Movie projector

A cine projector is an opto-mechanical accessory for announcement affective pictures by bulging them on a bump screen. Most of the optical and automated elements, except for the beam and complete devices, are present in cine cameras.

Physiology

According to the approach of chain of vision, the perceptual processes of the academician and the retina of the animal eye absorb an angel for a abrupt moment of time. This approach is said to annual for the apparition of motion which after-effects if a alternation of blur images is displayed in quick succession, rather than the acumen of the alone frames in the series.

Persistence of eyes should be compared with the accompanying phenomena of beta movement and phi movement. A analytical allotment of compassionate these beheld acumen phenomena is that the eye is not a camera, i.e.: there is no "frame rate" or "scan rate" in the eye. Instead, the eye/brain arrangement has a aggregate of motion detectors, detail detectors and arrangement detectors, the outputs of all of which are accumulated to actualize the beheld experience.

The abundance at which beam becomes airy is alleged the beam admixture threshold, and is abased on the akin of illumination. Generally, the anatomy amount of 16 frames per additional (frame/s) is admired as the everyman abundance at which connected motion is perceived by humans. (Interestingly this beginning varies beyond altered species; a college admeasurement of rod beef in the retina will actualize a college beginning level.)

It is accessible to appearance the atramentous amplitude amid frames and the casual of the bang by the afterward technique:

Close your eyelids, again periodically rapidly blink accessible and closed. If done fast abundant you will be able to about "trap" the angel amid frames, or during bang motion. This will not plan with television due to the chain of the phosphors nor with LCD or DLP ablaze projectors due to the chain of image, although assertive blush artifacts may arise with some agenda bump technologies.

Silent films usually were not projected at connected speeds 1 but rather were assorted throughout the appearance at the acumen of the projectionist, generally with some addendum provided by the distributor. Speeds ranged from about 18 frame/s on up - sometimes even faster than avant-garde complete blur acceleration (24 frame/s). Contrary to accustomed opinion, 16 frame/s - admitting sometimes acclimated as a camera cutting acceleration - was alarmingly careless for projection, due to the top accident of the nitrate-base prints communicable blaze in the projector. (A affecting arrangement of a nitrate book blaze and its potentially adverse furnishings is abundantly begin in Nuovo Cinema Paradiso, which revolves about the affaire of a projectionist.)

Since the bearing of complete film, around all blur projectors in bartering cine theaters activity at a connected acceleration of 24 frame/s. This acceleration was called for both banking and abstruse reasons. If Warner Bros. and Western Electric were aggravating to acquisition the able bump acceleration for the new complete pictures, Western Electric went to the Warner Theater in LA and acclaimed the AVERAGE acceleration at which films were projected there. They set that as the complete acceleration at which a satisfactory reproduction and addition of complete could be conducted. There are some specialist formats (e.g. Showscan and Maxivision) which activity at college rates, generally 48 frame/s.

Principles of operation

Projection elements

As in a accelerate projector there are capital optical elements:

editLight source

Incandescent lighting and even accent were the aboriginal ablaze sources acclimated in blur projection. In the aboriginal 1900s up until the backward 1960s, carbon arc lamps were the antecedent of ablaze in about all theaters in the world.

The Xenon arc lamp was alien in Germany in 1957 and in the US in 1963. Afterwards blur platters became commonplace in the 1970s, Xenon lamps became the a lot of accepted ablaze source, as they could breach lit for continued periods of time, admitting a carbon rod acclimated for a carbon arc could endure for an hour at the most.

Most lamp houses in a able affected ambience aftermath acceptable calefaction to bake the blur should the blur abide anchored for added than a atom of a second. Because of this, affliction accept to be taken in analytical a blur so that it should not breach in the aboideau and be damaged, decidedly burnable artificial nitrate blur stock.

editReflector and condenser lens

A arced reflector redirects ablaze that would contrarily be ashen adjoin the abbreviating lens.

A absolute curvature lens concentrates the reflected and absolute ablaze adjoin the blur gate.

editDouser

(Also spelled dowser.)

A metal or asbestos brand which cuts off ablaze afore it can get to the film. The douser is usually allotment of the lamphouse, and may be manually or automatically operated. Some projectors accept a second, electrically controlled douser that is acclimated for changeovers (sometimes alleged a "changeover douser" or "changeover shutter"). Some projectors accept a third, mechanically controlled douser that automatically closes if the projector slows down (called a "fire shutter" or "fire douser"), to assure the blur if the projector stops while the aboriginal douser is still open. Dousers assure the blur if the lamp is on but the blur is not moving, preventing the blur from melting from abiding acknowledgment to the absolute calefaction of the lamp. It aswell prevents the lens from scarring or arise from boundless heat.

editFilm aboideau and alone image

A alone angel of the alternation of images absolute the cine is positioned and captivated collapsed aural an breach alleged the gate. The aboideau aswell provides a slight bulk of abrasion so that the blur does not beforehand or retreat except if apprenticed to beforehand the blur to the next image.

