See also: Room

A darkroom (in Latin camera will obscura ) is a optical Instrument objective which makes it possible to obtain a Projection Lumière on a plane surface, i.e. to obtain a sight in two dimensions very close to the human Vision.

Principle

The basic principle is very simple: as the light is reflected by the objects in all the directions according to their specific qualities of absorption, reflection, of diffusion, each point of the surface of a screen receives luminous rays resulting from all the neighborhood objects; these rays mix and combine (additive Synthèse). The screen appears Blanc (or of the major color illuminant the decoration).

By restricting the external light so that its luminous rays, emanating from the decoration, enter only by one point a obscure room , the screen intercepting this light will not receive, of each precise point of its surface, that the rays resulting, in straight line (principles of geometrical optics) of only one point of the decoration placed opposite the wall comprising the hole. One will see creating the image reversed (left/right) and reversed (high/low) of the decoration, external with the obscure room, on the screen.

The projected image is real since received on a screen (that the eye of the observer is present or not): the instrument is known as objective .

The principle in is described as of Aristote and several times evoked by authors of the 13th century (Roger Bacon, Guillaume de Saint-Cloud)

Implementation

However one started to use this apparatus only at the 16th century, in particular for topographic surveys. One worked out a portable device in order to be able to follow contours of the image projected on a sheet of paper or a plate glass and to defer it on another support.

In 1515, Léonard de Vinci explains: By letting the images of the enlightened objects penetrate by a small hole in a very obscure room you will then intercept these images on a white sheet placed in this room. but they smaller and will be reversed.

The camera will obscura is gradually improved by the addition of a lens (towards 1550) then of a diaphragm and sometimes of an inclined mirror with 45°, the ancestor of the Reflex.

The theory whereby Johannes Vermeer would have used this camera will obscura to paint part of its work was exposed for the first time in 1891 by the American lithographer James Pennell. It since was largely rested by researchers in Histoire of art. The painter David Hockney made appear a work Secret Savoirs; Techniques Lost Of the Former Masters in whom it shows that since the beginning of the Renaissance, a great number of painters, among most famous, used optical copying processes, camera will obscura , but also Camera lucida , to set up their tables. Work of Hockney was criticized by Ross Woodrow, of the University of Newcastle in Australia.

He as probable as it was employed by other artists, of which Giovanni Baptista della Porta, Guardi and especially Antonio Canal, is said Canaletto, who used it in particular to put in prospect his famous landscapes for the channels of Venice but also Alberti share which, him, took part in his improvement (system of mirrors allowing to obtain reduced drawings of panoramas).

Other artists will not make mystery of the use of the camera will obscura , as for example the Daniells which traversed the India with this device to produce their watercolours.

It is this process which will be used by the Photographie by replacing the screen by a photosensitive surface fixing the light. In the case of a camera will obscura simple, without diaphragm nor lens, the camera thus made up names a Sténopé.

Recently, the duet of Felten-Massinger photographers rehabilitated the principle of the camera will obscura with their " caravana obscura" (mobile caravan, it is also the name of their asbl). The caravan is in itself a " camera obscura" that they will transport to the place where they want to take photographs. They make photograph without camera.

See too

Related articles

External bonds

  • Vermeer and the camera will obscura

  • Paleo-camera - the camera will obscura and the origins of art
  • the criticism of the work of David Hockney in the review “Lira”
  • a paper of Ross Woodrow on the site of the university of Newcastle
  • an English site on the camera will obscura
  • the camera will obscura has tourist destination
  • the camera will obscura, Universidad de Barcelona

Random links:Nanotube | François Marie d' Aboville | Yves Bachelot | Happy End Camenca | The War for stars