Movie camera

Development

In 1845, Francis Ronalds developed a photosensitive machine at the Kew Observatory. A photosensitive surface was drawn slowly past the aperture diaphragm of the camera by a clockwork mechanism to enable continuous recording over a 12- or 24-hour period. Ronalds applied his cameras to trace the ongoing variations of scientific instruments and they were used in observatories around the world for over a century.^[6][7][8]

In 1876, Wordsworth Donisthorpe and his cousin William Carr Crofts proposed a camera to take sequential pictures on glass plates, later to be printed on a roll of paper film. In 1889, he would patent a moving picture camera in which the film moved continuously. Both devices were called the Kinesigraph.^[9] In June 1878, Eadweard Muybridge created sequential series of photographs with a battery of 12 cameras along the race track at Stanford's Palo Alto Stock Farm (now the campus of Stanford University). John D. Isaacs, a technical expert at Stanford's Central Pacific Railway, was brought in to design the electromagnetic shutters and trip-wire system for the cameras. The subjects to be photographed stood against a white background with black vertical lines. Each frame was exposed for 1/500th of a second, and each exposure was separated by 1/25th of a second. The cameras were activated by the subjects (animals) snapping strings. By June 1878, Muybridge was able to photograph the racehorse Sallie Gardner. In 1879, Muybridge would develop an elaborate magic lantern attachment that he named the Zoopraxiscope, capable of replaying his photograph sequences. Around this time he began to photograph other animals and human subjects.^[10]

In 1882, Étienne-Jules Marey, a French scientist developed the chronophotographic gun, which could shoot 12 images per second and was the first photographic device to capture moving images on a plate using a metal shutter.^[11] Around 1888, Frenchman Louis Le Prince designed and described multiple camera systems with varying numbers of lenses. One prototype included a 16-lens system, which was developed at his workshop in Leeds. The first 8 lenses would be triggered in rapid succession by an electromagnetic shutter on the sensitive film; the film would then be moved forward allowing the other 8 lenses to operate on the film. After much trial and error, he was finally able to develop a single-lens camera in 1888, which he used to shoot sequences of moving pictures on paper film, including the Roundhay Garden Scene and Traffic Crossing Leeds Bridge.^[12]

Another early pioneer was the British inventor William Friese-Greene. In 1887, he began to experiment with the use of paper film, made transparent through oiling, to record motion pictures. He also said he attempted using experimental celluloid, made with the help of Alexander Parkes. In 1889, Friese-Greene took out a patent for a moving picture camera that was capable of taking up to ten photographs per second. Another model, built in 1890, used rolls of the new Eastman celluloid film, which he had perforated. A full report on the patented camera was published in the British Photographic News on February 28, 1890.^[13] He showed his cameras and film shot with them on many occasions, but never projected his films in public. He also sent details of his invention to the American inventor Thomas Edison in February 1890.^[14] After a meeting with Muybridge, Edison coined the terms Kinetograph and Kinetoscope for his envisioned devices which would capture moving images and replay them respectively. He then drew initial designs. Edison, who had already invented the phonograph, wrote that he was "experimenting upon an instrument which does for the Eye what the phonograph does for the Ear, which is the recording and reproduction of things in motion, and in such a form as to be both Cheap [sic] practical and convenient." His initial invention was a cylinder with images engraved on its surface in a spiral pattern and to be viewed through a microscope.^[15]