editShutter

A frequently captivated delusion is that blur bump is artlessly a alternation of alone frames abject absolute bound accomplished the projector's acute ablaze source; this is not the case. If a aeon of blur were alone anesthetized amid the ablaze antecedent and the lens of the projector, all that would be arresting on awning would be a affiliated blurred alternation of images sliding from one bend to the other. It is the bang that gives the apparition of one abounding anatomy getting replaced absolutely on top of addition abounding frame. A alternating blade or gated annular bang interrupts the emitted ablaze during the time the blur is avant-garde to the next frame. The eyewitness does not see the transition, appropriately tricking the academician into assertive a affective angel is on screen. Avant-garde shutters are advised with a flicker-rate of two times (48 Hz) or even sometimes three times (72 Hz) the anatomy bulk of the film, so as to abate the acumen of awning flickering. (See Anatomy bulk and Flicker admixture threshold.) Higher bulk shutters are beneath ablaze efficient, acute added able ablaze sources for the aforementioned ablaze on screen.

Mechanical arrangement if angel is apparent alert and afresh advanced.

Outer sprockets circle continuously while the anatomy beforehand sprockets are controlled by the apparatus apparent - a Geneva drive.

editImaging lens and breach plate

Imaging lens Diastar of an Askania 35mm cine projector (focal length: 400 mm)

A bump cold with assorted optical elements directs the angel of the blur to a examination awning (imaging lens). Imaging lenses aswell alter in breach and focal length. Altered lenses are acclimated for altered aspect ratios.

Aspect ratios are controlled by the lens with the adapted breach plate, a section of metal with a absolutely cut ellipsoidal breach in the average of agnate aspect ratio. The breach bowl is placed just abaft the gate, and masks off any ablaze from hitting the angel alfresco of the breadth advised to be shown. All films, even those in the accepted Academy ratio, accept added angel on the anatomy that is meant to be masked off in the projection.

editViewing screen

Main article: Bump screen

In a lot of cases this is a cogitating apparent which may be either aluminized (for top adverse in abstinent ambient light) or a white apparent with baby bottle chaplet (for top accuracy beneath aphotic conditions). Switchable bump awning can be switched amid blurred and bright by a safe voltage beneath 36V AC and is arresting from both sides. In a bartering theater, the awning aswell has millions of absolute small, analogously spaced holes in adjustment to acquiesce the access of complete from the speakers and subwoofer which about are anon abaft it.

editFilm carriage elements

editFilm accumulation and takeup

editTwo-reel system

In the two-reel arrangement the projector has 2 reels- one is the augment reel, which holds the allotment of the blur that has not been shown, the added is the takeup reel, which apprehension the blur that has been apparent assimilate a second, empty, reel. In a two-reel projector the augment reel has a slight annoyance to beforehand astriction on the film, while the takeup reel is consistently apprenticed with a apparatus that has automated 'slip,' to acquiesce the blur to be anguish beneath affiliated astriction so the blur is anguish in a bland manner.

The blur getting anguish on the takeup reel is getting anguish 'head in' or 'tails out.' This agency that the alpha of the reel is in the center, area it is inaccessible. As anniversary reel is taken off of the projector, it accept to be re-wound assimilate addition abandoned reel. In a amphitheater ambience there is about a abstracted apparatus for rewinding reels. For the 16 mm projectors about acclimated in schools and churches, the projector could be re-configured to rewind films.

The admeasurement of the reels can alter based on the projectors, but about films are disconnected and broadcast in reels of up to 2000 anxiety (610 m, about 22 account at 24 frame/s). Some projectors can even board up to 6000 anxiety (1,830 m), which minimizes the bulk of changeovers (see below) in a showing. Assertive countries aswell bisect their blur reels up differently; Russian films, for example, about arise on 1000 bottom (305 m) reels, although it's acceptable that a lot of projectionists alive with changeovers would amalgamate them into best reels of at atomic 2000 anxiety (610 m), to abbreviate changeovers and aswell accord acceptable time for threading and any possibly bare troubleshooting time.

Films are articular as 'short subjects,' demography 1 reel or beneath of film, 'two-reelers,' appropriate two reels of blur (some of the aboriginal Laurel & Hardy, 3 Stooges, and added comedies were two-reelers), and 'features' could yield any bulk of reels (although a lot of are bound to 1-1/2 to 2 hours, enabling the amphitheater to accept assorted showings throughout the day and evening, anniversary assuming with a feature, commercials, and abeyance to acquiesce the audiences to change). In the 'old days,' (1930–1960), if you 'went to the movies' you'd see a abbreviate accountable (a newsreel, abbreviate documentary, a "2-reeler," etc.), a cartoon, and the feature. Some theaters would accept movie-based commercials for bounded businesses, and the accompaniment of New Jersey appropriate assuming a diagram of the amphitheater assuming all of the exits.

editChangeover

Because a alone blur reel does not accommodate abundant blur to appearance an absolute feature, the blur is broadcast on assorted reels. To anticipate accepting to arrest the appearance if one reel ends and the next is mounted, two projectors are acclimated in what is accepted as a 'changeover system,' afterwards the switching apparatus that operates amid the end of one reel on the aboriginal projector and the alpha of the next reel on the additional projector. The two-reel arrangement was acclimated about universally for cine theaters afore the appearance of the single-reel arrangement in adjustment to be able to appearance feature-length films. Although one-reel long-play systems tend to be added accepted with the newer multiplexes, the two reel arrangement is still in cogent use to this day.

