ISO 7589:2002
(Main)Photography — Illuminants for sensitometry — Specifications for daylight, incandescent tungsten and printer
Photography — Illuminants for sensitometry — Specifications for daylight, incandescent tungsten and printer
This International Standard specifies the spectral characteristics of illuminants for sensitometry appropriate for evaluating camera films used for pictorial photography in natural daylight, studio tungsten and photoflood, including colour and black-and-white films, both reversal and negative types, and for evaluating black-and-white papers used with incandescent tungsten printers. It also describes methods for evaluating the acceptability of illuminants for sensitometry and specifies tolerances. It does not include illuminants for use with colour papers, since this would need to take account of the coloured mask of the negative material, for which no standard information is at present available.
Photographie — Illuminants sensitométriques — Spécifications pour la lumière du jour, la lumière artificielle et la tireuse
Photography - Illuminants for sensitometry - Specifications for daylight, incandescent tungsten and printer
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INTERNATIONAL ISO
STANDARD 7589
Second edition
2002-02-01
Photography — Illuminants for
sensitometry — Specifications for daylight,
incandescent tungsten and printer
Photographie — Illuminants sensitométriques — Spécifications pour la
lumière du jour, la lumière artificielle et la tireuse
Reference number
ISO 7589:2002(E)
©
ISO 2002
---------------------- Page: 1 ----------------------
ISO 7589:2002(E)
PDF disclaimer
This PDF file may contain embedded typefaces. In accordance with Adobe's licensing policy, this file may be printed or viewed but shall not
be edited unless the typefaces which are embedded are licensed to and installed on the computer performing the editing. In downloading this
file, parties accept therein the responsibility of not infringing Adobe's licensing policy. The ISO Central Secretariat accepts no liability in this
area.
Adobe is a trademark of Adobe Systems Incorporated.
Details of the software products used to create this PDF file can be found in the General Info relative to the file; the PDF-creation parameters
were optimized for printing. Every care has been taken to ensure that the file is suitable for use by ISO member bodies. In the unlikely event
that a problem relating to it is found, please inform the Central Secretariat at the address given below.
© ISO 2002
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic
or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or ISO's member body
in the country of the requester.
ISO copyright office
Case postale 56 • CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail copyright@iso.ch
Web www.iso.ch
Printed in Switzerland
ii © ISO 2002 – All rights reserved
---------------------- Page: 2 ----------------------
ISO 7589:2002(E)
Contents Page
Foreword.iv
Introduction.v
1 Scope .1
2 Normative references.1
3 Terms and definitions .1
4 ISO sensitometric illuminants .2
4.1 General.2
4.2 ISO sensitometric daylight illuminant .2
4.3 ISO sensitometric studio tungsten illuminant.3
4.4 ISO sensitometric photoflood illuminant .3
4.5 ISO sensitometric printer illuminant.3
5 Camera films: Spectral distribution index (ISO/SDI).3
5.1 General.3
5.2 Weighted spectral sensitivity values.3
5.3 Calculation of the ISO/SDI .3
5.4 Tolerances for ISO/SDI.4
6 Black-and-white papers: Spectral distribution index (ISO/SDI).4
6.1 General.4
6.2 Weighted spectral sensitivity values.4
6.3 Calculation of the ISO/SDI .4
6.4 Tolerances for ISO/SDI.5
Annex A (informative) Example sources .9
Annex B (informative) Exposure calculations.12
Annex C (informative) Average colour film sensitivities.13
Annex D (informative) Average black-and-white printing paper sensitivities .14
Bibliography.15
© ISO 2002 – All rights reserved iii
---------------------- Page: 3 ----------------------
ISO 7589:2002(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO
member bodies). The work of preparing International 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 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 3.
The main task of technical 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 the possibility that some of the elements of this International Standard may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 7589 was prepared by Technical Committee ISO/TC 42, Photography.
This second edition cancels and replaces the first edition (ISO 7589:1984), which has been technically revised and
enlarged to include a standard sensitometric illuminant for black-and-white papers.
Annexes A to D of this International Standard are for information only.
iv © ISO 2002 – All rights reserved
---------------------- Page: 4 ----------------------
ISO 7589:2002(E)
Introduction
Colour and black-and-white camera films are most commonly designed for use with three light sources, these being
daylight, studio tungsten (type B) and photoflood (type A), while black-and-white papers are most commonly used
with enlargers employing incandescent tungsten sources. This International Standard specifies three corresponding
illuminants for film sensitometry and one for black-and-white paper sensitometry, since most meaningful results are
obtained when exposing conditions match those of actual film or paper use. Two other important photographic light
sources for film, the electronic flashtube and blue photoflash lamps, give light of a colour that approximates daylight
so that the sensitometric daylight illuminant also serves for films used with them.
