ISO 7187:1995

INTERNATIONAL ISO
7187
STANDARD
Second edition
1995-12-15
Materials for direct-positive
Photography -
colour-print cameras - Determination of
ISO Speed
Photographie - Surfaces sensibles pour appareils pho tographiques
donnant directement une epreuve positive en couleur - Determination de
Ia sensibilite ISO
Reference number
ISO 7187:1995(E)

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ISO 7187:1995(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. Esch 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.
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.
International Standard ISO 7187 was prepared by Technical Committee
ISOnC 42, Photography.
This second edition cancels and replaces the first edition
which has been technically revised to include several
(ISO 7187:1983),
new definitions (clause 3) and a distinction between Speed, ISO Speed and
ISO Speed of a product (clause 6).
Annex A of this International Standard is for information only.
0 ISO 1995
All rights reserved. Unless otherwise specified, no part of this publication may be
reproduced or utilized in any form or by any means, electronie or mechanical, including
photocopying and microfilm, without Permission in writing from the publisher.
International Organization for Standardization
Case Postale 56 l CH-l 21 “l Geneve 20 l Switzerland
Printed in Switzerland
ii

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@ ISO ISO 7187:1995(E)
Introduction
The increased use of in-Camera processed colour-print materials, often
referred to as “instant print ”, and the introduction of equipment to permit
their use in general cameras makes it desirable to establish a Standard
method for determining the Speed of this type of product. This Inter-
national Standard applies to any directly viewed reflection colour-print
material made by Camera exposure of the original Scene onto a photo-
sensitive material and subsequent diffusion transfer of a dye image within
the same material or to a second receiver material. lt also applies to any
material similarly exposed, but later processed outside of the Camera by a
process other than diffusion transfer of the dyed image. lt does not apply
to copying or duplicating.
For diffusion-transfer materials, the Speed and colour of prints depend on
the ambient temperature during diffusion. Usually, Speed Problems as well
as serious colour mismatches will occur in prints made at temperatures
beyond the range recommended by the manufacturer. The conditions of
direct viewing of reflection prints are specified in ISO 3664.
The sensitometric method specified in this International Standard gives
ISO Speeds that are in close agreement with film Speeds obtained by
making practical Camera exposures. These Speeds follow the f/16 daylight
rule; that is, the ISO Speed is the reciprocal of the exposure time, in
seconds, which gives the best quality print when the Camera lens aperture
is set at fl16 in direct sunlight for an average front-lighted Scene with a
solar altitude between 35O and 50 ”.
When these ISO Speeds are used in conjunction with exposure meters
conforming to ISO 2720, resultant pictures will be of Optimum exposure.
For an average Scene, the Optimum exposure will be approximately
midway between the least exposure and the greatest exposure producing
satisfactory prints at normal viewing illuminance levels. The exposure
latitude for satisfactory prints is approximately one half stop for under-
exposure and one half stop for overexposure.

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ISO 7187:1995(E)
INTERNATIONAL STANDARD @ ISO
Materials for direct-positive colour-print
Photography -
cameras - Determination of ISO Speed
3 Definitions
1 Scope
For the purposes of this International Standard, the
This International Standard specifies a method for de-
following definitions apply.
termining the ISO Speed of materials for direct-
positive colour-print cameras when used in a Camera
3.1 exposure, H l): Time integral of the illuminance
for pictorial photography. lt also applies to diffusion-
on the sensitized material, measured in lux seconds.
transfer and conventional colour-print materials di-
rectly exposed in cameras and processed in or out of
Exposure is often expressed in logloH units.
.
the Camera.
3.2 Speed, S: Quantitative measure of the response
This International Standard does not apply to materials
of the photographic material to radiant energy for the
used for copying or duplicating applications.
specified conditions of exposure, processing and im-
age measurement.
3.3 direct-positive processing: Any one-exposure
2 Normative references
photographic process which results in a positive im-
age directly from the original subject matter.
The following Standards contain provisions which,
through reference in this text, constitute provisions of
3.4 diffusion transfer: Photographit process
this International Standard. At the time of publication,
whereby the image moves as a consequence of
the editions indicated were valid. All Standards are
development to a receiving medium to form (usually) a
subject to revision, and Parties to agreements based
positive image for viewing.
on this International Standard are encouraged to
investigate the possibility of applying the most recent 3.5 reversal processing: Photographit process in
editions of the Standards indicated below. Members
which the exposed negative latent image is formed,
of IEC and ISO maintain registers of currently valid
but that, either by uniform post-exposure or by
International Standards. fogging process chemicals, tan be made to yield a
positive reproduction.
ISO 5-3: 1995, Photography - Density measurements
- Part 3: Spectral conditions.
ISO 5-4: 1995, Photography - Density measurements
4 Sampling and storage
- Part 4: Geometrie conditions for reflection density.
In determining the ISO Speed of a product, it is im-
ISO 7589: 1984, Photography - Illuminants for sensi-
portant that the samples evaluated yield the average
tometry - Specifica tions for dayligh t and incan-
results obtained by users. This will require evaluating
descen t tungs ten.
1) CIE Publication No. 17.4 defines “Iuminous exposure, H ”. In this International Standard, “Iuminous exposure” is simply
referred to as “exposure ”.
1

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@ ISO
ISO 7187:1995(E)
light modulator throughout the wavelength interval
several different batches periodically under the con-
from 400 nm to 700 nm shall not exceed 5 % of the
ditions specified in this International Standard. Prior to
average density obtained over the same interval or
evaluation, the samples shall be stored according to
0,03 density, whichever is the greater. In the interval
the manufacturer ’s recommendations for a length of
from 360 nm to 400 nm, ‘l0 % of this same average
time to simulate the average age at which the product
density or 0,06 density, whichever is the greater, shall
is normally used. Several independent evaluations
not be exceeded.
shall be made to ensure the proper calibration of
equipment and processes. The basic objective in sel-
If a stepped modulator is. used, the logarithm to the
ecting and storing samples as described above is to
base 10 of the exposure increment shall not be
ensure that the product charac
...