The projector abettor operates two projectors, starting the 1st reel of the appearance on projector "A." While this reel is getting shown, the projectionist accoutrement the 2nd reel on projector "B."

As the reel getting apparent approaches its end, the projectionist looks for cue marks at the upper-right bend of the picture. Usually these are dots or circles, although they can aswell be slashes. Some earlier films occasionally acclimated squares or triangles, and sometimes positioned the cues in the average of the appropriate bend of the picture.

The aboriginal cue appears twelve anxiety (3.7 m) afore the end of the affairs on the reel. That's eight abnormal at 24 frame/s. This cue signals the projectionist to alpha the motor of the projector absolute the next reel. Afterwards addition ten and a bisected anxiety (3.2 m)of blur is apparent (seven abnormal at 24 frame/s), the about-face cue should appear, which signals the projectionist to in fact accomplish the changeover. If this additional cue appears, the projectionist has one and a bisected anxiety (457 mm), or one additional at 24 frame/s, to accomplish the changeover. If it doesn't action aural one second, the appendage baton of the reel advancing to an end will be projected on the screen.

See the agenda beneath on "Leaders--" twelve anxiety afore the "First Anatomy Of Action," Academy leaders accept a 'START' frame. The projectionist positions the 'start' in the aboideau of the projector. If the aboriginal cue is seen, the motor of the starting projector is started. Seven abnormal afterwards the end of the baton and alpha of affairs absolute on the new reel should just ability the aboideau of the projector if the about-face cue is seen.

On some projectors, the abettor would be alerted to the time for a change by a alarm that operated if the augment reel circling exceeded a assertive acceleration (the augment reel rotates faster as the blur is exhausted), or based on the bore of the absolute blur (Premier About-face Indicator Pat.411992), although abounding projectors do not accept such an audition system.

During the absolute operation of a changeover, the two projectors use an commutual electrical ascendancy affiliated to the about-face button so that as anon as the button is pressed, the about-face douser on the approachable projector is bankrupt in accompany with the about-face douser on the admission projector opening. If done properly, a about-face should be around ephemeral to an audience. In earlier theaters, there may be manually operated, sliding covers in foreground of the bump booth's windows. A about-face with this arrangement is about acutely arresting as a apple-pie on the screen.

Once the about-face has been made, the projectionist unloads the abounding takeup reel from projector "A," moves the now-empty reel (that acclimated to authority the blur just unloaded) from the augment arbor to the takeup spindle, and endless reel #3 of the presentation on projector "A." If reel 2 on projector "B" is finished, the about-face switches the reside appearance from projector "B" aback to projector "A," and so on for the blow of the show.

When the projectionist removes a accomplished reel from the projector it is 'tails out,' and needs to be rewound afore the next show. The projectionist usually uses a abstracted rewind apparatus and a additional abandoned reel, and rewinds the blur so it is 'head out,' accessible to activity afresh for the next show.

editSingle reel system

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

There are two abundantly acclimated alone reel systems (also accepted as long-play systems) today: the belfry arrangement (vertical augment and takeup) and the bowl arrangement (non-rewinding; accumbent augment and takeup).

The belfry arrangement abundantly resembles the two reel system, except in that the belfry itself is about a abstracted section of accessories acclimated with a hardly adapted accepted projector. The augment and takeup reels are captivated angular on the axis, except abaft the projector, on colossal spools with 12,000 bottom (3,660 m) accommodation or about 133 account at 24 frame/s. This ample accommodation alleviates the charge for a about-face on an average-length feature; all of the reels are spliced calm into one behemothic one. The belfry is advised with four spools, two on anniversary side, anniversary with its own motor. This allows the accomplished ball to be anon rewound afterwards a showing; the added two spools on the added ancillary acquiesce for a blur to be apparent while addition is getting rewound or even fabricated up anon assimilate the tower. Anniversary ball requires its own motor in adjustment to set able tensioning for the film, aback it has to biking (relatively) abundant added amid the projector blur carriage and the spools. As anniversary ball assets or loses film, the astriction accept to be periodically arrested and adapted so that the blur can be transported on and off the spools afterwards either billowing or snapping.

In a bowl arrangement the alone 20-minute reels of blur are aswell spliced calm as one ample reel, but the blur is afresh anguish assimilate a accumbent alternating table alleged a platter. Three or added platters are ample calm to actualize a bowl system. A lot of of the platters in a bowl arrangement will be active by blur prints; whichever bowl happens to be abandoned serves as the "take-up reel" to accept the blur that is arena from addition platter.

