Metering the Light

Last month, I wrote a basic article on exposure or how the camera’s controls capture an exposure. Exposure is best with metered light. How does your camera see the light? How is it measured? Metering light is different from Focus.

Metering the light is done to get the best exposure for the image. The best exposure is not always what the camera calculates. The light meter in your camera reads the amount of light, not the quality of light. The meter will calculate the exposure based on the ISO, shutter, and aperture. When you control those characteristics, the meter will compensate. Since the meter is technical and not artistic, use the metering as a suggestion only.

What do I mean by suggestion only? For example, in the simplest form, the meter is reading the light thru your lens and filters to get an exposure value (EV). It is a number, like EV 10. If the light doubles it is now an EV of 11 or half the light it is EV 9. The light meter uses the EV against the ISO, Shutter, and Aperture setting to capture

the light. An average image in the simplest form sets the camera to a gray value or 18% gray. This is considered average, and some manufacturers have slightly higher or lower percentages. The camera will suggest you take the image. But, what if the image is backlit or against a bright background like snow? If you allow the camera

to auto meter a snow scene, you’ll end up with gray snow. As your experience grows, you will understand that the suggestion will need to be modified for the scene and compensate the exposure using the exposure compensation button on the camera. So for snow, you’ll need to learn how to overexpose a bit and brighten things up.

Reflective Metering


The camera has a built-in exposure meter which reads “Reflective” light, or light that bounces off the subject and is read in the camera.

Incident Metering

External metering such as using a handheld light meter can be used to measure the light directly. It reads the intensity of the light falling on your subject, not the light reflected back from the subject. Handheld meters are great tools, but if you understand how light works you can do just as well with the internal metering of your camera.

 

Measuring Types

The simplest form of measurement is the 18% gray EV. As cameras became more technical, the metering improved. Cameras today may have manual, Matrix Metering (Nikon), Evaluative Metering (Canon), Center-weighted metering, as well as spot or partial metering. Each has its strengths for particular lighting situations. These types of metering may emphasize one area over another area.

Manual Metering
When looking in your viewfinder, you’ll see the light meter at the bottom. It is a scale of bars (EV) with the bars going left and right of “0”, which is in the middle. If you point your camera at a bright area, the bars will go to “+” side.

If you point at the dark area, the bars will go to “-” side. You would then need to increase or decrease exposure to optimal exposure, based on the subject.

Matrix/Evaluative Metering
This mode is the default metering mode for most cameras. Matrix/Evaluative Metering uses a matrix or zones that are considered more important. Each zone is analyzed individually for light and dark values. Factors such as the color, distance, subjects, highlights and where the focus point is weighted are all used by the camera to calculate EV for the exposure. For instance, when your camera focuses on a face, the metering will give priority to the focused area. It considers that area the most important.

External metering such as using a handheld light meter can be used to measure the light directly. It reads the intensity of the light falling on your subject, not the light reflected back from the subject. Handheld meters are great tools, but if you understand how light works you can do just as well with the internal metering of your camera.

Center-weighted Metering
For Center-weighted metering, the light will be metered In the middle/center of the frame. It does not look at the focus point as the priority area. It can be used for close- ups, portraits and relatively large subjects.

Spot Meter
Spot Metering only evaluates the light around a small area and ignores everything else. Some DSLRs are capable of multi-spot metering. You may need to meter in one spot and recompose to make the image, such as when you have a person with the sun behind them and they occupy a small part of the frame. Spot metering is also helpful photographing birds (against a bright sky), as well as for photographing the moon.

Setting the Metering
Not only does setting the metering vary from manufacturer to manufacturer, but also from model to model. On a Nikon D3300, D5300, it is done through the menu setting (Info button). On Nikon D810 and Nikon D4s, there is a separate button o n the top left dial for camera metering or camera menu.

You will need to research metering for your camera.

Experimentation is encouraged. You should try out the different modes and find what works for you.

In summary, understanding the different metering choices available on your camera will open up many more options for you and allow you to get that perfect exposure for the whatever you are trying to capture.

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