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Exposure compensation


12 September 2007 10:03

As clever as cameras and metering systems can get, they are still no substitute for human intelligence. Meter readings are often thrown off balance for a number of reasons, resulting in unuseable images, which is why exposure compensation is a feature on almost all cameras. Expressed in EV (exposure value) + or - units, it compensates for errors in the camera’s meter reading. One EV is also often called a stop.

For example, if your meter gives an exposure of 1/200sec at f/10, but you know that you’ll want your picture lighter, dialling in +1EV would give you an exposure of 1/125sec at f/8 and a lighter image. Alternatively, should you want a darker image, selecting -1EV would now give you an exposure of 1/250sec at f/11, and so a darker image.

Exposure compensation let's us trick cameras into getting the exposure right.  It is also useful to combat the characteristics of particular cameras to consistently over- or underexpose images. Many professionals always keep at least -2EV dialled in to preserve the delicate digital highlights, while many slide film users set -0.5EV to give more saturation to the colours.