ISO 9848:2003
(Main)Photography — Source document microfilms — Determination of ISO speed and ISO average gradient
Photography — Source document microfilms — Determination of ISO speed and ISO average gradient
ISO 9848:2003 specifies a method for determining the ISO speed and ISO average gradient of black-and-white camera negative photographic films used for first generation microfilming of source documents at exposure times typically found with tungsten sources. These source documents include any handwritten or printed alphanumeric and line documents such as books, periodicals, business correspondence, and engineering drawings. The value-rating system described in this ISO 9848:2003 is only useful to the consumer if his exposure illumination is from an incandescent tungsten source. It is not intended to include pictorial or continuous tone reproduction, computer output microfilm (COM), reversal processed or direct positive films or other films exposed by non-tungsten sources such as laser or cathode ray tube. The ISO speed and ISO average gradient values obtained by applying this ISO 9848:2003 are intended for practical use in comparing film/process combinations and for computing exposures.
Photographie — Microfilms de prises de vue — Détermination de la sensibilité ISO et du contraste moyen ISO
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Standards Content (Sample)
INTERNATIONAL ISO
STANDARD 9848
Second edition
2003-12-01
Photography — Source document
microfilms — Determination of ISO speed
and ISO average gradient
Photographie — Microfilms de prises de vue — Détermination de la
sensibilité ISO et du contraste moyen ISO
Reference number
ISO 9848:2003(E)
©
ISO 2003
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ISO 9848:2003(E)
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ii © ISO 2003 — All rights reserved
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ISO 9848:2003(E)
Contents Page
Foreword. iv
Introduction . v
1 Scope. 1
2 Normative references . 1
3 Terms and definitions. 1
4 Sampling and storage. 2
5 Test method. 2
5.1 Principle . 2
5.2 Safelights . 2
5.3 Exposure. 2
5.4 Processing. 4
5.5 Densitometry . 4
5.6 Evaluation . 4
6 Product classification. 5
6.1 ISO speed. 5
6.2 ISO average gradient . 5
6.3 Accuracy . 7
7 Product marking and labelling. 7
7.1 Speed. 7
7.2 Average gradient. 7
7.3 General. 7
Annex A (informative) Use of ISO speed values. 8
Bibliography . 9
© ISO 2003 — All rights reserved iii
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ISO 9848:2003(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 2.
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 document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 9848 was prepared by Technical Committee ISO/TC 42, Photography.
This second edition cancels and replaces the first edition (ISO 9848:1993), which has been technically revised.
iv © ISO 2003 — All rights reserved
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ISO 9848:2003(E)
Introduction
This International Standard describes the method for determining the ISO speed and ISO average gradient of
camera negative microfilms exposed with an incandescent tungsten source at a distribution temperature of
2 650 K ± 100 K (to simulate “undervolted” photoflood).
The ISO speed and ISO average gradient determined by applying this International Standard are for
film/process systems, not just the film alone. The sensitometric characteristics of microfilm are dependent on
the process conditions (developer, time, temperature, agitation, etc.) and some films will provide satisfactory
results only in specific processes. Therefore, process conditions are not specified in this International
Standard. They should be specified when the sensitometric values are quoted in manufacturer's literature to
enable proper interpretation.
Because of “reciprocity law failure”, it is desirable to specify the exposure time used when quoting ISO speed
and ISO average gradient values to ensure proper interpretation. Source document microfilming cameras do
not have a “standard” exposure time. The exposure time used in evaluating the sensitometric characteristics
of the film should be the same as that for which the film is intended to be used. The alternative of using only
one exposure time in this International Standard could be misleading if the film produces other results at its
“end use” exposure time. If the film is used in a variety of applications, speed and contrast values at a range of
exposure times may be helpful to the user. Typical light sources for microfilms include tungsten, xenon and
fluorescent. Since xenon and fluorescent sources are not yet standardized they are not included in this
International Standard, but will be incorporated in the document when standardized. Due to spectral output
differences, ISO values determined by using tungsten sensitometric exposure cannot be used for applications
where fluorescent or xenon illumination are used.
The effective density of film images depends on the geometry of the optical system in which they are used.
Many source document microfilms are used as “masters” for producing copies by contact printing, thereby
requiring diffuse density measurements. When film is viewed on a microfilm “reader”, projection densitometry
is more appropriate. Since the more critical end use is the former, this International Standard specifies diffuse
density.
Spectral conditions of the density measurement must also be specified. Printing density characteristics are
dependent upon the spectral sensitivity of the print film chosen for use as well as the spectral energy
distribution of the printing light source. These parameters are determined by “end use” system requirements.
Since no standard printing conditions have been agreed to or defined in this document, the use of printing
density is precluded and visual density measurements will, therefore, be used as a compromise.
The speed point density (1,20 above minimum density) was selected as a compromise of the proper image
background densities. Since microfilms have medium to high average gradients, exposure latitude is rather
narrow. Thus, the speed value should be considered “approximate” and used only as a guide for initial testing.
For critical work, the final exposure should be determined by testing the film over a range of exposures and
the optimum chosen. A measurement of contrast is provided by the average gradient which relates the line
density to the background density. This measurement correlates with the visual appearance of the recorded
image and should aid users in selecting the best film for their application. This International Standard is
concerned primarily with the evaluation of a few characteristics of source document microfilms that are
especially important in using the product. Therefore, the test method, sensitometric criteria and sampling
procedures can prove inadequate for controlling quality in a film manufacturing operation. Since speed and
contrast vary greatly depending on exposure time, illuminant quality and process conditions, it is important for
the user to consult the film manufacturer regarding the film and sensitometric characteristics that fit their
application.
© ISO 2003 — All rights reserved v
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INTERNATIONAL STANDARD ISO 9848:2003(E)
Photography — Source document microfilms — Determination
of ISO speed and ISO average gradient
1 Scope
This International Standard specifies a method for determining the ISO speed and ISO average gradient of
black-and-white camera negative photographic films used for first generation microfilming of source
documents at exposure times typically found with tungsten sources. These source documents include any
handwritten or printed alphanumeric and line documents such as books, periodicals, business
correspondence, and engineering drawings. The value-rating system described in this International Standard
is only useful to the consumer if his exposure illumination is from an incandescent tungsten source as
described in 5.3.3. It is not intended to include pictorial or continuous tone reproduction, computer output
microfilm (COM), reversal processed or direct positive films or other films exposed by non-tungsten sources
such as laser or cathode ray tube.
The ISO speed and ISO average gradient values obtained by applying this International Standard are
intended for practical use in comparing film/process combinations and for computing exposures.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
ISO 5-2, Photography — Density measurements — Part 2: Geometric conditions for transmission density
ISO 5-3, Photography — Density measurements — Part 3: Spectral conditions
ISO 554, Standard atmospheres for conditioning and/or testing — Specifications
ISO 6728, Photography — Camera lenses — Determination of ISO colour contribution index (ISO/CCI)
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
speed
quantitative measure of the response of the photographic material to radiant energy for the specified
conditions of exposure, processing, density measurement and analysis
3.2
exposure
H
time integral of illuminance measured on the plane of the film surface
[3]
NOTE 1 In the International lighting vocabulary , H is defined as the luminous exposure. In this International Standard,
“luminous exposure” is simply referred to as “exposure”.
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