This International Standard constitutes a revision of the first edition, ISO 7589:1984. It differs from the first edition
in that it includes a standard sensitometric illuminant for black-and-white papers (the first edition dealt with camera
film illuminants only). No standard exists for the determination of the speeds of colour papers.
The illuminants described in this International Standard are used in ISO 3028, ISO 6728 and other International
Standards which describe methods for determining the speed of various types of sensitized products.
© ISO 2002 – All rights reserved v
---------------------- Page: 5 ----------------------
INTERNATIONAL STANDARD ISO 7589:2002(E)
Photography — Illuminants for sensitometry — Specifications for
daylight, incandescent tungsten and printer
1 Scope
This International Standard specifies the spectral characteristics of illuminants for sensitometry appropriate for
evaluating camera films used for pictorial photography in natural daylight, studio tungsten and photoflood, including
colour and black-and-white films, both reversal and negative types, and for evaluating black-and-white papers used
with incandescent tungsten printers. It also describes methods for evaluating the acceptability of illuminants for
sensitometry and specifies tolerances.
It does not include illuminants for use with colour papers, since this would need to take account of the coloured
mask of the negative material, for which no standard information is at present available.
2 Normative references
The following normative documents contain provisions which, through reference in this text, constitute provisions of
this International Standard. For dated references, subsequent amendments to, or revisions of, any of these
publications do not apply. However, parties to agreements based on this International Standard are encouraged to
investigate the possibility of applying the most recent editions of the normative documents indicated below. For
undated references, the latest edition of the normative document referred to applies. Members of ISO and IEC
maintain registers of currently valid International Standards.
ISO 3028:1984, Photography — Camera flash illuminants — Determination of ISO spectral distribution index
(ISO/SDI)
ISO 6728:1983, Photography — Camera lenses — Determination of ISO colour contribution index (ISO/CCI)
3 Terms and definitions
For the purposes of this International Standard, the following terms and definitions apply.
3.1
source
physical emitter of energy
3.2
illuminant
light impinging on a sensitized material and having a specific spectral power distribution not necessarily provided
directly by a source and not necessarily realizable by a source
3.3
relative spectral power distribution
description of the spectral character of radiation by the relative spectral distribution of some radiometric quantity
(radiant flux, radiant intensity)
© ISO 2002 – All rights reserved 1
---------------------- Page: 6 ----------------------
ISO 7589:2002(E)
3.4
distribution temperature
thermodynamic temperature of the full radiator for which the ordinates of the spectral distribution curve of its
radiance are proportional, in the visible region, to those of the distribution curve of the radiation considered
3.5
photographic daylight
relative spectral power distribution of typical daylight having a correlated colour temperature of approximately
5 500 K
NOTE This describes the combination of skylight and sunlight when the sun is about 40° above the horizon with a clear
atmosphere, and is designated as D .
55
3.6
spectral distribution index
SDI
three-number designation for camera films which describes the degree to which a light source is expected to
change the overall colour of a photograph relative to that obtained with a specified illuminant, and two-number
designation for black-and-white enlarging papers which describes the degree to which a light source affects the
relative contributions from emulsion sensitivity and dye sensitivity
4 ISO sensitometric illuminants
4.1 General
This International Standard is concerned with the simulation of the spectral quality of radiation incident on the film
(not the camera) or on the enlarger baseboard (not the enlarger lamp).
In order to realize this simulation, a given photographic illuminant (which is concerned with the light illuminating the
subject matter or the light before passing through the optical system of a printer) has to be suitably modulated. For
the purposes of this International Standard, the ISO standard camera lens specified in ISO 6728 has been taken as
the best available modulator for which standard data are available.
The relative spectral power distributions of the four ISO sensitometric illuminants described in this International
Standard are normally obtained by operating a lamp at a specified condition and modulating the flux with
selectively absorbing filters of suitable spectral transmittance. It should be emphasized that this International
Standard specifies the relative spectral distribution of power incident on the exposure plane at 10 nm intervals, i.e.
the relative spectral power emitted by a source and its modulation by all elements in the sensitometer that affect
the spectral quality, for example filters, mirrors and optical wedge.
