Three camera settings determine the exposure for a photograph: shutter speed, aperture and ISO. Each setting controls light differently. Many combinations of these settings can be used to achieve the same exposure. A camera is simply a lightproof box with a lens at one end and light sensitive material at the other. In a digital camera, this light sensitive material is the camera’s image sensor. The ISO setting determines how sensitive the image sensor is to incoming light. As light enters the lens, its intensity is controlled by the aperture. The shutter opens and controls the amount of time the light is allowed to expose the image sensor, and an image is recorded.
Use this collection of resources as a review of the basics of aperture, shutter speed and ISO settings to help you determine proper exposure.