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Exposure Compensation and Auto Bracketing

A camera's automatic exposure meter is not always able to calculate the optimal exposure. As a result, exposure compensation is used to adjust the meter's exposure value. For example, when an image contains strong reflections, the reflected light can cause the image to become dark, or underexposed. When this happens, applying plus compensation creates an optimal exposure. Auto Bracketing automatically records three images, each with a different exposure--one normally exposed, one slightly underexposed, and one slightly overexposed.

Often your camera's automatic exposure function by itself cannot select the optimal exposure for every scene.These cases call for "exposure compensation". Exposure compensation is set using EV values(Exposure value). For example if the compensation range is from -2 to +2 in 1/3 value increments, the photographer can freely decide the level of compensation used. The change in light amount of 1 EV is equivalent to changing the shutter speed or aperture value one level.

For example, in scenes with a solid white color, the extremely high reflective ratio causes automatic exposure to darken the scene to compensate, which turns gray and darkens people's faces. In this case, using plus exposure compensation increases the amount of light.
Also, in scenes with a solid black color, the extremely low reflective ratio causes automatic exposure to increase the scene's brightness, which will make the faces of people look extremely white (called "blown out"). In this case, using minus exposure compensation will reduce the amount of light.

Plus Compensation	Minus Compensation	Other Compensation Examples
When the subject and scene are white	When the subject and scene are black	Strong sunlight streaming in from the window	Accentuating the flower's whiteness

The high reflective ratio of white causes the image to be underexposed, darkens people and turns white to gray.	The low reflective ratio of black causes the image to be overexposed and turns the black subject whitish.	Strong sunlight streaming in from the window causes the person in the foreground to become dark and underexposed.	Using the automatic exposure value.
(+4/3)EV	(-4/3)EV	(+1.0)EV	(+2.0)EV

Adding +4/3 compensation gives a natural color to people's skin and accurately reproduces white subjects.	Adding -4/3 compensation faithfully reproduces the black-colored subject and creates an optimal exposure.	Adding +1 compensation allows us to clearly see the person.	Adding an extremely large amount of plus compensation has the effect of accentuating its whiteness.

This convenient function automatically records three images, each at a different exposure setting, with a single press of the shutter button.This is especially useful in those fleeting, once-in-a-lifetime scenes when you only have once chance to get the exposure right.While this function would use up the film too quickly in a film camera, it can be freely used in a digital camera, because the photographer can easily check the images on the spot and simply delete any that are not needed.

(-1.0)EV (underexposure)	Normal	(+1.0)EV (overexposure)