| The camera device (photographic device or photo camera) is a device that converts a light stream from a real object into a recording (storing) for comfortable view and which stores still pictures from a real life picture.
Transformation of the light stream:
The light stream from a real subject is limited by the lens’s view angle; focused in the focal plane as required by the photographer’s point of view; gauged according to intensity (aperture) and time of the effect; balanced according to color and etc.
Recording (storing) of the light stream:
The detection (finding) and storing of pictures in analogue cameras are carried out by light-sensitive material (photo film, photo plate etc). The detection (finding) of pictures in digital camera is done by a matrix, and the storing is carried out in the buffer and external flash-memory of digital cameras.
The mechanism of a camera
Modern cameras consist of: light-tight housing; optical system with focus systems: stabilization, stopping-down; viewfinder; matrices, which, in turn, can have system of focusing and stabilization, or set-up mechanism and photo-film feeding; shutter; expositional meter and expositional pair devices (exposition and diaphragm) devices; microprocessors; automation; electronics; LCD; memory card; flash-light; battery etc.
Light-tight housing serves for fixing the camera mechanism and avoiding unauthorized light striking the sensitive material or matrices.
The optical system projects the real image of the photographed pictured on the focal plane, where the light-sensitive film or matrix is located.
In the optical system of all digital cameras for the reception of more contrast in pictures an infra-red filter is established behind an objective (before a matrix) which closes the matrix from an infra-red part of the spectrum.
On LCD and optical view-finders borders of a shot and a place for shooting are selected.
The optical view-finder shows that the frame borders are inaccurate. Usually in the documentation to the camera, the parity of a visible and real frame is indicated.
The mechanical photographic shutter doses out light falling on a photosensitive layer of film (for film devices) or a photosensitive matrix (for mirror digital devices).
The non-mirror digital chambers use a mechanical photographic shutter for prevention of light falling on the sensor after the termination of the endurance time so that there is no halation, blurring or smearing.
The mechanical shutter has an electric drive and is driven by the processor. The basic characteristic of a mechanical shutter is the minimum endurance which it can provide. The shutter works for simple digital cameras in a range from 5-15 seconds to about 1/500 second. Endurance is less than about 1/500 second and is always fulfilled by an electronic equivalent of the shutter - (up to 1/4000 second and less).
Digital video cameras and some (because of the price) special digital cameras have no mechanical shutter in which digital cameras without a mechanical shutter for providing the high speed capturing of the image (with a CCD-matrix with frame transfer of charging) are used. In this case, in the camera there is the second shaded "storing matrix" where the image, after the termination of exposition time, is located.
Irrespective of availability or non-availability of the mechanical shutter, all digital cameras are equipped with an electronic equivalent of a shutter which is built into a sensor.
The electronic shutter is a switch which includes a sensor for reception of a light stream and switches off at the command of the processor. The processor strobes the electronic shutter. |
