Whilst all this was happening in Europe and America, The Russians had quietly been experimenting with various 3D systems, from alternating frame, through anaglyph up to and including polarised 3D. But in the end they decided to explore a completely different route by attempting to perfect a method of 3D presentation that did not require the audience to wear glasses at all: the parallax stereogram.
This method of stereo photography had first been demonstrated in the early part of the century by A. Berthier, E. Estenave and our friend Frederick Ives, but by the early 1930s had been perfected by Russian engineer Semyon Pavlovich Ivanov. A parallax stereogram is produced by placing a screen, usually made up of fine wires, in front of a sensitive photographic surface, in such a way that parts of the surface are shielded from the left eye lens and other parts from the right eye lens. When exposed, this will produce a double image made up of interlaced left and right eye views of a scene. The printed photograph is then viewed through a similar screen which will allow each of the viewer’s eyes to see only the appropriate left or right eye parts of the image. The wire viewing screens were later replaced by plastic screens made up of fine lines which could be laminated directly on to a parallax stereogram, each line, in effect, acting as a tiny lens directing the eyes to their appropriate view. This type of stereoscopic process, which does not require viewing glasses and permits simultaneous viewing by any number of persons, is still used today, usually in the production of novelty 3D items such as 3D bubblegum cards, 3D postcards and even 3D posters.
Ivanov then went on to adapt the principle for use in motion pictures. In his book Stereoscopy, Russian stereographer Nikolai Valyus, describes in great detail the incredibly complex and cumbersome equipment that becomes necessary when the principle of the parallax stereogram is applied to the projection of moving stereoscopic images; but a more concise description can be found in Brian Coe’s previously mentioned 1981 book, The History of Movie Photography:
Ivanov adapted this idea for the cinema. His first patent was filed in 1935 and using a glass grating he demonstrated his process in 1937. In 1940 he replaced the glass grating with a fine wire screen. The system was installed in the Moskva cinema in Moscow in 1941; 112 miles of wire were used to make a grid over a screen of about 14 x 19 feet. The films were shot with a conventional camera with a beam-splitting device on the lens, producing two vertical format pictures side by side in the standard film area. The soundtrack ran between the two pictures on the print. The film was back-projected, with a grid on the projector side of the screen to divide the two pictures into interlaced line images. A similar grid on the audience side created the correct viewing conditions for 200 seats laid out in a fan-shaped area. This was necessary for in some places in the auditorium no true stereoscopic image was presented.
The Russians produced two films for this system in 1940, the first being Concerto, which premiered at the Moskva cinema on the 4th February 1941, and the second, entitled Day off in Moscow, which continued there until the cinema was closed in June of 1941 because of WWII
Coe goes on to explain that the wire screen was eventually replaced by a lenticular ribbed glass screen and the vertical format images changed to square by reducing the size of the sprocket holes on the film. In February of 1947 a film entitled Robinson Crusoe was shown on a 5 metre square screen at the Vostock Cinema in Moscow, and the Russians went on to produce several more 3D movies prior to the 1950s: Pal; The Pencil on the Ice; Precious Gift; Lalim; May Night; Crystal and Aleko.
By 1952 the format had changed again and the screen assumed the normal 1.33:1 ratio, with the image pairs recorded on the film one above the other by means of a prism attachment on the lens. By 1955 there were 12 cinemas of this type in the USSR, and though the system worked quite well, it required the audience to avoid unnecessary sideways movement of their heads as this would dispel the stereoscopic effect.
The parallax stereogram system was not taken up outside the USSR apart from one variation on the idea, called the Cyclostereoscope, that was demonstrated at the Luna Park, Paris in 1949, in which the grid screen was rotated rapidly in an attempt to remove the vertical line effect.