Photographic Techniques

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View Cameras

View cameras are generally larger and heavier than medium- and small-format cameras and are most often used for studio, landscape, and architectural photography. These cameras use large-format films that produce either negatives or transparencies with far greater detail and sharpness than smaller format film. View cameras have a metal or wooden base with a geared track on which two metal standards ride, one at the front and one at the back, connected by a bellows. The front standard contains the lens and shutter; the rear holds a framed ground-glass panel, in front of which the film holder is inserted. The body configuration of the view camera, unlike that of most general-purpose cameras, is adjustable. The front and rear standards can be shifted, tilted, raised, or swung, allowing the photographer unparalleled control of perspective and focus.

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Rangefinder Cameras

Rangefinder cameras have a viewfinder through which the photographer sees and frames the subject or scene. The viewfinder does not, however, show the scene through the lens but instead closely approximates what the lens would record. This situation, in which the point of view of the lens does not match that of the viewfinder, results in what is known as parallax. At longer distances, the effects of parallax are negligible; at short distances, they become more pronounced, making it difficult for the photographer to frame a scene or subject with certainty.

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Reflex Cameras

Reflex cameras, both the SLR and the TLR types, are equipped with mirrors that reflect in the viewfinder the scene to be photographed. The twin-lens reflex is box-shaped, with a viewfinder consisting of a horizontal ground-glass screen located at the top of the camera. Mounted vertically on the front panel of the camera are two lenses, one for taking photographs and the other for viewing. The lenses are coupled, so that focusing one automatically focuses the other. The image formed by the upper, or viewing, lens is reflected to the viewing screen by a fixed mirror mounted at a 45° angle. The photographer focuses the camera and adjusts the composition while looking at the screen. The image formed by the lower lens is focused on the film at the back of the camera. Like rangefinder cameras, TLRs are subject to parallax.

In the SLR type of reflex camera, a single lens is used for both viewing the scene and taking the photograph. A hinged mirror situated between the lens and the film reflects the image formed by the lens through a five-sided prism and on to a ground-glass screen on top of the camera. At the moment the shutter is opened, a spring automatically pulls the mirror out of the path between lens and film. Because of the prism, the image recorded on the film is almost exactly that which the camera lens “sees”, without any parallax effects.

Most SLRs are precision instruments equipped with focal-plane shutters. Many have automatic exposure-control features and built-in light meters. Most modern SLRs have electronically triggered shutters; apertures, too, may be electronically actuated or they may be adjusted manually. Increasingly, camera manufacturers produce SLRs with automatic focusing, an innovation originally reserved for amateur cameras. Minolta's Maxxum series, Canon's EOS series, and Nikon's advanced professional camera, the F-4, all have autofocus capability and are completely electronic. Central processing units (CPUs) control the electronic functions in these cameras. Minolta's Maxxum 7000i has software “cards” which, when inserted in a slot on the side of the camera, expand the camera's capabilities.

Autofocus cameras use electronics and a CPU to sample automatically the distance between camera and subject and to determine the optimum exposure level. Most autofocus cameras bounce either an infrared light beam or ultrasonic (sonar) waves off the subject to determine distance and set the focus. Some cameras, including Canon's EOS and Nikon's SLRs, use passive autofocus systems. Instead of emitting waves or beams, these cameras automatically adjust the focus of the lens until sensors detect the area of maximum contrast in a rectangular target at the centre of the focusing screen.

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Design Comparisons

Of the three most widely used designs, the SLR is the most popular among both professionals and amateurs. Its greatest advantage is that the image seen through the viewfinder is virtually identical with that on which the lens is focused. In addition, the SLR is generally easy and fast to operate and comes with a greater variety of interchangeable lenses and accessories than the other two camera types.

The rangefinder camera, previously used by photojournalists because of its compact size and ease of operation (compared with the big, slow 4 x 5 in press cameras used by an earlier generation) has largely been replaced by the SLR. Rangefinder cameras, however, have a simpler optical system with fewer moving parts and are thus inherently more rugged than SLRs, in addition to being quieter and weighing less. For these reasons, some photographers, mainly professionals, continue to use them.

Compared with the other two designs, TLRs have a relatively slow focusing system. As with rangefinder cameras, fewer interchangeable lenses are available, yet the TLR remains popular. The camera produces larger negatives than most SLRs and rangefinders, an advantage when fine detail must be rendered in the final image (the Apollo astronauts used Hasselblad TLRs on the Moon). In recognition of this, some manufacturers, including Hasselblad, Mamiya, Bronica, and Rollei, have combined the convenience of the SLR with the medium-film format, further reducing the market for the TLR.

Some cameras are designed primarily for amateurs: they are simple to operate, and they produce photographs acceptable to the average snapshot photographer. Many “point-and-shoot” amateur cameras now employ sophisticated technology, with features such as autofocus and exposure control systems that simplify the process of taking pictures and almost guarantee good-quality photos, while still limiting photographer control.

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Camera Lenses

The lens is as important a part of a camera as the body. Lenses are referred to in generic terms as wide-angle, normal, and telephoto. The three terms refer to the focal length of the lens, which is customarily measured in millimetres. Focal length is defined as the distance from the centre of the lens to the image it forms when the lens is set at infinity. In practice, focal length affects the field of view, magnification, and depth of field of a lens.

Cameras used by professional photographers and serious amateurs are designed to accept all three lens types interchangeably. In 35-mm photography, lenses with focal lengths from 20 to 35 mm are considered wide-angle lenses. They provide greater depth of field and encompass a larger field (or angle) of view but provide relatively low magnification. Extreme wide-angle, or fisheye, lenses provide fields of view of 180° or more. A 6-mm fisheye lens made by Nikon has a 220° field of view that produces a circular image on film, rather than the normal rectangular or square image.

Lenses with focal lengths of 45 to 55 mm are referred to as normal lenses because they produce an image that approximates the perspective perceived by the human eye. Lenses with longer focal lengths, called telephoto lenses, constrict the field of view and decrease the depth of field while greatly magnifying the image. For a 35-mm camera, lenses with focal lengths of 85 mm or more are considered telephoto.

A fourth generic lens type, the zoom lens, is designed to have a variable focal length, which can be adjusted continuously between two fixed limits. Zoom lenses are especially useful in conjunction with single-lens reflex cameras, for which they allow continuous control of image scale.