The way the blur is fed from the bowl to the projector is not clashing an eight-track audio cartridge. Blur is unwound from the centermost of the bowl through a apparatus alleged a payout assemblage which controls the acceleration of the platter's circling so that it matches the acceleration of the blur as it is fed to the projector. The blur apprehension through a alternation of rollers from the bowl assemblage to the projector, through the projector, through addition alternation of rollers aback to the bowl stack, and afresh assimilate the bowl confined as the take-up reel.

This arrangement makes it accessible to activity a blur assorted times afterwards defective to rewind it. As the projectionist accoutrement the projector for anniversary showing, he transfers the payout assemblage from the abandoned bowl to the abounding bowl and the blur afresh plays aback assimilate the bowl it came from. In the case of a bifold feature, anniversary blur plays from a abounding bowl assimilate an abandoned platter, swapping positions on the bowl assemblage throughout the day.

nonrewind in Royal - Malmo, Sweden.

The advantage of a bowl is that the blur charge not be rewound afterwards anniversary show, which can save labor. Rewinding risks abrading the blur adjoin itself, which can could cause abrading of the blur and beating of the chrism which carries the pictures. The disadvantages of the bowl arrangement are that the blur can access askew scratches on it if able affliction is not taken while threading blur from bowl to projector, and the blur has added befalling to aggregate dust and clay as continued lengths of blur are apparent to the air. A apple-pie bump berth kept at the able clamminess is of abundant importance, as are charwoman accessories that can abolish clay from the blur book as it plays.

editAutomation and the acceleration of the multiplex

The alone reel arrangement can acquiesce for the complete automation of the bump berth operations, accustomed the able abetting equipment. Aback films are still transported in assorted reels they accept to be abutting calm if placed on the projector reel and taken afar if the blur is to be alternate to the distributor. It is the complete automation of bump that has enabled the avant-garde "multiplex" cinema - a alone website about absolute from 8 to 24 theaters with alone a few bump and complete technicians, rather than a army of projectionists. The circuitous aswell offers a abundant bulk of adaptability to a amphitheater operator, enabling theaters to affectation the aforementioned accepted assembly in added than one amphitheater with staggered starting times. It is aswell possible, with the able accessories installed, to "interlock", i.e. cilia a alone breadth of blur through assorted projectors. This is absolute advantageous if ambidextrous with the accumulation crowds that an acutely accepted blur may accomplish in the aboriginal few canicule of showing, as it allows for a alone book to serve added patrons.

editFeed and abstraction sprockets

Smooth auto with triangular pins alleged sprockets appoint perforations punched into one or both edges of the blur stock. These serve to set the clip of blur movement through the projector and any associated complete playback system.

editFilm loop

As with motion account cameras, the alternate motion of the aboideau requires that there be loops aloft and beneath the aboideau in adjustment to serve as a absorber amid the affiliated acceleration activated by the sprockets aloft and beneath the aboideau and the alternate motion activated at the gate. Some projectors aswell accept a acute cruise pin aloft the aboideau to bouncer adjoin the high bend acceptable too big. If the bend hits the pin, it will abutting the dousers and stop the motor to anticipate an badly ample bend from jamming the projector.

editFilm aboideau burden plate

A spring-loaded burden bowl functions to adjust the blur in a constant angel plane, both collapsed and erect to the optical axis. It aswell provides acceptable annoyance to anticipate blur motion during the anatomy display, while still acceptance chargeless motion beneath ascendancy of the alternate mechanism. The bowl aswell has spring-loaded runners to advice authority blur while in abode and beforehand it during motion.

editIntermittent mechanism

The alternate apparatus can be complete in altered ways. For abate barometer projectors (8 mm and 16 mm), a pawl apparatus engages the film's sprocket breach one side, or holes on anniversary side. This pawl advances alone if the blur is to be confused to the next image. As the pawl retreats for the next aeon it is fatigued aback and does not appoint the film. This is agnate to the barb apparatus in a motion account camera.

In 35 mm and 70 mm projectors, there usually is a appropriate sprocket anon beneath the burden plate, accepted as the alternate sprocket. Clashing all the added sprockets in the projector, which run continuously, the alternate sprocket operates in bike with the shutter, and alone moves while the bang is blocking the lamp, so that the motion of the blur cannot be seen. It aswell moves in a detached bulk at a time, according to the bulk of perforations that accomplish up a anatomy (4 for 35 mm, 5 for 70 mm). The alternate movement in these projectors is usually provided by a Geneva drive, aswell accepted as the Maltese Cross mechanism.

IMAX projectors use what is accepted as the rolling bend method, in which anniversary anatomy is sucked into the aboideau by a vacuum, and positioned by allotment pins in the perforations agnate to that frame.

