Cameras Camera

A typical still camera takes one photo each time the user presses the shutter button (except in continuous-fire mode). A typical movie camera continuously takes 24 film frames per second as long as the user holds down the shutter button, or until the shutter button is pressed a second time.

When photographing rapidly moving objects, the use of a focal-plane shutter can produce some unexpected effects, since the film closest to the start position of the curtains is exposed earlier than the film closest to the end position. Typically this can result in a moving object leaving a slanting image. The direction of the slant depends on the direction the shutter curtains run in (noting also that as in all cameras the image is inverted and reversed by the lens, i.e. top-left is at the bottom right of the sensor as seen by a photographer behind the camera).

English philosopher Roger Bacon wrote about these optical principles in his 1267 treatise Perspectiva.

The electronic video camera tube was invented in the 1920s, starting a line of development that eventually resulted in digital cameras, which largely supplanted film cameras around the start of the 21st century.

The first camera obscura that was small enough for practical use as a portable drawing aid was built by Johann Zahn in 1685.

Some cameras have post focusing. Post focusing means take the pictures first and then focusing later at the personal computer. The camera uses many tiny lenses on the sensor to capture light from every camera angle of a scene and is called plenoptics technology. A current plenoptic camera design has 40,000 lenses working together to grab the optimal picture.

Some experimental cameras, for example the planar Fourier capture array (PFCA), do not require focusing to allow them to take pictures. In conventional digital photography, lenses or mirrors map all of the light originating from a single point of an in-focus object to a single point at the sensor plane. Each pixel thus relates an independent piece of information about the r-away scene. In contrast, a PFCA does not have a lens or mirror, but each pixel has an idiosyncratic pair of diffraction gratings above it, allowing each pixel to likewise relate an independent piece of information (specifically, one component of the 2D Fourier transform) about the r-away scene. Together, complete scene information is captured and images can be reconstructed by computation.

The Leaf shutter or more precisely the in-lens shutter is a shutter contained within the lens structure, often close to the diaphragm consisting of a number of metal leaves which are maintained under spring tension and which are opened and then closed when the shutter is released. The exposure time is determined by the interval between opening and closing. In this shutter design, the whole film frame is exposed at one time. This makes flash synchronisation much r as the flash only needs to fire once the shutter is fully open. Disadvantages of such shutters are their inability to reliably produce very st shutter speeds ( ster than 1/500th second or so) and the additional cost and weight of having to include a shutter mechanism for every lens.

Main article: Rangefinder cameraAs camera and lens technology developed and wide aperture lenses became more common, rangefinder cameras were introduced to make focussing more precise. Early rangefinders had two separate viewfinder windows, one of which is linked to the focusing mechanisms and moved right or left as the focusing ring is turned. The two separate images are brought together on a ground glass viewing screen. When vertical lines in the object being photographed meet exactly in the combined image, the object is in focus. A normal composition viewfinder is also provided. Later the viewfinder and rangefinder were combined. Many rangefinder cameras had interchangeable lenses, each lens requiring its own range- and viewfinder linkages.

Similar cameras were used for exposing the silver-suced copper Daguerreotype plates, commercially introduced in 1839, which were the first practical photographic medium. The collodion wet plate process that gradually replaced the Daguerreotype during the 1850s required photographers to coat and sensitize thin glass or iron plates shortly before use and expose them in the camera while still wet. Early wet plate cameras were very and little different from Daguerreotype cameras, but more sophisticated designs eventually appeared. The Dubroni of 1864 allowed the sensitizing and developing of the plates to be carried out inside the camera itself rather than in a separate darkroom. Other cameras were fitted with multiple lenses for photographing several small portraits on a single larger plate, useful when cartes de visite. It was during the wet plate era that the use of bellows for focusing became widespread, the bulkier and less easily adjusted nested box design obsolete.

He described observing a partial solar eclipse in 330 B.C. by seeing the image of the Sun projected through the small spaces between the leaves of a tree.

