camera: Features of Cameras

Most modern 35 mm film cameras, both reflex and rangefinder models, incorporate a rapid film-transport mechanism, lens interchangeability (whereby lenses of many focal lengths, such as wide-angle and telephoto, may be used with the same camera body), and a built-in light meter. Many also have an automatic exposure device whereby either the shutter speed or the aperture is regulated automatically (by means of a very sophisticated solid-state electronics system) to produce the “correct” exposure. Accessories include filters, which can be used to produce special affects and compensate for difficult lighting conditions (more important in film photography in some instances); flash mechanisms for supplying light; and monopods and tripods, for steady support. Digitial versions of reflex and rangefinder models (the former of which is much more common) also have similar features.

Simple box cameras, including cameras of the Eastman Kodak Instamatic type, are fixed-focus cameras with limited or no control over exposure. Twin-lens reflex cameras use one lens solely for viewing, while the other focuses the image on the film. Formerly very popular were compact 35-mm rangefinder cameras; 126 cartridge cameras; and the subminiature cameras, including the 110 “pocket” variation of the Instamatic type and the 9.5-mm Minox. Other types of film cameras include roll- and sheet-film single-lens reflex (SLR) cameras that use 120 and larger size films; self-processing Polaroid cameras (see Land, Edwin Herbert); press cameras and view cameras that use 21⁄4 × 31⁄4 in., 4 × 5 in., 5 × 7 in., 8 × 10 in., and 11 × 14 in. film sizes; stereo cameras, the double slides from which require a special viewer; and various special types such as the super wide-angle and the panoramic cameras. (The numbers 110, 120, and 126 are film-size designations from the manufacturer and do not refer to actual measurements.)

The smaller, pocket-sized, automatic cameras of the Advanced Photo System (APS), introduced in 1996 and now obsolete, were unique in that they were part of an integrated system. Using magnetic strips on the film to communicate with the photofinishing equipment, the camera could report shutter speed, aperture setting, and lighting conditions for each frame to the computerized photofinishing equipment, which could then compensate to avoid over- or underexposed photographic prints. Basic features of the APS cameras were drop-in loading, three print formats (classic, or 4 by 6 in.; hi vision, or 4 by 7 in.; and panoramic, or 4 by 11.5 in.) at the flick of a switch, and auto-focus, auto-exposure, “point-and-shoot” operation.

Digital cameras are similar in many respects to film cameras but capture the image electronically by means of a semiconductor-based imaging device rather than via a photographic emulsion. The imaging device uses either a complementary metal-oxide semiconductor (CMOS) image sensor or a charge-coupled device (CCD). Generally CMOS image sensors are cheaper and faster than those based on CCDs, but CCDs typically produce higher quality images. Because good quality digital cameras are now incorporated in cellphones, especially smartphones, the camera phone has superseded previously popular consumer cameras such as the “pocket” cameras. High-end digital single-lens reflex cameras and point-and-shoot digital cameras have also supplanted 35 mm cameras for most professionals and nearly all consumers.

Digital cameras have several unique features. Resolution is made up of building blocks called pixels, one million of which are called a megapixel. Digital cameras have resolutions ranging from less than one megapixel to greater than 24 megapixels. With more megapixels, more picture detail may be captured, resulting in sharper, larger images, but picture quality also benefits from the use of a larger imaging sensor with larger pixels, which will have more light-gathering capacity, so a digital camera with somewhat fewer but larger pixels may produce better images than one with more but smaller pixels. Focus is a function of “zoom.” Most digital cameras have an optical zoom, a digital zoom, or both. An optical zoom lens actually moves outward toward the subject to take sharp close-up photographs; this is the same kind of zoom lens found in traditional cameras. Digital zoom is a function of software inside the camera that crops the edges from a photograph and electronically enlarges the center portion of the image to fill the frame, resulting in a photograph with less detail. Some models also have a macro lens for close-ups of small, nearby objects. Storage of digital photographs may be in the camera's internal memory or in removable solid-state flash memory devices. The images can be transferred to a computer for viewing and editing or may be viewed on the camera's LCD screen. Digital cameras typically also have the ability to record video, but have less storage capacity and fewer video features than camcorders.

Camera phones have become the ubiquitous progeny of the marriage of microelectronics and digital technology, common in relatively simple cellular telephones and a defining and essential feature of smartphones, which really are small computers masquerading as cellphones. Like digital cameras, they can record both still images and video, and though they are limited by fixed apertures, relatively small image sensors, digital zoom, and reliance on an LCD screen as a viewfinder, CMOS-based smartphone cameras produce good quality images. The phone can be used to view the image or immediately send the picture to another camera phone or computer via the Internet, the telephone network, and the like, offering the opportunity to take and share pictures in real time. Unlike the traditional camera, and to some extent the equivalent digital camera, which are used primarily for scheduled events or special occasions, the omnipresent camera phone is available for impromptu or unanticipated photographic opportunities, including the always essential “selfie.”

See also photography, still.

Sections in this article:

• Introduction
• Development of the Camera
• Motion Picture Cameras
• Features of Cameras
• Controlling the Light Entering the Camera
• Focusing and Composing the Scene
• Bibliography

The Columbia Electronic Encyclopedia, 6th ed. Copyright © 2024, Columbia University Press. All rights reserved.

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