Camera

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CAMERA AS AN INPUT DEVICE
Camera
A camera is an optical instrument for recording images,
which may be stored locally, transmitted to another
location, or both. The images may be individual still
photographs or sequences of images constituting videos or
movies. The word camera comes from camera obscura,
which means "dark chamber" and is the Latin name of the
original device for projecting an image of external reality
onto a flat surface. The modern photographic camera
evolved from the camera obscura. The functioning of the
camera is very similar to the functioning of the human eye.
History
The forerunner to the photographic camera was the camera obscura. In the fifth century B.C.,
the Chinese philosopher Mo Ti noted that a pinhole can form an inverted and focused image,
when light passes through the hole and into a dark area. Mo Ti is the first recorded person to
have exploited this phenomenon to trace the inverted image to create a picture. Writing in the
fourth century B.C., Aristotle also mentioned this principle. He described observing a partial solar
eclipse in 330 B.C. by seeing the image of the Sun projected through the small spaces between
the leaves of a tree. In the tenth century, the Arabic scholar Ibn al-Haytham (Alhazen) also wrote
about observing a solar eclipse through a pinhole,[12] and he described how a sharper image
could be produced by making the opening of the pinhole smaller.
The use of photographic film was pioneered by George
Eastman, who started manufacturing paper film in 1885 before
switching to celluloid in 1889. His first camera, which he called
the "Kodak," was first offered for sale in 1888. It was a very
simple box camera with a fixed-focus lens and single shutter
speed, which along with its relatively low price appealed to the
average consumer. The Kodak came pre-loaded with enough film
for 100 exposures and needed to be sent back to the factory for
processing and reloading when the roll was finished. By the end
of the 19th century Eastman had expanded his lineup to several
models including both box and folding cameras. Films also
made possible capture of motion (cinematography)
establishing the movie industry by end of 19th century.
The first camera using digital electronics to capture and store images was developed by Kodak
engineer Steven Sasson in 1975. He used a charge-coupled device (CCD) provided by Fairchild
Semiconductor, which provided only 0.01 megapixels to capture images. Sasson combined the
CCD device with movie camera parts to create a digital camera that saved black and white
images onto a cassette tape.The images were then read from the cassette and viewed on a TV
monitor.Later, cassette tapes were replaced by flash memory. Gradually in the 2000s and
2010s, digital cameras became the dominant type of camera across consumer,
television and movies.
Mechanics


Image capture
Traditional cameras capture light onto photographic
plate or photographic film. Video and digital cameras
use an electronic image sensor, usually a charge
coupled device (CCD) or a CMOS sensor to capture
images which can be transferred or stored in a
memory card or other storage inside the camera for
later playback or processing.



Lens
The lens of a camera captures the light from the
subject and brings it to a focus on the sensor. The design and manufacture of the lens is
critical to the quality of the photograph being taken. The technological revolution in

CAMERA AS AN INPUT DEVICE
camera design in the 19th century revolutionized optical glass manufacture and lens
design with great benefits for modern lens manufacture in a wide range of optical
instruments from reading glasses to microscopes. Pioneers included Zeiss and Leitz.



Exposure control
The size of the aperture and the brightness of the scene controls the amount of light that
enters the camera during a period of time, and the shutter controls the length of time that
the light hits the recording surface. Equivalent exposures can be made using a large
aperture size with a fast shutter speed and a small aperture with a slow shutter.



Shutters
Although a range of different shutter devices have been used during the development of
the camera only two types have been widely used and remain in use today.
 The Leaf shutter or more precisely the in-lens shutter is a shutter contained within
the lens structure, often close to the diaphragm consisting of a number of metal
leaves which are maintained under spring tension and which are opened and then
closed when the shutter is released. The exposure time is determined by the interval
between opening and closing. In this shutter design, the whole film frame is exposed
at one time. This makes flash synchronisation much simpler as the flash only needs
to fire once the shutter is fully open. Disadvantages of such shutters are their
inability to reliably produce very fast shutter speeds ( faster than 1/500th second or
so) and the additional cost and weight of having to include a shutter mechanism for
every lens. The focal-plane shutter operates as close to the film plane as possible
and consists of cloth curtains that are pulled across the film plane with a carefully
determined gap between the two curtains (typically running horizontally) or
consisting of a series of metal plates (typically moving vertically) just in front of the
film plane.
 The focal-plane shutter is primarily associated with the single lens reflex type of
cameras, since covering the film rather than blocking light passing through the lens
allows the photographer to view through the lens at all times except during the
exposure itself. Covering the film also facilitates removing the lens from a loaded
camera (many SLRs have interchangeable lenses)

