Sometimes it is necessary to take a step back and review the basics. Camera controls are all about modifying light, either how much light strikes the film or how sensitive the film is to light. The two primary ways to control the light striking the film are shutter speed and aperture. Shutter speed
controls how long light is allowed to strike the film while aperture
controls how much light strikes the film. These two controls work in conjunction with the ISO setting
(that controls the film sensitivity in digital cameras and refers to the film sensitivity in film cameras) to fine tune the light recorded by the camera.