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.
Digital cameras also control the amount of light that actually reaches the sensor. They do this through the aperture or hole size, and through the shutter speed. Most cameras have automatic aperture setting though some do allow for manual control, which is preferable for professional photographers and advanced amateurs. Shutter speed is set electronically.
Lenses for digital cameras come in four varieties: digital-zoom lenses; fixed-zoom lenses; replaceable lens systems; and fixed-focus. Fixed lenses, both zoom and fixed focus, tend to be found in the cheaper cameras. Optical zoom lenses can have both wide angle and telephoto options. Digital zoom lenses don’t actually zoom a piece of glass, but rather take pixels from the central part of the image, and enlarge them. This appears to be a zoom, but if you look closely, you will notice that they are more grainy or fuzzy images than you get without invoking the zoom option.
Most digital cameras come with an LCD screen to preview images or to look at them after capture. Most LCD screens are rather small, because the size of the cameras overall is small, too. For better viewing, you must transfer the image to a computer. For quality of image, the biggest factor is the resolution, which is measured in megapixels. The higher the resolution, generally 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 4×6 inches. Four megapixels will create nice 16×20 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.
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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Author Wilfred Ursley writes for several respected web sites, with tips and resources on consumer products and family health topics.
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posted on January 18th, 2008




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