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Encyclopedia > Movie projector
35 mm Kinoton movie projector in operation.
35 mm movie projector.

A movie projector is an opto-mechanical device for displaying moving pictures by projecting them on a projection screen. Most of the optical and mechanical elements, except for the illumination and sound devices, are present in movie cameras. Image File history File linksMetadata Download high resolution version (1504x1000, 452 KB) Summary Kinoton FP30ST movie projector in operation. ... Image File history File linksMetadata Download high resolution version (1504x1000, 452 KB) Summary Kinoton FP30ST movie projector in operation. ... Simulated 35 mm film with soundtracks _ The outermost strips (on either side) contain the SDDS soundtrack as an image of a digital signal. ... Image File history File links Download high resolution version (1195x839, 287 KB) Summary Licensing File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Movie projector ... Image File history File links Download high resolution version (1195x839, 287 KB) Summary Licensing File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Movie projector ... Simulated 35 mm film with soundtracks _ The outermost strips (on either side) contain the SDDS soundtrack as an image of a digital signal. ... Table of Opticks, 1728 Cyclopaedia Optics ( appearance or look in ancient Greek) is a branch of physics that describes the behavior and properties of light and the interaction of light with matter. ... Mechanics (Greek ) is the branch of physics concerned with the behaviour of physical bodies when subjected to forces or displacements, and the subsequent effect of the bodies on their environment. ... Film is a term that encompasses individual motion pictures, the field of film as an art form, and the motion picture industry. ... Projection screens are installations consisting of blank surface and a support structure used for projecting an image for the view of an audience. ... The Arricam ST, a popular 35 mm film camera currently used on major productions. ...

Contents

Physiology

According to the theory of persistence of vision, the perceptual processes of the brain and the retina of the human eye retains an image for a brief moment of time. This theory is said to account for the illusion of motion which results when a series of film images is displayed in quick succession, rather than the perception of the individual frames in the series. According to the theory of persistence of vision, the perceptual processes of the brain or the retina of the human eye retains an image for a brief moment. ... In animals the brain, or encephalon (Greek for in the head), is the control center of the central nervous system, responsible for thought. ... Human eye cross-sectional view. ... Trinomial name Homo sapiens sapiens Linnaeus, 1758 Humans, or human beings, are bipedal primates belonging to the mammalian species Homo sapiens (Latin: wise man or knowing man) in the family Hominidae (the great apes). ... // A human eye. ... Film is a term that encompasses individual motion pictures, the field of film as an art form, and the motion picture industry. ...


Persistence of vision should be compared with the related phenomena of beta movement and phi movement. A critical part of understanding these visual perception phenomena is that the eye is not a camera, ie: there is no "frame rate" or "scan rate" in the eye. Instead, the eye/brain system has a combination of motion detectors, detail detectors and pattern detectors, the outputs of all of which are combined to create the visual experience. Beta movement is a perceptual illusion, described by Max Wertheimer in his 1912 Experimental Studies on the Seeing of Motion, whereby two or more still images are combined by the brain into surmised motion. ... The phi phenomenon is a perceptual illusion described by Max Wertheimer in his 1912 Experimental Studies on the Seeing of Motion, in which a disembodied perception of motion is produced by a succession of still images. ... This does not cite any references or sources. ... Frame rate, or frame frequency, is the measurement of how quickly an imaging device produces unique consecutive images called frames. ... Scan rate can refer to: Horizontal scan rate Vertical scan rate Category: ...


The frequency at which flicker becomes invisible is called the flicker fusion threshold, and is dependent on the level of illumination. Generally, the frame rate of 16 frames per second (fps) is regarded as the lowest frequency at which continuous motion is perceived by humans. (Interestingly this threshold varies across different species; a higher proportion of rod cells in the retina will create a higher threshold level.) The flicker fusion threshold (or flicker fusion rate) is a concept in the psychophysics of vision. ... Normalised absoption spectra of human rod (R) and cone (S,M,L) cells. ...


It is possible to view the black space between frames and the passing of the shutter by the following technique:
Close your eyelids, then periodically rapidly blink open and closed. If done fast enough you will be able to randomly "trap" the image between frames, or during shutter motion. This will not work with television due to the persistence of the phosphors nor with LCD or DLP light projectors due to the continuity of image, although certain color artifacts may appear with some digital projection technologies. LCD redirects here. ... The DLP Logo Digital Light Processing (DLP) is a technology used in projectors and video projectors. ... This is a disambiguation page — a navigational aid which lists other pages that might otherwise share the same title. ...


Since the birth of sound film, virtually all film projectors in commercial movie theaters project at a constant speed of 24 fps. This speed was chosen for financial and technical reasons - it was the slowest speed (and thus required the least film stock and was cheapest for producers) at which a satisfactory reproduction and amplification of sound could be conducted. There are some specialist formats (eg Showscan and Maxivision) which project at higher rates, often 48 fps. 1902 poster advertising Gaumonts sound films, depicting an optimistically vast auditorium A sound film is a motion picture with synchronized sound, or sound technologically coupled to image, as opposed to a silent film. ... This article or section does not adequately cite its references or sources. ... Maxivision 24 and Maxivision 48 are 35 mm motion picture film formats, created by Dean Goodhill in 1999. ...


