A Comprehensive Guide to Film Projection Systems & Techniques

Posted on Aug 24, 2024 in Technology

1.2 Components of Projection Systems

1. Cruz de Malta: This drive mechanism keeps the film in constant oscillation between movement and rest. It consists of two parts: the cross and the impeller plate. The arms of the cross move the film and place it for exposure to light.

2. Shutter: This component interrupts the projection during the process of changing the image.

3. Window: With dimensions smaller than the frame of the movie (21×17.5 mm, compared to the 21.5×18 mm frame), the window prevents separation lines and sound sidebands.

4. Optical Aperture: This rectangular opening allows for adjustments to the frame’s edges based on the film format.

5. Optic Group: Consisting of one to three lenses in a turret, these lenses are classified as normal, wide-angle, or telephoto, similar to camera or film lenses. The choice of lens depends on the distance between the projector and the screen.

6. Flashlight or Projection Lamp: This component provides the light beam for the projector. The type of lamp chosen depends on factors like required light intensity, screen size, and the distance between the screen and the projector.

7. Sound Reader: Two types of sound readers exist, depending on the film’s soundtrack:

  • A. Optical: Situated behind the film loop’s exit (after the Maltese Cross), this reader compensates for the gap with the image. It consists of a metal housing, a filter roll (to remove tape oscillations), a lamp emitting a light beam, a micro-lens (to collect the signal), and a photodetector.
  • B. Magnetic Reader: Less common than the optical reader, this type is exclusive to 70 mm and 16 mm formats and unusual for 35 mm. Located between the supply roller and the window, it compensates for the gap with the image. It consists of two pairs of cushioning rollers and a head with phone loop sensors to collect magnetic signals.

Sound Projection Quality

The quality of film sound projection depends on these factors:

  • The screen, responsible for reflected light intensity.
  • The projection lenses, responsible for light distribution on the screen.
  • The shutter and drag mechanism of the projector, responsible for flickering and blinking.
  • The intermittent drive mechanism, responsible for image oscillation.
  • The focus of light emitted from the projection lantern, responsible for the quantity and quality of light.

Traditional vs. Digital Projection Rooms

A. Traditional Room

The traditional film projection system relies on the physical presence of a film copy in the projection booth. The film is collected from a warehouse, transported to the cinema, and mounted onto the projector. This projector uses a powerful light source to emit white light onto a screen. The film passes through a window, with each frame held for 1/24th of a second in front of the light source, projecting the photographic image onto the screen with its full color range. This setup requires personnel to collect, transport, and return the film copy. The projection room needs acoustic isolation to prevent projector noise from reaching the audience. Additionally, two projectionists are needed for tasks like joining film reels, mounting the film, and controlling the projection.

B. Digital Room

Digital cinemas utilize automatic digital projectors that form images on the screen by combining red, green, and blue light to create the full spectrum of colors. These light sources within the projector respond to digital signals (received via cable, fiber optics, radio waves, or satellite) that determine the projection. These signals contain all necessary information, including chrominance (color points to be illuminated) and luminance (intensity of each point), as well as synchronization information (vertical and horizontal) to form the image on the screen. Digital projection eliminates the need for a physical copy, a separate projection booth, and a projectionist to handle the copy and projector.

Advantages of Digital Projection

Image Quality

Digital projection offers superior image quality, measured by resolution, brightness, color fidelity, accurate tonal reproduction, and the absence of noise and temporal distortions. High-resolution digital projection ensures resolutions of 4 million pixels per frame, brightness of 10,000 lumens, a billion colors, and consistent sharpness from opening day onwards.

Sound Quality

Digital cinema elevates sound quality by sending the encoded signal directly to the cinema, delivering sound to each speaker independently through 8 satellite channels. This accurately reproduces the film’s diverse sound effects.

Other Advantages

  • Live Releases: Simultaneous premieres with Hollywood, incorporating artist input and feedback.
  • Live Events: Enjoy front-row experiences of concerts, sports finals, or bullfights.
  • Ease of Management: Automated projection with satellite-based programming.
  • Cost Savings: Elimination of physical copies and reduced distribution costs.
  • Instant Control: Real-time monitoring of audience numbers and projection quality in each room.

1.6 Structure of Cinemas

A showroom refers to any local film screening venue open to the public for a fixed entry price, granting access to a specific film. Essential elements for a film session in a cinema include:

  1. Seats or Chairs: Various types are available, with recent trends focusing on comfort and convenience.
  2. Projection Booth: Houses all mechanisms, tools, and instruments for energy design and supply. Requires an air conditioning system to vent heat from gas lanterns and spotlights.
  3. Screen: As discussed in the previous section.
  4. Speakers: Strategically placed around the room, speakers specialize in reproducing specific frequencies (low, mid, and treble). Their location and layout are crucial for creating a realistic audio experience. Surround sound systems use a combination of speakers, with the screen speakers handling the inner soundtrack and the side speakers responsible for sideband audio.

1.7 New Projection Techniques

Emerging in the 1960s, new projection techniques resulted from experimentation with new formats, particularly the 70 mm format, increased projection speeds (48-60 frames per second), and the use of spherical screens. Some notable techniques include:

  1. Cinerama: Recording is done with three cameras, and projection uses three projectors on a concave screen with a 7-meter deep central arch. The optimal viewing point is limited to the center due to the screen’s curvature. A fourth projector handles the soundtrack.
  2. Cinemascope: Anamorphic lenses compress the image within the 35 mm negative during recording. The same lens type is used on the projector to decompress the image during playback. The screen has a 1.5-meter deep curvature at its central arch, allowing for viewing from any seat while maintaining the rectangular format. Cinemascope revolutionized large-format filmmaking with its speed, panoramic views, lighting, color, and epic staging capabilities.
  3. VistaVision: This technique increased the usable area of the 35 mm frame by transporting the film horizontally during recording, increasing the number of perforations per frame to eight. It served as a precursor to the IMAX system.
  4. IMAX: Developed by IMAX Corporation in Canada, this integrated system encompasses both recording and playback. The first IMAX exhibition took place at Expo 67 in Montreal with the film “Labyrinth,” recorded with five cameras in 65 mm format (15 perforations per frame). Five screens were assembled vertically and horizontally for playback. Today, two main IMAX types exist: IMAX HD (using 70 mm film) and IMAX 3D (using 70 mm film with 15 perforations and horizontal movement, projected at 48 frames per second on a giant screen).
  5. Omnimax: Also developed by IMAX Corporation, this technique was initially used for planetarium projections. Recording is done with a fisheye lens, and projection occurs on a hemispherical screen angled towards the audience, who are seated in reclining chairs. It fills the entire human field of vision, immersing the audience in the picture. Omnimax uses a 70 mm format with 15 horizontal perforations, projected at 48 frames per second.
  6. Solid (IMAX Corporation): This 3D simulation system projects onto a spherical screen using two synchronized projectors. The lenses alternate in projecting the image to the right and left eyes 96 times per second. The 3D effect is achieved through a 3D generator that utilizes the Photosynthesis system, creating a seamless 3D experience.
  7. Magnavision: This technique uses a 70 mm format with five perforations and projects onto a 180-degree screen.
  8. Showscan: Utilizing a 70 mm format with five perforations, Showscan projects at 60 frames per second.