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...
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