Inside a Digital Camera

A free article on Computers

By: Wilfred Ursley

Digital cameras have now fully completed their coup of the camera industry. If you recently got one yourself, it can be useful to have a bit more understanding of how they work. Simply put, digital cameras contain a lens or series of lenses that allow light passing through them to focus on a sensor, rather than traditional film. The sensor then transfers the image data to the core electronics of the camera, where it is organized and converted into binary forms of data. Thus it can more easily be stored onto reusable memory units for later viewing by a computer.

The most common digital camera sensor is a charge-coupled device, or CCD, but some models use a complementary metal oxide semiconductor (CMOS). In either case, light beams are converted to electrical charges, which are then transferred to the core electronic section, and eventually onto the storage media.

As part of this process the sensors filter the light into the three primary colors, which can be combined to create the full spectrum. The more expensive (and higher quality) cameras use three separate sensors to accomplish this task. Each sensor is fitted with a filter of a different color, making it read only the light that matches that color.

Aperture and shutter speed are the mechanisms used to control the amount of light that reaches the sensor. In most digital cameras the aperture setting is automatic, but some cameras also allow manual control. Professional photographers and enthusiasts prefer this option. The shutter, on the other hand, is set electronically.

There are four kinds of lenses used by digital cameras: optical-zoom lenses with automatic focus; fixed-focus, fixed-zoom lenses; digital-zoom lenses; and replaceable lens systems. Optical zoom lenses have both telephoto and wide options, while the fixed focus and fixed zoom lenses are used in the ordinary, inexpensive cameras that infrequent users own. The digital zoom lens creates the illusion of a zoom effect by culling pixels from the central part of the image and enlarging them to fill the frame. This, however, often results in a grainy or fuzzy image at the extreme limits of the camera's capabilities.

An LCD screen is included on most digital cameras to view the image. These screens are usually rather small, being constrained to the size of the camera. Thus the image needs to be transferred to a computer for better viewing or printing. The overall quality of the image depends primarily upon the resolution of a digital camera. The higher the resolution, measured in megapixels, the better the image quality.

For printing photos, resolution of the original image is also key. A low quality camera such as those found in many cell phones will create images that are really only useful for emailing or for web pages. A 2-megapixel camera produces images that can be blown up to about 4x6 inches. Four megapixels will create nice 16x20 inch images, but with falling prices on most digital cameras, if you enjoy photography and enlarging photos, don't settle for less than six megapixels.

Early digital cameras stored images on memory resources built into the camera. Images were then transferred to computers with the help of cables. Most modern digital camera makers utilize reusable and removable storage devices. These devices include SmartMedia cards, CompactFlash cards and other memory sticks. Other, less common removable storage devices include hard disks or microdrives, and writeable CDs or DVDs. These options have considerably enhanced the volume of visual data that can be stored as well as the overall flexibility of the modern digital camera.