Classification
Digital cameras can be classified into several categories:
Video cameras
Video cameras are classified as devices whose main purpose is to record moving images.
- Professional video cameras such as those used in television and movie production. These typically have multiple image sensors (one per color) to enhance resolution and color gamut. Professional video cameras usually do not have a built-in VCR or microphone.
- Camcorders used by amateurs. They generally include a microphone to record sound, and feature a small liquid crystal display to watch the video during taping and playback.
- Webcams are digital cameras attached to computers, used for video conferencing or other purposes. Webcams can capture full-motion video as well, and some models include microphones or zoom ability.
In addition, many Live-Preview Digital cameras have a "movie" mode, in which images are continuously acquired at a frame rate sufficient for video.
A Live-Preview Digital camera (LPD) is a camera that uses a conventionally generated digital image (live-preview) on an electronic screen as its principal means of framing and previewing before taking the photograph. With the exception of very few live-preview DSLRs, any digital camera that has live-preview falls into this category.
Many modern LPDs have a movie mode, and a growing number of camcorders can take still photographs. However, even a low-end LPD can take far better still pictures than a mid-range video camera, and mid-range LPDs have much lower video quality than low-end Video cameras. In addition, some newer camcorders record video directly to flash memory and transfer over USB and FireWire. Among digital LPDs, most have a rear liquid crystal display for reviewing photographs. They are rated in megapixels; that is, the product of their maximum resolution dimensions in millions. The actual transfers to a host computer are commonly carried out using the USB mass storage device class (so that the camera appears as a drive) or using the Picture Transfer Protocol and its derivatives, in addition firewire is becoming more popular and supported among more digital cameras. All use either a charge-coupled device (CCD) or a complementary metal-oxide semiconductor (CMOS) sensor or novel sensors based upon either of those two principles, i.e. chips comprised of a grid of phototransistors to sense the light intensities across the plane of focus of the camera lens. CMOS sensors are differentiated from CCDs 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.
Compact digital cameras
Also called digicams, this encompasses most digital cameras. They are characterized by great ease in operation and easy focusing; this design allows for limited motion picture capability. They tend to have significantly smaller zooms than prosumer and DSLR cameras. They have an extended depth of field. This allows objects at a larger range of depths to be in focus, which accounts for much of their ease of use. It is also part of the reason professional photographers find their images flat or artificial-looking. They excel in landscape photography and casual use. They typically save pictures in only the JPEG file format.
Bridge cameras
Prosumer or Bridge digital cameras form a general group of higher end LPDs that physically resemble DSLR cameras and share with these some advanced features but share with compacts the same basic LPD design. Traditionally DSLRs are considered much more professional than bridge cameras which have so far been prosumer or at best semi-professional. However since the introduction of the Canon EOS Digital Rebel (a small-sized, low-priced DSLR introduced in 2003) and what followed it of similar entry-level DSLRs from different manufacturers, a new class of DSLR has emerged and the distinction between bridge versus DSLR as prosumer versus professional cameras has become less black and white than it used to be. The new class of DSLRs can be described as consumer (compared to the higher classes of DSLRs), while the top bridge cameras remain prosumer (compared to compact LPDs). A Comparison between the bridge and entry-level DSLRs would reveal that they are on par. The name prosumer from professional (or producer) and consumer, means a professional-consumer or a producer-consumer (who is involved somehow in the production of the product that they consume).
Bridge cameras tend to have long- or ultrazoom lens, which compromises -in varying degrees, depending on the quality of the zoom lens- a "do it all" ability with barrel distortion and pincushioning. Prosumer cameras are sometimes marketed as and confused with digital SLR cameras since the bodies resemble each other. The distinguishing characteristics are that prosumer cameras lack the mirror and reflex system of DSLRs, have so far been always produced with only one single sealed (non-interchangeable) lens (but accessory wide angle or telephoto converters can be attached to the front of the sealed lens), can usually take movies, record audio and the scene composition is done with either the liquid crystal display or the electronic viewfinder (EVF). The overall performance tends to be slower than a true digital SLR, but they are capable of very good image quality while being more compact and lighter than DSLRs. The high-end models of this type have comparable resolutions to low and mid-range DSLRs. Many of the these cameras can save in JPEG or .RAW format.
Digital single lens reflex cameras
Digital single lens reflex cameras (DSLRs) are digital cameras based on film Single lens reflex cameras (SLRs), both types are characterized by the existence of a mirror and reflex system. See the main article on DSLRs for a detailed treatment of this category.
Digital rangefinders
For information on digital rangefinders specifically, check the digital rangefinder section in the main article linked above.
Professional modular digital camera systems
This category includes very high end professional equipment that that can be assembled from modular components (winders, grips, lenses, etc.) to suit particular purposes. Common makes include Hasselblad and Mamiya. They were developed for medium or large format film sizes, as these captured greater detail and could be enlarged more than 35mm.
Typically these cameras are used in studios for commercial production; being bulky and awkward to carry they are rarely used in action or nature photography. They can often be converted into either film or digital use by changing out the back part of the unit, hence the use of terms such as a "digital back" or "film back." These cameras are very expensive (up to $40,000) and are typically not seen in the hands of consumers.