Silent films usually were not projected at constant speeds [1] but rather were varied throughout the show at the discretion of the projectionist, often with some notes provided by the distributor. Speeds ranged from about 18 fps on up - sometimes even faster than modern sound film speed (24 fps). Contrary to received opinion, 16 fps - though sometimes used as a camera shooting speed - was dangerously inadvisable for projection, due to the high risk of the nitrate-base prints catching fire in the projector. (A dramatic rendition of a nitrate print fire and its potentially devastating effects is famously found in Nuovo Cinema Paradiso, which revolves around the goings-on of a projectionist.) A silent film is a film which has no accompanying soundtrack. ... Skeletal formula of nitrocellulose Ball-and-stick model of a section of nitrocellulose Nitrocellulose (also: cellulose nitrate, flash paper) is a highly flammable compound formed by nitrating cellulose through, for example, exposure to nitric acid or another powerful nitrating agent. ... Nuovo Cinema Paradiso (1989) is an Italian film written and directed by Giuseppe Tornatore. ...


Principles of operation

35 mm Kinoton FP30ST movie projector, with parts labeled. (Click thumbnail for larger text.)

Image File history File linksMetadata Download high resolution version (1504x1000, 809 KB) Summary Movie projector mechanisms with parts identified. ... Image File history File linksMetadata Download high resolution version (1504x1000, 809 KB) Summary Movie projector mechanisms with parts identified. ... Simulated 35 mm film with soundtracks _ The outermost strips (on either side) contain the SDDS soundtrack as an image of a digital signal. ...

Projection elements

As in a slide projector there are essential optical elements: [carousel slide projector, the most common form of projector] A slide projector is an opto-mechanical device to view photographic slides. ...


Light source

An incandescent lamp or an electric arc light produces illuminating photons. The traditional carbon arc or modern xenon arc light source produces sufficient heat to burn the film should the film remain stationary for more than a fraction of a second. Xenons were introduced in the 1950s and are now the more common source, being easier and safer to maintain for the most part. The incandescent light bulb uses a glowing wire filament heated to white-hot by electrical resistance, to generate light (a process known as thermal radiation). ... The 300,000-watt Plasma Arc Lamp in the Infrared Processing Center (IPC) at Oak Ridge National Laboratory An arc lamp is a device that produces light by the sparking (or arcing, from voltaic arc or electric arc) of a high current between two carbon rod electrodes. ... The word light is defined here as electromagnetic radiation of any wavelength; thus, X-rays, gamma rays, ultraviolet light, infrared radiation, microwaves, radio waves, and visible light are all forms of light. ... 15 kW Xenon short-arc lamp used in IMAX projectors Xenon arc lamps are an artificial light source. ...


Reflector and condenser lens

A curved reflector redirects light that would otherwise be wasted toward the condensing lens.


A positive curvature lens concentrates the reflected and direct light toward the film gate. A lens. ...


Douser

(Also spelled dowser.)


A metal blade which cuts off light before it can get to the film - usually this is part of the lamphouse, and may be manually or automatically operated. Some projectors have a second, electrically-controlled douser that is used for changeovers (sometimes called a "changeover douser" or "changeover shutter"). Some projectors have a third, mechanically-controlled douser that automatically closes when the projector slows down (called a "fire shutter" or "fire douser"), to protect the film if a failsafe causes the motor to shutdown. Dousers protect the film when the lamp is on but the film is not moving, preventing the film from melting from prolonged exposure to the direct heat of the lamp. It also prevents the lens from scarring or cracking from excessive heat.


Film gate and single image

A single image of the series of images comprising the movie is positioned and held flat within an aperture called the gate. The gate also provides a slight amount of friction so that the film does not advance or retreat except when driven to advance the film to the next image.


Shutter

A commonly-held misconception is that film projection is simply a series of individual frames dragged very quickly past the projector's intense light source; this is not the case. If a roll of film were merely passed between the light source and the lens of the projector, all that would be visible on screen would be a continuous blurred series of images sliding from one edge to the other. It is the shutter that gives the illusion of one full frame being replaced exactly on top of another full frame. A rotating petal or gated cylindrical shutter interrupts the emitted light during the time the film is advanced to the next frame. The viewer does not see the transition, thus tricking the brain into believing a moving image is on screen. Modern shutters are designed with a flicker-rate of two times (48 Hz) or even sometimes three times (72 Hz) the frame rate of the film, so as to reduce the perception of screen flickering. (See Frame rate and Flicker fusion threshold.) Higher rate shutters are less light efficient, requiring more powerful light sources for the same light on screen. Frame rate, or frame frequency, is the measurement of how quickly an imaging device produces unique consecutive images called frames. ... The flicker fusion threshold (or flicker fusion rate) is a concept in the psychophysics of vision. ...

Mechanical sequence when image is shown twice and then advanced.
Outer sprockets rotate continuously while the frame advance sprockets are controlled by the mechanism shown.

Image File history File links Size of this preview: 800 × 325 pixelsFull resolution (838 × 340 pixel, file size: 17 KB, MIME type: image/png)English language and layout modification of original French language commons image by User:Cdang, Image:Cinema_projection_4_temps. ...

Imaging lens and aperture plate

A lens system with multiple optical elements directs the image of the film to a viewing screen. Different lenses are used for different aspect ratios. Each of these lenses comes with an aperture plate, a piece of metal with a precisely cut rectangular hole in the middle of equivalent aspect ratio. The aperture plate is placed just behind the gate, and masks off any light from hitting the image outside of the area intended to be shown (most modern films have extra image on the frame that is meant to be masked off in the projector). A lens. ...