William Kennedy Laurie Dickson, a Scottish inventor and employee of Edison, designed the Kinetograph Camera in 1891. The camera was powered by an electric motor and was capable of shooting with the new perforated film. To govern the intermittent movement of the film in the camera, allowing the strip to stop long enough so each frame could be fully exposed and then advancing it quickly (in about 1/460 of a second) to the next frame, the sprocket wheel that engaged the strip was driven by an escapement disc mechanism—the first practical system for the high-speed stop-and-go film movement that would be the foundation for the next century of cinematography.^[16] In 1893 Auguste and Louis Lumière collaborated with Georges Demenÿ, who proposed using an intermittent mechanism similar to that inside a sewing machine to transport film.^[17] The chief mechanic at the Lumière Factory in Lyon, Charles Moisson, helped design and build their combined camera-projector system, which they named the Cinematograph.^[18] The intention was only to produce short sequences of image, so the capacity for film was kept to approximately 55 feet (17-18 meters). The camera initially used photographic paper, but later the Lumière brothers shifted to celluloid film, which they bought from New-York's Celluloid Manufacturing Co. This they covered with their own emulsion, and had it cut into strips and perforated.^[19] In 1894, the Polish inventor Kazimierz Prószyński constructed a projector and camera in one, an invention he called the Pleograph.^{[20][21][22][23][24]}

Mass-market

Due to the work of Le Prince, Friese-Greene, Edison, and the Lumière brothers, the movie camera had become a practical reality by the mid-1890s. The first firms were soon established for the manufacture of movie camera, including Birt Acres, Eugene Augustin Lauste, Dickson, Pathé frères, Prestwich, Newman & Guardia, de Bedts, Gaumont-Démény, Schneider, Schimpf, Akeley, Debrie, Bell & Howell, Leonard-Mitchell, Ertel, Ernemann, Eclair, Stachow, Universal, Institute, Wall, Lytax, and many others.^{[citation needed]}

The Aeroscope was built and patented in England in the period 1909–1911 by Polish inventor Kazimierz Prószyński.^[25] Aeroscope was the first successful hand-held operated film camera. The cameraman did not have to turn the crank to advance the film, as in all cameras of that time, so he could operate the camera with both hands, holding the camera and controlling the focus. This made it possible to film with the Aeroscope in difficult circumstances including from the air and for military purposes.^[26]

The first all-metal cine camera was the Bell & Howell Standard of 1911-12.^[27] One of the most complicated models was the Mitchell-Technicolor Beam Splitting Three-Strip Camera of 1932. With it, three color separation originals are obtained behind a purple, a green, and a red light filter, the latter being part of one of the three different raw materials in use.

In 1923, Eastman Kodak introduced a 16mm film stock, principally as a lower-cost alternative to 35 mm and several camera makers launched models to take advantage of the new market of amateur movie-makers. Thought initially to be of inferior quality to 35 mm, 16 mm cameras continued to be manufactured until the 2000s by the likes of Bolex, Arri, and Aaton.^{[citation needed]}

Digital movie cameras

Digital movie cameras do not use analog film stock to capture images, as had been the standard since the 1890s. Rather, an electronic image sensor is employed and the images are typically recorded on hard drives or flash memory—using a variety of acquisition formats. Digital SLR cameras (DSLR) designed for consumer use have also been used for some low-budget independent productions.^{[citation needed]}

Since the 2010s, digital movie cameras have become the dominant type of camera in the motion picture industry, being employed in film, television productions and even (to a lesser extent) video games.^{[citation needed]}

Camera mechanics

The Lens

Main article: Camera lens

The basic form of a camera is a box with a hole to allow in light, a portable camera obscura. These smaller portable versions are pinhole cameras. Camera obscuras were used to view solar eclipses, and eventually included converging lenses.^[28] Overtime the lenses were moved out of the camera body into external attachments with various glass elements contained in a barrel, with a lens mount on one end to attach to the camera body.^[29] Internal to the lens is a series of blades called the aperture that close in a circular fashion, changing the amount of light that goes through the lens and enters the camera body. Changing the aperture changes the depth of field, which allows for selective focus in the image. Apertures are typically measured in f-stops.^[30] By manipulating the placement of the internal glass elements, the area of the image that is in focus can be changed.^[31]

The Shutter

Internal to the camera's body is the shutter, which is designed to momentarily block light from entering the camera body and striking the imaging medium (which may be photographic film or a digital sensor).^[32] In motion picture film cameras, the shutter must move in time with the movement of the film and the camera's set frame rate. Early examples of motion picture camera shutters that allowed for this timing were half circles that spun.^[33] Cameras can have shutters at different angles to the film gate and with a different number of blades, depending on their design.^[34] In 1937, Erich Kästner designed the mirrored shutter, which allowed camera operators to see through the lens for the first time^[35] and avoid parallax between what they saw and photographed.

