A 'digital camera' (also 'digicam' or 'camera' for short) is a camera that takes
video or still photographs, or both, digitally by recording images via an
electronic image sensor.
95 Many compact digital still cameras can record sound and moving video as
well as still photographs. Most 21st century cameras are digital. Digital cameras can do things film cameras cannot: displaying images on a screen
immediately after they are recorded, storing thousands of images on a single
small memory device, recording video with sound, and deleting images to free
storage space. Some can crop pictures and perform other elementary image
editing. The optical system works the same as in film cameras, typically using a
lens with a variable diaphragm to focus light onto an image pickup device. The
diaphragm and shutter admit the correct amount of light to the imager, just as
with film but the image pickup device is electronic rather than chemical. Digital cameras are incorporated into many devices ranging from PDAs and mobile
phones (called camera phones) to vehicles. The Hubble Space Telescope and other
astronomical devices are essentially specialized digital cameras.
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