3-D System Formats
Williams, Alan D, American Cinematographer
In the time period of 1952 to 1955, when most of the so-called "vintage" 3-D pictures were made, there was only one format in general usage: double 35mm cameras for photography and double 35mm projectors for exhibition. Today 3-D pictures are generally shot either with a double 35mm camera rig or with a special lens system which divides the 35mm frame in half horizontally, placing one image on the top half and the other one on the bottom half. Exhibition is almost invariably single-projector in the over/under format. The evolution of formats over the last 30 years is interesting, because it is both straight as an arrow and also branches to all sides.
Between 1955 and 1965 very few pictures were shot in 3-D, and the medium seemed relegated to the pile of failed motion picture experiments. However in 1965, the late CoI. Robert V. Bernier, who had been experimenting with stereoscopic films and photography for over 20 years, perfected a new way to shoot and show 3-D using a single camera and a single projector. (Actually, single-camera, single-projector systems existed prior to CoI. Bernier's development, but his is generally credited as the start of the current over/under format convention.) The process, originally called Perspective 3-D, used a special lens system with a conventional BNC mount to take left and right-eye views of a subject and position them, one over the other, within the area of one conventional film frame. The advantages of SpaceVision®, as it became known later, were immediate and obvious: only one camera required for photography, no synchronization problems between cameras, widescreen aspect ratio without anamorphics, one projector needed (enabling changeovers in the booth and eliminating the necessity for an intermission in pictures longer than 64 minutes), no need to match release prints (left and right) for density and color, etc. This over/under format has become the major standard for projection today (mainly because of its wide-screen aspect ratio) and also the preferred format for single-camera photography. The major differences in over/under format systems are the vertical spacings between the centers of the two images, which range from 0.366 inches to 0.404 inches, depending upon the camera system employed (dual-camera films must be printed into the over/ under format and their center spacings can be virtually anything).
But to photograph two images separated by a horizontal distance and stack them so that they are separated by a vertical distance on the film in the camera requires a highly sophisticated optical system. It is much easier, from a design standpoint, to place the image side-by-side within one frame. Such a device can be constructed using as little as two first-surface mirrors, and numerous side-by-side attachments and lens systems were developed for amateur stereo photography in the 1950s. Experimentation in the late 1960s and early 1970s by a company which would later be known as Stereovision International, led to the development of the side-by-side format which was used to film one of the most financially successful 3-D films of all time, THE STEWARDESSES. To eliminate the problem of a "door frame" aspect ratio, anamorphics were used in the printing and in the projection lenses, giving the two side-by-side images a horizontal squeeze of 2:1 on the print film and expanding it back to about a 1.33:1 aspect ratio upon projection. This same format was used for making prints for the 35mm single film 3-D re-release of HOUSE OF WAX in 1971. For "showcase" engagements of HOUSE OF WAX, the two images were printed, side-by-side, on 70mm film without an anamorphic squeeze, yielding an aspect ratio approximating academy aperture. …