Cameras & Photography
Photographs are all around us, from family snapshots at home, to the professionally taken images printed in newspapers, on posters and in fashion magazines. But did you know that the first photograph was taken less than 200 years ago?
HOW WERE CAMERAS INVENTED?
A discovery made in China around 1500 bc helps to explain how a modern camera works. If you stand in a very dark room, and allow light to enter through just a pinhole, a fuzzy, upside-down image of the outside world appears on the wall where the light lands. For hundreds of years, people did not know how to use this interesting discovery. During the 11th century, Arabs used it to watch solar eclipses without looking directly at the Sun. Europeans called the invention a camera obscura, which is Latin for “darkened room”.
During the 17th century, some people began experimenting with smaller camera obscuras made out of boxes. Soon, they found that by replacing the pinhole with a piece of curved glass called a lens, they could make the image much sharper and brighter. However, they could not make the image permanent, so they could not get it out of the box.
In 1727, a German professor called Johann Schulze discovered that a chemical called silver nitrate darkens when it is exposed to light. Scientists realized that if the light in a camera obscura fell on a film of chemical, instead of simply on the back of the box, the film would darken in places and be turned into a permanent image. One hundred years after Schulze’s discovery, a Frenchman called Joseph Niépce took the first ever photograph. It took eight hours to create an image on the film, which was very dark and fuzzy. Soon afterwards, in 1837, another Frenchman, Louis Daguerre, invented an improved camera that took much sharper photographs in just a few minutes.
HOW IS A PHOTOGRAPH DEVELOPED?
In 1839, an English scientist called William Fox Talbot invented a process of developing films so that copies could be made of the image. This is the basic process used for creating photographs today.
To develop a black-and-white camera film, you need to work in a room with no light, called a dark room. First, you fix the image permanently on the film by soaking the film in baths of special chemicals and then washing it. But the fixed image turns out negative—areas that should be light are dark, and areas that should be dark are light. So you re-photograph the negative using print paper, which is light sensitive just like camera film. You use a camera with an enlarger lens, to increase the image to the size you want your photograph to be. This way, a larger image appears on the print paper with the black and white the right way round. You then soak the print paper in fixing chemicals, wash it and leave it to dry. You can make as many prints as you like from just one negative.
You use a similar process for developing colour photographs. Colour camera film and print paper have more layers of light-sensitive chemicals than black-and-white film. Colour photography was invented in 1907 by two French brothers called Auguste and Louis Lumière.
WHAT HAPPENS INSIDE A CAMERA?
A modern camera is a sophisticated version of a camera obscura. The outside of the camera acts as the dark room or dark box. Light enters the camera not through a pinhole but through a curved glass lens. Lenses of different shapes and sizes allow you to photograph a scene in different ways. For instance, a standard lens shows the scene just as you see it through the window at the front of the camera called the view-finder. A wide-angle lens allows more of the scene to appear in the photograph than a standard lens. And a telephoto lens brings the scene into close-up.
Two devices that sit behind the lens allow you to control the amount of light that enters the camera through the lens. This helps to make the image sharp, or focused. The first device is a mechanism made of metal plates called a diaphragm. You can twist the metal plates in or out to make the hole behind the lens bigger or smaller. This lets more or less light into the camera. The second device is a small flap called a shutter. A camera’s shutter is usually closed, so no light enters the inside of the camera box. However, when you take a photograph, the shutter springs open and lets light in, before springing shut once more. You can set the shutter to open and close at different speeds, which determines how long the film is exposed to the light. (If there is not enough light to create a sharp, bright image, a photographer attaches a flashbulb to the camera or sets up studio spotlights.)
Many cameras have two spools inside to hold the film in place. When you load the film, you slot the cartridge over one spool and feed the end of the film around the other spool. After you take a photograph, a motor winds a little more of the film across. When the film is finished, the motor rewinds the film on to the original spool so you can take it out of the camera.
TYPES OF CAMERA
The first photographic cameras were large and bulky. To keep the inside dark, the photographer often hid under a large cloth while taking the shot. To focus the lens, the photographer moved a concertina-like tube called a bellows in and out. People in early photographs often look stiff and serious, because they had to stand still for several minutes while the photographer allowed enough light into the camera to create an image on the film.
Many cameras today have sophisticated electronics that make sure each photograph gets the right amount of light and is perfectly sharp. This technology includes autoexposure, autoflash and autofocus. Modern cameras are compact and made of light materials such as plastic or aluminium, so they are easy to carry.
Most cameras take their name from the type of film they use. For instance, a 35 mm camera uses a roll of film that is 35 mm wide. Advanced Photo System cameras use rolls of film that you simply drop into the camera instead of having to wind on to spools. Polaroid instant cameras take only a minute or so to process photographs in the form of thin plastic envelopes. The envelopes have sheets of film inside and capsules of chemicals that burst and develop the picture. Digital cameras do not use film at all. The images are stored on a microchip, so you can download them on to your computer.
Some modern cameras have been designed for special purposes. For instance, high-speed cameras can capture movements that are too fast for you to see under normal circumstances, such as a frog snatching a fly with its tongue. Divers use underwater cameras to photograph the mysterious world beneath the sea. And cameras launched into space on satellites can beam back to Earth fascinating photographs of stars and planets.