The Canon EOS Digital Rebel XS/1000D Companion

Cleaning and Maintenance

At a fundamental level, all cameras are the same: A lens focuses light onto a recording medium. Because the recording medium is light-sensitive, it must be kept in a lightproof box. A shutter in front of the recording medium allows for control of when the sensor is exposed and how long the exposure will last. Cameras have worked this way since the beginning of photography in the 1850s, and while all sorts of new technologies have come along—everything from light meters to stabilized lenses to self-timers, color film, and autofocus—the basic principles of a lens that focuses light onto a light-sensitive medium held in a lightproof box have remained the same.

Of course, the significant change in a digital camera is the recording medium that's being exposed. Rather than a piece of celluloid covered with light-sensitive chemicals, a digital camera employs a silicon chip covered with light-sensitive bits of metal. And, where a film camera needs a bunch of mechanics to move the film in and out of the roll, a digital camera needs an onboard computer and storage device to process and store the images that it captures.

Other than this change, though, your Rebel XS is similar in design to a traditional 35mm SLR. The camera body is the lightproof box that houses the image sensor, shutter, and viewfinder. Of course, it also has lots of other things, like the shutter button, controls, LCD screen, battery, media card, tripod mount, pop-up flash, and more.

The Rebel XS is ...