The amount of light that reaches the film in a camera depends on the lens aperture (the effective area) as con-trolled by the diaphragm. The f-number is the ratio of the focal length of the lens to its effective diameter. For example, an f/8 setting means that the diameter of the aperture is one-eighth of the focal length of the lens. The lens setting is commonly referred to as the f-stop.
(a) Determine how much light each of the following lens settings admits to the camera as compared with f/8: (1) f/3.2 and (2) f/16.
(b) The exposure time of a camera is controlled by the shutter speed. If a photographer correctly uses a lens setting of with a film exposure time of 1/60 s, what exposure time should she use to get the same amount of light exposure if she sets the f-stop at t/5.6?