Bewildered by how to use your handheld light meter? Join professional photographer Jim Zuckerman as he explains Incident, Reflected and Flash metering modes and how to use them.
Jim Zuckerman's images and articles on photography have been featured in hundreds of publications, and he has taught at many institutions, as well as through his own workshops. He is the author of thirteen books on photography. To learn more about his work and subscribe to his newsletter, read our interview with him and visit his website.
Photographs © Jim Zuckerman. All rights reserved.
Handheld light meters have three important functions:
- They read light being reflected from a subject.
- They read the light falling on a scene or subject, that is, the incident light.
- They read the light from an electronic flash.
All meters are programmed to assume the subjects in a scene are middle gray, which is to say that they reflect about 18% of the light that strikes them. If a subject is very light, like snow, or very dark, like a man wearing a black tuxedo standing close to the camera, the meter will be "fooled" into providing an inaccurate exposure. By calculating the exposure that will make the snow appear middle gray, it underexposes the subject. If the man wearing the tux fills much of the frame, a typical in-camera meter will overexpose the picture because it assumes the black fabric is gray.
One reason why built-in meters fail so often in giving you an accurate reading is that they don’t allow you to read a very narrow portion of the composition. Even in spot mode, they read 3% to 5% of the scene, and that is not specific enough to take an accurate reading in many circumstances. A handheld meter reads the light in one degree, i.e., .05% of the composition. This means that you can choose the portion of the picture that you have identified as middle gray and obtain an accurate reading from it.
When you use a handheld meter in reflected mode, you simply identify a middle-toned area of the scene and point the meter at that area. If your meter has a viewfinder, you can look through it and position the viewfinder’s target circle over the middle-toned area before you take the reading. When you push the button to take the reading, the f-stop/shutter speed combination that you need to use to get the proper exposure will appear instantly on the meter’s LCD. The accuracy of fine meters like Sekonic’s falls within a tenth of an f-stop. A typical reading, then, would look like f/8 plus .7, which equates to f/8 and about two-thirds. If you want to use a different lens aperture or shutter speed than the ones displayed—for example, for more depth of field or to creatively blur a moving subject—then you can simply rotate the main dial or press the arrow buttons on the meter to see the f-stop/shutter speed combinations that will achieve the correct exposure.
When you use a middle-toned portion of a scene as the basis for the meter reading, all of the other tones fall into place correctly. For example, in the shot of an iceberg below, I used the dark gray clouds as the middle tone, and in the picture of the trucks, I had a choice between the dark red paint or the rich blue sky. Both of those areas are middle tone, and reading them allows the entire picture to be properly exposed.
The incident metering mode is not available on cameras. It is a function that is available only with a handheld light meter. In my opinion, this makes a handheld meter like any of the Sekonic models worth its weight in gold.
In incident mode, you use the lens covered by a white hemispherical dome (below) to read the light falling on your subject, instead of measuring the light reflected from it. The difference is that in reflected mode, the meter can be fooled because a white subject and a black subject reflect light very differently. When using incident mode, how light or dark the subject is doesn’t matter because the meter is reading the light emanating from the sky or from an artificial light source before it gets to the subject.
To use the incident mode, you select it on the meter and then hold the device in the light that is falling on the subject when you take a reading. If you and the subject are both in open sunlight, you can take a reading from where you’re standing, near the camera. However, if you are standing under the shade of a tree and your subject is being illuminated by direct sunlight, you must walk over to the subject–or at least into the sunlight–so that the meter detects the same level of light that is falling on the subject.
When you are taking an incident reading from the subject’s position, the meter should be held so that the white dome faces the camera lens, not the light source. This ensures that the light strikes the dome exactly as it is falling upon the subject. For example, if you are photographing a face that is side lit, as with the young Indian girl in the photo below, the light must hit the meter from the side. Hence, the dome must face the lens just like the subject’s face does. By positioning the meter correctly, you will allow it to calculate the exposure correctly, regardless of the colors or the reflectivity of the subject.
You can tweak the exposure for artistic purposes by changing the angle of the meter with respect to the light source. This works for portraiture, landscapes, and anything else. The picture below of a photographer at work on the California coast is a good example. If I held the dome of the meter so that it faced the lens, I would get an exposure that matched what I saw with my eyes. However, if I turned the dome slightly toward the sunlight, the picture would become darker. The choice you make is solely a matter of personal taste; some photographers prefer images that are slightly underexposed, and you can easily get a reading for slight underexposure by angling the dome toward the light.
Incident mode can’t be used when you’re photographing backlit subjects. This includes shooting into a glowing sunrise or sunset sky or any situation in which the light can’t fall on the dome of the meter when it is pointed at the camera. In these situations, you have to switch back to reflected mode. The image below with a tree against the sky is a good example of a scene in which an incident reading won’t work. The incredible spiral staircase in the Vatican Museum provides another example. Even though they are very different pictures, the fact that both of the compositions are backlit means that only a reflected light meter can be used to accurately determine their exposure.
In the backlit photo below, taken in Venice, Italy during carnival, an incident meter could have been used if I had walked up to the model and placed the meter next to the mask. This would have given me a perfect exposure on the costume, but there would have been two problems: The other photographers photographing this person would have been annoyed, and I would have been ignoring the bright background. Therefore, I used the reflected mode to choose the middle-toned area of the composition (I elected to use the gray stone tiles).
Most handheld meters also function as a flash meter. This is extremely valuable in the studio and on location when you are using one or more flash units. The meter is able to detect the brief burst of light, and it will give you a perfect exposure. All the insecurity of flash exposure is gone. Notice in the photos below that the lighting on the model’s face is different. In the first shot I used only one light while in the second I used a main and a fill, and yet the meter in flash mode produced perfect results in both types of light. If you want to do multiple pops from strobe units, a flash meter can evaluate the accumulated bursts of light to determine the correct lens aperture.
When you’re using flash mode, you push a button on the meter and then fire your flash within the next 60 seconds. The meter measures the flash, and its LCD tells you what your camera settings should be. It’s that easy. You can take both incident and reflected readings of a flash, but I have always found the incident readings to be flawless and have always used that method.
Flash mode works beautifully on location as well. When I was in Venice, I did a lot of off-camera flash work, such as in the image below, and the balance between the flash and the ambient light was perfect. When I shot famine figures in Dublin, Ireland, the meter was unaffected by the background darkness. It read the flash perfectly in incident mode.