How does your camera know what the correct exposure is? Your camera's
exposure system evaluates light reflecting from your subject and
selects an aperture value and shutter speed combination that will
represent your subject in an approximate average tone (not too bright
and not too dark). Pros refer to this as “18% gray.” This
works well for almost all your shooting situations except when your
subject happens to be darker or lighter than an average tone. This is
where it is helpful to apply the following rule of thumb: (-) exposure
compensation darkens the image; (+) exposure compensation brightens the
image.
Overexpose for
lightly toned objects or subjects that dominate the scene:
Apply exposure compensation on the (over) plus (+) side.
Camera's Exposure
Image with +1 Exposure Compensation
Underexpose for
darker toned objects or subjects that dominate the scene:
Apply exposure compensation on the (under) minus (-) side.
Camera's Exposure
Image with -1 Exposure Compensation
Although we are using white or black objects in the above examples, the
same principle can be applied towards colored subjects. For example,
you may need to underexpose to show the true deep blue of an afternoon
sky.
Camera's Exposure
Image with -1 Exposure Compensation
If you are unsure whether to apply -1, -2, etc., take a few shots and
download them to a computer to evaluate which gave you the best
image. Some camera models let you increase or decrease
exposure gradually in 1/2 or 1/3rd increments. Your camera may also
offer Auto Bracketing which lets you take several images in a row with
different exposure compensations set. Remember, (-) exposure
compensation darkens the image and (+) exposure compensation brightens
the image.
Depending on your camera model, exposure compensation may be located in the camera's shooting menu or accessed by pressing the left or right arrow buttons on the back of the camera. Refer to the full reference manual located on your CD-ROM or download the manual by clicking here and look for Exposure Compensation.
