Beecher's Handouts > Camera >
3.8.4 - Default Settings >
4 - Light Meter
Your camera has a light meter that measures the amount of light
in a scene.
What this light meter "sees" can be changed.
There are three light metering patterns:
• Multiple point
• Center weighted
• Spot
Multiple Point
The multiple point light meter setting is called matrix
metering on Nikon cameras, and evaluative metering on Canons.
When using the multiple point light meter setting, the light
meter measures many points on the frame.
Before the shutter opens, the data from these many areas is compared
to thousands of patterns, called algorithms, stored in your camera's
computer.
If there's a match between the pattern of the scene you're photographing,
and one of the algorithms, the computer will base the exposure setting
on the matching algorithm.
The reading at the focus point will be given greater weight,
as this is probably the subject of the photograph.
Therefore, when you're using multiple point metering, set your
focusing system to where the focus point is decided by the camera.
The multiple point light meter setting works well—but not all
of the time.
Where setting the best exposure may be tricky—compare multiple
point metering with center-weighted or spot metering (described
below).
When Is Setting the Exposure Tricky?
Contrasty scenes and backlighted subjects can confuse the multiple
point light meter setting.
Your judgment may be better than that of your camera's computer.
Use the center weighted or spot light meter settings.
Center Weighted & Spot
Center Weighted
With center-weighted metering, the light meter measures most
of the light (60 to 75% depending on the camera) in the central
area of the frame.
For example, if you're photographing a landscape, and you don't
want a bright sky throwing off the exposure, point the central area
of the frame down, removing the sky from the frame.
Lock in the exposure using the autoexposure lock button (AEL
button on Nikons, star icon button on Canons).
Then, recompose your photograph in the frame.
Go to Autoexposure Lock.
Spot
With spot metering, the light meter measures a small area in
the center of the frame.
This area may be from 1% to several percent of the entire area
of the frame.
On some cameras, you can adjust the size of the area.
For example, if you're photographing an eagle nest against a
bright sky, point the center of the frame at the nest.
As described above, lock in the exposure using the autoexposure
lock button (AEL button on Nikons, star button on Canon Digital
Rebel XT).
Then, recompose your photograph in the frame.
None of the Above Work
For this Situation
If you're photographing a subject that's very light colored or
toned, or dark colored or toned, all of the above metering systems
will fail.
Your judgment will be 100% better.
For example, if you're photographing snow in the sun, all of
the above metering types will underexpose (darken) the snow.
Similarly, if you're photographing the face of a gorilla, all
of the above metering types will overexpose (lighten) the gorilla's
face.
You have to measure the light in the scene on a surface that's
medium colored or toned.
Lock in this exposure, and recompose the scene in the frame.
Go to Light
Meters Are Stupid.