Main article: Twin-lens reflex cameraTwin-lens reflex cameras used a pair of nearly identical lenses, one to form the image and one as a viewfinder. The lenses were arranged with the viewing lens immediately above the taking lens. The viewing lens projects an image onto a viewing screen which can be seen from above. Some manucturers such as Mamiya also provided a reflex head to attach to the viewing screen to allow the camera to be held to the eye when in use. The advantage of a TLR was that it could be easily focussed using the viewing screen and that under most circumstances the view seen in the viewing screen was identical to that recorded on film. At close distances however, parallax errors were encountered and some cameras also included an indicator to show what part of the composition would be excluded.

The name camera obscura, Latin for dark room, derives from this early implementation of the optical phenomenon.

Main article: Film formatsA wide range of film and plate formats has been used by cameras. In the early history plate sizes were often specific for the make and model of camera although there quickly developed some standardisation for the more popular cameras. The introduction of roll film drove the standardization process still further so that by the 1950s only a few standard roll films were in use. These included 120 film providing 8, 12 or 16 exposures, 220 film providing 16 or 24 exposures, 127 film providing 8 or 12 exposures (principally in Brownie cameras) and 135 (35 mm film providing 12, 20 or 36 exposures or up to 72 exposures in the half-frame format or in bulk cassettes for the Leica Camera range.

Cameras may work with the light of the visible spectrum or with other portions of the electromagnetic spectrum. A camera generally consists of an enclosed hollow with an opening (aperture) at one end for light to enter, and a recording or viewing suce for capturing the light at the other end. A majority of cameras have a lens positioned in front of the cameras opening to gather the incoming light and focus all or part of the image on the recording suce. The diameter of the aperture is often controlled by a diaphragm mechanism, but some cameras have a fixed-size aperture. Most cameras use an electronic image sensor to store photographs on flash memory. Other cameras, particularly the majority of cameras from the 20th century, use photographic film.

Main article: Subminiature cameraCameras taking film significantly smaller than 35mm were made. Subminiature cameras were first produced in the nineteenth century. The expensive 811mm Minox, the only type of camera produced by the company from 1937 to 1976, became very widely known and was often used for espionage (the Minox company later also produced larger cameras). Later inexpensive subminiatures were made for general use, some using rewound 16mm cine film. Image quality with these small film sizes was limited.

The size of the aperture and the brightness of the scene controls the amount of light that enters the camera during a period of time, and the shutter controls the length of time that the light hits the recording suce. Equivalent exposures can be made with a larger aperture and a ster shutter speed or a corresponding smaller aperture and with the shutter speed slowed down.

Large format cameras use special equipment which includes magnifier loupe, view finder, angle finder, focusing rail /truck.

Mo Ti is the first recorded person to have exploited this phenomenon to trace the inverted image to create a picture.

Main article: Box cameraBox cameras were introduced as a budget level camera and had few if any controls. The original box Brownie models had a small reflex viewfinder mounted on the top of the camera and had no aperture or focusing controls and just a shutter. Later models such as the Brownie 127 had larger direct view optical viewfinders together with a curved film path to reduce the impact of deficiencies in the lens.

Cameras that capture many images in sequence are known as movie cameras or as cin cameras in Europe; those designed for single images are still cameras. However these categories overlap as still cameras are often used to capture moving images in special effects work and many modern cameras can quickly switch between still and motion recording modes. A video camera is a category of movie camera that captures images electronically (either using analog or digital technology).

Main articles: Camera lens and Photographic lens designThe lens of a camera captures the light from the subject and brings it to a focus on the film or detector. The design and manucture of the lens is critical to the quality of the photograph being taken. The technological revolution in camera design in the 19th century revolutionized optical glass manucture and lens design with great benefits for modern lens manucture in a wide range of optical instruments from reading glasses to microscopes. Pioneers included Zeiss and Leitz.

Cameras which take single exposures on sheet film and are functionally identical to plate cameras are still used for static, high-image-quality work; see Large-format camera, below.

Camera lenses are made in a wide range of focal lengths. They range from extreme wide angle, wide angle, standard, medium telephoto and telephoto. Each lens is best suited a certain type of photography. The extreme wide angle may be preferred for architecture because it has the capacity to capture a wide view of a building. The normal lens, because it often has a wide aperture, is often used for street and documentary photography. The telephoto lens is useful for sports, and wildlife but it is more susceptible to camera shake.

