Exposure compensation is used to alter the camera’s standard exposure settings.

Introduction

In the Auto Exposure Mode, your camera will select the aperture and shutter speed to set the exposure. But if the subject is not medium tone, The Auto Exposure mode can get fooled. You will need to use the exposure compensation dial to allow more or less light to your sensor. Use plus compensation for light subjects and minus compensation for dark ones. Some experimentation may be required before your pictures turn out exactly the way you want them to.

As we mentioned in the earlier article on Auto Exposure, the light meter in your camera assumes that all subjects are medium in tone and reflect 18% of the available light. However, in actuality some subjects reflect more light than others.

If your subject is water that either reflects a lot of sky or appears white because it is moving, using the Auto Exposure Mode will leave you with a picture that is too dark. This is called underexposure. It occurs because white subjects reflect about 36% of light instead of the normal average of 18%.

To achieve proper exposure in such an instance, set the exposure compensation to plus 1. This will allow more light to enter the camera, and will yield a picture in which the white water looks white and the darker water a lighter, more natural, color.

Snow is another subject that is not medium tone. If you rely on your light meter alone to govern your exposure, the white snow will appear gray.

To get proper exposure for a snow scene, dial plus 1 compensation to allow more light to reach your sensor. This will make the snow in your picture appear as brilliant and white as it does in nature.

As with light subjects, when shooting a darker subject, your camera still assumes a reflection of 18% of light. Because the tortoise only reflects 9% of the light, your camera will allow in an amount of light that will make this tortoise appear medium gray instead of dark brown. This is called overexposure.

To get proper exposure of a dark subject, set your exposure compensation to minus 1. The subject will appear darker, and in the case of this tortoise, a more natural color.

Conclusion

For subjects that are medium in tone, use the camera settings indicated by the light meter. For subjects with a lot of white such as moving water, snow or iceberg, use plus compensation to let in more light. For darker subjects, choose minus compensation to reduce the amount of light let into the camera.

To use exposure compensation, you need to refer to your camera manual for your camera.