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.
Camera
Focus
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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