Using a Handheld Meter

If a camera with non-manual settings is at the low end of the exposure-control spectrum, then using a handheld light meter is at the high end. Handheld meters usually employ two or three metering methods that overcome many of the shortcomings of your camera's onboard meter. For starters, handheld meters allow you to take reflected light readings by pointing the meter at the subject and measuring the light as it bounces off the subject. Note that this kind of reflected metering is susceptible to false readings from objects with above and below average reflectivity, just as is true with the meter in your camera.

Remember that your objective is to record the amount of light in the scene; the reflection part is a necessity imposed by the meter's placement inside the lens. So how do you avoid false readings from reflected light? Avoid the reflection by turning your handheld meter around, pointing it at the camera, and record the light as it falls onto the subject, before the light is distorted by reflectance or averaged into a generic, homogenous reading. This type of measurement is called an incident reading, and it can produce some very accurate exposures.

Most handheld meters include some sort of dome attachment or slider used to take incident readings. The meter averages the light falling on the dome from all angles. This type of averaging is good in that you've avoided the reflectance problem, ensuring that the reading does not overcompensate for light or dark subjects. Just make sure that there are no shadows falling across the meter, and that the meter shares the same light as the subject.

TECHnote: Handheld Metering Techniques

A typical handheld light meter.

Using a handheld meter takes some practice and technique to get it just right. Follow these tips when taking incident readings in both general use and specific lighting situations.

Metering Angles

When taking an incident reading, make sure that you point the metering dome directly into the lens of the camera. When shooting outdoors in a landscape, you might want to tilt the meter 1020° up towards the sky to lighten the image slightly. You might choose to slightly vary the upward or downward angle of the meter in the landscape to emphasize either the ground or the sky. Side to side angles are more critical because this lighting angle can throw off exposure considerably. Again, point the meter into the lens, not off to the side.

Strong Backlighting

Subjects standing against a bright background pose a problem in that the contrast is so great that both reflective and incident readings usually fall short of an accurate reading. One way to work around this is to take an incident reading at a right angle to the subject and light direction, so that the light and shadow fall down the middle of the dome. Another approach, called duplex metering, is to take a reading with the meter pointed towards the light source, take a second reading pointing away from the light source, and then average the two readings.

The third type of measurement available on advanced meters is a spot meter option that narrows the angle of the metering cell to take readings from specific spots in a scene in as little as a 1-degree metering angle over long distances. Spot metering involves looking through the viewfinder, lining up the center spot on the subject of your image, and pushing the button to take the reading off the subject. Because spot metering is a reflective technique, it produces a reading that renders the sampled area as neutral gray. Make sure that this is what you want, or use some form of exposure compensation to lighten or darken the area. Spot metering is also good for measuring the relative brightness between different areas of the scene.