
Light can be measured in 2 basic ways:
Reflected the brightness of the light in
the scene or bounced off the
subject.
Incident the light falling on the subject
or scene.
A hand held meter makes exposure reading simple. Point the meter
towards the ambient or flash light source.
Incident Metering
This is the most accurate way to measure either the
ambient light or flashlight on a subject when shooting
weddings and portraiture as well as still life and
product photography?
This method is usually done with a light meter. A light
meter is used to measure accurately the light falling on
a subject, based on a calibrated sensor in the meter
itself. It gives a reading based on a tone of grey, so no
guess work is involved in choosing the right tone in an
image to take a reflected reading off.
To use a hand held meter first set it to either ambient
or flash mode, hold it by the subject and point it back
toward the light source. This will now give you a
correct exposure based on a combination of your
chosen ISO, as well as the aperture F-Stop and the
shutter speed setting.
All text and photography ÇMark Cleghorn 2009. All rights reserved.
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Even though a light meter is usually used to take an
Incident light reading, they can also take a reflective
reading when used in a different mode or with
different accessories, even a spot meter reading.
Reflective Metering
This is the most common metering as this uses the
cameras built in sensor and is perfect for landscape
photography when it is impossible to take an incident
reading from the subject in the distance. Instead the
reflective light is measured by accessing the light levels
in the scene.
In DSLR's the exposure is determined by the light
hitting the sensor through the lens, hence the term
'Through The Lens' metering (TTL)
Accurate exposure can be difficult with landscape photogaphy.
To take an accurate reflective meter reading takes a
little more skill, as you have to be able to read the
scene and decide which part of the image is going to
give you the tone to record. As almost every image has
highlights, mid tones and shadow areas the equation
can be more confusing.
Mark Cleghorn
www.phototraining4u.com