Monday, 9 May 2011

Types of Camera

Camera Types

These are all film cameras but none the less some of the same features exist on digital cameras.

For more than several decades the box camera (viewfinder) was the instrument of choice for the casual amateur photographer. Inexpensive and simple, it was, nevertheless, capable of excellent results under many conditions. Box cameras were normally fitted with a single-element lens, a limited range of aperture control, and a single-speed leaf shutter. The Folding-Roll Film Camera Second in popularity only to the box camera, the folding camera was manufactured in a variety of formats. Basically, though, it was a box camera whose lens was incorporated into a movable bellows that could slide back and forth on a rail, allowing the lens to change focus.

Lenses and shutters were often one-piece units. More elaborate models were first-rate instruments with high-quality optical systems and precision shutters. Many were fitted with coupled rangefinders. The most significant advantage they have over the box camera, however, was their compact design when folded, which made them easier to pack and transport. There has been something of a minor renaissance in folding-roll film cameras in recent years, with appearance of several new professional instruments. They are appreciated for their large negative size and compact design.

Range Finder Camera

Similar to a Viewfinder type camera this camera does not use a lens to view the subject but instead relies on a separate viewing system in the camera for aiming and for focus. The range finder camera allows for accurate focus, however, by using two views of the same subject to adjust focus. In this camera there are two images in the viewfinder. One is usually only a portion of the viewer area and is usually slightly yellowish in color. The photographer adjusts the focus ring on the lens and as they do the two images move. When both on directly on top of each other they blend together and almost disappear signifying the camera is in focus. The rangefinder is accurate and usually very quiet and very light weight. It is useful for taking pictures in low light conditions or for candids when quiet is important. These cameras can easily be identified by their double view windows in the front.

Twin-Lens Reflex Cameras

A medium-format camera--one that uses film larger than 35mm--the twin-lens reflex was immensely popular after World War II. It is fitted with two lenses of identical focal length, one mounted atop the other. The lower, or taking, lens focuses its image directly on the film, while the image produced by the upper viewing lens is reflected through 90 degrees by a mirror, and brought to focus on a horizontal ground-glass focusing screen. The light paths to the film plane and the focusing screen are equal, so that if the photographer brings the scene on the focusing screen to sharp focus, the image on the film plane will be equally sharp.

Single-Lens Reflex Cameras

One of the most popular designs available today, the single-lens reflex (SLR) both views and photographs through one lens. Light passing through the lens is reflected by a mirror and brought to focus on a ground glass. The mirror causes a reversal of the image seen on the ground glass, but the addition of a pentaprism mounted over the ground glass allows the camera to be used at eye level, with the image seen upright and in proper left/right orientation. An instant before the exposure is made, the mirror swings upward, and the shutter is activated. A single control cocks the shutter for the next exposure, advances the film, and returns the mirror to focusing position.

View Cameras and Technical Cameras

Cameras in this category are used almost exclusively by professional photographers. The most common film formats are 4 x 5 or 8 x 10 inches, the latter often used in the very large cameras found in portrait studios. Film for these cameras is loaded in the darkroom into two-sided holders, which are inserted at the back of the camera. Both the camera's back and front can be tilted in various positions, to permit the photographer to make certain types of corrections in the image. By raising the lens in relation to the film plane, when photographing a tall building, for example, the tendency for parallel lines to look as if they converge is eliminated.

Instant Cameras

An instant camera will produce a finished print in from 20 seconds to about 4 minutes. The film, after exposure, is passed between two stainless steel rollers inside the camera. These rupture a chemical pod on the film and spread developing agent evenly over the film's surface. In the original Polaroid system it was necessary for the user to peel the finished print from the base material. Professional Polaroid films, both color and black and white, are still developed in this manner. Beginning in 1972 with the all new model, the SX-70, Polaroid Instant Cameras eject the developing picture from the camera, and the film reaches its final development in full daylight. The process is completed in about 4 minutes. The Spectra, introduced in 1986, employs this type of technology and a more advanced type of electronic exposure control and automatic focusing system. Like the later SX-70 models, it employs an ultra-high-frequency sound emitter. An electronic circuit in the camera measures the time required for the sound to be reflected back from the object photographed. This time measurement is converted into a measurement of distance, and an electrical mechanism coupled to the focusing circuit sets the lens for the proper exposure.

Disc Cameras

Since its introduction in the 1880s, flexible film has usually been rolled onto a spool or loaded into a cassette. In 1980 the Eastman Kodak Company introduced a new format for mass-market cameras. Fifteen images, each 5/16 x 3/8 inches, can be photographed on a piece of circular film about 2 1/2 inches in diameter, which is housed in a thin, light-tight film disc. Disc cameras are exceptionally compact, and most are fitted with an electronic flash and a motor that advances the disc after each exposure.

Point and Shoot Cameras

are a viewfinder type camera with added focus abilities that make it an ideal camera for vacation and travel snapshots. These cameras will often have an infrared focus system in them that bounces infra red light out of the camera like radar and determines the distance to the subject. Point and shoot cameras usually have a fairly wide angle lens and require you to get close to the subject to make a dominant photograph. For doing a group shot or a scenic or snap shot where there is a lot of material to include in a frame these cameras are ideal. For the SCHS photo class this type of camera will work for assignments that do not require using special exposure or shutter techniques because these cameras are usually fully automatic. For a quick photo these are tops.

Electronic Imaging

The world's first electronic still camera, the Japanese Canon, uses a cluster of light-sensitive electronic CHARGE-COUPLED DEVICES (CCDS), instead of film, at the focal plane. Each light sensor on a CCD is called a pixel. The pixel converts light into an electronic signal, which is recorded on a magnetic disc in the camera. The more dense the grouping of pixels, the sharper the resulting picture, which is recorded in full color. Once recorded, the image can be "played" on a television set by inserting the magnetic disc in a still video recorder, or a paper print can be made using a new 3-color electrostatic process. The quality of the image, while not as fine as that on the photographic film, is still very good and certainly will be improved during the coming years. At the present time the system will be used primarily by photojournalists, who will be able to transmit the information on the magnetic disc over ordinary telephone lines by using a Canon analog transceiver. A picture taken in Los Angeles can be viewed in full color a few minutes later in New York City. Massive research efforts and increased production can be expected eventually to lower cost of all-electronic still systems. Traditional film, however, will dominate the market for the foreseeable future.

No comments:

Post a Comment