Olympus E-20N - Manual (Page 71)

5
Taking Pictures:
Brightness (Exposure)
(Aperture and Shutter Speed)
In this section we will show you how to adjust aperture and shutter
speed to achieve the best exposure in your pictures for normal or
special effects.
The camera uses the aperture value and shutter speed to determine
the brightness (exposure) of an image. The shutter speed determines
the length of time that the shutter remains open. With a large aperture
the image becomes brighter (a greater area of the lens is used to
increase the amount of light), but the depth of field becomes shorter,
causing objects closer and farther away from the camera to be out of
focus. Slower shutter speeds create brighter images but increase the
possibility of blurring the image as result of subject movement or
camera shake.