If you hold the meter so close to one of the white
squares that the black squares have no effect on the
meter reading, the reading is higher than the integrated
reading and the meter indicates that the scene requires
less exposure. The same principle applies when a
reading is taken close to a black square. The reading
indicates that the scene requires more exposure. Each of
the meter readings is a measurement of 18-percent gray.
You can apply this checkerboard example when you
photograph scenes that are predominately light or dark
Compensation is required to expose such scenes
correctly.
As a general guide, you should double the indicated
exposure when the light measurement is taken from a
predominately light scene and detail is desired in the
shadows. When you take a light meter reading from a
predominately dark scene and detail is desired in the
highlight areas, you should reduce the exposure by one
half.
Brightness Range Method
This method requires you to take two readings from
the scene: one from the highlight area where detail is
desired and another from the shadow area where detail
is desired. You then base your exposure on a point
midway between the two readings.
The brightness range method of determining
exposures for most scenes usually provides detail in
both the highlight and the shadow areas. An exception
to this is when the exposure latitude of a film is not
capable of recording the brightness range of the scene.
This can occur with scenes that have extremely great
brightness ranges. A scene brightness range is the
difference between the brightest and the darkest areas
of a scene and is usually expressed as a ratio. The
average brightness range of a normal scene is 160:1.
Films used for pictorial work are capable of reproducing
this brightness range. When the scene exceeds a
brightness range of 160:1, you must compromise the
exposure. This compromise can be as follows:
Underexpose and sacrifice shadow detail to
retain highlight detail.
Overexpose and sacrifice highlight detail to
retain shadow detail.
Do not compensate and expose for the midtones
and sacrifice both highlight detail and shadow
detail.
Darkest Object Method
The darkest object method of determining
exposures is actually a variation of the brightness range
method. When you desire detail in the shadow area or
darkest object within the scene, you take the light meter
reading from this area. This method actually
overexposes the film overall, causing the highlight areas
of the scene to be greatly overexposed. This
overexposure occurs because the light meter averages
the light reflected from the shadow area and indicates
an exposure to produce middle gray. When a great
amount of detail is not needed in the shadow area and
you want to expose the overall scene normally, you can
take your light meter reading from the darkest object or
shadow area and stop down two f/stops. This method
provides a good overall film exposure of the shadows,
midtones, and highlights.
Brightest Object Method
Another variation of the brightness range method is
the brightest object method. The brightest object method
of calculating exposures is used when a highlight area
within a scene is the only area within the scene from
which you can take a light meter reading. This method
can also be used when you want to record detail in the
highlight area In both situations, you take only one light
meter reading of an important highlight area. When you
do not want the highlight to record as a middle-gray tone
and desire a good overall exposure of the scene, you
simply open up two or three f/stops from the indicated
exposure. When you need maximum detail in the
highlight area, you can use the reading that the light
meter provides. This records the highlight area as
medium gray. This method underexposes the film in
other areas of the scene that reflect less light.
Substitution Method
With the substitution method, you replace an object
within the scene with an object, such as a gray card. You
then take a reflected-light meter reading from this
object. You use this method when the other methods of
determining exposure are not possible. Such situations
may be caused by excessive distance between the light
meter and the scene, barriers in front of the scene, or the
size of the scene makes it impossible to get an accurate
light meter reading. The substitution method is often
used in studio situations where objects may be too small
to obtain an accurate light meter reading.
You should select substitution objects that match the
light reflectance quality of the object in the scene; for
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