“Almost like a real web site”

Search | Contact
News | e-News |
Rumour Mill | Stories
Foreign Language
in70mm.com auf Deutsch


Todd-AO Festival
KRRR! 7OMM Seminar
GIFF 70, Gentofte
Oslo 7OMM Festival
Widescreen Weekend

Premiere | Films
People | Equipment
Library | Cinemas
Todd-AO Projector
Distortion Correcting

Ultra Panavision 70
Super Panavision 70

1926 Natural Vision
1929 Grandeur
1930 Magnifilm
1930 Realife
1930 Vitascope
1952 Cinerama
1953 CinemaScope
1955 Todd-AO
1955 Circle Vision 360
1956 CinemaScope 55
1957 Ultra Panavision 70
1958 Cinemiracle
1958 Kinopanorama
1959 Super Panavision 70
1959 Super Technirama 70
1960 Smell-O-Vision
1961 Sovscope 70
Cinerama 360
1962 MCS-70
1963 70mm Blow Up
1963 Circarama
1963 Circlorama
1966 Dimension 150
1967 DEFA 70
1967 Pik-A-Movie
1970 IMAX / Omnimax
1974 Cinema 180
1976 Dolby Stereo
1984 Showscan
1984 Swissorama
1986 iWERKS
1989 ARRI 765
1990 CDS
1994 DTS / Datasat
2001 Super Dimension 70
2018 Magellan 65

Various Large format | 70mm to 3-strip | 3-strip to 70mm | Specialty Large Format | Special Effects in 65mm | ARC-120 | Super Dimension 70Early Large Format
7OMM Premiere in Chronological Order


Australia | Brazil
Canada | Denmark
England | France
Germany | Iran
Mexico | Norway
Sweden | Turkey

7OMM Projectors
People | Eulogy
65mm/70mm Workshop
The 7OMM Newsletter
Back issue | PDF
Academy of the WSW

• 2026 | 2025 | 2024
2023 | 2022 | 2021
2020 | 2019 | 2018
2017 | 2016 | 2015
2014 | 2013 | 2012
2011 | 2010 | 2009
2008 | 2007 | 2006
2005 | 2004 | 2003
2002 | 2001 | 2000
1999 | 1998 | 1997
1996 | 1995 | 1994

in70mm.com Mission:
• To record the history of the large format movies and the 70mm cinemas as remembered by the people who worked with the films. Both during making and during running the films in projection rooms and as the audience, looking at the curved screen.
in70mm.com, a unique internet based magazine, with articles about 70mm cinemas, 70mm people, 70mm films, 70mm sound, 70mm film credits, 70mm history and 70mm technology. Readers and fans of 70mm are always welcome to contribute.

Disclaimer | Updates
Support us
Table of Content

Extracts and longer parts of in70mm.com may be reprinted with the written permission from the editor.
Copyright © 1800 - 2070. All rights reserved.

Visit biografmuseet.dk about Danish cinemas


The Basics of The Rolling Loop IMAX Projector
IMAX Dome Luxury, Copenhagen, Denmark

This article first appeared in
..in 70mm
The 70mm Newsletter

Written By: Chief projectionist Rene Sørensen, Tycho Brahe Planetarium & Omnimax Theatre. Pictures by Thomas Hauerslev Issue 48 - March 1997

EXPO 1967


Exterior of the Tycho Brahe Planetarium

The IMAX system has its' roots in Montreal's EXPO 1967, where multi-screen films were the hit of the fair. A small group of Canadian film makers/ entrepreneurs, (Graeme Ferguson, Roman Kroiter and Robert Kerr), who had made some of those popular films, decided to design a new system using a single, powerful projector, rather than the cumbersome multiple projector systems used at that time. The result: The IMAX motion picture projection system which would revolutionize giant screen cinema.

IMAX premiered at the Fuji Pavilion at EXPO 1970 in Osaka, Japan. The first permanent IMAX projection system was installed at Ontario Place Cinesphere in Toronto in 1971. Dome screen Omnimax, its' sister system, debuted at the Ruben H. Fleet Space Theatre in San Diego on March 10, 1973. A few years ago the trade name Omnimax was changed to IMAX Dome.

The IMAX image 70mm/15 Perf. is ten times larger than a conventional 35mm/4 perf. frame and three times larger than a standard 70mm/5 perf. frame.