Viewing screen

Main article: Projection screen

In most cases this is a reflective surface which may be either aluminized (for high contrast in moderate ambient light) or a white surface with small glass beads (for high brilliance under dark conditions). In a commercial theater, the screen also has hundreds of small, evenly spaced holes in order to allow the passage of sound from the speakers and subwoofer which often are directly behind it. Home theater projection screen (119 in. ...


Film transport elements

Film supply and takeup

Two reel system

The two reel system is also known as a changeover system, after the switching mechanism that operates between the end of one reel and the beginning of the next. In a two reel system the feed reel has a slight drag to maintain tensioning in the film, while the takeup reel is driven with a constant tension by a mechanism that is allowed to slip.


The two reel system was almost universally used before the advent of the single reel system for movie theaters in order to be able to show feature-length films. Although one reel long-play systems tend to be more popular with the newer multiplexes, the two reel system is still in significant use to this day. The projector operator operates two projectors, threading one with the next reel while the other projector plays the current reel. As the outgoing reel approaches its end, the projectionist looks for cue marks, at the upper right corner of the picture. Usually these are dots or circles, although they can also be slashes. (Some older films have occasionally been known to have used squares or triangles, and even positioned the cues in the middle of the right edge of the picture.) The first cue appears twelve feet (3.7 m) or eight seconds at 24 fps before the end of the reel, and signals the projectionist to start the motor of the projector containing the incoming reel. After another ten and a half feet (3.2 m) or seven seconds at 24 fps, the changeover cue should appear, which signals the projectionist to actually make the changeover. When this second cue appears, the projectionist has one and a half feet (457 mm) or one second at 24 fps to make the changeover - if it doesn't occur within one second, the tail leader of the outgoing reel will be projected on the screen. On some projectors, the operator would be alerted to the change by a bell that operated when the feed reel rotation exceeded a certain speed (that reel rotates faster as the film is exhausted), or based on the diameter of the remaining film (Premier Changeover Indicator Pat.411992), although many such projectors do not have such an auditory system. A cue mark, also known as a cue dot, a changeover cue[1] or simply a cue is a visual indicator used with motion picture film prints, usually placed on the right-hand upper corner of a frame of the film. ...


During the actual operation of a changeover, the two projectors use an interconnected electrical control connected to the changeover button so that as soon as the button is pressed, the changeover douser on the outgoing projector is closed in sync with the changeover douser on the incoming projector. If done properly, a changeover should be virtually unnoticeable to an audience. In older theaters, there may be manually operated, sliding covers in front of the projection booth's windows. A changeover with this system is often clearly visible as a wipe on the screen. In film editing, a wipe is a gradual spatial transition from one image to another. ...


The size of the reels can vary based on the projectors, but generally films are divided and distributed in reels of up to 2000 feet (610 m, about 22 minutes at 24 fps). Some projectors can even accommodate up to 6000 feet (1,830 m), which minimizes the number of changeovers in a showing. Certain countries also divide their film reels up differently; Russian films, for example, often come on 1000 foot (305 m) reels, although it's likely that most projectionists working with changeovers would combine them into longer reels of at least 2000 feet (610 m), to minimize changeovers and also give sufficient time for threading and any possibly needed troubleshooting time.


Single reel system
Christie AW3 platter, BIG SKY Industries console, and Century SA projector.

There are two largely used single reel systems (also known as long-play systems) today: the tower system (vertical feed and takeup) and the platter system (non-rewinding; horizontal feed and takeup). Image File history File linksMetadata Download high resolution version (3072x2304, 621 KB) Summary Christie AW3 platter, BIG SKY Industries console, and Century SA projector. ... Image File history File linksMetadata Download high resolution version (3072x2304, 621 KB) Summary Christie AW3 platter, BIG SKY Industries console, and Century SA projector. ...


The tower system largely resembles the two reel system, except in that the tower itself is generally a separate piece of equipment used with a slightly modified standard projector. The feed and takeup reels are held vertically on the axis, except behind the projector, on oversized spools with 12,000 foot (3,660 m) capacity or about 133 minutes at 24 fps. This large capacity alleviates the need for a changeover on an average-length feature; all of the reels are spliced together into one giant one. The tower is designed with four spools, two on each side, each with its own motor. This allows the whole spool to be immediately rewound after a showing; the extra two spools on the other side allow for a film to be shown while another is being rewound or even made up directly onto the tower. Each spool requires its own motor in order to set proper tensioning for the film, since it has to travel (relatively) much further between the projector film transport and the spools. As each spool gains or loses film, the tension must be periodically checked and adjusted so that the film can be transported on and off the spools without either sagging or snapping.


In a platter system the individual 20-minute reels of film are also spliced together as one large reel, but the film is then wound onto a horizontal rotating table called a platter. Three or more platters are stacked together to create a platter system. Most of the platters in a platter system will be occupied by film prints; whichever platter happens to be empty serves as the "take-up reel" to receive the film that is playing from another platter.


