The camera
The cameraThe Camera
The camera is defined as an apparatus for taking photographs or film or television pictures. It is a lightproof box through which an image is focused and recorded on film. Today there are many different types of cameras in use, all of them more or less advanced versions of the first camera. Nearly all of them are made up of the same basic parts:
-A body (the lightproof box)
-A lens and a shutter to control the amount of light reaching the light-sensitive medium
-A viewfinder to frame the scene
-A focusing mechanism.
Still Cameras
Focusing and Composing the Scene
All cameras use a lens for focusing, except for pinhole cameras, which focus the image on the film through a tiny hole. The focal length of a lens, i.e., the distance between the rear of the lens (when focused on infinity) and the film, determines the angle of view and the size of objects as they appear on the film. The image is focused on the film by adjusting the distance between the lens and the film. In most 35-mm cameras, this is done by rotating the lens. With twin-lens reflex and larger view cameras, the whole lens and the panel are moved toward or away from the film. To view an object for composing nearly every camera has some kind of viewfinder. One of the simplest types is a screen that is placed on the back of the camera and replaced by the film in making the exposure. This time-consuming procedure is avoided in the modern 35-mm single-lens reflex cameras by placing the screen in a special housing on top of the camera. Inside the camera there is a movable mirror that bounces the image from the lens to the screen for viewing and focusing, and then flips out of the way when the shutter is tripped, so that the image hits the film instead of the mirror. The mirror automatically returns to place after the exposure has been made. In rangefinding cameras, the object is viewed by two separate windows; one views the scene directly and the other contains an adjustable optical mirror device. When this device is adjusted by rotating the lens, the image entering through the lens can be brought into display with the image from the direct view focusing the object on the film.
Controlling the Light Entering the Camera
Its maximum opening through which light enters the camera indicates the speed of a lens. This is controlled by an iris diaphragm, which is a series of overlapping metal blades that form a circle with a hole in the center whose diameter can be increased or decreased. A shutter controls the time during which light is permitted to enter the camera. There are two basic types of shutters:
- Leaf-type
- Focal-plane.
The leaf-type shutter employs a ring of overlapping metal blades similar to those of the iris diaphragm. It is normally located between the lens elements but sometimes placed behind or in front of the lens. The focal-plane shutter is located just in front of the film plane and has one or two cloth or metal curtains that travel vertically or horizontally across the film frame. By adjusting the shutter speed, the proper amount of light for a good exposure can be obtained.
Features of Modern Cameras
Most of today's 35-mm cameras incorporate a rapid film-transport mechanism, lens interchangeability, and a built-in light meter. Many also have an automatic exposure device where the shutter speed is regulated automatically to produce the “correct” exposure. Accessories include filters, which correct for deficiencies in film sensitivity; flash bulbs and flash mechanisms for supplying light; and monopods and tripods, for steady support. Simple box cameras are fixed-focus cameras with limited or no control over exposure. Twin-lens reflex cameras use one lens solely for viewing while the other focuses the image on the film. Other popular cameras are compact 35-mm rangefinding cameras, 126 cartridge cameras, and the subminiature cameras, which uses 9.5-mm film.
Development of the Camera
The first camera was invented during the Grecian times. It was a dark box large enough for the viewer to stand inside; with a small hole in one side. A lens was not employed for focusing until the Middle Ages. An inverted image of a scene was formed on an interior screen. An artist then traced it. The first diagram of a camera appeared in a manuscript by Leonardo da Vinci in 1519, but he did not claim the invention. Joseph Nic�phore Ni�pce first achieved the recording of a negative image on a light-sensitive material in 1826. He coated a piece of paper with asphalt and exposed it inside the camera for eight hours. Even though different kinds of devices for making pictures had been invented as early as the 1860s, E. J. Marey built the first motion picture camera in 1887. Two years later Thomas Edison invented the first successful camera. However, cinematography was not accessible to amateurs until 1923, when Eastman Kodak produced the first 16-mm reversal safety film, and Bell & Howell introduced cameras and projectors that use 16-mm reversal safety film. Systems using 8-mm film were introduced in 1923 and larger frame sizes appeared in 1965.
Bibliography
The Encyclopedia of Photography (1971);
The Focal Encyclopedia of Photography (1972).