The work of a camera – photography
is considered to be one of the greatest inventions of mankind. It has
not only helped us see the entire world through a click, but has also
transformed how people conceive the world. They can also be kept as a
remembrance for the rest of our life.
Camera can be defined as a device that is used to capture and record photos or videos.
After years of work by many prominent
people the first colour photo was invented by the famous physicist James
Clark Maxwell along with Thomas Sutton. Then came the invention of the
video made in cameras during the early 1920s. This technology has
eventually grown to such heights that in this 21st century, these
ordinary film cameras have been replaced by digital cameras.
Parts of a camera
A camera has mainly three parts. They are
- Mechanical part or the camera body
- Optical part or the lens section
- The chemical part or the film
The way in which these three parts are
connected represents the different types of cameras. Thus by combining
these three parts and using them under the correct calibration produces a
correct picture. They are capable of working in both the visible
spectrum as well as in other portions of the electromagnetic spectrum.
The basic shape of a camera needs an enclosed hollow chamber with an
opening at one end. This opening, also called aperture helps in the
entrance of light. This light is the actual image that has to be
captured. So a capturing mechanism is set at the other end. All cameras
have the lens assembled in the front. This lens helps in capturing the
light, which is in turn captured and stored by the recording surface.
Most ordinary cameras can take one image at a time. Most video cameras
can take a maximum of 24 film frames/sec.
Mechanism of a camera
To know the complete mechanism of the camera, it is better to know each and every parameter of the camera.
1. Focus
A camera’s focus greatly depends on the
clarity of the picture taken. But the focus can be limited only to a
certain distance. This range is limited to the range of the lens. This
range when adjusted to get a perfect image is called the focus of the
camera. For accurate focussing of cameras, the device is comprised of a
fixed focus and also consists of a wide-angle lens and a small aperture
in front of the camera. The range of focus will be clearly indicated in
the camera with symbols like two people standing upright, mountains and
so on. For a simple camera, a reasonable focus of about 3 meters to
infinity is available. The focus available on each camera is different.
Single-lens reflex (SLR) cameras have a focus that can be changed
according to our like. This is done by providing a objective lens and a
moving mirror so as to projecting the image to a ground glass or plastic
micro-prism screen. Similarly each camera has different settings which
will be explained briefly later.
- The focus of a camera depends on two main features. They are
- The structure and position of the lens.
- The angle in which the light beams enter into the lens.
Consider a pencil kept at a short
distance from the lens. When the distance is altered, that is kept near
and then farther away from the lens, the angle of entry of the light
changes accordingly. This light is hit on the film surface kept inside
the camera. The angle becomes sharper when the image is close to the
lens and will become narrower when the image is kept far away. Thus when
the lens is focused farther and then nearer from the pencil, the image
is actually moving closer or farther away from the film surface. The
correct image will be obtained when the focus is adjusted in such a way
that you can line up the focused real image of an object so it falls
directly on the film surface.
2. Camera Lens
The quality of the photograph taken
largely depends on the type of lens used. The precision of a lens
depends on a factor called “bending angle”. This in turn, depends on the
structure of the lens. If the lens has a flat shape, the bending angle
is less. Thus the light beams will converge a little distance farther
away from the lens. Thus the image is also formed farther away. Thus
when the distance increases, the size of the image also increases,
though the size of the film is constant. If the lens has a round shape,
the bending angle will be high. Thus the image will be formed a lot more
nearer to the lens.
Costly cameras have a lot of lenses,
which are replaced or combined according to the magnification required.
This magnification power of a lens is called the focal length. Greater
the focal length, greater the magnification.
3. Camera Film
For an image to be recorded and viewed
it must be stored in a film. When an image is captured, it is actually
being “chemically” recorded onto a film. The film mainly consists of
millions of light-sensitive grains, which are suspended on a plastic
strip. These grains chemically react, when exposed to light. This
reaction causes the image to be recorded on the film. This film is then
developed by reacting it with other chemicals. For black and white
films, the chemicals cause the grains to appear darker when exposed to
light. Thus, the darker areas appear lighter and the lighter areas
appear darker. This is reversed while printing out the photos.
For producing colour films, the film
consists of light sensitive materials that respond to colours red, green
and blue. When they are washed and chemically reacted, you get a
negative of a colour photo.
Different camera designs
There are a lot of types of cameras like
Plate camera, large format camera, medium format camera, folding
camera, rangefinder camera and so on. Out of these the most used ones
are the single-lens reflex camera (SLR) and the point and shoot camera.
The difference comes in the manner in which the photographer visualizes
the scene. In a point and shoot camera, you do not see the real image
through the camera lens. Instead, you get to see only a blurred vision
of the image.
In an SLR camera, you can see the real
image of the scee you are about to capture. It has the same
configuration as that of a periscope. When the image is seen from the
lens, it hits the lower mirror and bounces from there. It then hits the
prism. This prism flips the image to form the original image. The mirror
and translucent screen help in providing the exact image to the
photographer. Thus, you can focus and compose the image so as to get the
exact picture you have in mind.
- SLR Camera
With upcoming technology, the point and
shoot cameras are nowadays fully automatic. SLR is built with both
manual and automatic controls. The only difference between the manual
and automatic cameras is that the former will be controlled by a central
processor, instead of the photographer.
The focus system and the light meter
transmit the signals to the microprocessor and thus activate all the
motors accordingly. These motors control the adjusting lens and also
open and close the aperture.
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