The Film Movement

The motion picture film is perforated, allowing sprockets in the camera to grab and move the film through the camera at a controlled, predictable rate.^[36] The rate the film moves through the body and is exposed to light is the frame rate. Early cameras were not motorized but instead used hand cranks on the exterior body to move the film through the camera, resulting in variable and inconsistent frame rates. Roughly 16 frames per second was something of a standard, because it captured fairly smooth motion while saving money on film.^[37] Frame rates below 10 or 12 frames per second tend to look like individual images, rather than continuous motion.^[38]

As the film moves, two elements play into its precision: advancement (the ability to move from one frame to the next) and registration (the ability to hold the film steady during exposure to light). Advancement occurs via a mechanism called the pull-down claw, which grabs the perforations and moves the film one frame away from the film gate. Registration is achieved via one or more pins that engage the perforations while in the film gate to hold it still during exposure to light.^[39] During this intermittent (stop-and-go) motion of the film, the celluloid is under intense tension that can cause it to break. For this reason, on either side of the film gate, loops are formed to alleviate tension on the film.^[40] These loops are necessary in both film projectors and film cameras to prevent the film from breaking.^[41]

Multiple cameras

Multiple cameras may be placed side-by-side to record a single angle of a scene and repeated throughout the runtime. The film is then later projected simultaneously, either on a single three-image screen (Cinerama) or upon multiple screens forming a complete circle, with gaps between screens through which the projectors illuminate an opposite screen. (See Circle-Vision 360°) Convex and concave mirrors are used in cameras as well as mirrors.

Sound synchronization

One of the problems in film is synchronizing a sound recording with the film. Most film cameras do not record sound internally; instead, the sound is captured separately by a precision audio device (see double-system recording). The exceptions to this are the single-system news film cameras, which had either an optical—or later—magnetic recording head inside the camera. For optical recording, the film only had a single perforation and the area where the other set of perforations would have been was exposed to a controlled bright light that would burn a waveform image that would later regulate the passage of light and playback the sound. For magnetic recording, that same area of the single perf 16 mm film that was prestriped with a magnetic stripe. A smaller balance stripe existed between the perforations and the edge to compensate the thickness of the recording stripe to keep the film wound evenly.

Double-system cameras are generally categorized as either "sync" or "non-sync." Sync cameras use crystal-controlled motors that ensure that film is advanced through the camera at a precise speed. In addition, they're designed to be quiet enough to not hamper sound recording of the scene being shot. Non-sync or "MOS" cameras do not offer these features; any attempt to match location sound to these cameras' footage will eventually result in "sync drift", and the noise they emit typically renders location sound recording useless.

To synchronize double-system footage, the clapper board which typically starts a take is used as a reference point for the editor to match the picture to the sound (provided the scene and take are also called out so that the editor knows which picture take goes with any given sound take). It also permits scene and take numbers and other essential information to be seen on the film itself. Aaton cameras have a system called AatonCode that can "jam sync" with a timecode-based audio recorder and prints a digital timecode directly on the edge of the film itself. However, the most commonly used system at the moment is unique identifier numbers exposed on the edge of the film by the film stock manufacturer (KeyKode is the name for Kodak's system). These are then logged (usually by a computer editing system, but sometimes by hand) and recorded along with audio timecode during editing. In the case of no better alternative, a handclap can work if done clearly and properly, but often a quick tap on the microphone (provided it is in the frame for this gesture) is preferred.

One of the most common uses of non-sync cameras is the spring-wound cameras used in hazardous special effects, known as "crash cams". Scenes shot with these have to be kept short or resynchronized manually with the sound. MOS cameras are also often used for second unit work or anything involving slow or fast-motion filming.

With the advent of digital cameras, synchronization became a redundant term, as both visual and audio is simultaneously captured electronically.