Beecher's Handouts /
Setting Exposure /
13.2 - More about Light Meters
What Your Light Meter "Sees"
Your light meter can be set to see different parts of the
scene.
Evaluative/Matrix Metering
Your light meter can be set to measure many different parts
of a scene.
This is called evaluative or matrix metering.
The multiple measurements are compared to exposure algorithms
stored in the camera computer.
The lens opening and shutter speed are set according to the best
match between the multiple measurements and the algorithms.
Spot Metering
On many cameras, the light meter can be set to measure only a
small portion of the scene.
This is called spot metering.
Only about 3% of the scene is measured.
Spot metering is useful when you're photographing someone with
backlighting.
For example, let's say Renaldo is standing on a beach with the
setting sun behind him.
If your light meter is set for evaluative metering, the exposure
chosen by your camera may make Renaldo too dark.
That's because the light meter will "see" the bright sky, and
will set the exposure for the sky.
Renaldo will be a silhouette in your photograph.
The light meter won't "realize" that you're most interested in
Renaldo, who is in shadow.
If you measure the light on Renaldo's face using spot
metering, you'll have a better exposure.
Do the following.
1) Engage spot metering.
Check your camera instruction manual
for how to do this.
2) Center the spot meter zone, the area in the viewfinder
that corresponds to what the the spot meter can see, on Renaldo's face.
3) Press the shutter release down slightly to take a light reading
on Renaldo's face.
4) Lock in the exposure from the face by using the autoexposure
lock button (AEL).
Check your camera instruction manual for how to use this feature.
5) Take the photograph.
Light Meters Are Stupid
Light meters give you acceptable exposures most of the time.
However, there are several situations where the light meter will
give you the wrong exposure.
You'll learn about these situations below.
