Why see The Dark Knight Rises in an IMAX 15/70 film theater?
(See the
list of theaters showing The Dark Knight Rises in
15/70 here.)
Director Christopher Nolan shot about one hour of
The Dark Knight Rises using IMAX 15-perf, 70mm film cameras, which expose a frame that is about ten times larger than a standard 35mm film frame. (See
here for a comparison of film sizes.) The extra large frame captures much more information, permitting classic IMAX theaters to project sharp, clear images onto screens as large as 96 feet tall and 117 feet wide (29x36 meters).

Cinematographer Wally Pfister (left) and director Chris
Nolan, shooting for
The
Dark Knight Rises with the IMAX
15/70 camera. (Getty Images.)
In addition to being much larger, the 15/70 frame also has a different shape, or aspect ratio, from standard movies. The ratio between the width and height is 4 to 3 or 1.33 to 1, often referred to simply as 1.33. This is also the ratio of standard-definition television.
Wide-screen TV has a ratio of 16:9, or 1.78, very close to the ratio of most current Hollywood films, which is 1.85, known within the industry as “flat.” The widest Hollywood ratio is
generally known as “scope,” and is 2.4. On a screen 80 feet wide, the scope image is about 33.3 feet tall.
When images of one ratio are shown on a screen of a different ratio, either some portion of the screen will not be used, or some portion of the image will not be shown. In the old days, wide-screen movies shown on television were either shown “letterboxed,” with black bars at the top and bottom of the screen, or “pan and scan,” in which the image filled the height of the screen, but the sides of the image were
cut off.
This is the key to what happens when The Dark Knight Rises switches from conventional 35mm footage to 15/70: the letterboxed 35mm “scope” image will expand to fill the full height of the screen. This change will occur only in IMAX theaters, but not all IMAX theaters are created equal.

In the average classic IMAX film theater with a 60x80-foot (18x24-meter) screen, the image will expand from about 33 feet high to the full 60-foot height of the screen. The effect of this
dramatic transformation is the reason that Nolan reportedly insisted that Warner Bros. make at least one hundred 15/70 prints of the film.
In IMAX digital theaters, and IMAX MPX film theaters, whose average ratio is 1.75, this transition will be much less
noticeable, expanding by about 4.5 feet (1.5 meters) at the top and bottom of the screen.