Abstract
IN colour photography it is necessary to analyse the light reflected by coloured objects into at least three spectral regions which, where there are three only, may be termed red, green and blue respectively. This is done by means of colour filters which transmit definite portions of the spectrum and absorb the rest; the three negatives are produced either successively or simultaneously. In cinematography the negatives must, of course, be made simultaneously unless the rate of movement of the film is increased threefold, to which there are grave objections. The three negatives may be made simultaneously by means of three lenses; this results in colour parallax, and the three images will never exactly superpose. Alternatively, the beam of light issuing from a single objective must be divided. This division may be made by means of superposed filters, the components of white light being successively subtracted and acting on sensitised films superposed. The objections to this are that the films and filters must be very thin if the composite ‘tri-pack’ and filter film is not to be too thick, and that each layer of emulsion produces a certain amount of scattering, so that the successive images are more and more diffused. Other methods of dividing the beam are by successive reflections from thin, partly-reflecting and partly-transmitting films, which may be either isolated films of collodion or films of silver on glass surfaces. The silver may be in the form of totally reflecting films partly covering the surfaces they are deposited on, a method not without objection since the areas of film must be small if there is not to be differentiation between different parts of the light beams; alternatively, the silver films may be so thin as both to reflect and transmit.
Article PDF
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Lee, H. Lenses Employed in the Technicolor Process of Cinematography. Nature 136, 879–880 (1935). https://doi.org/10.1038/136879a0
Published:
Issue Date:
DOI: https://doi.org/10.1038/136879a0