Light Metering Behavior

and Some Principles for Using It

by Barry Walton

Most cameras these days have built-in light meters (digital point-shoot or PS, digital and non-digital SLRs). These light meters while often thought of as "automatic" actually have quite a lot of flexibility to allow you to get the desired look/feel of the photograph. Many camera users do not realize they can choose the metering independent of focus and framing of the shot. Learning the basic technique described here can really improve your outdoor shots.

1. Determine the types of Metering available (read your manual and be sure to determine which shooting mode they apply to):

• Spot (the meter is set based on the lighting where the spot meter is centered).
• Partial (larger spot such as 9% of the frame area) (DSLRs primarily).
• Center Weighted (bases the meter setting on what is in central area of the viewfinder).
• Intelligent or Matrix, (the meter is set based on getting the best overall exposure balancing the dark, mid-tone, and high-light areas). This is the mode that is normally the default for cameras.
• Some cameras these days detect faces and may meter based on the faces detected. (Read your manual).

2. Setting the Metering

Most cameras including point-and-shoot cameras allow you to lock the metering independent of the framing of the final shot. This capability is very important to allow you to flexibly set the metering for best results for scene.

In a PS, this can be done in most shooting modes (so check your manual) by pointing the camera at the area of your shot that you want best metered and holding down the shutter button half way. For example, point the camera at the sky (highly recommended for outdoor shots) and push the shutter button half-way down. This locks the metering (and the focus as well unless you have a metering lock button…check your manual carefully for this capability). While holding the button re-frame your shot and take the photo. Using the live view screen enables you to get a great idea of how the final photo will look when you use this method.

SLRs generally have a separate button to lock the metering, which then allows the final shot to be both framed and re-focused prior to the shot. But you can easily use the same process as a PS user. DLSRs with live-view (pretty new feature for these cameras) allow you to preview the metering.

Using Metering modes to your advantage.

High contrast scenes are the hardest to properly meter so I recommend you take a sequence of test photos. The easiest scene to test your camera with is on a partly cloudy day in mid to late afternoon with the camera facing in the direction of the sun (but keep the sun out of the frame). This scene nearly alway gives you bright sky and dark areas in the foreground.

Take 3 photos of the same scene in each metering mode (spot, partial, center weighted, intelligent). Point first at the sky, push the button half way, reframe for the horizon and shoot. Do the same metering on the horizon, then the ground. With these nine (or twelve photos depending on how many metering modes your camera has) do the following comparison:

Spot metering sequence, through, Intelligent (or matrix) average sequence. You can see how strongly the spot metering affects the results and the more subtle way the averaging metering affects them. Look for the photos that look the best to you. And the metering methods you used. The averaging methods are more forgiving than spot metering, but you should see the best results in color and contrast in those photos where the sky was main element used for metering.

For those who like to really understand their camera, run similar tests for the various shot modes your camera has (scene, people, sports, etc.) but you should find subtle differences relative to the test in the main shot mode you use.

Remember that brightening the darker areas of your photo is easier by far than fixing the sky! And a final piece of advice, use a polarizing filter for even better drama in sky scenes.