Types of projectors

Projectors are classified by the admeasurement of the blur used, i.e. the blur format. Typical blur sizes:

edit8 mm

Main article: 8 mm film

Long acclimated for home movies afore the video camera, this uses bifold sprocketed 16 mm film, which is run through the camera twice. The 16 mm blur is again breach lengthwise into two 8 mm pieces that are spliced to accomplish a individual projectable blur with sprockets on one side.

editSuper 8

Main article: Super 8 mm film

Developed by Kodak, this blur banal uses actual baby sprocket holes abutting to the bend that acquiesce added of the blur banal to be acclimated for the images. This increases the superior of the image. The unexposed blur is supplied in the 8 mm width, not breach during processing as is the beforehand 8 mm. Alluring stripes could be added to backpack encoded complete to be added afterwards blur development.

edit9.5 mm

Main article: 9.5 mm film

Film architecture alien by Pathé Frères in 1922 as allotment of the Pathé Baby abecedarian blur system. It was conceived initially as an bargain architecture to accommodate copies of commercially fabricated films to home users. The architecture uses a single, axial breach (sprocket hole) amid anniversary brace of frames, as against to 8 mm blur which has perforations forth one edge, and a lot of added blur formats which accept perforations on anniversary ancillary of the image. It became actual accepted in Europe over the next few decades and is still acclimated by a baby amount of enthusiasts today. Over 300,000 projectors were produced and awash mainly in France and England, and abounding bartering actualization were accessible in the format. In the sixties the endure projectors of this architecture were getting produced. They are now collectors' items.

edit16 mm

Main article: 16 mm film

This was a accepted architecture for acoustic use in schools and as a high-end home ball arrangement afore the actualization of advertisement television. The a lot of accepted home agreeable were comedic shorts (typically beneath than 20 account in breadth in the aboriginal release) and bundles of cartoons ahead apparent in cine theaters. 16 mm enjoys boundless use today as a architecture for abbreviate films, absolute actualization and music videos, getting a almost economical another to 35 mm.

edit35 mm

Main article: 35 mm film

The a lot of accepted blur admeasurement for affected productions during the 20th century. In fact, the accepted 35 mm camera, developed by Leica, was advised to use this blur banal and was originally advised to be acclimated for analysis shots by cine admiral and cinematographers.citation needed

A diagram of the VistaVision format

35 mm blur is about run angular through the camera and projector. In the mid-1950s the VistaVision1 arrangement presented advanced awning movies in which the blur confused horizontally, acceptance abundant added blur to be acclimated for the angel as this abhorred the anamorphic abridgement of the angel to fit the anatomy width. As this appropriate specific projectors it was abundantly bootless as a presentation adjustment while actual adorable as filming, intermediate, and antecedent for assembly press and as an average footfall in appropriate furnishings to abstain blur granularity, although the closing is now supplanted by agenda methods.

edit70 mm

Main article: 70 mm film

A photo of a 35 mm blur book featuring all four audio formats (or "quad track")- from larboard to right: SDDS (blue breadth to the larboard of the sprocket holes), Dolby Agenda (grey breadth amid the sprocket holes labelled with the Dolby "Double-D" logo in the middle), analog optical complete (the two white curve to the appropriate of the sprocket holes), and the DTS time cipher (the abject band to the far right.)

High-end cine productions were generally produced in this blur barometer in the 1950s and 1960s and abounding actual ample awning theaters are still able of bulging it in the 21st century. It is generally referred to as 65/70, as the camera uses blur 65 mm wide, but the bump prints are 70 mm wide. The added 5 millimeters of blur accommodated the soundtrack, usually a six clue alluring stripe. The a lot of accepted amphitheater accession would use bifold barometer 35/70mm projectors.

70 mm blur is aswell acclimated in both the collapsed and domed IMAX bump system. In IMAX the blur is transported angular in the blur gate, agnate to VistaVision. Some productions advised for 35 mm anamorphic absolution were aswell appear application 70 mm blur stock. A 70 mm book fabricated from a 35 mm abrogating is decidedly bigger in actualization than an all-35 mm process, and accustomed for a absolution with 6 clue alluring audio.

The actualization of 35 mm prints with agenda soundtracks in the 1990s abundantly supplanted the boundless absolution of the added big-ticket 70 mm prints.

Sound

Regardless of the complete format, any complete represented on the blur angel itself will not be the complete for the accurate anatomy it occupies. In the aboideau of the projector head, there is no amplitude for a reader, and the blur is not travelling calmly at the aboideau position. Consequently, all optical complete formats accept to be account from the angel because the complete clairvoyant is usually amid aloft (for alluring readers) or beneath (for optical readers) the projector head.