For cine cameras, film 35mm wide and perforated with sprocket holes was established as the standard format in the 1890s. It is still used for nearly all film-based professional motion picture production. For amateur use, several smaller and therefore less expensive formats were introduced. 17.5mm film, created by splitting 35mm film, was one early amateur format, but 9.5 mm film, introduced in Europe in 1922, and 16 mm film, introduced in the US in 1923, soon became the standards for home movies in their respective hemispheres. In 1932, the even more economical 8 mm format was created by doubling the number of perforations in 16mm film, then splitting it, usually after exposure and processing. The Super 8 format, still 8mm wide but with smaller perforations to make room for substantially larger film frames, was introduced in 1965.

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Cin-Kodak Special II – 16mm movie camera (ca. 1948)The frames are later played back in a cin projector at a specific speed, called the frame rate (number of frames per second). While viewing,new york asian escort a persons eyes and brain merge the separate pictures to create the illusion of motion. The first cin camera was built around 1888 and by 1890 several types were being manuctured. The standard film size for cin cameras was quickly established as 35mm film and this remains in use to this day. Other professional standard formats include 70 mm film and 16mm film whilst amateurs film makers used 9.5 mm film, 8mm film or Standard 8 and Super 8 before the move into digital format.

Main article: Movie cameraA cin camera or movie camera takes a rapid sequence of photographs on strips of film. In contrast to a still camera, which captures a single snapshot at a time, the cin camera takes a series of images, each called a frame through the use of an intermittent mechanism.

Main article: Shutter (photography)Although a range of different shutter devices have been used during the development of the camera only two types have been widely used and remain in use today.

19th century studio camera, with bellows for focusingTraditional cameras capture light onto photographic film or photographic plate. Video and digital cameras use an electronic image sensor, usually a charge coupled device (CCD) or a CMOS sensor to capture images which can be transferred or stored in a memory card or other storage inside the camera for later playback or processing.

The size and complexity of cin cameras varies greatly depending on the uses required of the camera. Some professional equipment is very large and too heavy to be hand held whilst some amateur cameras were designed to be very small and light for single-handed operation. In the last quarter of the 20th century supplanted film motion cameras for amateurs. Professional video cameras did the same for professional users around the start of the 20th century.

Four Thirds entry-level DSLR with a 25mm pancake lens.In the single-lens reflex camera the photographer sees the scene through the camera lens. This avoids the problem of parallax which occurs when the viewfinder or viewing lens is separated from the taking lens. Single-lens reflex cameras have been made in several formats including 220/120 taking 8, 12 or 16 photographs on a 120 roll and twice that number of a 220 film. These correspond to 6×9, 6×6 and 6×4.5 respectively (all dimensions in cm). Notable manucturers of large format SLR include Hasselblad, Mamiya, Bronica and Pentax. However the most common format of SLRs has been 35mm and subsequently the migration to digital SLRs, using almost identical sized bodies and sometimes using the same lens systems.

The earliest cameras produced in significant numbers used sensitised glass plates and are now termed plate cameras. Light entered a lens mounted on a lens board which was separaCameras Camerated from the plate by an extendible bellows. Many of these cameras, had controls to raise or lower the lens and to tilt it forwards or backwards to control perspective. Focussing of these plate cameras was by the use of a ground glass screen at the point of focus. Because lens design only allowed rather small aperture lenses, the image on the ground glass screen was int and most photographers had a dark cloth to cover their heads to allow focussing and composition to be carried out more easily. When focus and composition were satisctory, the ground glass screen was removed and a sensitised plate put in its place protected by a dark slide. To make the exposure, the dark slide was carefully slid out and the shutter opened and then closed and the dark slide replaced. Glass plates were later replaced by sheet film in a dark slide for sheet film; adaptor sleeves were made to allow sheet film to be used in plate holders. In addition to the ground glass, a optical viewfinder was often fitted.

