CAMERAS - what are they?
October 11th 2007 05:26
A good old fashioned photograph of unquestionable charm
So, what is a camera? Wikipedia takes us through some definitions.
A camera is a device used to capture images, as still photographs or as sequences of moving images (movies or videos). The term as well as the modern-day camera evolved from the camera obscura, Latin for "dark chamber", an early mechanism for projecting images, in which an entire room functioned as a real-time imaging system. The camera obscura was first invented by the Iraqi scientist Alhazen and described in his Book of Optics (1011-1021). English scientists Robert Boyle and Robert Hooke later invented a portable camera obscura in 1665-1666.
The old fashioned way
Camera obscura
All cameras, all different
Cameras may work with the light of the visible spectrum or with other portions of the electromagnetic spectrum. A camera generally consists of some kind of enclosed hollow, with an opening or aperture at one end for light to enter, and a recording or viewing surface for capturing the light at the other end. Most cameras have a lens positioned in front of the camera's opening to gather the incoming light and to focus the image, or part of the image, on the recording surface. The diameter of the aperture is often controlled by a diaphragm mechanism, but some cameras have a fixed-size aperture.
The first colour photograph
The size of the aperture and the brightness of the scene control the amount of light that enters the camera during a period of time, and the shutter controls the length of time that the light hits the recording surface.
Focus
Due to the optical properties of photographic lenses, only objects within a certain range of distances from the camera will be reproduced clearly. The process of adjusting this range is known as changing the camera's focus.
Image capture
The 19th century studio camera had bellows for focusing.Traditional cameras capture light onto photographic film or photographic plate. Video and digital cameras use electronics, usually a charge coupled device (CCD) or sometimes a CMOS sensor to capture images which can be transferred or stored in tape or computer memory inside the camera for later playback or processing.
modern day lens
The pin hole camera
A pinhole camera is a camera without a conventional glass lens.
The picture gives you the idea of how they work.The image may be projected on a translucent screen for real-time viewing (popular for viewing solar eclipses;, or can expose film or a charge coupled device (CCD). Pinhole cameras with CCDs are sometimes used for surveillance work because of their small size.
Pinhole camera
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