Broad format anamorphosis

A broad format anamorphosis is a Format of projection using a process of Anamorphose.

The cinematographic Projection uses out of standard a film of 35 mm broad. Because of the technical constraints - presence of perforations for the advance of film, of a Bande its optical, standardized run with four perforations per image -, the size of the frame is limited to 22×18 mm ², which represents an image having a width report/ratio on height of 1,22.

However, a room is increasingly broader than high; if one wants to have a larger image, to have a “large spectacle”, thus should be projected a broader image. The broad formats of projection can be obtained by reducing the height of the image on the film, and by increasing it more with the screen. One can thus have an image having a ratio of 1,85, the frame making 22×11,90 mm ², but one is limited by the grain of the film: if one enlarges too the image, one obtains a poor image of quality.

To have a broader image with a good resolution, with a film 35 mm, one use an anamorphosis: the image is compressed in the direction of the width on the film (either with the catch of sight, or during pulling) then is decompressed with projection. The most famous system is the CinemaScope.

The first patent of anamorphosor was deposited in 1862, but the device more the current is the Hypergonar, invented in 1927; this one uses cylindrical lenses . Certain device use prism S, but because of the aberrations create for raised reports/ratios, they are in general limited to the Vidéoprojecteur S, to transform an image 4/3 into 16/9 (report/ratio of anamorphosis of 1,33, for example the Prismasonic system); anamorphoseurs with prism were marketed for the cinema (Super Panatar de Brewster, Superscope of the Tushinsky brothers). There exists other system, in particular using Miroir S - curves (anamorphosor Delrama, which uses also prisms to reduce the size of the device) or not - and if required of the variable components to vary the rate of anamorphosis, but they are not used any more.

Spherical projection is another type of broad format anamorphosis. Here, the frame with the form of a Disc.

List processes

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