Concepts in Photography

How the aperture setting, shutter speed, and ISO sensitivity control exposure

The aperture setting, shutter speed, and ISO sensitivity are closely interconnected in photography. The aperture setting controls the opening that regulates the light that enters the camera, while the shutter speed determines the length of time that light is allowed to enter.

ISO sensitivity determines the speed at which the film reacts to light. Together, these three aspects are described as the triangle of exposure.

A change in shutter speed, aperture value, or ISO sensitivity can be offset by adjustments to the others to maintain the amount of light. The results, however, change according to the settings. For example, shutter speed is useful in expressing movement, aperture can control the depth of field, and ISO sensitivity can control the graininess of a

Shutter speed

SettingsResults

Fast speed = less light Slow speed = more light

Fast = still

Slow = blurry

High sensitivity

photo.

ISO sensitivity

= more sensitive to light Low sensitivity

Aperture

SettingsResults

Wide aperture = more light Narrow aperture = less light

Wide = small depth of field

Narrow = large depth of field

= less sensitive to light

High = more grainy

Low = less grainy

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