16
Concepts in Photography
Aperture
The aperture, a hole that controls the amount of light that enters the
camera, is one of the three factors that determine the exposure. The
aperture housing contains thin, metal plates that open and close to let
light through the aperture and into the camera. The size of the aperture
is closely related to the brightness of a photo: the larger the aperture, the
brighter the photo; the smaller the aperture, the darker the photo.
Aperture sizes
Minimum aperture Medium aperture Maximum aperture
Darker photo
(aperture opened slightly)
Brighter photo
(aperture opened wide)
The size of the aperture is represented by a value known as an โ€œF-number.โ€
The f-number represents the focal length divided by the diameter of the
lens. For example, if a lens with a 50 mm focal length has an f-number of
F2, the diameter of the aperture is 25 mm. (50 mm/25 mm=F2) The smaller
the f-number, the greater the size of the aperture.
The opening in the aperture is described as the Exposure Value (EV).
Increasing the Exposure Value (+1 EV) means the amount of light doubles.
Decreasing the Exposure Value (-1 EV) means the amount of light halves.
You can also use the exposure compensation feature to ๎€‚ne-tune the
amount of light by subdividing exposure values into 1/2, 1/3 EV, and so on.
+1 EV
F1.4 F2 F2.8 F4 F5.6 F8
-1 EV
Exposure Value Steps