Further in 70mm reading:

Omnimax in Copenhagen. Tycho Brahe Planetarium, 7OMM 1989 - 2020

IMAX Sound

The First 70MM IMAX Cinema in England

The Passing of Bill Shaw - IMAX Pioneer

IMAX, IMAX Dome, IMAX Solido, IMAX 3D, IMAX Magic Carpet, IMAX HD

Internet link:

Tycho Brahe Planetarium & Omimax Theatre
Gammel Kongevej 10
1782  Copenhagen V

Phone: +45 3312 1224
Web site www.tycho.dk


Superior Performance

The Rolling Loop projector at the Tycho Brahe Planetarium & IMAX Dome theatre, Copenhagen.

IMAX and IMAX Dome projectors are the most advanced, highest precision and most powerful projectors ever built. The key to their superior performance and reliability is the unique Rolling Loop film movement system, used in no other projector. The Rolling Loop was invented by Ron Jones from Australia. 

The film run horizontally 24 frames per sec. in a smooth, wave-like motion. 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. As a result, the picture and focus steadiness is far above normal standard. The projector mechanism has six mechanical components which must act in precise synchronism to advance the film, frame by frame, with high accuracy and negligible wear and tear. These elements make up what is called the Rolling Loop Film Transport System.

Air Valve

Rotor (1) and front section of projector.

1: Rotor. A 37,5 inch diameter drum containing eight windows or gaps, each of which forms a loop or wave in the film as it passes the input sprocket, and then advances the film by carrying the loops past the aperture.
Input Sprocket (2) and Rotary Air Valve (6).

2: Input Sprocket. A sprocket is driven in synchronism with the rotor to feed one frame of film (15 perforations) per rotor gap. It positions the film so that the cam pins enter the intended perforation at a precisely determined point.
Registration Pins (4) and Cam Unit (3).

3: Cam Unit. A mechanism which oscillates the film-engaging pins or claws (two pins at each edge of the film) to catch and slow down the film, fed by the input sprocket, and to preposition the perforations which are engaged by the registration pins at the aperture.

4: Registration Pins. Four fixed pins (one at each edge of the aperture) which engage the film perforations to precisely position the film during projection.

5: Output Sprocket. Like input sprocket, it rotates in sync with the rotor.

6: Rotary Air Valve. This valve, which has one outlet for each rotor gap, pulses air to a row of jets at the rotor gap as it passes the input sprocket in order to help shape and accelerate the loop of film which forms in the gap at that point.

Vacuum on the Lens

A typical lift off in Omnimax

The images are moved every time the rotor gap passes the aperture block with a "wave" of one frame (15 perforations). The images are then fixed by the four pins on the aperture block, helped by the vacuum on the lens, in order to keep the pictures in focus. Between every rotor gap a shutter is placed so the pictures are shown twice. This 68 per cent shutter transmits one third more light then does the 50 per cent shutter in conventional projectors.

The IMAX projector is equipped with a 15.000 watt water cooled Xenon lamp. In smaller theatres a 4.000 watt lamp is enough.

The IMAX Dome projector is the same type projector as an IMAX; the lens design is different, however. IMAX Dome was developed for use in tilted planetarium- type domes. The projector and lens are located slightly behind and above the center of the dome (the planetarium's star projector is placed in the geometric center of the dome).

IMAX Dome produces a picture extending 180 degrees horizontally, about 100 degrees above the horizon and 22 degrees below. Our dome in Copenhagen is 23 meters (76 feet) in diameter. The dome surface area is 1000 square meters; 800 square meters are used for IMAX Dome projection. The screen is made of many small plates of aluminum with 20% of the area perforated with holes. You can see through the screen if the backstage area is lit up. The maximum size of an IMAX screen is 26 x 35 meters (87' x 17') and 27 meters in diameter for an IMAX Dome screen.
The Omnimax in Copenhagen

Any Questions?

A total of 144 IMAX/IMAX Dome theatres are currently operating world wide [By 1996/97]. There are more than 110 IMAX films. If you have any IMAX related questions please do not hesitate to ask Rene Sørensen directly through E-mail or through ..in 70mm - The 70mm Newsletter.

Sources: IMAX Fact Sheet and J. Creighton Douglas "What is IMAX, and why".

• Go to
Imax/Omnimax Motion Picture Projection Systems
Go: back - top - back issues
Updated 21-01-24