Fifteen perforations per frame, running sideways. That is the entire trick. Standard 35mm cinema film runs vertically, four perfs per frame, giving roughly 350 square millimetres of image. IMAX turns the stock on its side and pulls 15 perfs across 70mm film, producing a negative area near 3,700 square millimetres. Almost ten times the capture area, resolving to something in the region of a 12K digital equivalent. The physics that follows is brutal. - Frame pitch is 71.25mm, so at 24 frames per second the film travels about 1.7 metres every second - A three-hour feature runs to roughly 18 kilometres of print, weighing a few hundred kilograms across the platters - Camera magazines hold 1,000 feet, near three minutes of footage, and the cameras weigh 25 to 30kg and run loud enough that dialogue is usually replaced later Projection is the harder problem. Yanking that much polyester to a dead stop 24 times a second would tear it apart. The answer is the rolling loop, patented by Austral...