The way the film is fed from the platter to the projector is not unlike an eight-track audio cartridge. Film is unwound from the center of the platter through a mechanism called a "brain" which controls the speed of the platter's rotation so that it matches the speed of the film as it is fed to the projector. The film winds through a series of rollers from the platter stack to the projector, through the projector, through another series of rollers back to the platter stack, and then onto the platter serving as the take-up reel. The 8-track cartridge or Stereo 8 is a magnetic tape technology for audio storage, popular from the mid-1960s to the early 1980s. ...


This system makes it possible to project a film multiple times without needing to rewind it. As the projectionist threads the projector for each showing, he transfers the brain mechanism from the empty platter to the full platter and the film then plays back onto the platter it came from. In the case of a double feature, each film plays from a full platter onto an empty platter, swapping positions on the platter stack throughout the day.


The advantage of a platter is that the film need not be rewound after each show, which can save labor. Rewinding risks rubbing the film against itself, which can cause scratching of the film and smearing of the emulsion which carries the pictures. The disadvantages of the platter system are that the film can acquire diagonal scratches on it if proper care is not taken while threading film from platter to projector, and the film has more opportunity to collect dust and dirt as long lengths of film are exposed to the air. A clean projection booth kept at the proper humidity is of great importance, as are cleaning devices that can remove dirt from the film print as it plays.


Automation and the rise of the multiplex

The single reel system can allow for the complete automation of the projection booth operations, given the proper auxiliary equipment. Since films are still transported in multiple reels they must be joined together when placed on the projector reel and taken apart when the film is to be returned to the distributor. It is the complete automation that has enabled the modern "multiplex" cinema - a single site typically containing from 8 to 24 theaters with only a few projection and sound technicians, rather than a platoon of projectionists. The multiplex also offers a great amount of flexibility to a theater operator, enabling theaters to exhibit the same popular production in more than one auditorium with staggered starting times. It is also possible, with the proper equipment installed, to "interlock", i.e. thread a single length of film through multiple projectors. This is very useful when dealing with the mass crowds that an extremely popular film may generate in the first few days of showing, as it allows for a single print to serve more patrons. This article or section does not cite any references or sources. ... A typical multiplex (AMC Promenade 16 in Woodland Hills, Los Angeles, United States). ...


Feed and extraction sprockets

Smooth wheels with triangular pins called sprockets engage perforations punched into one or both edges of the film stock. These serve to set the pace of film movement through the projector and any associated sound playback system. Sprockets was a fictional television talk show created by actor, writer and comedian Mike Myers for the American sketch comedy show Saturday Night Live. ...


Film loop

As with motion picture cameras, the intermittent motion of the gate requires that there be loops above and below the gate in order to serve as a buffer between the constant speed enforced by the sprockets above and below the gate and the intermittent motion enforced at the gate. Some projectors also have a sensitive trip pin above the gate to guard against the upper loop becoming too big. If the loop hits the pin, it will close the dousers and stop the motor to prevent an excessively large loop from jamming the projector.


Film gate pressure plate

A spring loaded pressure plate functions to align the film in a consistent image plane, both flat and perpendicular to the optical axis. It also provides sufficient drag to prevent film motion during the frame display, while still allowing free motion under control of the intermittent mechanism. The plate also has spring-loaded runners to help hold film while in place and advance it during motion.


Intermittent mechanism

The intermittent mechanism can be constructed in different ways. For smaller gauge projectors (8 mm and 16 mm), a pawl mechanism engages the film's sprocket hole one side, or holes on each side. This pawl advances only when the film is to be moved to the next image. As the pawl retreats for the next cycle it is drawn back and does not engage the film. This is similar to the claw mechanism in a motion picture camera. The intermittent mechanism (or movement) is the device by which film is regularly advanced and then held in place for a brief duration of time in a movie camera or movie projector. ...


In 35 mm and 70 mm projectors, there usually is a special sprocket immediately underneath the pressure plate known as the intermittent sprocket. Unlike all the other sprockets in the projector, which run continuously, the intermittent sprocket operates in tandem with the shutter, and only moves while the shutter is blocking the lamp, so that the motion of the film cannot be seen. It also moves in a discrete amount at a time, equal to the number of perforations that make up a frame (4 for 35 mm, 5 for 70 mm). The intermittent movement in these projectors is usually provided by a Maltese Cross mechanism (also known as the Geneva Mechanism). The Geneva drive is a mechanism that translates a continuous rotation into an intermittent rotary motion. ...


IMAX projectors use what is known as the rolling loop method, in which each frame is sucked into the gate by a vacuum, and positioned by registration pins in the perforations corresponding to that frame.


Types of projectors

Projectors are classified by the size of the film used, i.e. the film format. Typical film sizes: Movie film formats Amateur formats: 8 mm Single-8 Super 8 mm 9,5 mm film 17. ...


8 mm

Main article: 8 mm film

Long used for home movies before the video camera, this uses double sprocketed 16 mm film, which is run through the camera twice. The 16 mm film is then split lengthwise into two 8 mm pieces that are spliced to make a single projectable film with sprockets on one side. 8mm film is a motion picture film format in which the filmstrip is eight millimeters wide. ...


Super 8

Main article: Super 8 mm film

Developed by Kodak, this film stock uses very small sprocket holes close to the edge that allow more of the film stock to be used for the images. This increases the quality of the image. The film is premade in the 8 mm width, not split during processing as is the earlier 8 mm. Magnetic stripes could be added to carry encoded sound to be added after film development. Kodachrome 40 KMA464P Super 8 Catridge Super 8 mm film, also called Super 8 is a motion picture film format that was developed in the 1960s and released on the market in 1965 by Eastman Kodak as an improvement of the older 8mm home movie format, and the Cine 8... Eastman Kodak Company (NYSE: EK) is a large multinational public company producing photographic equipment. ...