By the fifteenth century, artists and scientists were using this phenomenon to make observations. Originally, an observer had to enter an actual room, in a which a pinhole was made on one wall. On the opposite wall, the observer would view the inverted image of the outside.

Early photographic cameras were usually in the form of a pair of nested boxes, the end of one carrying the lens and the end of the other carrying a removable ground glass focusing screen. By sliding them closer together or rther apart, objects at various distances could be brought to the sharpest focus as desired. After a satisctory image had been focused on the screen, the lens was covered and the screen was replaced with the light-sensitive material. The lens was then uncovered and the exposure continued for the required time, which for early experimental materials could be several hours or even days. The first permanent photograph of a camera image was made in 1826 by Joseph Nicphore Nipce using a sliding wooden box camera made by Charles and Vincent Chevalier in Paris.

Rangefinder cameras were produced in half- and full-frame 35mm and rollfim (medium format).

Rangefinder cameras allow the distance to objects to be measured by means of a coupled parallax unit on top of the camera, allowing the focus to be set with accuracy. Single-lens reflex cameras allow the photographer to determine the focus and composition visually using the objective lens and a moving mirror to project the image onto a ground glass or plastic micro-prism screen. Twin-lens reflex cameras use an objective lens and a focusing lens unit (usually identical to the objective lens.) in a parallel body for composition and focusing. View cameras use a ground glass screen which is removed and replaced by either a photographic plate or a reusable holder containing sheet film before exposure. Modern cameras often offer autofocus systems to focus the camera automatically by a variety of methods.

For many years, exposure times were long enough that the photographer simply removed the lens cap, counted off the number of seconds (or minutes) estimated to be required by the lighting conditions, then replaced the cap. As more sensitive photographic materials became available, cameras began to incorporate mechanical shutter mechanisms that allowed very short and accurately timed exposures to be made.

Almost all SLR used a front suced mirror in the optical path to direct the light from the lens via a viewing screen and pentaprism to the eyepiece. At the time of exposure the mirror flipped up out of the light path before the shutter opened. Some early cameras experimented other methods of providing through the lens viewing including the use of a semi transparent pellicle as in the CanonPellix

The actual name of camera obscura was applied by mathematician and astronomer Johannes Kepler in his Ad Vitellionem paralipomena of 1604. He later added a lens and made the apparatus transportable, in the form of a tent.

Using a focal-plane shutter, exposing the whole film plane can take much longer than the exposure time. The exposure time does not depend on the time taken to make the exposure over all, only on the difference between the time a specific point on the film is uncovered and then covered up again. For example an exposure of 1/1000 second may be achieved by the shutter curtains moving across the film plane in 1/50th of a second but with the two curtains only separated by 1/20th of the frame width. In ct in practice the curtains do not run at a constant speed as they would in an ideal design, obtaining an even exposure time depends mainly on being able to make the two curtains accelerate in a similar manner.

The focal-plane shutter operates as close to the film plane as possible and consists of cloth curtains that are pulled across the film plane with a carefully determined gap between the two curtains (typically running horizontally) or consisting of a series of metal plates (typically moving vertically) just in front of the film plane. The focal-plane shutter is primarily associated with the single lens reflex type of cameras, since covering the film rather than blocking light passing through the lens allows the photographer to view through the lens at all times except during the exposure itself. Covering the film also cilitates removing the lens from a loaded camera (many SLRs have interchangeable lenses).

Professional medium format SLR (single-lens-reflex) cameras (typically using 120/220 roll film) use a hybrid solution, since such a large focal-plane shutter would be difficult to make and/or may run slowly. A manually inserted blade known as a dark slide allows the film to be covered when changing lenses or film backs. A blind inside the camera covers the film prior to and after the exposure (but is not designed to be able to give accurately controlled exposure times) and a leaf shutter that is normally open is installed in the lens. To take a picture, the leaf shutter closes, the blind opens, the leaf shutter opens then closes again, and finally the blind closes and the leaf shutter re-opens (the last step may only occur when the shutter is re-cocked).