4.2 ISO sensitometric daylight illuminant
This is suitable for the sensitometry of “daylight balanced” colour films and is also normally used for black-and-
white camera films. These films are designed to be exposed in photographic daylight (see 3.5) or with flash. The
[4]
spectral power distribution used to represent photographic daylight was taken from the data of Judd et al. who
give typical spectral irradiance data for five different conditions of daylight (skylight and sunlight plus skylight). Data
corresponding to a correlated colour temperature of 5 500 K were selected as the most appropriate for
photography and designated as D . This is the prevailing condition in temperate zones during the daylight hours
55
recommended for colour photography.
The ISO sensitometric daylight illuminant is defined as the product of the spectral power distribution of
photographic daylight (D ) and the spectral transmittance of the International Standard camera lens, τλ . The
( )
55
aim values, S , for the relative spectral power distribution for this illuminant are given in Table 1. An illuminant
λ
complying with these values within the tolerances specified in 5.4 may be designated “ISO sensitometric daylight
illuminant”.
2 © ISO 2002 – All rights reserved
---------------------- Page: 7 ----------------------
ISO 7589:2002(E)
4.3 ISO sensitometric studio tungsten illuminant
This is suitable for the sensitometry of type B colour films which are normally exposed with lamps described as
3 200 K lamps. However, the effect of lamp age, reflectors, diffusers and general studio conditions is to reduce the
average effective distribution temperature to about 3 050 K. The spectral power distribution used to represent
studio tungsten was obtained by spectroradiometric measurements in several professional photographic studios.
The aim values, S , for the relative spectral power distribution for this source after modulation by the ISO standard
λ
lens are given in Table 2. An illuminant complying with these values within the tolerances specified in 5.4 may be
designated “ISO sensitometric studio tungsten illuminant”.
4.4 ISO sensitometric photoflood illuminant
This illuminant is suitable for the sensitometry of type A colour films. The spectral power distribution used to
represent photoflood lamps is that of a black body at 3 400 K. The aim values, S , for the relative spectral power
λ
distribution of this source after modulation by the ISO standard lens are given in Table 3. An illuminant complying
with these values within the tolerances specified in 5.4 may be designated “ISO sensitometric photoflood
illuminant”.
4.5 ISO sensitometric printer illuminant
This illuminant is suitable for the sensitometry of black-and-white continuous-tone papers. The spectral power
distribution used to represent typical printers is that of a studio tungsten source modified by the ISO standard lens
as specified in ISO 6728 and a typical diffusing screen. The aim values, S , for the relative spectral power
λ
distribution of this illuminant are given in Table 4. An illuminant complying with these values within the tolerances
specified in 6.4 may be designated “ISO sensitometric printer illuminant.”
5 Camera films: Spectral distribution index (ISO/SDI)
5.1 General
The spectral distribution index for camera films is a three-number designation which describes how well a film
illuminant matches a specified spectral power distribution in terms of the total photographic responses of the three
component emulsions of average colour films. In this International Standard, three different distributions are
involved. ISO 3028 gives a more complete description of SDI.
NOTE Other colour imaging systems may exhibit weighted spectral sensitivities similar to those listed in Table 1, 2 or 3. In
such a case, the relevant table can be used to calculate SDI values which will estimate illuminant performance.
5.2 Weighted spectral sensitivity values
Weighted spectral sensitivity values for use in evaluating candidate illuminants for acceptability are given in
Tables 1, 2 and 3. These values have been weighted so that the aim relative spectral power values for the ISO
illuminant in the same table will yield an ISO/SDI of 0/0/0.
5.3 Calculation of the ISO/SDI
The relative spectral power values of a candidate illuminant need to be determined at 10 nm intervals. These
values, S , are multiplied by the appropriate blue, green and red weighted spectral sensitivity values W(λ). For
λ
example, to determine if the illuminant is satisfactory for sensitometric daylight, the weighted spectral sensitivity
values in Table 1 would be used. The total photographic responses, R , R and R are obtained by summation
B G R
R = ΣW(λ)S . Logarithms to the base 10 of the total response values are determined to two decimal places. The
λ
smallest element of this three-number designation is made equal to zero by subtracting it from all three log
10
values. The decimal is eliminated by multiplying by 100. The resultant three numbers are the ISO/SDI for the
candidate illuminant. The above calculations are illustrated in Table A.1 for a candidate ISO sensitometric daylight
illuminant.
© ISO 2002 – All rights reserved 3
---------------------- Page: 8 ----------------------
ISO 7589:2002(E)
5.4 Tolerances for ISO/SDI
To meet the requirements of this International Standard, the red index shall not differ from the green index by more
than ± 3, and the blue index shall not differ from the green index by more
...