9.5 mm

Main article: 9.5 mm film

Film format introduced by Pathé Frères in 1922 as part of the Pathé Baby amateur film system. It was conceived initially as an inexpensive format to provide copies of commercially-made films to home users. The format uses a single, central perforation (sprocket hole) between each pair of frames, as opposed to 8 mm film which has perforations along one edge, and most other film formats which have perforations on each side of the image. It became very popular in Europe over the next few decades and is still used by a small number of enthusiasts today. Over 300,000 projectors were produced and sold mainly in France and England, and many commercial features were available in the format. In the sixties the last projectors of this format were being produced. They are now collectors' items. Three frames of 9. ...


16 mm

Main article: 16 mm film

This was a popular format for audio-visual use in schools and as a high-end home entertainment system before the advent of broadcast television. 16 mm film was introduced by Eastman Kodak in 1923 as an inexpensive amateur alternative to the conventional 35 mm film format. ...


35 mm

Main article: 35 mm film

The most common film size for theatrical productions during the 20th century. In fact, the common 35 mm camera, developed by Leica, was designed to use this film stock and was originally intended to be used for test shots by movie directors and cinematographers. 35 mm film frames. ... Image:Leica-Logo. ...


70 mm

Main article: 70 mm film

High end movie productions were often produced in this film gauge in the 1950s and 1960s and many very large screen theaters are still capable of projecting it in the 21st century. It is often referred to as 65/70, as the camera uses film 65mm wide, but the projection prints are 70mm wide. The extra five millimeters of film accommodated the soundtrack, usually a six track magnetic stripe. The most common theater installation would use dual gauge 35/70mm projectors. 70 mm film (or 65 mm film) is a high-resolution film stock, of superior quality to standard 35 mm motion picture film format. ...


70 mm film is also used in both the flat and domed IMAX projection system. In IMAX the film is transported horizontally in the film gate, similar to VistaVision. Some productions intended for 35 mm anamorphic release were also released using 70 mm film stock. A 70 mm print made from a 35 mm negative is significantly better in appearance than an all 35 mm process, and allowed for a release with 6 track magnetic audio. IMAX theatre at the Melbourne Museum complex, Australia BFI London IMAX by night IMAX dome in Guayaquil, Ecuador Glasgow Imax on the left (Part of the Glasgow Science Centre IMAX (short for Image Maximum) is a film format created by Canadas IMAX Corporation that has the capacity to display... A VistaVision 35 mm horizontal camera film frame. ...


The advent of 35mm prints with digital soundtracks in the 1990s largely supplanted the widespread release of the more expensive 70mm prints.


Sound

35mm film audio tracks, from left to right: SDDS, Dolby Digital, analog optical, and DTS time code.

Regardless of the sound format, any sound represented on the film image itself will not be the sound for the particular frame it occupies. All optical sound formats must be offset from the image because the image is projected with intermittent motion. If the sound head on the projector was adjacent to the gate, the sound would be a jerky start-stop-start-stop and so on. Therefore the sound head requires continuous motion and will be located a certain number of frames before or after the gate. Image File history File linksMetadata Download high resolution version (1914x1393, 459 KB) Summary Macro of 35mm film audio tracks, from left to right: Sony SDDS, Dolby Digital, analog Optical, and finally DTS time code. ... Image File history File linksMetadata Download high resolution version (1914x1393, 459 KB) Summary Macro of 35mm film audio tracks, from left to right: Sony SDDS, Dolby Digital, analog Optical, and finally DTS time code. ... SDDS stands for Sony Dynamic Digital Sound, which is a cinema sound system developed by Sony. ... Dolby Digital logotype Dolby Digital is the marketing name for a series of lossy audio compression technologies by Dolby Laboratories. ... DTS (formerly known as Digital Theater Systems), owned by DTS, Inc. ...

See the 35 mm film article for more information on both digital and analog methods.

35 mm film frames. ...

Optical

With 16 mm and the larger sizes it is practical to add a narrow channel of optically encoded sound track. This is read using an illuminating light or laser and a photocell or photodiode. In 16 mm, this is a single mono track, and the sound head is 26 frames after the gate. In 35 mm, this can be mono or stereo, the latter including several different Dolby noise reduction systems (including Dolby A and Dolby SR). The sound head is located twenty frames after the gate for 35 mm projectors. Originally optical sound was variable density, where the transparency/opacity level of the sound track was used to represent sound. This had disadvantages because the grain of the film caused a background hiss, and so was replaced with the now-universal standard variable area. In this system, a clear waveform on black background represents the sound, and the width of the waveform is equivalent to the amplitude. Variable area does have slightly less frequency response than variable density. In the 1970s and early 1980s, optical sound Super-8 mm copies were produced mainly for airline in-flight movies. This technology was soon made obsolete by video equipment. A photoresistor is an electronic component whose resistance decreases with increasing incident light intensity. ... A photodiode Photodiode closeup A photodiode is a semiconductor diode that functions as a photodetector. ... Dolby NR is the name given to a series of noise reduction systems developed by Dolby Laboratories for use in analogue magnetic tape recording. ... Dolby Analog SR or Dolby SR format (Spectral Recording), was developed by Dolby Laboratories and has been in common use in professional audio since 1986. ...


