About Cameras….

In olden days, whenever people used to go to hillside, they used to carry a camera with me and used to take extra film rolls.

As they are not very professional photographer’s, whenever they had to take photos, they used to take 2 photos so that they could get the photo positively.

Now with new digital camera technology, they don’t have to take 2 photographs. He can just check the photo on LCD and decide whether to keep it or delete it. If he delete’s it, he can take new photo. This saves a lot of time and anxiety, With new cool digital camera technology.

Digital camera is a camera without film. The basic principle is the same. It has lens, flash and shutter. However there are no mechanical moving parts. The advanced model has LCD screen which displays the photo. If you don’t like the photo, simply delete it and click it again. That’s the beauty of digital camera technology. There is no film hence no processing and development.

How Camera Focus Works

We’ve seen that a real image is formed by light moving through a convex lens. The nature of this real image varies depending on how the light travels through the lens. This light path depends on two major factors:

  • The angle of the light beam’s entry into the lens
  • The structure of the lens

The angle of light entry changes when you move the object closer or farther away from the lens. You can see this in the diagram below. The light beams from the pencil point enter the lens at a sharper angle when the pencil is closer to the lens and a more obtuse angle when the pencil is farther away. But overall, the lens only bends the light b­eam to a certain total degree, no matter how it enters. Consequently, light beams that enter at a sharper angle will exit at a more obtuse angle, and vice versa. The total “bending angle” at any particular point on the lens remains constant.

As you can see, light beams from a closer point converge farther away from the lens than light beams from a point that’s farther away. In other words, the real image of a closer object forms farther away from the lens than the real image from a more distant object.

You can observe this phenomenon with a simple experiment. Light a candle in the dark, and hold a magnifying glass between it and the wall. You will see an upside down image of the candle on the wall. If the real image of the candle does not fall directly on the wall, it will appear somewhat blurry. The light beams from a particular point don’t quite converge at this point. To focus the image, move the magnifying glass closer or farther away from the candle.

This is what you’re doing when you turn the lens of a camera to focus it — you’re moving it closer or farther away from the film surface. As you move the lens, you can line up the focused real image of an object so it falls directly on the film surface.

You now know that at any one point, a lens bends light beams to a certain total degree, no matter the light beam’s angle of entry. This total “bending angle” is determined by the structure of the lens.

Digital Technology in Cameras

The film in analog camera is replaced by CCD (Charge Coupled Device) or CMOS chip. Whenever you take a photo, based on the light, color and intensity, charge is developed on CCD. This charge is converted into digital information with the help of analog to digital converter. This digital data is ultimately converted into image format by onboard computer chip.

Understand what happens when you take a photograph. When you take a photograph, light enters through aperture through a series of lenses and falls on CCD. The charge generated in CCD is proportional to light falling on it.

As the light intensity increases, the CCD charge also increases. This signal is converted from analog to digital data. The digital data is stored in an on-board memory buffer and then converted into jpeg format by on board computer chip. Then it is transferred to flash memory. You can later watch the photograph as it is stored in flash memory.

Difference between CCD and CMOS:

There are 2 types of sensors inside the digital camera, CCD & CMOS.

  • The CCD sensors are more accurate and generate high-quality, low-noise images. However CMOS sensors are generally more prone to noise.
  • Due to large number of transistors present in CMOS, the light sensitivity of CMOS chip is lower than CCD sensor. Each pixel is divided into transistors and photo-diodes.
  • The CCD sensor system is more mature and is proven over the period.
  • CMOS sensors require very less power compared to CCD. The CCD sensor system requires 100 times more power than CMOS sensor system.Resolution:Resolution is the amount of detail a digital camera can display in a photograph. It is generally measured in pixels. That means the digital camera with more number of pixels is capable of showing more details in an image. If price is no constraint, go for the highest resolution.

    Some typical resolutions include:

    • 256×256 – If you want cheapest digital camera, then you should select this low resolution. But you will not get very high quality due to low number of pixels.
    • 640×480 – If you want to send the pictures thro’ Internet this is the ideal resolution as the image size is low with this resolution.
    • 1216×912 – With this starts the mega pixel series. Here you get more than 1 million pixels. The printed pictures will also look sharp.
    • 1600×1200 – If you want more than 2 million pixels, you should go for 1600×1200 resolution.
    • 2240×1680 – For more than 4 million pixels, you should select this resolution. This is high end digital camera. You can print large size photo directly with this resolution.

    Higher resolutions in the range of 10 million and more pixels are available in the market. But as resolution increases, price also increases.

Latest Cameras in town



COOL PIX.P500COOL PIX.P300Source :howstuffworks , www.build-your-own-cheap-computer.com

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Mahesh ( MGIT ECE 3rd year)

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