A digital camera focuses light through a lens or a series of lenses onto a sensor, which records the image electronically. This electronic information is then converted into binary digital data, and stored on a fixed or a removable device for being read by a computer. This is, of course, a simple explanation of how digital cameras work.

In practice, most digital cameras use a charge coupled device (CCD) as an image sensor. Some digital cameras use a complimentary metal oxide semiconductor (CMOS) instead. Both these sensors convert light into electrical charges, which are transferred to a storage disc.

The sensors also filter the light into the three primary colors and then combine them to create the full spectrum. The more expensive cameras use three sensors. Each of them has a filter of a different color.

Aperture and shutter speed is used to control the amount of light that reaches the sensor. The aperture setting is automatic in most digital cameras. Some cameras also allow manual control, for professionals and enthusiasts. The shutter, in contrast, is set electronically.

The digital cameras use four kinds of lenses. These are: fixed-focus, fixed-zoom lenses; optical-zoom lenses with automatic focus; digital-zoom lenses, and replaceable lens systems. The fixed focus and fixed zoom lenses are used in inexpensive cameras while the optical zoom lenses have both wide and telephoto options. The digital zoom lens culls pixels from the central part of the image and enlarges them to fill the frame. However, this can at times result in a grainy or fuzzy image.

Most digital cameras have an LCD screen to view the image. For better viewing or printing, the image needs to be transferred to a computer. The quality of the image depends on the resolution of a digital camera, and is measured in megapixels. The higher the resolution, the better is the image quality.

The resolution is also important in deciding the size of printed photographs. A 1 megapixel digital camera will produce images that are good for e-mailing or posting on the Web. This is because their resolution is low. The images taken from a 2 megapixel camera are suitable for 4×5 inch prints while those taken from a 4 megapixel camera can produce 16×20 inch prints.

The early digital cameras used to store images on memory devices within the camera. These were then transferred with the help of cables to computers. Today, most digital camera makers provide reusable and removable storage devices. These include SmartMedia cards, CompactFlash cards and Memory Sticks. Some other removable storage devices include: floppy disks, hard disks, or microdrives, writeable CDs and DVDs. This has considerably enhanced the volume of visual data that can be stored.

It is important to understand the basics of a digital camera, especially terms like pixel, pixel count, white balance, sensor, sensitivity, optical zoom, digital zoom etc. These improve your understanding of digital photography, and can help you become a better photographer.

A pixel is the basic unit of measurement used to define a digital photograph. The more the number of pixels per square inch the higher is the clarity or resolution of a digital picture. Each pixel is made up of three color channels – red, green and blue — and has a numerical value of between 0 and 255.

The makers of digital cameras use the term pixel count to describe their cameras. A camera that can shoot images whose pixel count is one million is categorized as 1 MP or one million pixel camera. These are the low-end cameras, used by beginners. The high-end cameras used by professionals range from 14MP to 22MP. The pixel count in these cameras is as high as 14 million or 22 million per image.

The pixel count also decides the size of a print in case you want to print photographs. A 3MP camera can provide excellent 4×6 inch prints, while a 4 or 5MP digital camera can deliver high quality 8×10 inch prints.

Another important term is digital sensor. A typical digital camera may have a digital sensor element that is as big as a small finger nail. Most 5MP digital cameras use a sensor that is 7mm x 5mm in size. This is much smaller than the size of the negative of a 35 mm camera. However, high-end digital cameras have large sensors, and generate superior images.

With a digital camera you can pick the white balance to suit the light source. This is meant to ensure that white looks white and not yellow, or blue. Normally your digital camera will do this automatically. You can also set the white balance yourself for better effect.

Digital cameras also have sensitivity settings similar to ISO ratings on film. Most digital cameras will have settings for sensitivity equivalent to ISO 100 and ISO 200. Many also have a setting for ISO 400. A few expensive digital SLR cameras with large sensors have settings for ISO 3200 or even for ISO 6400.

Most digital cameras also have an optical and a digital zoom. An optical zoom lens works by changing the focal length and magnification as it is zoomed. Image quality remains high. Digital zoom works by cropping the image to a smaller size. The cropped image is enlarged to fill the frame, causing a significant loss of quality.

