A camera is an optical instrument for recording or capturing images, which may be stored locally, transmitted to another location, or both. The images may be individual still photographs or sequences of images constituting videos or movies.The camera is a remote sensing device as it senses subjects without physical contact. The word camera comes from camera obscura, which means "dark chamber" and is the Latin name of the original device for projecting an image of external reality onto a flat surface. The modern photographic camera evolved from the camera obscura. The functioning of the camera is very similar to the functioning of the human eye.A camera may work with the light of the visible spectrum or with other portions of the electromagnetic spectrum.[1] A still camera is an optical device which creates a single image of an object or scene, and records it on an electronic sensor or photographic film. All cameras use the same basic design: light enters an enclosed box through a converging lens/convex lens and an image is recorded on a light-sensitive medium(mainly a transition metal-hallide). A shutter mechanism controls the length of time that light can enter the camera.[2] Most photographic cameras have functions that allow a person to view the scene to be recorded, allow for a desired part of the scene to be in focus, and to control the exposure so that it is not too bright or too dim.[3] A display, often a liquid crystal display (LCD), permits the user to view scene to be recorded and settings such as ISO speed, exposure, and shutter speed.A movie camera or a video camera operates similarly to a still camera, except it records a series of static images in rapid succession, commonly at a rate of 24 frames per second. When the images are combined and displayed in order, the illusion of motion is achieved.The forerunner to the photographic camera was the camera obscura.[7] In the fifth century B.C., the Chinese philosopher Mo Ti noted that a pinhole can form an inverted and focused image, when light passes through the hole and into a dark area.[8] Mo Ti is the first recorded person to have exploited this phenomenon to trace the inverted image to create a picture.[9] Writing in the fourth century B.C., Aristotle also mentioned this principle.[10] He described observing a partial solar eclipse in 330 B.C. by seeing the image of the Sun projected through the small spaces between the leaves of a tree.[11] In the tenth century, the Arabic scholar Ibn al-Haytham (Alhazen) also wrote about observing a solar eclipse through a pinhole,[12] and he described how a sharper image could be produced by making the opening of the pinhole smaller.[11] English philosopher Roger Bacon wrote about these optical principles in his 1267 treatise Perspectiva.[11] By the fifteenth century, artists and scientists were using this phenomenon to make observations. Originally, an observer had to enter an actual room, in which a pinhole was made on one wall. On the opposite wall, the observer would view the inverted image of the outside.[13] The name camera obscura, Latin for "dark room", derives from this early implementation of the optical phenomenon.[14] The term was first coined by mathematician and astronomer Johannes Kepler in his Ad Vitellionem paralipomena of 1604.
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