7 cm
It refers to the actual film that the movie is filmed on. It holds more data than standard 35mm. Think of the old film reels and projectors - almost everything now is digital, but some scenes are filmed on analog becaise it actually holds more data. It's ideal for IMAX. Only a few dozen true 70mm physcial theaters still exist, with one of them being in san jose. If you get a chance, go watch stsr wars in that - spectacular.
Actually, 70 mm film is a wide high-resolution film gauge for motion picture photography, with higher resolution than the standard 35 mm motion picture film format.
It's the resolution of the movie!
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