shot anamorphically used reserve stocks of 70 mm film for SFX shots involving CGI or blue-screen compositing as the anamorphic format creates problems with said effects. It has also been used to sometimes strike 70 mm blow-up prints for "roadshow" tours in select cities from the 35 mm camera negative in order to capitalize on the extra sound channels provided. The introduction of digital sound systems and diminishing number of installed 70 mm projectors has made a 70 mm release largely obsolete. However, blowups from 35 mm formats to IMAX have been used for a limited number of blockbuster films. Paramount's VistaVision was a larger gauge precursor to 70 mm film. Introduced in 1954, it ran standard 35 mm film through the camera horizontally to achieve a widescreen effect using greater negative area, in order to create a finer-grained four-perforation 35 mm prints in an era where standard monopack stock could not produce finer results. Negative frames were eight perforations wide. Eight-perf photography is sometimes used for shooting special effects in order to produce a finer grained matte that can be used in optical printing without image degradation, and is notable for its use in Lucasfilm's original three Star Wars films, among others. Another similar system with horizontal orientation was MGM's Arnoldscope. Multiple lens camera/multiple projectors – The Cinerama system originally involved shooting with three lens camera, and projecting the three resulting films on a curved screen with three synchronized projectors, resulting in an ultrawide aspect ratio of 2.89. Later Cinerama movies were shot in 70 mm anamorphic (see below), and the resultant widescreen image was divided into three by optical printers to produce the final threefold prints. The technical drawbacks of Cinerama are discussed in its own article. Only two narrative feature films, The Wonderful World of the Brothers Grimm and How the West Was Won, were filmed in three-camera Cinerama, and several sequences from the latter were actually filmed in Ultra-Panavision. With the exception of a few films created sporadically for use in specialty Cinerama theaters, the format is effectively obsolete. A non-Cinerama, three-projector process was pioneered for the final reel of Abel Gance's epic film Napoléon (1927) The process, called Polyvision by Gance, consisted of three 1.33 images side by side, so that the total aspect ratio of the image is 4:1. The technical difficulties in mounting a full screening of the film, however, make most theaters