Understanding Exposure

 

The exposure of an image is determined by the amount of light that strikes your digital camera’s image sensor. If too much light makes its way to the sensor (over exposure) the resulting photo will be too bright with little or no discernable detail in the image. Too little light (under exposure) results in a dark image making it hard to see anything in the picture at all. A quick look at the photos below will let you see what I’m talking about.


An under-exposed photo…


Over-exposed…


And the same photo at the proper exposure.

 

Your digital camera’s exposure level is controlled by two settings:

  1. Shutter Speed – The camera’s shutter can be set to open and close within a discrete length of time. Fast shutter speeds allow less light to pass through the lens while slow shutter speeds allow more light in. Given the same aperture setting, the slower the shutter speed the brighter the resulting image will be (the greater the exposure level).
     
  2. Aperture – The aperture setting (known as f-stops) determines the size of the “hole” through which the light passes while the shutter is open. The wider the aperture (the larger the hole), the more light that passes through and the higher the exposure level for a given shutter speed.

You can choose one of several picture-taking modes that allow you to vary the shutter speed and aperture for the best picture in most any situation, or you can select a mode that instructs the camera to choose the settings for you!