Metering and Metering Modes

Every modern DSLR has something called “Metering Modes”, also known as “Camera Metering”, “Exposure Metering” or simply “Metering”. Knowing how metering works and what each of the metering modes does is important in photography, because it helps photographers control their exposure with minimum effort and take better pictures in unusual lighting situations. In this understanding metering modes article, I will explain what metering is, how it works and how you can use it for your digital photography.

What is Metering?

Metering is how your camera determines what the correct shutter speed and aperture should be, depending on the amount of light that goes into the camera and the ISO. Back in the old days of photography, cameras were not equipped with a light “meter”, which is a sensor that measures the amount and intensity of light. Photographers had to use hand-held light meters to determine the optimal exposure. Obviously, because the work was shot on film, they could not preview or see the results immediately, which is why they religiously relied on those light meters.

Today, every DSLR has an integrated light meter that automatically measures the reflected light and determines the optimal exposure. The most common metering modes in digital cameras today are:

1. Matrix Metering (Nikon), also known as Evaluative Metering (Canon)
2. Center-weighted Metering
3. Spot Metering

Some Canon EOS models also offer “Partial Metering”, which is similar to Spot Metering, except the covered area is larger (approximately 8% of the viewfinder area near the center vs 3.5% in Spot Metering).

You can see the camera meter in action when you shoot in Manual Mode – look inside the viewfinder and you will see bars going left or right, with a zero in the middle, as illustrated below.

Problems with Metering

Camera meters work great when the scene is lit evenly. However, it gets problematic and challenging for light meters to determine the exposure, when there are objects with different light levels and intensities. For example, if you are taking a picture of the blue sky with no clouds or sun in the frame, the image will be correctly exposed, because there is just one light level to deal with. The job gets a little harder if you add a few clouds into the image – the meter now needs to evaluate the brightness of the clouds versus the brightness of the sky and try to determine the optimal exposure. As a result, the camera meter might brighten up the sky a little bit in order to properly expose the white clouds – otherwise, the clouds would look too white or “overexposed”.

How to Change Camera Metering Mode

Unfortunately, this varies not only from manufacturer to manufacturer, but also from model to model. On the Nikon D5500, for example, it is done through the Info button. On professional cameras such as the Nikon D810 and Nikon D5, there is a separate button on the top left dial for camera metering. Changing metering on Canon cameras also varies from model to model, but generally it is done through a key combination (“Set” button), camera menu or a dedicated metering button close to the top LCD.

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