Translations of Encyclopedia about Physics

Photographic Equipment

Photographic equipment, or cameras, are devices used to make photographs. A camera is made of the following parts: a case used to prevent light from passing through it, equipment used to save on and shift material sensitive to light (plate, film), a lens, a stop, a shutter, and a view finder to help aim the camera when taking a picture. The lens of a camera is made up of a set of several types of lenses which make it possible to create a photograph.

At present, the film used for taking pictures is covered with a thin layer of emulsion sensitive to light (sensitive layer) which registers differences between various brightnesses created by an optical image. The light beams which fall on the emulsion as a result of their reflection (or emission) from various points on an object (on which the camera is aimed) result in an uneven dissolution of silver bromides. During this dissolution, electrons are removed from halogen ions. After chemical processing, an image is formed on the film, as such creating a negative from which copies can be made.

The most important parts or functional principles of a camera are:

The Lens

The lens or objective is made of a set of lenses and or mirrors located within a metal cylinder. The photographed object is projected as an image by the lens onto photographic material sensitive to light. With standard lenses, the focal point distance is roughly diagonal to the picture format, but larger angles are possible with wide angle lenses. Zoom lenses are then used to photograph objects located at a distance. Lenses or objectives are also used in microscopes and telescopes.

Stop

A stop is an adjustable shutter located between the lens and the film and which may be increased or decreased in size. In this manner, it regulates the amount of light which enters the camera. It can also affect sharpness, the depth of sharpness, and the brightness of the object as it appears on the negative, which can also be changed by adjusting the exposure time.

Focal Point Distance

The focal point distance is the distance between the main plane of the lens’s optical centre and the surface of the photographic material (film or plate) and is the fundamental parameter of each photographic equipment which creates an optical image. The size of the picture captured on the film depends on this focal point distance.

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