SLOVENSKI STANDARD
SIST ISO 7589:2004
01-december-2004
Photography - Illuminants for sensitometry - Specifications for daylight,
incandescent tungsten and printer
Photography -- Illuminants for sensitometry -- Specifications for daylight, incandescent
tungsten and printer
Photographie -- Illuminants sensitométriques -- Spécifications pour la lumière du jour, la
lumière artificielle et la tireuse
Ta slovenski standard je istoveten z: ISO 7589:2002
ICS:
37.040.10 Fotografska oprema. Photographic equipment.
Projektorji Projectors
SIST ISO 7589:2004 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
---------------------- Page: 1 ----------------------
SIST ISO 7589:2004
---------------------- Page: 2 ----------------------
SIST ISO 7589:2004
INTERNATIONAL ISO
STANDARD 7589
Second edition
2002-02-01
Photography — Illuminants for
sensitometry — Specifications for daylight,
incandescent tungsten and printer
Photographie — Illuminants sensitométriques — Spécifications pour la
lumière du jour, la lumière artificielle et la tireuse
Reference number
ISO 7589:2002(E)
©
ISO 2002
---------------------- Page: 3 ----------------------
SIST ISO 7589:2004
ISO 7589:2002(E)
PDF disclaimer
This PDF file may contain embedded typefaces. In accordance with Adobe's licensing policy, this file may be printed or viewed but shall not
be edited unless the typefaces which are embedded are licensed to and installed on the computer performing the editing. In downloading this
file, parties accept therein the responsibility of not infringing Adobe's licensing policy. The ISO Central Secretariat accepts no liability in this
area.
Adobe is a trademark of Adobe Systems Incorporated.
Details of the software products used to create this PDF file can be found in the General Info relative to the file; the PDF-creation parameters
were optimized for printing. Every care has been taken to ensure that the file is suitable for use by ISO member bodies. In the unlikely event
that a problem relating to it is found, please inform the Central Secretariat at the address given below.
© ISO 2002
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic
or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or ISO's member body
in the country of the requester.
ISO copyright office
Case postale 56 • CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail copyright@iso.ch
Web www.iso.ch
Printed in Switzerland
ii © ISO 2002 – All rights reserved
---------------------- Page: 4 ----------------------
SIST ISO 7589:2004
ISO 7589:2002(E)
Contents Page
Foreword.iv
Introduction.v
1 Scope .1
2 Normative references.1
3 Terms and definitions .1
4 ISO sensitometric illuminants .2
4.1 General.2
4.2 ISO sensitometric daylight illuminant .2
4.3 ISO sensitometric studio tungsten illuminant.3
4.4 ISO sensitometric photoflood illuminant .3
4.5 ISO sensitometric printer illuminant.3
5 Camera films: Spectral distribution index (ISO/SDI).3
5.1 General.3
5.2 Weighted spectral sensitivity values.3
5.3 Calculation of the ISO/SDI .3
5.4 Tolerances for ISO/SDI.4
6 Black-and-white papers: Spectral distribution index (ISO/SDI).4
6.1 General.4
6.2 Weighted spectral sensitivity values.4
6.3 Calculation of the ISO/SDI .4
6.4 Tolerances for ISO/SDI.5
Annex A (informative) Example sources .9
Annex B (informative) Exposure calculations.12
Annex C (informative) Average colour film sensitivities.13
Annex D (informative) Average black-and-white printing paper sensitivities .14
Bibliography.15
© ISO 2002 – All rights reserved iii
---------------------- Page: 5 ----------------------
SIST ISO 7589:2004
ISO 7589:2002(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO
member bodies). The work of preparing International 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 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 3.
The main task of technical 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 the possibility that some of the elements of this International Standard may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 7589 was prepared by Technical Committee ISO/TC 42, Photography.
This second edition cancels and replaces the first edition (ISO 7589:1984), which has been technically revised and
enlarged to include a standard sensitometric illuminant for black-and-white papers.
