The Inner Workings of Digital Cameras
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 we all learned in grade school, there are three primary colors. Digital cameras use filters to divide the light into those three colors during the conversion process. Good quality cameras have three separate sensors for filtering, with each sensor matching one strand of light.
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 main types of lenses for digital cameras: fixed focus, replaceable lens systems, fixed zoom, and digital zoom. Less expensive cameras typically have fixed focus or fixed zoom lenses. Digital zoom lenses have a way of enlarging the pixels from the middle of the image, rather than actually zooming in on an object in the distance. Therefore, they tend to make images grainy or fuzzy, unlike the much more cleanly zoomed images that an optical zoom lens can produce.
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.
Resolution also plays a role in the quality and size of the printed photographs. A cell phone camera or other low quality camera with a one megapixel resolution will produce images that are really only good for emailing or web pages, not printing. With a 2-megapixel camera, the images are good for printing at 4x6 inch sizes or so, while a 4-megapixel camera can be detailed enough to produce good prints at 16x20 inch size. With prices falling continually, if you love photos and hope to make some enlargements, you are best to only consider cameras above 6-megapixels.
In the early days of digital cameras, images were stored on fixed memory locations built into the device. When it came time to transfer images, you needed a cable to attach to your computer. Today, removable memory storage is the way to go, as the flexibility and convenience of the camera is enhanced. And reusable memory means you can enhance the amount of data you can comfortably keep with the camera -- more pictures and higher resolution pictures. Removable memory is stored on various devices such as CompactFlash cards, SmartMedia cards, and other memory sticks. Some cameras use small hard drivers, called microdrives, or burnable DVDs. No matter what you choose, having a digital camera is fun, and frees you from the costs of film.
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