Ultimately, all photography boils down to light. The exposure of a photograph can make or break an image. Your camera’s metering system is the way it measures the amount of light entering the camera through the lens. It only picks up reflected light, not the actual light that is falling on the scene (unless you have an incident light meter in the scene).
Your camera assesses this reflected light, then sends information that ultimately dictates exposure settings such as shutter speed and aperture. With the help of Clifton Cameras – specialists in cameras and retailers of Canon lenses – we provide you with useful and tips regarding your camera’s metering system.
Metering on a camera functions as a guide, which means you can alter it or ignore it at any time when taking more creative shots. Because you’re only measuring reflected light, you may also need to manually adjust anyway – as shooting reflective, bright surfaces like snow can skew an image. Your camera has distinct metering modes to try and cope with changeable lighting, but knowing how to use them can be complicated.
Depending on which brand of DSLR you’re using, matrix or evaluative metering is the default mode that measures light across the entire frame of the viewfinder. It aims to present a more even exposure based on the entire scene. The image is broken down into small zones, which is then combined to form a better choice for exposure.
On a modern camera, the sun can be compensated for when it makes everything else look too dark – this is because evaluative and matrix metering helps to establish the most important parts of the image in the frame.
Evaluative metering puts bias on the auto focus points that you’ve selected on the camera, which can affect the final look of the image, depending on where you’re focusing.
In general photography, matrix/evaluative metering is the best solution. When a scene is evenly lit and you need to capture shots quickly, there’s no better mode to use. It’s essentially the fire and forget metering system.
In this mode, the importance of light is placed within the centre of the frame. However, this isn’t the same as spot metering — a measurement of a small part of a scene. Instead, centre-weighted metering takes around 60-80% of the importance from quite a large circle in the centre of the screen. Essentially this means the camera measures the light across the entire frame, but biases the centre point. It doesn’t use the focus point, like with matrix/evaluative metering.
This is best for portrait photography, as they benefit from centre-weighted metering, as typically it will provide weight to the subject, and doesn’t provide emphasis on the background of the photo. Because it doesn’t give much weight to backgrounds, it’s very useful when your subject is heavily backlit. Centre-weighted metering doesn’t have automatic exposure compensation, however, so you’ll need to manually compensate to get the perfect settings.
If you want to isolate your subject, then use spot metering. It’s a mode that sets a small area of focus for your metering – measuring the intensity of light over the circular area in the centre of the viewfinder. From this, the average is calculated by measuring something between 1 to 5% of the total area of the frame. Most spot metering systems do this over your selected focus point.
Spot metering is favoured by professionals, as you are able to focus on the specific details that you’d like. In a backlit portrait, for example, you can eliminate silhouetting by using spot metering on the subject’s face. It’s great for macro photography and wildlife photography at a distance, as the exposure will be calculated based on the light around your subject rather than the full frame.
When taking photographs of the moon, spot metering is also useful. By focusing on the moon’s light – the camera will not focus on light within the rest of the sky. A different mode would result in a lack of detail in the moon, as the metering tries to even out the light.