1、BRITISH STANDARD BS ISO 20859:2005 Cinematography Spectral response of photographic audio reproducers for analog dye sound tracks on 35 mm film ICS 37.060.20 BS ISO 20859:2005 This British Standard was published under the authority of the Standards Policy and Strategy Committee on 3 October 2005 BSI
2、 3 October 2005 ISBN 0 580 46649 3 National foreword This British Standard reproduces verbatim ISO 20859:2005 and implements it as the UK national standard. The UK participation in its preparation was entrusted to Technical Committee CPW/36, Cinematography, which has the responsibility to: A list of
3、 organizations represented on this committee can be obtained on request to its secretary. Cross-references The British Standards which implement international publications referred to in this document may be found in the BSI Catalogue under the section entitled “International Standards Correspondenc
4、e Index”, or by using the “Search” facility of the BSI Electronic Catalogue or of British Standards Online. This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application. Compliance with a British Standard does not of itsel
5、f confer immunity from legal obligations. aid enquirers to understand the text; present to the responsible international/European committee any enquiries on the interpretation, or proposals for change, and keep UK interests informed; monitor related international and European developments and promul
6、gate them in the UK. Summary of pages This document comprises a front cover, an inside front cover, the ISO title page, pages ii and iii, a blank page, pages 1 and 2, an inside back cover and a back cover. The BSI copyright notice displayed in this document indicates when the document was last issue
7、d. Amendments issued since publication Amd. No. Date Comments Reference number ISO 20859:2005(E)INTERNATIONAL STANDARD ISO 20859 First edition 2005-06-15 Cinematography Spectral response of photographic audio reproducers for analog dye sound tracks on 35 mm film Cinmatographie Rponse spectrale de le
8、cteurs audio avec des pistes sonores analogiques de couleurs sur film de tirage 35 mm BS ISO 20859:2005 ii BS ISO 20859:2005 iii Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing Interna
9、tional Standards is normally carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with
10、ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2. The main task of technical
11、committees is to prepare International Standards. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote. Attention is drawn to t
12、he possibility that some of the elements of this document may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. ISO 20859 was prepared by Technical Committee ISO/TC 36, Cinematography. blank 1 Cinematography Spectral response of photogr
13、aphic audio reproducers for analog dye sound tracks on 35 mm film 1 Scope This International Standard specifies the spectral response of the photographic audio reproducer light source and receptor as a unit, including any optical filtering that can be interposed. The analog sound track formats suita
14、ble for reproduction using such a reproducer include the cyan dye-only track (without redevelopment of silver) and both conventional and “high magenta” soundtracks (with redevelopment of silver). 2 Spectral response 2.1 The peak or maximum response of the combined audio reproducer light source, filt
15、er and receptor shall be 660 nm 20 30 + nm. 2.2 The integrated response of the unit to all wavelengths greater than 800 nm shall be less than 5 % of the total integrated response measured from 400 nm to 800 nm. BS ISO 20859:2005 BS ISO 20859:2005 2 Annex A (informative) Additional data The reproduct
16、ion of analog photographic sound tracks has long employed a tungsten light source and an infrared-sensitive photocell. The light beam is modulated by changes in the infrared energy absorption of the silver sound track image. This practice dates from black and white practice. When colour release prin
17、ts were introduced, the practice of redeveloping a silver sound track, which consists of silver, magenta dye and cyan dye, was employed in order to maintain compatibility with all existing infrared-sensitive reproducers fitted to projectors. A change to dye-only sound tracks is taking place in order
18、 to provide environmental and other benefits. The elimination of the need for silver sound track redevelopment will allow a simplification of the colour positive process with savings in the use of hazardous chemicals and water. Discontinuation of silver redevelopment in release prints will eliminate
19、 the discharge of silver into the environment because, when used, release prints are ultimately destroyed. The red-sensitive sound reproducers required for dye tracks employ solid-state light emitting diodes (LED) or lasers with a longer lifetime than tungsten lamps, providing increased reliability
20、of sound reproduction in theatres. The conversion of sound reproducers from infrared-sensitive devices (for silver sound tracks) to red-sensitive devices (for cyan dye sound tracks) requires an intermediate sound track format called “high magenta”. The “high magenta” sound track eliminates the cyan
21、dye from the silver sound track, thus making the transmission level from 600 nm to 1 000 nm almost equal. This almost equal transmission range produces good sound quality, including cancellation of cross-modulation distortion, for infrared-sensitive readers and all types of red-sensitive readers. A
22、dye-only soundtrack needs to use the dye density to modulate the scanning beam. Unlike the silver density that exists at all wavelengths, the cyan dye in film does not have sufficient density to modulate the scanning beam at wavelengths of less than 600 nm and at wavelengths of greater than 750 nm.
23、Reading the cyan dye-only soundtrack too far away from its wavelength of maximum absorption will cause degradation of sound quality (higher cross-modulation distortion, lower high-frequency response and lower signal-to-noise ratio). The purpose of limiting the spectral response of the audio reproduc
24、er is to use advantageously the absorption of the cyan dye image to modulate the scanning beam and to maintain the maximum sound quality of which the cyan dye record is capable. blankBS ISO 20859:2005 BSI 389 Chiswick High Road London W4 4AL BSI British Standards Institution BSI is the independent n
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