When light rays reflect off objects and pass through the small hole in the shade the image flips and is projected upside-down on the wall opposite the window. This is an example of a "camera obscura". The literal translation of camera obscura from Latin is "room dark" (camera = room; obscura = dark). Used as both a drawing aid for artists and as a device for solar observation, the camera obscura is one of the earliest forms of a camera.
The earliest mention of this type of device was made by the Chinese philosopher Mo-Ti (5th century BC). He formally recorded the creation of an inverted image formed by light rays passing through a pinhole into a darkened room. He called this darkened room a "collecting place" or the "locked treasure room".
Aristotle (384-322 BC) understood the optical principle of the camera obscura. He viewed the crescent shape of a partially eclipsed sun projected on the ground through the holes in a sieve, and the gaps between leaves of a plane tree.
Alhazen of Basra, the 10th century Iraqi scholar, had a portable tent room for solar observation and gave a full account of the principle.
In 1490, Leonardo Da Vinci gave two clear descriptions of the camera obscura in his notebooks.
Many of the first camera obscuras were large rooms like that illustrated by the Dutch scientist Reinerus Gemma-Frisius in 1544, for observing a solar eclipse.
The image quality improved with the additions of a convex lens into the aperture in the 16th century, and later, a mirror to reflect the image down onto a viewing surface. Giovanni Battista Della Porta, in his 1558 book Magiae Naturalis, recommended the use of this device as an aid for artists' renderings.
The term "camera obscura" was first used by the German astronomer Johannes Kepler in the early 17th century. He used it for astronomical applications, and similar to Alhazen had a portable tent camera for surveying.
The development of the camera obscura took two tracks. One led to the portable box device, that was a drawing tool. This development was an aid to artists of the 17th and 18th century, such as Jan Vermeer, Canaletto, Guardi and Paul Sandby. By the beginning of the 19th century light sensitive material, known as film, was a part of the camera obscura, which developed into the modern photographic camera.
The other track became the camera obscura room, a combination of education and entertainment. In the 19th century, improved lenses could cast larger and sharper images, and the camera obscura flourished at the seaside and in areas of scenic beauty.
Today the camera obscura is enjoying a revival of interest. Older camera obscuras are celebrated as cultural and historic treasures, and new camera obscuras are being built around the world.
Make your own Camera Obscura
Box it up!
1. Clean out the inside of a potato chip canister. [Don't forget to save the lid].
2. Draw around the canister 2 inches from the bottom.
3. Have a grown-up use an X-acto knife to cut along the line.
4. Using a pushpin, make a hole in the center of the metal bottom of the 2 inch piece that you cut from the canister.
5. Put the lid on the 2 inch piece you cut off, then stack the longer part of the canister on top. Once in place, tape the two parts together.
6. Take a piece of aluminum foil and tape one end to the side of the canister. Wrap the foil twice around the canister and tape it, You can tuck the extra foil inside the tube.
7. Take your camera obscura outside on a sunny day. Look through the large opening in your tube, cupping your hands around the opening to keep as much light out as possible.
The image that you aim your camera obscura at will appear upside down on the lid.
To improve the quality of your camera obscure, attach a foam soda can holder to the large eyepiece. The holder will prevent more light from entering the tube.
In a room!
Go into a very dark room on a sunny day. Make a small hole in a window cover and look at the opposite wall. There in full color and movement will be the world outside the window--upside down. Magic!
This magic is created by the bright light of the sun traveling in a straight line. When a bright light passes through a small hole in thin material such as the window cover, the light rays cross and reform as an upside down image on a flat surface held parallel to the hole, This law of optics has been known since ancient times.
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|Date:||Jan 1, 2003|
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