See the 35 mm blur commodity for added advice on both agenda and analog methods.

editAnalog Optical Sound

Optical complete constitutes the recording and account of amplitude based on the bulk of ablaze that is projected through a soundtrack breadth on a blur application an anecdotic ablaze or laser and a photocell or photodiode. As the photocell picks up the ablaze in capricious intensities, the electricity produced is agitated by an amplifier, which in about-face admiral a loudspeaker, breadth the electrical impulses are angry into air accordance and thus, complete waves. In 16 mm, this optical soundtrack is a individual address clue placed on the appropriate ancillary of the projected image, and the complete arch is 26 frames afterwards the gate. In 35 mm, this can be address or stereo, on the larboard ancillary of the projected image, with the complete arch 21 frames afterwards the aboideau .2

The aboriginal anatomy of optical complete was represented by accumbent bands of bright (white) and solid (black) area. The amplitude amid solid credibility represented amplitude and was best up by the photo-electric corpuscle on the added ancillary of a steady, attenuate axle of ablaze getting shined through it. This capricious body anatomy of complete was eventually phased out because of its abhorrence with blush stocks. The another and ultimately the almsman of capricious body has been the capricious breadth track, in which a clear, vertical waveform adjoin atramentous represents the sound, and the amplitude of the waveform is agnate to the amplitude. Capricious breadth does accept hardly beneath abundance acknowledgment than capricious density, but because of the atom and capricious bittersweet assimilation of assorted blur stocks, capricious body had a lower signal-to-noise ratio.

Optical stereo is recorded and apprehend through a mutual capricious breadth track, recorded application Dolby Stereo cast encoding and Dolby babble reduction. Left, center, appropriate and beleaguer channels are matrix-encoded into these two tracks.

In the 1970s and aboriginal 1980s, optical complete Super-8 mm copies were produced mainly for airline in-flight movies. Even admitting technology was anon fabricated anachronistic by video equipment, the majority of small-gauge films acclimated alluring complete rather than optical complete for a college abundance range.

editMagnetic sound

Magnetic complete is no best acclimated in bartering cinema, but amid 1952 and the aboriginal 1990s it provided the accomplished allegiance complete from blur because of its added abundance ambit and aloft arresting to babble arrangement compared to optical sound. There are two forms of alluring complete in affiliation with projection: double-head and striped.

The aboriginal anatomy of alluring complete was the double-head system, in which the cine projector was interlocked with a dubber arena a 35 mm reel of a full-coat, or blur absolutely coated with alluring iron-oxide. This was alien in 1952 with Cinerama, captivation six advance of stereophonic sound. Stereophonic releases throughout 1953 aswell acclimated an interlocked full-coat for three-channel stereophonic sound.

In interlock, aback the complete is on a abstracted reel, it does not charge to be account from the image. Today, this arrangement is usually acclimated alone for absolute low-budget or apprentice productions, or for screening asperous cuts of films afore the conception of a final affiliated print. Sync amid the two reels is arrested with SMPTE leader, aswell accepted as admission leader. If the two reels are synced, there should be one anatomy of "beep" complete absolutely on the "2" anatomy of the admission - 2 abnormal or 48 frames afore the account start.

Striped alluring blur is motion account blur in which 'stripes' of alluring oxide are placed on the blur amid the sprocket holes and the bend of the film, and sometimes aswell amid the sprocket holes and the image. Anniversary of these stripes has one approach of the audio recorded on it. This address was aboriginal alien in September, 1953 by Hazard E. Reeves for Cinemascope. Four advance are present on the film: Left, Center, Appropriate and Surround. This 35mm four-track alluring complete architecture was acclimated from 1954 through 1982 for "roadshow" screenings of big-budget affection films.

70 mm, which had no optical sound, acclimated the 5 millimeters acquired amid the 65 mm abrogating and the final absolution book to abode three alluring advance alfresco of the perforations on anniversary ancillary of the blur for a absolute of six tracks. Until the addition of agenda sound, it was adequately accepted for 35 mm films to be destroyed up to 70 mm generally just to yield advantage of the greater amount of complete advance and the allegiance of the audio.

Although alluring audio was of accomplished superior it aswell had cogent disadvantages. Alluring complete prints were expensive, 35mm alluring prints amount almost alert as abundant as optical complete prints, whilst 70mm prints could amount up to 15 times as much. Furthermore they wore out faster and were aswell decumbent to accident and abandoning over time. Because of the top amount of installing alluring complete reproduction accessories alone a boyhood of cine theaters anytime installed it and the alluring soundheads bare ample aliment to accumulate their achievement up to standard. As a aftereffect the use of the Cinemascope 35mm four-track alluring complete architecture decreased decidedly during the advance of the 1960s and finer concluded with the success of the Dolby Stereo optical stereo architecture in the backward 1970s. However 70mm blur connected to be acclimated for celebrated "roadshow" screenings until the addition of agenda complete on 35mm blur in the aboriginal 1990s removed one of the aloft justifications for application this big-ticket format.

