The difference between IMAX and standard 70mm
by Mr. Nobel
This is something plenty of folks already know, but something I found out quite recently. Feel free to ignore if you’re more knowledgeable than me, but I think this bit of technology’s pretty neat.
So standard 35mm and 70mm film is oriented such that the vertical is parallel to the perforations and the horizontal goes from left perforations to right perforations. This maximizes the number of frames per unit length of film. It’s all fine and dandy until you decide to make a 6 story tall theater screen. In that case, you’ll need much more resolution to get good image quality.
IMAX solves this problem by flipping the horizontal and the vertical, so that the horizontal is parallel to the perforations and the vice versa. This dramatically increases the area of each frame, increasing the resolution offered by the film. VistaVision uses the same idea to boost resolution for 35mm film.
The obvious downside of this approach is that you drastically decrease the efficiency of the film stock. For IMAX, each camera magazine can only hold up to 3 minutes of film. 3 minutes. For comparison, a standard 35mm film magazine can hold 12 minutes worth of film. This, coupled with the fact that only a handful of IMAX cameras exist in the world (3 or 4 of the kind used in The Dark Knight and Mission Impossible 4), makes filming long takes in IMAX difficult.
Something to keep in mind when you see The Dark Knight Rises (hopefully in IMAX).