Digital

Modern theatrical systems use optical representations of digitally encoded multi-channel sound. An advantage of digital systems is that the offset between the sound and picture heads can be varied and then set with the digital processors. Digital sound heads are usually above the gate. All digital sound systems currently in use have the ability to instantly and gracefully fall back to the optical sound system should the digital data be corrupt or the whole system fail.


Cinema Digital Sound (CDS)

Created by Kodak and ORC (Optical Radiation Corporation), Cinema Digital Sound was the first attempt to bring multi-channel digital sound to first-run theaters. CDS was available on both 35 mm and 70 mm films. Film prints equipped with CDS did not have the conventional analog optical or magnetic soundtracks to serve as a "back-up" in case the digital sound was unreadable. Another disadvantage of not having an analog back-up track is that CDS required extra film prints be made for the theaters equipped to play CDS. The three formats that followed, Dolby Digital, DTS and SDDS, can co-exist with each other and the analog optical soundtrack on a single version of the film print. This means that a film print carrying all three of these formats (and the analog optical format, usually Dolby SR) can be played in whichever format the theater is equipped to handle. CDS did not achieve wide-spread use and ultimately failed. It premiered with the film Dick Tracy and was used with several other films, such as Days of Thunder and Terminator 2: Judgement Day.


Sony Dynamic Digital Sound (SDDS)

Main article: SDDS

SDDS sound runs on the outside of 35 mm film, between the perforations and the edges, on both edges of the film. SDDS was the first digital system that could handle up to eight channels of sound. The additional two tracks are for an extra pair of screen channels (Left Center and Right Center) located between the 3 regular screen channels (Left, Center and Right). A pair of CCD's located in a unit above the projector read the two SDDS tracks. The information is decoded and decompressed before being passed along to the cinema sound processor. By default, SDDS units use an onboard Sony Cinema Sound Processor, and when the system is set up in this manner, the theatre's entire sound system can be equalized in the digital domain. In contrast, both DTS and Dolby Digital soundtracks must be passed through to standard analog cinema sound processors - which are also used for analog optical sound, so equalization of the sound remains in the analog domain. The audio data in a SDDS track is compressed in the 20-bit ATRAC2 compression scheme at a ratio of about 4.5:1. SDDS premiered with the film Last Action Hero. Sony ceased the sale of SDDS processors in 2001-2002. SDDS stands for Sony Dynamic Digital Sound, which is a cinema sound system developed by Sony. ... A specially developed CCD used for ultraviolet imaging in a wire bonded package. ... Last Action Hero is a 1993 action comedy directed by John McTiernan. ...


Dolby Digital

Main article: Dolby Digital

Also known as Spectral Recording Digital or "SR•D." Sound is printed between the perforations and is 26 frames before the picture (the offset can be varied based on processing presets). Dolby Digital produces 6 discrete channels. In a variant called SR•D EX, the left and right surround channels can be dematrixed into left, right, and back surround, using Dolby Pro Logic. The audio data in a Dolby Digital track is compressed in the 16-bit AC-3 compression scheme at a ratio of about 12:1. The images between each perforation are read by a CCD located either above the projector or in the regular analog sound head below the film gate. The information is then decoded, decompressed, and converted to analog; this can happen either in a separate SR-D processor that feeds signals to the cinema sound processor, or SR-D decoding can be built-in to the cinema processor. Dolby Digital logotype Dolby Digital is the marketing name for a series of lossy audio compression technologies by Dolby Laboratories. ... It has been suggested that this article or section be merged with Dolby Surround. ... A specially developed CCD used for ultraviolet imaging in a wire bonded package. ...


As of 2006, Dolby has discontinued sale of their external SR-D processor (the DA20), so, aside from the used market, purchasing a Dolby processor with integrated SR-D is the only way to purchase an SR-D decoder.


A consumer version of Dolby Digital is also used on most DVD's, often at higher data rates than the original film. Dolby Digital officially premiered with the film Batman Returns, but it was earlier tested at some screenings of Star Trek: The Undiscovered Country. DVD (also known as Digital Versatile Disc or, incorrectly, Digital Video Disc) is an optical disc storage media format that can be used for data storage, including movies with high video and sound quality. ... Batman Returns is a 1992 motion picture based on the Batman character created by Bob Kane and Bill Finger. ... Star Trek VI: The Undiscovered Country (Paramount Pictures, 1991; see also 1991 in film) is the sixth feature film based on the popular Star Trek science fiction television series. ...