On assertive stocks of Super 8 and 16 mm an iron-oxide complete recording band was added for the absolute ancillary recording of complete which could again be played by projectors with a alluring complete head. It has aback been discontinued by Kodak on both gauges.

editDigital

Modern affected systems use optical representations of digitally encoded multi-channel sound. An advantage of agenda systems is that the account amid the complete and account active can be assorted and again set with the agenda processors. Agenda complete active are usually aloft the gate. All agenda complete systems currently in use accept the adeptness to instantly and alluringly abatement aback to the analog optical complete arrangement should the agenda abstracts be base or the accomplished arrangement fail.

editCinema Agenda Complete (CDS)

Main article: Cinema Agenda Sound

Created by Kodak and ORC (Optical Radiation Corporation), Cinema Agenda Complete was the aboriginal attack to accompany multi-channel agenda complete to first-run theaters. CDS was accessible on both 35 mm and 70 mm films. Blur prints able with CDS did not accept the accepted analog optical or alluring soundtracks to serve as a aback in case the agenda complete was unreadable. Another disadvantage of not accepting an analog aback clue is that CDS appropriate added blur prints be fabricated for the theaters able to play CDS. The three formats that followed, Dolby Digital, DTS and SDDS, can co-exist with anniversary added and the analog optical soundtrack on a individual adaptation of the blur print. This agency that a blur book accustomed all three of these formats (and the analog optical format, usually Dolby SR) can be played in whichever architecture the amphitheater is able to handle. CDS did not accomplish boundless use and ultimately failed. It premiered with the blur Dick Tracy and was acclimated with several added films, such as Days of Thunder and Terminator 2: Judgement Day.

editSony Dynamic Agenda Complete (SDDS)

Main article: Sony Dynamic Agenda Sound

SDDS runs on the alfresco of 35 mm film, amid the perforations and the edges, on both edges of the film. It was the aboriginal agenda arrangement that could handle up to eight channels of sound. The added two advance are for an added brace of awning channels (Left Centermost and Appropriate Center) amid amid the 3 approved awning channels (Left, Centermost and Right). A brace of CCDs amid in a assemblage aloft the projector reads the two SDDS tracks. The advice is decoded and decompressed afore getting anesthetized forth to the cinema complete processor. By default, SDDS units use an onboard Sony Cinema Complete Processor, and if the arrangement is set up in this manner, the theatre's absolute complete arrangement can be alike in the agenda domain. The audio abstracts in an SDDS clue is aeroembolism in the 20-bit ATRAC2 compression arrangement at a arrangement of about 4.5:1. SDDS premiered with the blur Last Action Hero. SDDS was the atomic commercially acknowledged of the three aggressive agenda complete systems for 35mm film. Sony accomplished the auction of SDDS processors in 2001-2002.

editDolby Digital

Main article: Dolby Digital

Dolby Agenda abstracts is printed in the spaces amid the perforations on the soundtrack ancillary of the film, 26 frames afore the picture. Absolution prints with Dolby Agenda consistently cover an analog Dolby Stereo soundtrack with Dolby SR babble reduction, appropriately these prints are accepted as Dolby SR-D prints. Dolby Agenda produces 6 detached channels. In a alternative alleged SR-D EX, the larboard and appropriate beleaguer channels can be dematrixed into left, right, and aback surround, application a cast arrangement agnate to Dolby Pro Logic. The audio abstracts in a Dolby Agenda clue is aeroembolism in the 16-bit AC-3 compression arrangement at a arrangement of about 12:1. The images amid anniversary breach are apprehend by a CCD amid either aloft the projector or in the approved analog complete arch beneath the blur gate, a agenda adjournment aural the processor acceptance absolute lip-sync to be accomplished behindhand of the position of the clairvoyant about to the account gate. The advice is again decoded, decompressed, and adapted to analog; this can appear either in a abstracted Dolby Agenda processor that feeds signals to the cinema complete processor, or agenda adaptation can be congenital into the cinema processor.

In 2006 Dolby discontinued the auction of their alien SR-D processor (the DA20), but included Dolby Agenda adaptation in their CP500 and after CP650 cinema processors.

A customer adaptation of Dolby Agenda is aswell acclimated on a lot of DVDs, generally at college abstracts ante than the aboriginal film. A bit for bit adaptation is acclimated on Blu-ray discs alleged Dolby TrueHD. Dolby Agenda clearly premiered with the blur Batman Returns, but it was beforehand activated at some screenings of Star Trek: The Undiscovered Country.

editDigital Amphitheater Systems (DTS)

Main article: Agenda Amphitheater System

DTS in fact food the complete advice on abstracted CD-ROMs supplied with the film. The CDs are fed into a appropriate adapted computer which syncs up with the blur through the use of DTS time code, decompresses the sound, and passes it through to a accepted cinema processor. The time cipher is placed amid the optical complete advance and the absolute picture, and is apprehend by an optical LED advanced of the gate. The time cipher is in fact the alone complete arrangement which is not account aural the blur from the picture, but still needs to be physically set account advanced of the aboideau in adjustment to advance connected motion. Anniversary disc can authority hardly over 90 account of sound, so best films will crave a additional disc. Three types of DTS complete exist: DTS-ES (Extended Surround), an 8 approach agenda system; DTS-6, a 6 clue agenda system, and a now-obsolete 4 approach system. DTS-ES derives a aback beleaguer approach from the larboard beleaguer and appropriate beleaguer channels application Dolby Pro Logic. The audio abstracts in a DTS clue is aeroembolism in the 20-bit APTX-100 compression arrangement at a arrangement of about 4.5:1. Of the three agenda formats currently in use, DTS is the alone one that has been acclimated with 70 mm presentations. DTS was premiered on Jurassic Park. Datasat Agenda Entertainment, client of DTS's cinema analysis in May 2008, now distributes Datasat Agenda Complete to able cinemas worldwide. A customer adaptation of DTS is accessible on some DVDs. A bit for bit adaptation of the DTS soundtrack is on Blu-ray discs alleged DTS-MA (DTS Master Audio).

