As early as the
fourth century BC (circa 336-323 BC), Aristotle described a method for
viewing a solar eclipse without damaging the eye. If a metal plate punched
with small holes was held up to the sun, he said, then a corresponding
image of the sun could be projected through it and onto the ground. The
method was not novel to Aristotle, and likely well established before he
wrote about it. This simple optical principle is the foundation of photography.
In 1038 AD, an
Arab scholar named Alhazan described a working model of the camera obscura.
Literally meaning dark chamber, the camera obscura was a room or box lit
only by a small hole that admitted sunshine. Light rays poured through
the hole, eerily assembling an image of the outside world on the opposite
wall.
Although Alhazan
did not actually construct the device, his work would influence a medieval
tinkerer named Roger Bacon. In 1267 AD, Bacon created convincing optical
illusions by using mirrors and the basic principles of the camera obscura.
Later, he used a camera obscura to project an image of the sun directly
upon an opposite wall.
Throughout the
middle ages, Bacon's ideas were adapted for astronomical observations of
the sun. The camera obscura became a popular tool for safely studying eclipses.
It was not until
the Renaissance that the instrument was widely used as a drawing tool.
Although Leonardo Da Vinci is popularly credited for using the camera obscura
to draw, that is only partially true. A student of physiology, Da Vinci
built a small camera obscura to test his theories about the workings of
the human eye and the concept of perspective. Da Vinci never used the camera
obscura to draw. Without a lens, the camera was not a very effective or
portable tool for viewing the world.
The introduction
of the orbem e vitro, a kind of primitive biconvex lens, revolutionized
the utility of the camera obscura. Like the lens that C.C. Harrison and
J. Schinitzler would perfect in 1860, the orbem was constructed
of two convex lenses. The design reduced distortion and increased clarity.
Although no inventor is known, the lens was first mentioned by Girolamo
Cardano, a Milanese mathematics professor, in the 1550 edition of his scientific
encyclopedia.
In 1558 the Neapolitan
scientist Giovanni Battista della Porta suggested the camera obscura would
make a wondrous aid to artists. In his Magiae naturalis, he discussed
the applications to portraiture, landscapes, and the copying of other paintings.
With the lens, he wrote, "You will see everything clearer, the faces
of men walking in the street, the colors, clothes, and everything as if
you stood nearby."
Another notable
improvement came in 1568 when Daniele Barbaro, a Venetian nobleman, described
a camera obscura outfitted with a lens and diaphragm. This forerunner of
the aperture could be made progressively smaller so the image would become
ever sharper. With continuing improvements in optics, the camera obscura
no longer needed a large, stationary room to create an image.
In 1572 Friedrich
Risner constructed a small hut that could be carried around the countryside
and used to make topographical drawings. Camera obscuras began to shrink
in size and improve in optical quality. By 1657, camera obscuras were small
enough to be carried under one arm. During the latter half of the 17th
century, they proliferated across Europe, with uses as varied as painting,
architectural drawing and spying.
As remarkable
as the instruments were, they didn't fully satisfy the needs of artists.
While canvas painting is a vertical pursuit, many artists preferred to
sketch a scene on a laptop pad. In 1676, Johann Christoph Sturm, a professor
of mathematics at Altdorf University in Germany, introduced a reflex mirror.
Mounted at a 45 degree angle from the lens, the mirror projected the image
to a screen above. This elegant configuration is at the core of modern
single lens reflex cameras.
In 1685, Johann
Zahn, a monk from Wurzburg, solved the final piece in the optical puzzle.
Improving upon Sturm's design, he introduced lenses of longer and shorter
focal lengths. Scenes as wide as a landscape or as close as a portrait
could be viewed with a simple change of lens. He also painted the interior
of his camera obscura black to avoid internal reflections. Excepting a
mechanical shutter, Zahn's invention was the prototype for today's camera.
Yet it would be over one hundred and fifty years before the camera obscura
and photosensitive chemicals were combined to make permanent photographs.