Digital Theater Systems (DTS)

DTS actually stores the sound information on separate CD-ROMs supplied with the film. The CDs are fed into a special modified computer which syncs up with the film through the use of DTS time code, decompresses the sound, and passes it through to a standard cinema processor. The time code is placed between the optical sound tracks and the actual picture, and is read by an optical LED ahead of the gate. The time code is actually the only sound system which is not offset within the film from the picture, but still needs to be physically set offset ahead of the gate in order to maintain continuous motion. Each disc can hold slightly over two hours of sound, so longer films will require a second disc. Three types of DTS sound exist: DTS-ES (Extended Surround), an 8 channel digital system; DTS-6, a 6 track digital system, and a now obsolete 4 channel system. DTS-ES derives a back surround channel from the left surround and right surround channels using Dolby Pro Logic. The audio data in a DTS track is compressed in the 20-bit APTX-100 compression scheme at a ratio of about 4.5:1. Of the three digital formats currently in use, DTS is the only one that has been used with 70 mm presentations. DTS was premiered on Jurassic Park. A consumer version of DTS is available on some DVDs. DTS (formerly known as Digital Theater Systems), owned by DTS, Inc. ... It has been suggested that this article or section be merged with Dolby Surround. ... Jurassic Park is a 1993 science fiction film directed by Steven Spielberg, based upon the novel of the same name by Michael Crichton. ... DVD (also known as Digital Versatile Disc or, incorrectly, Digital Video Disc) is an optical disc storage media format that can be used for data storage, including movies with high video and sound quality. ...


Magnetic sound

70 mm, which had no optical sound, used the 5 millimeters gained between the 65 mm negative and the final release print to place three magnetic tracks on each side of the perforations, for a total of six tracks. Unlike all other non-double head magnetic sound, 70 mm magnetic heads are located before the gate. Until the introduction of digital sound, it was fairly common for 35 mm films to be blown up to 70 mm often just to take advantage of the greater number of sound tracks. 35 mm four-track magnetic sound was used from the 1950s through the mid 1970s for big-budget feature prints. It was of excellent quality, although somewhat prone to damage and erasure over time. As analog optical stereo gained popularity (it was also more durable and far less expensive to include on a film print), 35 mm four-track magnetic sound was increasingly only used for special road show screenings, and the development of digital sound systems made it completely obsolete.


35 mm and 16 mm each are sometimes run in sync with a separate reel of magnetic sound (known as double head projection because two reels are running on one projector in sync); the image goes through a gate while the magnetic reel passes over a sound head. Since the sound is on a separate reel, it does not need to be offset from the image. This system is usually used only for very low-budget or student productions, or for screening rough cuts of films before the creation of a final married print. Sync between the two reels is checked with SMPTE leader, also known as countdown leader. If the two reels are synced, there should be one frame of "beep" sound exactly on the "2" frame of the countdown - 2 seconds or 48 frames before the picture start.


On certain stocks of Super 8 and 16 mm an iron-oxide sound recording strip was added for the direct synchronous recording of sound which could then be played by projectors with a magnetic sound head. It has since been discontinued by Kodak on both gauges.


Leaders

Academy leader is placed at the head of release prints containing information for the projectionist and featuring numbers which are black on a clear background, counting from 11 to 3 at 16 frame intervals (35mm).


SMPTE leader is placed at the head of release prints or video masters containing information for the projectionist or video playback tech. The numbers count down from 8 to 2 at 24 frame intervals ending at the first frame of the "2" followed by 47 frames of black.


Types of lenses and screens

Orthographic

Before the advent of certain wide screen technologies, lenses always reproduced the exact proportions of the film image onto the screen. Such lenses are relatively simple to design and manufacture. Prior to modern wide screen, the industry standard image ratio of width to height was 4:3.


35 mm VistaVision was a wide screen orthographic system. The wide image was obtained by running the film horizontally across the gate so that the width limitation of the film was transformed to a height limitation. See the VistaVision article for more information. A VistaVision 35 mm horizontal camera film frame. ... A VistaVision 35 mm horizontal camera film frame. ...


Anamorphic

Simulated wide screen image with 1.96 to 1 ratio as it would be seen in a camera viewfinder or on a theater screen
Simulated anamorphed image with 1.33 to 1 ratio (4:3) as it would appear on a frame of film

The 1950's saw the development of wide screen films using special lenses for filming and projection. The images on these films retained the same proportions as in the earlier films (a 4:3 width to height ratio). The wide image is compressed onto the film in the camera using additional cylindrical elements within the lens, with a corresponding lens used in the projector to expand the image to the wide screen. This technique is called anamorphic projection and various implementations have been marketed under several brand names, including CinemaScope, Panavision and Superscope, with Technirama implementing a slightly different anamorphic technique using vertical expansion to the film rather than horizontal compression. Of the anamorphic methods, arguably the best image was produced by the Todd-AO (for Michael Todd and American Optical) using 70 mm film and a large, curved screen. The 1956 version of Around the World in Eighty Days starring David Niven and Cantinflas was the leading general release production using this process. Similar 70 mm processes include Super (and Ultra) Panavision and VistaVision. An edit of Non Anamorphed image for movie projector page File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... An edit of Non Anamorphed image for movie projector page File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... An edit of Image:WpGreatWallReproWeapons. ... An edit of Image:WpGreatWallReproWeapons. ... The inner box (green) is the format used in most pre-1952 films and pre-widescreen television. ... Anamorphic widescreen is a cinematography and photography technique for capturing a widescreen picture on standard 35mm film. ... A Fox logo used to promote the CinemaScope process. ... Panavision is a motion picture equipment company specializing in camera, lens, and grip equipment, along with related accessories. ... Several people have been called Michael Todd: Michael Todd (Movie Industry Executive) Michael Todd (Computer Pioneer) This is a disambiguation page — a navigational aid which lists other pages that might otherwise share the same title. ... 1956 (MCMLVI) was a leap year starting on Sunday of the Gregorian calendar. ... Around the World in Eighty Days is a 1956 movie based on the novel of the same name by Jules Verne. ... David Niven (March 1, 1910 – July 29, 1983) was an Academy Award-winning British actor. ... Mario Moreno Reyes (August 12, 1911 – April 20, 1993) was a comedian of the Mexican theatre and film industry. ...