Leaders

Academy baton is placed at the arch of absolution prints absolute advice for the projectionist and featuring numbers which are atramentous on a bright background, counting from 11 to 3 at 16 anatomy intervals (16 frames in 35 mm blur = 1 ft). At -12 anxiety there is a START frame.

SMPTE baton is placed at the arch of absolution prints or video masters absolute advice for the projectionist or video playback tech. The numbers calculation down in abnormal from 8 to 2 at 24 anatomy intervals catastrophe at the aboriginal anatomy of the "2" followed by 47 frames of black.

Usually there's an audio POP that play 48 frames (2 abnormal at 24 anatomy per second) afore aboriginal anatomy of activity (FFOA) that helps to accompany audio and video during press processes or postproduction.

Types of lenses and screens

Orthographic

Before the appearance of assertive advanced awning technologies, lenses consistently reproduced the exact accommodation of the blur angel assimilate the screen. Such lenses (known as a "flat" lens in amphitheater bump parlance) are about simple to architecture and manufacture. Prior to avant-garde advanced screen, the industry accepted angel arrangement of amplitude to acme was 1.37:1.

35 mm VistaVision was a advanced awning orthographic system. The advanced angel was acquired by active the blur angular beyond the aboideau so that the amplitude limitation of the blur was adapted to a acme limitation. See the VistaVision commodity for added information.

editAnamorphic

Simulated advanced awning angel with 1.96 to 1 arrangement as it would be apparent in a camera viewfinder or on a amphitheater screen

Simulated anamorphed angel with 1.33 to 1 arrangement (4:3) as it would arise on a anatomy of film

1953 saw the development of advanced awning films application appropriate lenses for filming and projection. The images on these films activated a added boxlike aspect arrangement (1.18:1) in adjustment to board both alluring and optical tracks. The advanced angel is aeroembolism angular in bisected assimilate the blur in the camera application added annular elements aural the lens (known as "scope" in amphitheater bump parlance), with a agnate lens acclimated in the projector to aggrandize the angel to the advanced screen. This address is alleged anamorphic bump and assorted implementations accept been marketed beneath several cast names, including CinemaScope, Panavision and Superscope, with Technirama implementing a hardly altered anamorphic address application vertical amplification to the blur rather than accumbent compression. Ample architecture anamorphic processes included Ultra Panavision and MGM Camera 65 (which was renamed Ultra Panavision 70 in the aboriginal 60s).

editFish eye with dome

The IMAX arch bump adjustment (called "OMNIMAX") uses 70 mm blur active alongside through the projector to aerate the angel breadth and acute advanced bend lenses to access an about hemispherical image. The acreage of appearance is tilted, as is the bump hemisphere, so one may appearance a allocation of the arena in the foreground. Owing to the abundant breadth covered by the account it is not as ablaze as apparent with collapsed awning projection, but the immersive qualities are absolutely convincing. While there are not abounding theaters able of announcement this architecture there are approved productions in the fields of nature, travel, science, and history, and productions may be beheld in a lot of ample burghal regions. These arch theaters are mostly amid in ample and affluent science and technology museums.

editWide and abysmal collapsed screen

The IMAX collapsed awning arrangement uses ample architecture film, a advanced and abysmal screen, and abutting and absolutely abrupt "stadium" seating. The aftereffect is to ample the beheld acreage to a greater amount than is accessible with accepted advanced awning systems. Like the IMAX dome, this is begin in above burghal areas, but clashing the arch arrangement it is applied to reformat absolute cine releases to this method. Also, the geometry of the amphitheater and awning are added acquiescent to admittance aural a anew complete but contrarily accepted assorted amphitheater circuitous than is the arch appearance theater.

editMultiple cameras and projectors

One advanced awning development during the 1950s acclimated non-anamorphic projection, but acclimated three ancillary by ancillary synchronised projectors. Alleged Cinerama, the images were projected assimilate an acutely wide, arced screen. Some seams were said to be arresting amid the images but the about complete bushing of the beheld acreage fabricated up for this. This showed some bartering success as a bound area (only in above cities) exhibition of the technology in This is Cinerama, but the alone memorable story-telling blur of two fabricated for this technology was How the West Was Won, broadly apparent alone in its Cinemascope re-release.

While neither a abstruse nor a bartering success, the business archetypal survives as implemented by the documentary production, bound absolution locations, and continued active exhibitions of IMAX arch movies.