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How Do Projectors Work for Movies?

Movie images form in someone’s mind because they are fictitious characters but we can see these images moving on a projector as real images. How is possible to see still images as moving characters? Of course, they are created digitally through a technology that tricked the mind into seeing the moving image.

This technology is obviously what we called projectors. How do projectors work for movies? Our inquisitive minds make us think about it while watching movies in cinemas or somewhere when watching a football match on a big screen.

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How Projectors Work for Movies?

To see the image on the screen, first of all, we need a light source and lens that focuses the light onto the screen. The source of light furnishes bright illumination that cast the image on the film through a lens on the screen and we see a moving image. But how is such a big, clear, and moving image is produced?

A projector produces an image by spooling the film for a short duration by taking it from the computer or blue ray player and generating the image onto the projecting screen. All you need is a white wall or any flat light-colored surface that is much larger so that everyone can see it while sitting in a large room.

Projectors can produce either still (slides) or moving (videos) images. But we know that movies are moving pictures so the films that are producing the images onto the screen are continuously moving in a reel.

The following system plays its part to see the image on the display screen

  • A system to advance each frame of the film
  • A system to project the image from the film
  •  A system to read the audio
  • A system to play the audio
  • Projecting screen to display the image

How Does the Movie Projector Work?

The movie projector is a device or machine that continuously advances the film so that each frame of the film passes through the light source for a small duration of time to cast the image onto the screen. This section will discuss the basic working principle of projectors to project movies onto big screens. Learn more about how to use projector outside in daytime.

It works in four different steps which are as follows

  • Spooling the film
  • Light source
  • Lens
  • Audio system

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Spooling the Film

Spooling is the process of temporary storage of data executed by a device, program, or system. It means to load a film on a reel and then develop it into images. It is easy to use and does not require filming out of the camera and rewinding on it

A typical two-hour movie is divided into five or six reels which are projected one after the other. However, in old movie projectors, two to four large discs of about 4 to 5 feet in diameter are used to show the entire film and these discs were stacked on another commonly called platter. These discs were large enough to hold the large spool of the film and then splice together from different reels.

 Splicing is the process of cutting one end of the strip of film and then matches exactly with the other half end of the strip of film and then taping all these strips together.

Nowadays, projectionists put all the film on a single spool and follow the things that happened.

  • You can see the entire film on the projector without a single pause or without changing the side of the reel.
  • You can easily run the movie in several auditoriums at the same time at different places.

Light Source

When projectors work for movies, their light source or assembly consists of a bulb, condenser, fan, or mirror. In earlier times carbon arc was used as a light source. But nowadays Xenon bulbs are used. Xenon is a rare gas and has certain qualities best suited for use in projectors.

 It has certain benefits like

  • It acts as a conductor even when no filaments are used or placed in this bulb.
  • It generates electricity when it is in large or dense quantities.
  • It glows very brightly.
  • It has a long life and can illuminate light for about 2000 to 6000 hours.

Xenon Bulb Assembly in Projectors

The xenon bulb is made of quartz instead of glass because it has to be very hot. Because it is self-conductive, it does not need filament. When a current is applied, charge arc the cathode and anode. For a bulb to shine brightly, xenon must be pure and the quartz shell must be vacuum sealed.

This bulb is then placed in the center of the parabolic mirror which is located in the lamphouse. The mirror reflects light from the bulb and focuses it on the condenser which is a pair of lenses used to further intensify the light and direct it to the main lens assembly.

Lens Assembly

From the aperture gate, the light passes into the main lens. The lens is removable and various types of lenses are used depending on the typical format of the film. The most common lens is flat and cinemascope. Many projectors have a turret that permits both kinds of lenses and the projector will rotate the required type of lens into place. After that, the light goes into the viewport at the projection booth and then to the auditorium, and reaches the screen finally to form the image.

Audio System

Sound is recorded in movies optically on the edge of the film. After the film passes through the lamp, it also passes through the sound drum. This focuses the light on the soundtrack. A photosensor on the other side measures the amount of light and converts this amount of light into the current which drives the speakers. If it vibrates and oscillates more rapidly, it will produce higher frequencies. The greater the amplitude or width of the soundtrack, the louder the volume.


If you are curious about how a projector work for movies, this has been written for you. We have discussed the basic working principle, components, and function of all parts of projectors for movies, how they work, and how they are used to project images on the screen.

Frequently Asked Questions (FAQs)

How does a 35mm film projector work?

A 35mm filmstrip is a device that uses to display an image on the screen. It is mainly used for movies and consists of negative film wound on a drum. When the filmstrip is exposed to light it creates images on the screen. The pins are embedded in the long filmstrip which is constantly moving and creating images on the screen.

How much light can a film projector produce?

The light produced from a movie projector can be different depending upon a variety of factors including the type of film being watched, the brightness of the light, and the distance of the screen from the projector.

Do you need WiFi for a movie projector?

Some wireless projectors contain a built-in wireless card. Others require an optional accessory, like a USB dongle. Some projectors use an app installed on phones or tabs to display presentations and documents stored on your devices. Others work with your existing WiFi networks.