What makes giant movie film so different? How does the film stock differ from the film used in a conventional movie? What technology has been developed to accommodate this large-scale film?

Insights

IMAXreg. and OMNIMAXreg. are counterpart motion picture systems using state-of-the-art technology to project huge images of tremendous clarity. The projected picture, which is up to 10 times the size of a conventional screen, extends beyond the human peripheral vision on all sides and puts the viewer in the middle of the scenes as it zooms between microcosmic and macrocosmic views. It tends to have subliminal effects on the viewers as well, often giving them the feeling of motion sickness, as if they were actually taking part in the event they are watching.

The first giant-screen IMAX showing premiered at EXPO `70 in Osaka, Japan. The IMAX image is projected on a vertical flat screen that is eight stories high and 70 feet wide. The sister OMNIMAX system premiered in 1973. This system projects images to fill 86% of a surrounding dome screen. The OMNIMAX screen is four stories high and 76 feet in diameter, with views of 180 degrees that wrap around a tilted tier of seats. The projected images fill the entire field of vision, creating a three-dimensional (3-D) illusion of being transported through any environment. Eighty-four speakers project music and sound. The movie reel for an average feature of 34 to 45 minutes is 48 inches in diameter and weighs 150 pounds, so heavy that two people must load it into the projector.

The secret to creating the clear, big-screen imagery of the IMAX and OMNIMAX theaters begins with the film itself. The specially-designed IMAX and OMNIMAX cameras photograph the largest frames ever used in motion pictures: 70mm wide and 15 perforations per frame compared to a standard 35mm, 4-perforation motion-picture frame. The large film size is necessary because the image is projected over such a large area.

The projection process also requires special adaptations. The high performance and reliability of IMAX and OMNIMAX projectors come from the unique way the film loops, or "caterpillars," through them. This "Rolling Loop" projector advances the film horizontally, instead of vertically as does a regular film projector. This gives the super high-speed film flexibility and helps prevent shredding. To keep the projected image steady during projection, each frame is positioned on fixed registration pins, and the film is held firmly against the rear element of the lens by a vacuum. The resulting picture and focus are steady and clear.

The future of IMAX and OMNIMAX rests in the development of computer animation and 3-D technology, already underway.

Connections

1. Modern planetariums use domed theaters for projecting astronomy multimedia illusions. To what other uses could planetariums and their special light, sound, and motion effects be put?
2. Ask your students if any of them has been to a giant-screen movie. What were their experiences?

Vocabulary

animation a motion picture made by photographing successive positions of inanimate objects to create the illusion of apparently spontaneous lifelike movements
mm a metric measure that is .001 of a meter, or approximately .039 inches
peripheral lying at the outside or away from the center part
subliminal below the threshold of consciousness

Resources

Culhane, J. (1981) Special effects in the movies: How they do it. New York: Ballantine Books.

Elmer-DeWitt, P. (1990) Grab your goggles, 3-D is back! Time (Apr 16): 77-78.

Park, E. (1990) Around the mall and beyond. Smithsonian (Nov): 25-28.

Walt Disney's moving picture flip book. (1986) New York: B. Shackman & Co.

Additional source of information:

IMAX Corporation
Communications Department
38 Isabella Street
Toronto, Ontario, Canada M4Y 1N1
(416) 960-8509

Community resources:

Television stations
Movie theaters
Video or film production houses

Main Activity

Animation is made possible because our eyes perceive two slightly different pictures, one after the other, as a moving image. It is a physiological fact that an image is registered onto our retina, remaining there for a bit even though the source of the image is out of view. The eye can register 12 pictures per second as separate images, so if the pictures appear more quickly than this, the eye perceives them as moving pictures. Motion pictures appear at the rate of 24 photographs (frames) every second.

Films today consist of a strip of transparent acetate with a series of small, sequenced frames, each representing a visual record of a moment in time. When the series of pictures is projected rapidly onto a screen, the illusion of continuous action is created.

Before motion pictures were invented, people created the illusion of moving pictures by drawing a slightly different image on each page of a book, and then flipping through the book with a thumb. The pictures appeared so quickly that the eyes "saw" a steady movement. The first "flickerbook" appeared around 1890.

Invite your students to create a small flickerbook.

Materials

• pencil, pen, or markers
  
• paper, needle and thread, and staples OR a small bound notebook OR a pad of removable sticky notes

1. If you are making your small books from scratch, use the paper, needle and thread, or staples to create some books of your design. If you are using a notebook or a pad of sticky notes, these can be your "books."
2. Have each student think of a simple story he or she would like to illustrate.
3. On the back side only of each page, draw a picture (close to the cut edge of the paper) in which the action is slightly different than the action in the previous picture. When the picture story is finished, hold the book in the one hand and flip the pages from front to back with the thumb of the other hand.

Questions

1. Are there certain actions or pictures that are particularly well-suited to this technology? Are there certain actions not well-suited to this device?

2. What happens if you flip through the pictures too quickly? Too slowly?

Explore the differences between animal and human eyes. Is there any connection between the "fish-eye view" that some animals have and the domed images in an OMNIMAX theater?

Arrange a visit to a local motion-picture theater or an IMAX theater to tour the projection booth, or ask a theater owner or manager to visit your classroom to answer some questions about theater projection. How many rolls of film are there in a two-hour film? Why are so many films about two hours in length? How do movie theaters avoid a "break" in projection when they switch projectors? What changes have occurred in the technology in the last five years? What changes do they predict? How does standard projection differ from what the students saw in the segment?

Find out about planetariums, then visit one. What technology is used to create realistic otherworlds, landscapes, and skyscapes? How are planetariums similar to OMNIMAX theaters? How are they different?

Newton's Apple is a production of KTCA Twin Cities Public Television.
Made possible by a grant from 3M.
Educational materials developed with the National Science Teachers Association.