Annexes A to D of this International Standard are for information only.
iv © ISO 2002 – All rights reserved
---------------------- Page: 6 ----------------------
SIST ISO 7589:2004
ISO 7589:2002(E)
Introduction
Colour and black-and-white camera films are most commonly designed for use with three light sources, these being
daylight, studio tungsten (type B) and photoflood (type A), while black-and-white papers are most commonly used
with enlargers employing incandescent tungsten sources. This International Standard specifies three corresponding
illuminants for film sensitometry and one for black-and-white paper sensitometry, since most meaningful results are
obtained when exposing conditions match those of actual film or paper use. Two other important photographic light
sources for film, the electronic flashtube and blue photoflash lamps, give light of a colour that approximates daylight
so that the sensitometric daylight illuminant also serves for films used with them.
This International Standard constitutes a revision of the first edition, ISO 7589:1984. It differs from the first edition
in that it includes a standard sensitometric illuminant for black-and-white papers (the first edition dealt with camera
film illuminants only). No standard exists for the determination of the speeds of colour papers.
The illuminants described in this International Standard are used in ISO 3028, ISO 6728 and other International
Standards which describe methods for determining the speed of various types of sensitized products.
© ISO 2002 – All rights reserved v
---------------------- Page: 7 ----------------------
SIST ISO 7589:2004
---------------------- Page: 8 ----------------------
SIST ISO 7589:2004
INTERNATIONAL STANDARD ISO 7589:2002(E)
Photography — Illuminants for sensitometry — Specifications for
daylight, incandescent tungsten and printer
1 Scope
This International Standard specifies the spectral characteristics of illuminants for sensitometry appropriate for
evaluating camera films used for pictorial photography in natural daylight, studio tungsten and photoflood, including
colour and black-and-white films, both reversal and negative types, and for evaluating black-and-white papers used
with incandescent tungsten printers. It also describes methods for evaluating the acceptability of illuminants for
sensitometry and specifies tolerances.
It does not include illuminants for use with colour papers, since this would need to take account of the coloured
mask of the negative material, for which no standard information is at present available.
2 Normative references
The following normative documents contain provisions which, through reference in this text, constitute provisions of
this International Standard. For dated references, subsequent amendments to, or revisions of, any of these
publications do not apply. However, parties to agreements based on this International Standard are encouraged to
investigate the possibility of applying the most recent editions of the normative documents indicated below. For
undated references, the latest edition of the normative document referred to applies. Members of ISO and IEC
maintain registers of currently valid International Standards.
ISO 3028:1984, Photography — Camera flash illuminants — Determination of ISO spectral distribution index
(ISO/SDI)
ISO 6728:1983, Photography — Camera lenses — Determination of ISO colour contribution index (ISO/CCI)
3 Terms and definitions
For the purposes of this International Standard, the following terms and definitions apply.
3.1
source
physical emitter of energy
3.2
illuminant
light impinging on a sensitized material and having a specific spectral power distribution not necessarily provided
directly by a source and not necessarily realizable by a source
3.3
relative spectral power distribution
description of the spectral character of radiation by the relative spectral distribution of some radiometric quantity
(radiant flux, radiant intensity)
© ISO 2002 – All rights reserved 1
---------------------- Page: 9 ----------------------
SIST ISO 7589:2004
ISO 7589:2002(E)
3.4
distribution temperature
thermodynamic temperature of the full radiator for which the ordinates of the spectral distribution curve of its
radiance are proportional, in the visible region, to those of the distribution curve of the radiation considered
3.5
photographic daylight
relative spectral power distribution of typical daylight having a correlated colour temperature of approximately
5 500 K
NOTE This describes the combination of skylight and sunlight when the sun is about 40° above the horizon with a clear
atmosphere, and is designated as D .
55
3.6
spectral distribution index
SDI
three-number designation for camera films which describes the degree to which a light source is expected to
change the overall colour of a photograph relative to that obtained with a specified illuminant, and two-number
designation for black-and-white enlarging papers which describes the degree to which a light source affects the
relative contributions from emulsion sensitivity and dye sensitivity
4 ISO sensitometric illuminants
4.1 General
This International Standard is concerned with the simulation of the spectral quality of radiation incident on the film
(not the camera) or on the enlarger baseboard (not the enlarger lamp).
In order to realize this simulation, a given photographic illuminant (which is concerned with the light illuminating the
subject matter or the light before passing through the optical system of a printer) has to be suitably modulated. For
the purposes of this International Standard, the ISO standard camera lens specified in ISO 6728 has been taken as
the best available modulator for which standard data are available.
The relative spectral power distributions of the four ISO sensitometric illuminants described in this International
Standard are normally obtained by operating a lamp at a specified condition and modulating the flux with
selectively absorbing filters of suitable spectral transmittance. It should be emphasized that this International
Standard specifies the relative spectral distribution of power incident on the exposure plane at 10 nm intervals, i.e.
the relative spectral power emitted by a source and its modulation by all elements in the sensitometer that affect
the spectral quality, for example filters, mirrors and optical wedge.
