Exposure Compensation

In many extreme situations, you perhaps should not trust completely the exposure measure provided to you from the camera exposure metering system. In these cases, you need to use Exposure Compensation. This can be done easily with the +/- button and the command dial:

The +/- Button The Command Dial

Pressing the +/- while turning the command dial increases or decreases the compensation level. Nikon Coolpix 950 permits a 1/3 stop increment/decrement. More precisely, turning the command dial to the right (resp., left) increases (resp., decreases) the compensation level in +1/3 stop (resp., -1/3 stop). The range of the compensation level is from -2 stop to +2 stop. The bottom of the LCD monitor displays the current compensation level. In fact, the compensation values are rounded and, as a result, the displayed values are -2.0, -1.7, -1.3, -1.0, -0.7, -0.3, 0.0, +0.3, +0.7, +1.0, +1.3, +1.7 and +2.0. Therefore, with the current setting of aperture and shutter speed, we still have plus-minus 2 stops for fine-tuning the exposure measure.

Why Is Exposure Compensation Necessary?

A camera's exposure meter is always calibrated at the so-called middle gray level, which means the gray color that is between white and complete black and reflects 18% of the incoming light. When you point your camera at your subject and take a meter reading, the meter will consider the intensity of light being read as the middle gray. So, this creates problems!

Suppose most area in your photograph is white, say snow covered. The exposure meter will treat that white area as middle gray. When you take your shot, the white area will look grayish. The following photographs were taken in an early morning. Because the scene is snow covered, the camera exposure meter considers this white area being middle gray. So, the snow covered area looks grayish.

No Compensation
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Because the exposure meter treats white as gray in the photograph, to make a gray color a white one, we need to increase the exposure with the +/- button. The first photograph below is taken by setting the compensation level to +2/3 stop. As you can see, the snow covered area is not so gray. Increasing the compensation level to +1 stop, the snow covered looks even whiter as shown in the second photograph. You can increase the compensation level to other value to get a more realistic looking snow covered area.

+2/3 stop +1 stop +1 1/3 stop +1 2/3 stop
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In general, if your subject is bright, you perhaps need to increase the compensation value so that the bright area looks white. On the other hand, if your subject is dark, you should decrease the compensation level. Why? Since the exposure meter now considers a dark area as middle gray, this will make the darker area brighter in your photograph. Therefore, to make dark area dark, you need to decrease the compensation level.

Other Common Uses

The most commonly seen situation is backlighting. That is, the light sources are behind the subjects. In this situation, the subjects are not illuminated by the light sources and hence look dark. The left image is an example. Because we need to emphasize the subjects rather than the background, exposure has to be increased to show the details of the subjects. In this case of the image below, I chose to increase exposure one stop and obtained the right image below. Now the details can be seen clearly.

No compensation +1 stop
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Another frequently encountered situation looks like the left image below. The scene contains two areas, one in the shadow and the other under strong sunlight. It is a challenging situation for one on-camera meter, and, as a result, the background (light) area may be exposed correctly while the foreground could become too dark. Should this happen, using exposure compensation is a better strategy. The middle image was taken with a 2/3 stop increase, while the right one has 1 1/3 stop. Note that the middle one has a better balance than the right one because it preserves the background and includes foreground details. The right one exposes the foreground very well, but washes out the background.

No compensation +2/3 stop +1 1/3 stop
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What is "the" Correct Exposure?

It is really difficult to answer this question, because it depends on your artistic point of view. An exposure value you like may not be a good one from a different point of view. The following shows three photographs taken about the same time. The left one has no compensation. But, I know I would get an overexposed photograph without some of the (color) details if I increase the compensation level. The middle and the right photographs have -0.7 and -1.7 stop decrements, respectively. So, the one you like most has "the" correct exposure!

No Compensation -0.7 stop -1.7 stop
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