Digital camera
A camera that stores images digitally rather than recording them on film. Once a picture has
been taken, it can be downloaded to a computer system, and then
manipulated with a graphics program and printed. Unlike film
photographs, which have an almost infinite resolution, digital
photos are limited by the amount of memory in the camera, the
optical resolution of the digitizing mechanism, and, finally, by the
resolution of the final output device. Even the best digital
cameras connected to the best printers cannot produce filmquality photos. However, if the final output device is a laser printer, it
doesn't really matter whether you take a real photo and then scan it, or
take a digital photo. In both cases, the image must eventually be reduced to the resolution of the
printer.
The big advantage of digital cameras is that making photos is both inexpensive and fast because
there is no film processing. Interestingly, one of the biggest boosters of digital photography is
Kodak, the largest producer of film. Kodak developed the Kodak PhotoCD format, which has
become the de facto standard for storing digital photographs.
Most digital cameras use CCDs to capture images, though some of the newer less expensive
cameras use CMOS chips instead.
a. How They Work.

CAMERA AS AN INPUT DEVICE
1. A digital camera takes a photograph by using sensors to capture the light that comes in
through the lens.
2. It then converts the light into binary numbers that are recorded on backing storage.
3. This digital version of the photograph can then be displayed on the small screen that is set
into the camera.
4. A digital camera also has software that lets you delete unwanted photos while they are
still stored in the camera.
5. You can connect your camera to your PC and transfer your photos across.
6. Once they are in the PC you can edit your photos further by using a good graphics
package.
b. Advantages of a digital camera
1. It can hold lots of photos without the need to buy film.
2. You can see what your photo is like straight away and you can delete any you do not want.
3. The photos are digital so you can transfer them to your PC and then do all sorts of things
with them such as edit, print, store on a writable CD, attach to an e-mail.
4. You do not need to have photos developed, saving time and money.
c. Buying a Camera? The key features to look for.
1. The number of megapixels the camera has. A megapixel is a million pixels. This is a
measure of how accurately the camera captures images. It refers to the number of sensors
the camera uses to detect the light. The more pixels, the better the quality of pictures the
camera can take.
2. The amount of onboard memory the camera has.
3. The larger the onboard memory the more photos it can store.
Digital Video Cameras
a. How it works
A digital video camera captures moving images using technology similar to that used by a still
digital camera.
1. It uses light sensors to capture the images.
2. The images are then changed into binary numbers.
3. The binary numbers are then stored in files on the camera’s backing storage
b. Key features of a video camera?
The accuracy of the image sensors used to take the film. This is measured by the number of
pixels that the camera uses to capture the images.
Webcam
A webcam is a video camera that feeds or streams its image in real
time to or through a computer to computer network. When "captured"
by the computer, the video stream may be saved, viewed or sent on to
other networks via systems such as the internet, and email as an
attachment. When sent to a remote location, the video stream may be
saved, viewed or on sent there. Unlike an IP camera (which connects
using Ethernet or Wi-Fi), a webcam is generally connected by a USB
cable, or similar cable, or built into computer hardware, such as
laptops.
The term 'webcam' (a clipped compound) may also be used in its
original sense of a video camera connected to the Web continuously for
an indefinite time, rather than for a particular session, generally
supplying a view for anyone who visits its web page over the Internet. Some of them, for
example, those used as online traffic cameras, are expensive, rugged professional video
cameras.
The technology for capturing the images is similar to that used in the other digital cameras. The
difference is that once an image is captured it is transmitted automatically to a computer
system. Webcam software in the computer system then transfers it to a web page.

CAMERA AS AN INPUT DEVICE
Web Cams are used for:





set up video conferencing monitor
traffic advertise
tourist sites
advertise businesses.

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