Main article: Medium-formatMedium-format cameras have a film size between the large-format cameras and smaller 35mm cameras. Typically these systems use 120 or 220 rollfilm. The most common image sizes are 64.5cm, 66cm and 67cm; the older 69cm is rarely used. The designs of this kind of camera show greater variation than their larger brethren, ranging from monorail systems through the classic Hasselblad model with separate backs, to smaller rangefinder cameras. There are even compact amateur cameras available in this format.

A rangefinder camera.A camera is a device that records images that can be stored directly, transmitted to another location, or both. These images may be still photographs or moving images such as videos or movies. The term camera comes from the word camera obscura (Latin for dark chamber), an early mechanism for projecting images. The modern camera evolved from the camera obscura.

Focal-plane shutters are also difficult to synchronise with flash bulbs and electronic flash and it is often only possible to use flash at shutter speeds where the curtain that opens to reveal the film completes its run and the film is fully uncovered, before the second curtain starts to travel and cover it up again. Typically 35mm film SLRs could sync flash at only up to 1/60th second if the camera has horizontal run cloth curtains, and 1/125th if using a vertical run metal shutter.

Main article: Folding cameraThe introduction of films enabled the existing designs for plate cameras to be made much smaller and for the base-plate to be hinged so that it could be folded up compressing the bellows. These designs were very compact and small models were dubbed vest pocket cameras. Folding rollfilm cameras were preceded by folding plate cameras, more compact than other designs.

At that time there was no way to preserve the images produced by such cameras except by manually tracing them. However, it had long been known that various substances were bleached or darkened or otherwise changed by exposure to light. Seeing the magical miniature pictures that light temporarily painted on the screen of a small camera obscura inspired several experimenters to search for some way of automatically highly detailed permanent copies of them by means of some such substance.

Lens hood: used on the end of a lens to block the sun or other light source to prevent glare and lens flare.

. pp.7885. ISBN0-262–4. The camera obscura looms large in traditional historical accounts of photographys invention.

British scientist Robert Boyle and his assistant Robert Hooke developed a portable camera obscura in the 1660s.

Main article: View cameraThe large-format camera, taking sheet film, is a direct successor of the early plate cameras and remain in use for high quality photography and for technical, architectural and industrial photography. There are three common types, the view camera with its monorail and field camera variants, and the press camera. They have an extensible bellows with the lens and shutter mounted on a lens plate at the front. Backs taking rollfilm, and digital backs are available in addition to the standard dark slideback. These cameras have a wide range of movements allowing very close control of focus and perspective. Composition and focussing is done on view cameras by viewing a ground-glass screen which is replaced by the film to make the exposure; they are suitable for static subjects only, and are slow to use.

The distance range in which objects appear clear and shaCamerasrp, called depth of field, can be adjusted by many cameras. This allows for a photographer to control which objects appear in focus, and which do not.Due to the optical properties of photographic lenses, only objects within a limited range of distances from the camera will be reproduced clearly. The process of adjusting this range is known as changing the cameras focus. There are various ways of focusing a camera accurately. The st cameras have fixed focus and use a small aperture and wide-angle lens to ensure that everything within a certain range of distance from the lens, usually around 3 metres (10ft) to infinity, is in reasonable focus. Fixed focus cameras are usually inexpensive types, such as single-use cameras. The camera can also have a limited focusing range or scale-focus that is indicated on the camera body. The user will guess or calculate the distance to the subject and adjust the focus accordingly. On some cameras this is indicated by symbols (head-and-shoulders; two people standing upright; one tree; mountains).

In the tenth century, Cameras the Arabic scholar Ibn al-Haytham (Alhazen) also wrote about observing a solar eclipse through a pinhole,

and he described how a sharper image could be produced by the opening of the pinhole smaller.

Some TLR had interchangeable lenses but as these had to be paired lenses they were relatively heavy and did not provide the range of focal lengths that the SLR could support. Most TLRs used 120 or 220 film; some used the smaller 127 film.

In the fifth century B.C., the Chinese philosopher Mo Ti noted that a pinhole can form an inverted and focused image, when light passes through the hole and into a dark area.

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