How digital cameras work

How digital cameras work?

Digital cameras look very much like ordinary film cameras but they work in a completely different way. 

When you press the button to take a photograph with a digital camera, an aperture opens at the front of the camera and light streams in through the lens. So far, it's just the same as a film camera. 

From this point on, however, everything is different. There is no film in a digital camera. Instead, there is a piece of electronic equipment that captures the incoming light rays and turns them into electrical signals. This light detector is one of two types, either a charge-coupled device (CCD)

 or a CMOS image sensor.

Notes:   An image sensor or imaging sensor is a sensor that detects and conveys the information that constitutes an image. It does so by converting the variable attenuation of light waves (as they pass through or reflect off objects) into signals, small bursts of current that convey the information. The waves can be light or other electromagnetic radiation. Image sensors are used in electronic imaging devices of both analog and digital types, which include digital cameras, camera modules, medical imaging equipment, night vision equipment such as thermal imagingdevices, radar, sonar, and others. As technology changes, digital imaging tends to replace analog imaging.

Early analog sensors for visible light were video camera tubes. Currently, used types are semiconductor charge-coupled devices (CCD) or active pixel sensors in complementary metal–oxide–semiconductor (CMOS) or N-type metal-oxide-semiconductor (NMOS, Live MOS) technologies. Analog sensors for invisible radiation tend to involve vacuum tubes of various kinds. Digital sensors include flat panel detectors.

 Is CMOS or CCD better?

CCD(Charge-coupled Device) and CMOS (Complementary Metal-oxide Semiconductor). CCD sensors are that they are analog components that require more electronic circuitry outside the sensor, they are more expensive to produce, and can consume up to 100 times more power than CMOS sensors.

If you've ever looked at a television screen close up, you will have noticed that the picture is made up of millions of tiny colored dots or squares called pixels. Laptop LCD computer screens also make up their images using pixels, although they are often much too small to see. In a television or computer screen, electronic equipment switches all these colored pixels on and off very quickly. Light from the screen travels out to your eyes and your brain is fooled into see a large, moving picture.

In a digital camera, exactly the opposite happens.

 Light from the thing you are photographing zooms into the camera lens. This incoming "picture" hits the image sensor chip, which breaks it up into millions of pixels. The sensor measures the color and brightness of each pixel and stores it as a number. Your digital photograph is effectively an enormously long string of numbers describing the exact details of each pixel it contains. 

Inside a digital camera

Ever wondered what's inside a digital camera? What takes the photo? Where's it stored? What makes the flash work? And how do all these bits connect together? When you take electronic gadgets apart, they're much harder to understand than ordinary machines (things that work through a clear physical mechanism): you can't always see which part does which job or how. Even so, it can be quite illuminating to peer into your favorite gadgets to see what's hiding inside. I don't recommend you try this at home: opening things up is the quickest way to invalidate your warranty; it's also a good way to ensure they'll never work again!

The main parts of a digital camera

Photo: The parts in a basic digital camera. Were it not for the LCD screen and batteries (the two biggest components), you could probably make a camera like this as small as a postage stamp!

I've opened up the camera in our top photo—and these are the parts I've found inside:

1. Battery compartment: This camera takes two 1.5-volt batteries, so it runs on a total voltage of 3 volts (3 V).
2. Flash capacitor: The capacitor charges up for several seconds to store enough energy to fire the flash.
3. Flash lamp: Operated by the capacitor. It takes a fair bit of energy to fire a xenon flash like this, which is why a lot of indoor flash photography quickly uses up your batteries.
4. LED: A small red LED (light-emitting diode) indicates when the self-timer is operating, so you can take photos of yourself more easily.
5. Lens: The lens catches light from the object you're photographing and focuses it on the CCD.
6. Focusing mechanism: This camera has a simple switch-operated focus that toggles the lens between two positions for taking either close-ups or distant shots.
7. Image sensor: This is the light-detecting microchip in a digital camera and it uses either CCD or CMOS technology. You can't actually see the chip in this photo, because it's directly underneath the lens. But you can see what it looks like in our article on webcams.
8. USB connector: Attach a USB cable here and connect it to your computer to download the photos you've taken. To your computer, your camera looks like just another memory device (like a hard drive).
9. SD (secure digital) card slot: You can slide a flash memory card in here for storing more photos. The camera has a very small internal memory that will store photos too.
10. Processor chip: The camera's main digital "brain". This controls all the camera's functions. It's an example of an integrated circuit.
11. Wrist connector: The strap that keeps the camera securely tied to your wrist attaches here.
12. Top case: Simply screws on top of the bottom case shown here.

Another important part, not shown here, is the LCD display that shows you the photos you've taken. It's mounted on the back of the electronic circuit board so you can't see it in this photo.