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How to use exposure lock
Techniques
24 October 2007 09:23
The multi-segment metering built into every DSLR is great at getting the exposure right, most of the time. However, some situations will fool the meter into under or overexposure – especially when the viewfinder is dominated by very bright or very dark areas.
Experienced photographers can override the camera’s automatic metering system by using either exposure compensation, or shooting in full manual mode. But there is an easy way to help without having to know about f-stops or setting the exposure yourself.
Automatic exposure lock allows you to remain in a full auto mode but, as the name suggests, it locks a reading taken from another, easier to meter, area of the scene.
The key to using this function is in selecting the right area to take that reading from.
1. Choose a section of the scene that contains as few really bright or dark sections as possible. This will mean that the camera is much more likely to get the exposure right, and you won’t have to spend as much time adjusting your images later. So, if you’re shooting a typical landscape, tilt the camera down and meter from the foreground.
2. Assess the wrong exposure. In our example, the bright sky taking up a large area of the frame has led the camera to underexpose the image.
3. Point the viewfinder at a less contrasty part of the scene. To get a more balanced exposure we’ve re-framed so that only a small amount of sky is visible.
4. Press the exposure lock button on your camera to set and lock that exposure.
5. Reframe and take the shot. With the exposure lock set, it’s simple to go back to the original framing. The reading from the foreground mid-tones gives a more evenly exposed result.