Since each pixel generates three bytes of data, a photographer using a 3MP camera will need a storage space of 9 million bytes or 9MB to store a single image. This is a huge amount of space. Camera companies therefore allow for a compression of image using a format called JPEG. This reduces the file size significantly but while doing so a lot of data is lost. To overcome this problem companies have come up with different storage formats. Canon calls it RAW while Nikon calls it NEF. The data loss is less in these formats.

Canon PowerShot A590IS Highlights

8 megapixels with 4x optical zoom and optical image stabilizer With the PowerShot A590 IS, dramatic, personal pictures have never been easier to shoot and share. The 8.0-megapixel design lets you create impressive high resolution images of family and friends you’ll be proud display. The genuine Canon 4x zoom lens moves you in for powerful close-ups — like a bird in flight or a child’s winning goal — at the touch of a button. Plus, Canon’s highly sophisticated Optical Image Stabilizer keeps every shot absolutely steady even when you’re not.

2.5-inch LCD screen The camera’s 2.5-inch LCD screen gives you the big picture, whether you’re shooting, reviewing or showing off your images. This high-resolution screen offers a crisp, clear and bright picture. It also features Night Display for easy viewing in low light.

New Easy Mode simplifies operation Even if you’ve never picked up a camera before, with Canon’s new Easy Mode you can take inspiring, dramatic pictures that will impress everyone. Once you choose Easy Mode, the PowerShot A590 IS handles all the details automatically. It automatically sets every camera control including the flash to reduce blur and improve image quality. So you get pictures that are bright, clear and natural just by pushing a button. Best of all, you can relax and concentrate on what really counts — your subject.

Selectable shooting modes With 19 Shooting Modes including 7 Special Scene Modes, you’re ready for whatever shot comes your way.

DIGIC III Image Processor With DIGIC III, your images boast superior quality, the camera operates at top efficiency and battery life is enhanced. What’s more, DIGIC III enables Canon’s Face Detection Technology and Red-eye Correction to give you better, more true-to-life people shots. Simply press the Shutter Button halfway down, and the camera automatically pinpoints the faces in the scene and chooses the ideal focus point. The camera controls exposure settings and flash to keep every face looking bright and natural. Red-eye Correction can be handled in-camera, in two ways. The entirely new Red-eye Correction during shooting uses the Face Detection Technology to recognize and remove red-eye from flash images as they’re taken, before the file is written to the memory card. It’s also possible to correct red-eye during image playback, using simple settings in the A590 IS’s menu.

iSAPS Technology is an entirely original scene-recognition technology developed for digital cameras by Canon. Using an internal database of thousands of different photos, iSAPS works with the fast DIGIC III Image Processor to improve focus speed and accuracy, as well as exposure and white balance.

Face Detection Technology Canon’s powerful Face Detection Technology delivers even better results with the new A590 IS. The Face Detection Technology continues to recognize faces in a scene, and concentrate exposure (daylight or flash) and focus upon them. But the A590 IS adds more: Face Detection WB means the camera concentrates upon faces when calculating white balance for the best possible skin tones. Face Select and Track lets the A590 IS user highlight one face among several in a scene, and the camera concentrates on that person, even as they move around the scene. Face Detection Technology is a powerful contributing factor in Canon’s new Motion Detection Technology.

Red-eye Correction Red-eye Correction provides three options for removing red-eye from subjects in flash pictures.

• The new Red-eye Correction during shooting actually identifies and corrects red-eye in human subjects as pictures are taken.
• The A590 IS can be set to automatically detect and correct red-eye during image playback.
• The user can manually locate any red eyes in a scene during image playback on the LCD screen, and command the camera to remove them.

High ISO The PowerShot A590 IS features ISO 1600 and High ISO Auto settings that reduce the effects of camera shake and sharpen subjects in low-light situations, giving you greater shooting flexibility.

Motion Detection Technology automatically reduces blur Life doesn’t stand still for picture-taking. That’s why Canon included its advanced Motion Detection Technology in the PowerShot A590 IS. This sophisticated feature works in the background to instantly evaluate how fast your subject is moving. Then it automatically selects and sets the optimal exposure and ISO settings to keep everything looking sharp and clear. So whether you’re shooting a bride walking down the aisle, a ballet recital or even a child’s soccer game, you can relax and shoot with confidence knowing you’ve got the picture you intended.

Accepts Wide-Angle and Telephoto Converter Lenses To expand your creativity, the PowerShot A590 IS is compatible with shooting accessories such as wide and tele converter lenses, High-Power Flash designed for all of the PowerShot models.