Camera obscura
The camera obscura (Latin camera " room, vault "; obscura "dark" ) is a further development of the pinhole camera. From this it differs in the attached in place of the hole lens. Both are original forms of photographic camera, they are used to generate images of the real environment.
- 5.1 German Speaking
- 5.2 English spoken
Construction
A camera obscura consists of a light-tight box or room, in the strikes by a provided with a collecting lens hole light on the opposite rear wall. On the rear panel upside-down and reversed image of the area located in front of the lens is formed. In transparent back wall you can see the picture from the outside. The picture is good to see faint and only with adequate darkening. This is often done through a cloth that covers the camera obscura and the viewer. Or the observer enters - with corresponding dimensions - in the blackened chamber, the ongoing adaptation of the eye to the darkness facilitates the viewing experience.
Operation
When light through a converging lens or a small hole in an otherwise light-tight hollow body, it is a reversed and upside-down image, a projection of the outside space generated in him. The diagram on the right shows an example of two beams entering from two points of an object in the hole. The small diameter of the aperture limits the bundle on a small opening angle and prevents the complete overlap of the light rays. Rays from the top of an object fall to the bottom of the screen, radiation from the lower portion will be redirected to above. Each point of the object is imaged on the projection slice. The superposition of the slice images produces a distortion-free image. In mathematical terms, the picture is the result of a convolution of an ideal image of the object with the aperture area.
Imaging geometry of a convex lens
G denotes the object height ( = actual size of the object being viewed ), g is the object distance ( = distance of the object from the lens), b is the image distance ( = distance from the washer to the ground glass ) and B is the image height (height of the image formed on the focusing screen ), then:
Equation (1) is known from geometrical optics as the first lens equation. For the mathematical derivation is referred to the intercept theorem in geometry. Thus, the image size but depends only on the distances, not by the aperture size or hole size.
History
The principle already recognized Aristotle ( 384-322 BC) in the 4th century BC In the apocryphal text Problemata physica generating an upside-down image was described for the first time, the light passes through a small hole in a dark room falls.
First tests with a pinhole camera has already hired around 980 Arab Alhazen.
From the end of the 13th century, the camera obscura was used by astronomers to observe sunspots and solar eclipses, in order not to have to look into the bright light of the sun with the naked eye. Roger Bacon (1214-1292 or 1294 ) built for solar observations, the first apparatus in the form of a camera obscura.
Similar experiments has probably hired Filippo Brunelleschi (1377-1446) in its application to the central perspective.
Leonardo da Vinci (1452-1519) examined the beam path and found that this principle can be found in nature in the eye again.
Having succeeded in the Middle Ages to grind lenses were replaced the small hole through a larger lens. This improved camera described in 1568 by the Venetians Daniele Barbaro in his work La pratica della prospeltiva and Giambattista della Porta ( 1563-1615 ) in his Magia Naturalis. Such a device seems to have been known also Johannes Kepler ( 1571-1630 ).
In 1686 Johann Zahn designed a portable camera obscura. A mirror was mounted at an angle of 45 degrees to the lens inside the camera, the image projected upwards onto a screen, where it could be easily signed. Therefore, the Camera Obscura of painters before photography was readily used as a drawing aid. You could paint them the landscape on paper and play it all the proportions right in it. The best known example is the painter Canaletto with his famous paintings of Dresden and Warsaw.
You may already used the painter Jan Vermeer, a camera obscura, which would explain the detail of his work. The cut right out of his landscape paintings View of Delft shows distant rooftops. Their complex geometry could not possibly capture the painters in that he was coming closer to the building. Had he only followed his intuition, he probably would have chosen a more vivid image construction.
At the beginning of the 19th century, the camera lucida was more popular and replaced the camera obscura largely as a drawing aid from.
1826 succeeded Joseph Nicéphore Nièpce with a camera obscura in heliography process to produce the first known and preserved to this day Photography La cour du domaine du Gras.
Known walk Camerae obscura
- Germany: Camera obscura with 3 lines of sight (horizontal) in Limpsturm / light tower in Arnsberg / Westfalen ( Opened on August 10, 2012)
- Camera obscura ( " Third Breath " ) by James Turrell with view of the sky at the Centre for International Light Art Unna.
- Camera obscura on the mountain Oybin in Zittau, built in 1852, renovated 1980-83, 360 ° view, feature: projection screen is the roof of a Trabant.
- Camera obscura in Hainichen near Freiberg, built in 1883, renovated in 1985
- Camera obscura in Mülheim an der Ruhr 1992
- Camera obscura at the German Film Museum in Frankfurt am Main
- Camera obscura in Stade, Lower Saxony, built in 2008
- Camera obscura in Dresden in the Technical Collections of Dresden
- Camera obscura in Ingolstadt ( in the new Town Hall)
- Camera obscura in Biberach an der Riss in Jordanbad ( in the sensible world )
- Camera obscura in Hamburg Altona balcony ( Hamburg overlooking the harbor Köhlbrandbrücke )
- Camera obscura in Marburg, Hesse, built in 2002, before the Landgrave's Castle with panoramic view of Marburg
- Camera obscura in Dennenlohe, Bavaria, built in 2006, in the castle park Dennenlohe with panoramic views over the 16 acres of landscaped grounds
- Austria: Camera obscura in Spitz, Lower Austria, on the Danube ferry / " Rollfähre " ( Artwork by the Icelandic artist Olafur Eliasson )
- Portugal: Camera obscura in Lisbon, Portugal ( in the fortress above the city)
- Camera obscura in Tavira
- Camera obscura in Cádiz ( Torre Tavira )
- Camera obscura in Jerez de la Frontera ( the Alcazar )
- Camera obscura in Tudela ( Torre Monreal )
- Camera obscura in Seville ( Torre de los Perdigones )
- Camera obscura in Eger ( this already in 1552 the invading Turks were observed. )
- Camera obscura in the Budapest University
- United States: Camera Obscura in San Francisco
- Other countries: Camera obscura in Biel, Switzerland (as part of Cinécollection Piasio the Museum Neuhaus)
- Camera obscura in the Moscow State University
- Camera Obscura Building on Aegina in Greece, built in 2003, 360 ° view *
- Camera obscura in Grahamstown, South Africa
- Camera obscura in Havana, Cuba ( on the Plaza Vieja )
- Camera obscura in Hampi, Karnataka, India ( Virupaksha temple ).