ABSTRACT
This chapter outlines the major features of cameras as an introduction to the important topics. It shows under what conditions an "equivalent image" can be obtained with cameras having film/sensors of different sizes. A camera is essentially a box that contains a lens and a light sensor. The earliest cameras were quite large, and the light detector was a sensitized photographic plate. In the early days of photography, the way to make a larger photograph was to use a larger camera. In spite of successful efforts to develop enlargers for photographs, many professional photographers preferred large plate film cameras. The modern history of the camera consists of a series of steps toward total automation. Digital cameras in 21st century are evolving quickly. In 2010 most camera sensors were found in cell phones, and cell phone cameras had attained such high quality that the market for small digital cameras was decimated.