4.2 ISO sensitometric daylight illuminant
This is suitable for the sensitometry of “daylight balanced” colour films and is also normally used for black-and-
white camera films. These films are designed to be exposed in photographic daylight (see 3.5) or with flash. The
[4]
spectral power distribution used to represent photographic daylight was taken from the data of Judd et al. who
give typical spectral irradiance data for five different conditions of daylight (skylight and sunlight plus skylight). Data
corresponding to a correlated colour temperature of 5 500 K were selected as the most appropriate for
photography and designated as D . This is the prevailing condition in temperate zones during the daylight hours
55
recommended for colour photography.
The ISO sensitometric daylight illuminant is defined as the product of the spectral power distribution of
photographic daylight (D ) and the spectral transmittance of the International Standard camera lens, τλ . The
( )
55
aim values, S , for the relative spectral power distribution for this illuminant are given in Table 1. An illuminant
λ
complying with these values within the tolerances specified in 5.4 may be designated “ISO sensitometric daylight
illuminant”.
2 © ISO 2002 – All rights reserved
---------------------- Page: 10 ----------------------
SIST ISO 7589:2004
ISO 7589:2002(E)
4.3 ISO sensitometric studio tungsten illuminant
This is suitable for the sensitometry of type B colour films which are normally exposed with lamps described as
3 200 K lamps. However, the effect of lamp age, reflectors, diffusers and general studio conditions is to reduce the
average effective distribution temperature to about 3 050 K. The spectral power distribution used to represent
studio tungsten was obtained by spectroradiometric measurements in several professional photographic studios.
The aim values, S , for the relative spectral power distribution for this source after modulation by the ISO standard
λ
lens are given in Table 2. An illuminant complying with these values within the tolerances specified in 5.4 may be
designated “ISO sensitometric studio tungsten illuminant”.
4.4 ISO sensitometric photoflood illuminant
This illuminant is suitable for the sensitometry of type A colour films. The spectral power distribution used to
represent photoflood lamps is that of a black body at 3 400 K. The aim values, S , for the relative spectral power
λ
distribution of this source after modulation by the ISO standard lens are given in Table 3. An illuminant complying
with these values within the tolerances specified in 5.4 may be designated “ISO sensitometric photoflood
illuminant”.
4.5 ISO sensitometric printer illuminant
This illuminant is suitable for the sensitometry of black-and-white continuous-tone papers. The spectral power
distribution used to represent typical printers is that of a studio tungsten source modified by the ISO standard lens
as specified in ISO 6728 and a typical diffusing screen. The aim values, S , for the relative spectral power
λ
distribution of this illuminant are given in Table 4. An illuminant complying with these values within the tolerances
specified in 6.4 may be designated “ISO sensitometric printer illuminant.”
5 Camera films: Spectral distribution index (ISO/SDI)
5.1 General
The spectral distribution index for camera films is a three-number designation which describes how well a film
illuminant matches a specified spectral power distribution in terms of the total photographic responses of the three
component emulsions of average colour films. In this International Standard, three different distributions are
involved. ISO 3028 gives a more complete description of SDI.
NOTE Other colour imaging systems may exhibit weighted spectral sensitivities similar to those listed in Table 1, 2 or 3. In
such a case, the relevant table can be used to calculate SDI values which will estimate illuminant performance.
5.2 Weighted spectral sensitivity values
Weighted spectral sensitivity values for use in evaluating candidate illuminants for acceptability are given in
Tables 1, 2 and 3. These values have been weighted so that the aim relative spectral power values for the ISO
illuminant in the same table will yield an ISO/SDI of 0/0/0.
5.3 Calculation of the ISO/SDI
The relative spectral power values of a candidate illuminant need to be determined at 10 nm intervals. These
values, S , are multiplied by the appropriate blue, green and red weighted spectral sensitivity values W(λ). For
λ
example, to determine if the illuminant is satisfactory for sensitometric daylight, the weighted spectral sensitivity
values in Table 1 would be used. The total photographic responses, R , R and R are obtained by summation
B G R
R = ΣW(λ)S . Logarithms to the base 10 of the total response values are determined to two decimal places. The
λ
smallest element of this three-number designation is made equal to zero by subtracting it from all three log
10
values. The decimal is eliminated by multiplying by 100. The resultant three numbers are the ISO
...
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