16Concepts in PhotographyApertureThe aperture is one of the three factors that determine the exposure. Theaperture housing contains thin, metal plates that open and close to letlight through the aperture and into the camera. The size of the apertureis related to the amount of light: a larger aperture allows more light and asmaller aperture allows less light.Aperture sizesMinimum aperture Medium aperture Maximum apertureAperture opened slightly Aperture opened wideThe size of the aperture is represented by a value known as an "F-number."The f-number represents the focal length divided by the diameter of thelens. For example, if a lens with a 50 mm focal length has an f-number ofF2, 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 fine-tune theamount of light by subdividing exposure values into 1/2, 1/3 EV, and so on.+1 EVF1.4 F2 F2.8 F4 F5.6 F8-1 EVExposure Value Steps
