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 cameras, including Arri, Bell & Howell, Birt Acres, Eclair, Eugene Augustin Lauste, Dickson, Gaumont, Lytax, Mitchell Camera, Pathé Frères, Schneider Kreuznach, Universal Camera Corp., and 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]

Mitchell Cameras were one of the primary cameras used in the production of newsreels and Hollywood movies from around 1929, when Fox Studios bought Mitchell, until the Mitchell closed in the 1970s. Their main camera was the Mitchell Standard.^[28] Panavision cameras were brought into use during the 1950s due to anamorphic widescreen processes.^[29] During World War II, cinematographers working as field photographers made use of Bell & Howell Eyemo cameras if they were American and Arri Arriflex 35 cameras if they were German. The Arriflex 35s were brought back to the United States after the war via the US Army Pictorial Center and became popular due to the models mirrored, twin-bladed shutter, which allowed for single-lens reflex viewing.^[30]

Digital movie cameras

Experiments with electronic moving images date back to the use of selenium solar cells and the transmission by wire of their signal in the 1880s.^[31] But the first widespread use came after the invention of the Baird Televisor by John Logie Baird, when tube amplifier gave the ability to strengthen the signals created by solar cells. Baird then captured lines of light using a scanning system through a Nipkow disk. In his early work, he could successfully transmit captured images, but the images were low quality and could not be stored. His work eventually led to broadcast television.^[32] The first fully digital still photography camera was designed and built by Steven Sasson, an employee at Eastman Kodak in Rochester, New York in 1975. The camera used a CCD sensor.^[33]

Digital movie cameras do not use analog film stock to capture images, as had been the standard since the 1890s. In digital technology, there are two common image sensors that replaced solar cells: the CCD sensor and the CMOS sensor.^[34] Captured images are then recorded on a storage medium like a hard drive 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.^[35] Since the 2010s, digital movie cameras have become the dominant type of camera in the motion picture industry, being employed in movies and television productions, although analog film is still used as well.^[36]

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.^[37] 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.^[38] 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.^[39] By manipulating the placement of the internal glass elements, the area of the image that is in focus can be changed.^[40]

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).^[41] 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.^[42] Cameras can have shutters at different angles to the film gate and with a different number of blades, depending on their design.^[43] In 1937, Erich Kästner designed the mirrored shutter, which allowed camera operators to see through the lens for the first time^[44] 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.^[45] 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.^[46] Frame rates below 10 or 12 frames per second tend to look like individual images, rather than continuous motion.^[47]

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.^[48] 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.^[49] These loops are necessary in both film projectors and film cameras to prevent the film from breaking.^[50]

Aspect Ratios

A film's aspect ratio is the shape of the image and is independent of the film gauge (eg. 35 mm or 65 mm) on which it was shot. The aspect ratio is describe as the width of the image divided by its height, and is expressed as a ratio with height as the unity, such as 1.78:1. The standardized aspect ratio for motion pictures with sound was the Academy ratio of 1.37:1 until the introduction of CinemaScope's 2.55:1 anamorphic aspect ratio in 1955.^[53] Silent films and those without a printed audio track (such as films which used sound-on-disc systems) used a 1.33:1 aspect ratio. The earliest sound films used an aspect ratio of 1.18:1.^[54]

Anamorphic widescreen

In the United States, the two most common aspect ratios are 1.85:1 (called flat) and 2.40:1 (called 'scope).^[53] These terms arise from the differences between the Academy ratio of 1.37:1, and CinemaScope's 2.55:1 which was captured on the same image area but with an anamorphic lens rather than a spherical lens. Spherical lenses focus light onto the imaging area (photographic film or an image sensor) without changing any features of its aspect ratio, while anamorphic lenses compress the image in one direction (usually horizontally, its long side) by a factor of two. This compression of the image is stretched either during post-production or when the film is projected.^[55] The anamorphic system allows for more image information to be captured in the same imaging area and allows for widescreen. Another method to achieve widescreen is to shoot in the standard 1.37:1 aspect ratio and then to matte the top and bottom of image during projection.^[53]

Multiple cameras

Multiple cameras may be placed side-by-side to record a single angle of a scene, with the intention of being projected together to produce a larger image than one one camera could produce. This can be done to produce seamless images like in How the West Was Won, or collages of images like in Napoléon.

In the Cinerama process, a camera with three lenses captured the scene on three strips of film simultaneously.^[56] Projection then took place from three projectors, pointed at a screen to create a seamless image, with a fourth strip of film that carried seven tracks of audio.^[57] Cinerama used three strips of standard 35 mm movie film, traveling at 24 frames per second, with an aspect ratio of 2.55:1.^[58] Circle-Vision 360° is a similar technology, which makes use of nine cameras aligned in a circle to capture a 360° image.^[59]

Color Processes

That all early films were made to be seen in black and white is a misconception. Early films were often colored via hand coloring, film tinting or toning, or mixtures of these processes. Existing nitrate film prints and surviving film distributor catalogues demonstrate that theaters could rent black and white or color versions of films. Color was used in dramatic and documentary films more often than comedies, and a film's production value did not necessarily dictate whether it was in color or not.^[60]

Natural color

Natural color can be achieved through either additive color or subtractive color systems. In an additive system, when the primary colors are mixed, white light is made; while in a subtractive system the primary colors mix, block light and create black.^[62] The Finlay colour process was an additive system where a color mosaic influenced the underlying black and white image, allowing a color image to be seen.^[63] Other systems, like Technicolor Process 1, used a beam splitter to record the scene through two color filters (one red and one green) onto two strips of black and white film. The images were then projected through alternating, corresponding red and green filters in the film projector, allowing the display of color.^[64] Technicolor Process 4 also used a beam splitter, through three color filters onto three strips of black and white film, but the projection prints were made via a dye-transfer process.^[65] The final development was chromogenic photography, first brought into widespread use through the Eastman Kodak company's Kodachrome 16mm reversal film. Kodachrome captured natural color in a single strip of film (called a monopack) via different layers of light-sensitive film emulsion.^[66] In digital cinema cameras one strategy for capturing color is the use of a Bayer filter, which records colors on the camera's image sensor via red, green, and blue sensitive areas and then blends the colors via interpolation.^[67]

Sound Synchronization

In order to achieve higher quality audio, sound is usually recorded on a separate device than the camera.^[68] This is called double-system recording. While on set, the camera records the image under the operation of the camera operator, while the sound is recorded by an audio engineer on an audio recorder. In order to ensure sync sound is achieved, a clapperboard is used.^[69] During post-production, the sound of the clapperboard on the audio track is aligned with the image of the clapperboard captured by the camera, which will align the audio and image tracks.