How Do Digital Cameras Work?

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.

When it comes to the sensor, most digital cameras use a charge-coupled device (CCD), while other cameras use a complementary metal oxide semiconductor (CMOS) instead. Both sensors convert light into electrical charges, which are then read by the electronics in the camera and transferred to the relevant storage media.

During the conversion, the light is filtered into the three primary colors, which are combinable to create a full spectrum light. Better quality digital cameras use three separate sensors to do this. Each sensor contains a filter of a different color, allowing it to read just the light that matches.

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 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.