"Camera obscura
" is a Latin term that translates as "dark room." A camera obscura is exactly that: a small room or chamber that is kept completely dark except for a single small hole on one end. When light enters this hole, the action taking place outside the chamber is projected on the far wall, inverted but with perspective and color still intact. The camera obscura acted as a direct precursor to the photographic camera.
History
Aristotle is credited as being the first to conceptualize the camera obscura as far back as 300 B.C. However, Ibn al-Haytham, a 10th century scholar and mathematician from what is now known as Iraq, is credited with first conducting the experiments that led to the invention of the camera obscura. The device was not utilized as an artists' aid until Roger Bacon did so in the 13th century.
Technology
Camera obscuras can be made in a variety of sizes from a portable box or pinhole camera to one that is the size of a room. As light passes through the hole in the box or wall, it is projected onto the far wall in an inverted state. The technology behind them is quite simple and mimics how light enters the human eye---into the iris, through the lens and against the retina. The sharpest image is projected when the hole's diameter is 1/100th of the distance of the hole to the far wall of the device.
Correcting the Inverted Image
While the camera obscura was the precursor to modern photography, it also was used as an aid for artists because it allowed them to trace their images on paper before painting them. However, many artists found the backward and upside-down image unsatisfactory. To remedy this, the plain hole was replaced by a glass lens and the lens was turned 45-degrees upward. A mirror would be placed to catch the light from the lens, and it then would be bounced, right-side-up, down to the surface below.
Other Uses
Though the camera obscura is known primarily through its use in photography and art, its technology has been used in a variety of other ways. It was used by early astronomers to discover the direction light travels. Later, the camera obscura was employed to aid in the observation of eclipses and sunspots. The British military used it in World War I and World War II to test the accuracy of bomb simulations, wind velocity and pilots' flying ability.
Camera Obscura Today
Because of advances in technology, the camera obscura is no longer widely used for photographic or artistic use. Though fewer than a dozen camera obscuras exist today in the United States, they still remain popular tourist attractions and are open to the public in cities like San Francisco; Los Angeles; New York City; Rochester, N.Y.; Portland, Maine; and Baltimore.
Tags: camera obscura, Camera Obscura, hole wall, light enters, wall inverted
