Movie prints cost a lot of money to produce (35mm film stock isn't cheap). Many multiplexes show major movies in several auditoriums with slightly different start times. Because any given portion of the film is only being shown on one screen at a time, it should be possible to "share" one print between two screens (note that the producers and distributors shouldn't mind, since their profits are based on ticket sales rather than the number of prints circulated).
Sharing prints would have been fairly straightforward a few years ago, when theaters used multiple projectors. One approach to solving the 'sharing' problem would be to return using two projectors, at least for movies being shown on multiple screens.
An alternative method would be to equip adjoining theaters with a film-holding device somewhat like the 'loop platters' at the Museum of Moving Image in London, but slack racks (whatever they're called) on either side of it. The film in the first theater's booth would have a long leader attached which would be fed through an opening the second theater's booth, where it would go onto a loop platter (preferably after going through a slack rack). Once the film was started, it would begin to accumulate on the loop platter until the projectionst was ready to start threading the second projector and just about ready to start it. At that point, the projectionist would stop the platter loop reel (film would start accumulating in the first slack rack), feed the film through the second slack rack, and then start feeding the projector. When the first slack rack was nearly full, the platter loop would restart and start feeding film into the second slack rack. Hopefully by the time the second slack rack filled up, the projector would be threaded and ready to roll (if not, the first theater's showing would probably have to be interrupted). Once the projector was ready, the projectionist would flip a switch and take a well-deserved rest.
To be sure, this latter approach would probably be more difficult than the first, but the first wouldn't be much of an 'invention'. Movie film for 35mm travels at about 2 feet per second. A platter loop like the ones at MOMI would have no difficulty holding 20-30 minutes or so of film. Slack racks wouldn't be able to hold nearly so much film (a 6' rack with 10 pulleys on the top and bottom would hold about a minute's worth) but if the projectionist is reasonably quick, a minute's worth of rack before the loop platter and a minute after should suffice.
Even cooler would be a figure-eight loop platter design which could accommodate varying amounts of film, but I'm not sure if that would be practical.-- supercat, Apr 11 2004 A single, long continuous piece of film winding its way throughout a theater would be kind of cool, in an artsy sort of way. Other than that, probably cheaper to go digital.-- phoenix, Apr 11 2004 Well, digital would have its advantages, but acetate (*NOT* celluloid!) will still be around for awhile. And while it is, it would seem one should try to make the most of it.
As noted, probably the most practical method of sharing a print between two screens would be to keep reels of the film separate and use two projectors per screen. This would keep a projectionist fairly busy, to be sure, but it shouldn't be unmanageable. The approach I suggested would demand a bit more skill on the part of the projectionist (I don't think threading a slack rack and projector in two minutes should be a problem, but would require the projectionist to be reasonably adept) but would only require the projectionist to do tricky stuff once per booth per movie (instead of less-tricky stuff once per booth per reel).-- supercat, Apr 11 2004 Toadinov: Unless you want to have all four rooms running movies about 30 seconds apart, you'll need to have something to hold film between projectors.-- supercat, Apr 11 2004 This is definitely necessary because the film industry hardly makes any money at all, and they certainly need to scrimp and save wherever they can.-- waugsqueke, Apr 11 2004 with multiple film reels this might be semi-baked already. When reel 1 is done and reel 2 is in, pass reel 1 to theater 2 where everyone is taking their seats...-- sninctown, Sep 26 2005 random, halfbakery