Digital photography, as opposed to film photography, uses an electronic sensor to record the image as binary data. This facilitates storage and editing of the images on personal computers. Digital cameras now outsell film cameras and include features not found in film cameras such as the ability to shoot video and record audio. Some other devices, such as mobile phones, now include digital photography features.
Digital still cameras are cameras whose primary purpose is to capture photography in a digital format. Initially, a digital camera was characterized by the use of flash memory and USB or FireWire for storage and transfer of still photographs, and this is still the common meaning of the unadorned term.
However, modern digital photography cameras have a video function, and a growing number of camcorders have a still photography function. In addition, some newer camcorders record video directly to flash memory and transfer over USB and FireWire. Among digital still cameras, most have a rear LCD for reviewing photographs. They are rated in megapixels; that is, the product of their maximum resolution dimensions.
The actual transfers to a host computer are commonly carried out using the USB mass storage device class (so that the camera appear as a drive) or using the Picture Transfer Protocol and its derivatives. All use a CCD (for Charge-Coupled Device) which is a chip comprised of a grid of phototransistors to sense the light intensities across the plane of focus of the camera lens.
There has recently been some application of a second kind of chip, called a CMOS (Complementary Metal-Oxide Semiconductor) sensor, and this chip is often differentiated from a CCD proper in that it uses less power and a different kind of light sensing material, however the differences are highly technical and many manufacturers still consider the CMOS chip a charged coupled device. For our purposes, a chip sensor is a CCD.
Except for some linear array type at the highest-end and simple web cams at the lowest-end, a digital memory device (usually flash memory; floppy disks and CD-RWs are less common) is usually used for storing images, which may then be transferred to a computer later.
Digital cameras can usually take pictures and additionally sound and video. Some can be used like webcams, some can use the PictBridge standard to connect to a printer without using a computer, and some can display pictures directly on a television set. Similarly, many camcorders can take still photographs, and store them on videotape or on flash memory cards.
Most digital cameras can connect directly to a computer in order to store pictures or to be used as a webcam. Digital cameras generally include a USB or FireWire port, and a memory card slot.
Some digital cameras can record movies but may be limited by storage capacity. A 1GB memory card will store approximately 1 hour's worth of video in an MP4 format. Newer digital cameras, such as the Canon PowerShot S1 IS, Canon PowerShot SD200/300 and the Pentax Optio MX/MX4 will capture continuous footage at a rate of 30 frames per second at a display resolution of 640x480 pixels (similar to a television screen). Some digital cameras can connect directly to a computer and store video on the computer's hard disk or DVD recorder.