Metering Techniques:
Introduction to Handheld Exposure Meters

A handheld light meter is, I believe, the single most important accessory that a photographer can own. They provide more useful and accurate readings than the meters built in to cameras.

This tutorial is a basic introduction to handheld meters. Later tutorials will teach more advanced metering techniques.

There are two types of exposure meters. Reflected light meters, and incident light meters. In addition, there are also Color Meters, which do not give exposure information; they tell you the white balance settings to use with your camera. If you want to know more about them, my Color Temperature Meter Tutorial dicusses their use.

 

A collection of handheld exposure meters.

 

Reflected Light Meters

If you have ever used a camera with a built-in light meter, you have already used a reflected light meter. All of the meters built in to cameras that read the light coming in through the lens are reflected light meters. There are also handheld reflected light meters.

To use a reflected light meter, you stand at the camera position and point the meter toward the subject. As the name implies, a reflected light meter measures the light that reflects off of the subject. This is a serious disadvantage because the meter has no way of knowing if you are photographing something that should be rendered as a light tone (like a white building) or as a dark tone, or a middle tone. Because of this, the meters are calibrated to assume that you are photographing an "average" subject; one whose various parts will average out to a middle-gray tone.

If you only photograph such "average" scenes, then a reflected light meter will give you accurate results. In the real world, that is not often the case. As we'll see later in this tutorial, reflected light readings of a light-toned subject will produce an underexposed photograph, as the meter tries to render the light tones as a middle gray. A reflected light reading of a dark-toned subject will produce an overexposed photograph, as the meter tries to render the dark tones as a middle gray.

 

Two reflected light meters. The Weston Master V is a classic meter from the 1960s, a development of the original handheld meters invented by Weston in the 1930s. The Gossen Ultra-Pro is mainly designed as a reflected light meter, but includes a small incident light dome that can be slid over the front of the sensor.

 

Incident Light Meters

A handheld incident light meter ignores the subject and just measures the light that hits the subject. This might seem counter-intuitive, but it is actually superior to reflected light metering in most circumstances. Because it ignores the subject, it cannot be fooled into underexposing light tones and overexposing dark tones, as a reflected light meter does.

Incident light meters are instantly recognizable because they have a white dome covering the meter's sensor. To use the meter, you stand close to your subject, so that the meter will be in the same light as your subject, and point the white dome directly toward the camera.

The reason for the white dome over the sensor is that the three dimensional dome simulates a three dimensional subject. Light hits the subject from different directions, and the dome allows the meter to see light coming from the sides, from above or below, and from straight on.

The system isn't perfect. The dome cannot take into account backlighting, and they don't do well with extreme side-lighting. For those conditions, I recommend taking both an incident reading and a reflected light reading and then averaging them. I have a tutorial that explains this method in more detail.

Self-illuminated or trans-illuminated objects, such as stained glass windows and neon signs cannot be measured with an incident light meter. For those, a reflected light meter is required. Because an incident meter requires you to meter from the location of the subject, or in the same light as the subject, it cannot be used for inaccessible places like a theatre stage during a play or concert.

 

A couple of incident light meters. These meters, though primarily designed as incident meters, are actually "System Meters." A wide variety of accessories were made for them that expanded their capabilities. Along the top are the enlarging meter attachment, the reflected light attachment, and a flat incident light diffuser. The flat diffuser is for photographing flat subjects, like artwork. It is also used in studio work to take readings from individual lights to set lighting ratios.

The 5 degree viewfinder turns the meter into a reflected light meter with a smaller angle of view, allowing you to take readings from different parts of the scene. An actual 1 degree spotmeter (discussed on Page 3) is better for this, though.

 

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