Movies : Behind the Lens

Even though ticket prices continue to rise, millions of people flock to movie theaters world-wide week after week. There are over 37,000 movie screens in the United States alone.

There are several key elements of the current movie-watching experience.

The Film

Movie film vs. camera filmIt takes thousands of feet of film to make a movie. There are 16 frames on one foot of film, which passes through the projector at 24 frames per second.

Look at these calculations from howstuffworks:

  • One second = 1.5 feet (24 frames per second divided by 16 frames per foot)
  • One minute = 90 feet (1.5 feet per second multiplied by 60 seconds)
  • One hour = 5,400 feet (90 feet per minute multiplied by 60 minutes)
  • Typical two-hour movie plus five minutes of previews = 2.13 miles (11,250 feet divided by 5,280)
  • Therfore, a long movie like the three-and-a-half hour Titanic from 1997, is approximately 18,900 feet of film. That's 3.58 miles of film for one movie.

    Film cansSince it takes so much film to make one movie, the film is chopped up into a number of reels to make it portable. The reels are then loaded into cans and distributed to the theaters. The projectionist unloads the reels and splices them together, matching the ends together and tapes them, to build the movie.

    A built movie can have a diameter of up to four feet.

    Movie film also contains the soundtrack information. The soundtrack is encoded on the film and the projector has different readers that translate it. There are four types of soundtracks on the film:

  • Spectral Recording (standard sound)
  • Sony Dynamic Digital Sound (SDDS)
  • Dolby Digital
  • Digital Theater System (DTS)
  • The Projection System

    ProjectorOnce the film reels are spliced together and the movie is built, there has to be a way to project the movie onto the screen. That's where the projector comes in.

    The built film is carefully placed on a feedout platter, threaded through the projector and attached to a rewind platter. For a seasoned projectionist, the threading process can be done in about one minute. The movie is threaded before every show.

    The film travels on a one-way path through the rollers and gears. Unlike using a VCR, the film cannot be rewound in the projector.

    The film travels a long way from the feedout platter to the rewind platter. One single sprocket that is misaligned with the film can cause problems once the movie is started.

    The power of the xenonProjecting the small frame of film to the screen several hundred feet away, depending on auditorium size, takes a powerful and long-lasting light source. Xenon bulbs, made up of rare xenon gas, are the most commonly used lamps. They can provide bright illumination for 2,000 to 6,000. The bulb is so powerful that If the film snags and stops in front of it for even a second, it will burn a hole through it.

    (Photos by Tina Hasko)

    American Film Institute
    Check out a list of the American Film Institute's top 100 movies.

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