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The Big Three
When anyone talks about digital cameras, they mean digital still cameras. That is, handheld cameras designed like the film cameras of old. You peer through a viewfinder, push a button, and take a picture.
The most important characteristic of digital still cameras is high resolution. The images they capture contain as much image information—detail—as the photographs taken by classic film cameras. The high-resolution images are suitable for printing as conventional photographs. Their quality is high enough you can even publish them in print magazines and books. But you can also take lower-resolution images—or reduce the resolution of high-resolution images—to make pictures for the Web and electronic publications. Depending on the memory you have available to your digital still camera, you can cram from a dozen to more than a hundred images into a single session.
To match their high resolution, digital still cameras have top-quality lenses characterized by their sharpness. Most digital still camera lenses also have optical zooming capabilities, ranging from 2x zooming in inexpensive cameras to a maximum (currently) of about 10x.
Digital still cameras are meant to work like their film-based counterparts—handheld or on a tripod—by using the available light or a flash. But most offer additional features. Some capture short video clips. Most have video outputs so you can plug them into your computer and capture moving images, just as you would with a video camera. You can also use this video output as a Web cam (providing your computer has a video input).
Digital video cameras are made for capturing movies digitally. They are characterized by their fast capture rate. They have to snap at least 30 frames every second. But they do not need to have as much resolution as digital still cameras. Most have resolution that matches that of your computer's most basic display mode, VGA. That means resolution of 640-by-480 pixels.
Because of the low resolution of digital video cameras, their lenses need not be as sharp as those of digital still cameras. On the other hand, to give you more versatility in movie-making, digital video cameras usually have extended zoom ranges, often higher than 30x.
Most digital video cameras also have single-shot modes in which they operate as digital still cameras—but with a difference. They produce video-like resolution rather than still-camera resolution when taking snapshots. You can also used a digital video camera for a Web camera if your computer has the proper input and software.
Web cameras are the low end of the digital-photo spectrum. They have about the same resolution capabilities as a digital video camera (sometimes less) but skimp on the lens. Most have a fixed focus lens without zoom—which means low-cost, at least to manufacturers. Their low resolution level is tailored to match the needs of Webcasting and video messaging.
Most Web cameras have USB outputs inside of standard video outputs so you can plug them into computers that don't have video inputs. With the right software, however, you can use a Web cam to make low-grade movies or still images. In fact, the quality you get from a Web cam may be enough for posting on the Web (what did you expect?) or even for putting images into electronic publications.
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