Fish eye with dome

The IMAX dome projection method (called "OMNIMAX") uses 70 mm film oriented to maximize the image area and extreme wide angle lenses to obtain an almost hemispherical image. The field of view is tilted, as is the projection hemisphere, so one may view a portion of the ground in the foreground. Owing to the great area covered by the picture it is not as bright as seen with flat screen projection, but the immersive qualities are quite convincing. While there are not many theaters capable of displaying this format there are regular productions in the fields of nature, travel, science, and history, and productions may be viewed in most U.S. large urban regions. These dome theaters are mostly located in large and prosperous science and technology museums. IMAX theatre at the Melbourne Museum complex, Australia BFI London IMAX by night IMAX dome in Guayaquil, Ecuador Glasgow Imax on the left (Part of the Glasgow Science Centre IMAX (short for Image Maximum) is a film format created by Canadas IMAX Corporation that has the capacity to display...


Wide and deep flat screen

The IMAX flat screen system uses large format film, a wide and deep screen, and close and quite steep "stadium" seating. The effect is to fill the visual field to a greater degree than is possible with conventional wide screen systems. Like the IMAX dome, this is found in major urban areas, but unlike the dome system it is practical to reformat existing movie releases to this method. Also, the geometry of the theater and screen are more amenable to inclusion within a newly constructed but otherwise conventional multiple theater complex than is the dome style theater. IMAX theatre at the Melbourne Museum complex, Australia BFI London IMAX by night IMAX dome in Guayaquil, Ecuador Glasgow Imax on the left (Part of the Glasgow Science Centre IMAX (short for Image Maximum) is a film format created by Canadas IMAX Corporation that has the capacity to display...


Multiple cameras and projectors

One wide screen development during the 1950's used non-anamorphic projection, but used three side by side synchronised projectors. Called Cinerama, the images were projected onto an extremely wide, curved screen. Some seams were said to be visible between the images but the almost complete filling of the visual field made up for this. This showed some commercial success as a limited location (only in major cities) exhibition of the technology in This is Cinerama, but the only memorable story-telling film of two made for this technology was How the West Was Won, widely seen only in its Cinemascope re-release. Cinerama is the trademarked name for a widescreen process which works by simultaneously projecting images from three synchronized 35 mm projectors onto a huge, deeply-curved screen, subtending 146° of arc, and for the corporation which was formed to market it. ... This is Cinerama is a 1952 film which shows how film makers could use the new technology of Cinerama to make movies more realistic by broadening the aspect ratio so the viewers peripheral vision was involved. ... For other articles named How the West Was Won, see the disambiguation page, How the West Was Won. ...


While neither a technical nor a commercial success, the business model survives as implemented by the documentary production, limited release locations, and long running exhibitions of IMAX dome movies. The term business model describes a broad range of informal and formal models that are used by enterprises to represent various aspects of business, such as operational processes, organizational structures, and financial forecasts. ...


Three-dimensional

For techniques used to display pictures with a three-dimensional appearance, see the 3-D film article for some movie history and the stereoscopy article for technical information. In film, the term 3-D (or 3D) is used to describe any visual presentation system that attempts to maintain or recreate moving images of the third dimension, the illusion of depth as seen by the viewer. ... Stereo card image modified for crossed eye viewing. ...


See also

An incandescent light bulb and its glowing filament. ... A 3D display prototype by Philips A 3D display is any display device capable of conveying three-dimensional images to the viewer. ... Stereo card image modified for crossed eye viewing. ... A volumetric display device is a graphical display device that forms a visual representation of an object in three physical dimensions, as opposed to the planar image of traditional screens that simulate depth through a number of different visual effects. ... Copper Bromide laser in operation. ... [carousel slide projector, the most common form of projector] A slide projector is an opto-mechanical device to view photographic slides. ... Holography (from the Greek, Όλος-holos whole + γραφή-graphe writing) is the science of producing holograms; it is an advanced form of photography that allows an image to be recorded in three dimensions. ... Neon signs are often used to advertise for hotels, bars and entertainment venues. ...

External links

Wikimedia Commons has media related to:
Movie projector
  • Film-Tech
  • American Wide Screen Museum
  • The story of the DP70 - The Todd-AO Projector
  • A Cinerama site
  • List of 3000 movie projectors and cameras

  Results from FactBites:
 
Movie projector - Wikipedia, the free encyclopedia (5295 words)
35 mm Cinemeccanica movie projector with a Zenith X4000H lamphouse
During the actual operation of a changeover, the two projectors use an interconnected electrical control connected to the changeover button so that as soon as the button is pressed, the douser on the old reel is closed in sync with the douser for the new reel.
IMAX projectors use what is known as the rolling loop method, in which each frame is sucked into the gate by a vacuum, and positioned by registration pins in the perforations corresponding to that frame.
Movie projector (1885 words)
A movie projector is an opto-mechanical device for displaying moving pictures.
Before the advent of the single reel system for movie theaters, the projector operator would operate two projectors, preloading one with a reel while the other played and switching when cueing marks were displayed on the picture.
Projectors are classified by the size of the film used.
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