The first thing noticeable about an IMAX theater is the size of the screen. A traditional IMAX screen built to original specifications is 30 meters (approximately 98 feet) tall, as tall as an 8 story building, and 23 meters (approximately 76 feet) wide. The enormous screen allows for the film to fill the entirety of your vision, including peripheral, giving an incredibly immersive experience. Some screen are even built concave, so that the picture wraps around you, giving a sense of three-dimensional depth.
Special film is used to film movies for IMAX theaters. Traditional theatrical quality movies are recorded on 35mm film, while IMAX uses a special 70-15 film. 70-15 means that the film is 70mm wide and each frame of film is 15 perforations tall; perforations being the small holes you see along the sides of projector film. Using film this size allows IMAX to project their movies at a much higher resolution, and with far greater detail, than traditional film.
Special cameras are required because of the special film used to produce the high definition of IMAX movies. Also, the massive screens for IMAX theaters requires that the special theaters be built specifically to accommodate not only the size of the screen, but the angles of seats, which are designed to maximize the viewing angle for every member of the audience. The specialty nature of IMAX film and theaters means that IMAX movies are costly for movie companies and theater owners alike. Additionally, IMAX films that require special effects require much more rendering time because of the high resolution being displayed: displaying the image nearly 100 feet tall makes poor CGI very noticeable.
IMAX theaters are appealing to filmmakers, despite the additional cost of producing IMAX quality films, because of the appeal to consumers of watching the highest quality of the film available. Film companies are in a constant battle against bootleggers distributing cheap, or even free, copies of their films on street corners and the Internet. However, the specialty nature of IMAX theaters is not something that can be reproduced in the average home, so ticket sales remain strong even for widely pirated films.