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Photography: Exposure and light metering modes

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All digital cameras have a built-in light meter or "exposure meter". Point the lens at your subject and it will measure the amount of light reflected by all or part of the scene seen through the lens. In order to obtain an appropriate calculation of the required exposure, you can take the brightness of either the entire scene, a broad region in the middle of the scene, or a tiny part of the scene.

1. Measuring exposure

Multi-zone or matrix metering

Used to calculate the average brightness of the entire frame. Includes the ability to ignore a small abnormally bright area (such as the sun or reflections of glass), giving correct exposure in most cases.

  •  Particularly suitable for scenes lit by a single light source such as family portraits or  group photos.

Centre-weighted metering
Gives a 75% weighting to a broad section in the centre of the image, and a 25% weighting to sections at the edges of the picture.

  • Good for classic outdoor shots or scenes with differences in contrast.

Partial or spot metering
Designed to measure a tiny section (typically represented by a small circle in the centre of your camera's viewfinder) covering 1-4% of the frame. The exposure is therefore set based on a small section of the image, leaving you to produce interesting effects with the contrast.

  • Useful e.g. for taking a child's face against the light, or a subject lit up against a dark background.

2 . Fixing the exposure

Once you have taken the exposure, you may need to re-frame or re-focus your image.

  •  Press Ý or AEL (Auto-Exposure Lock) to fix the exposure setting prior to re-framing and re-focusing as required. When you let go, the picture will be taken with these settings. If you let go of the shutter, the stored setting will be wiped after a few seconds.
  • Tip: see your camera instructions for details.