ISO 6:1993 download free.Photography — Black-and-white pictorial still camera negative film/process systems — Determination of ISO speed.
Introduction
Black-and-white films will generally provide excellent results in several different developers and processing conditions. At the tame time, it is realized that the speed of a film depends on the process used. Therefore. ISO 6 specities a method for determining the photographic speed of filmlprocess cortlbindtiuns. This means a particular film may have several ISO speeds associated with it depending on the pro cosses used. For this reason, it is important that manufacturers indicate the processing conditions for which ISO speed values are quoted.
ISO 6 recognizes that black-and-white films do not generally have a unique speed Il several different processes are recommended. This conflicts with the tradition of associating a specific speed value with a particular product. In the future, the process used for determining speed values should be unequivocally described to avoid misinterpretation. Since users often do not know how these films will be processed, manufacturers have an obligation to pruviiie a speed value for this situation which will ensure good results. Usually they will take ad vantage of the overexposure tonal latitude of the film and give it a conservative speed value to protect users from underexposure effects in case the film Is PUT through a process which yields low speed.
It’S rer.oçJnI7ed that the speed at which a film can be exposed is dependent on the extent of dtveloprnent. scene luminance range, subject matter, printing paper, etc. ISO 6 specifics that film/process speed is determined when the film is processed to obtain a specified contrast level The relative ISO speed ranking of various films in different process systems will generally ditfei, The ISO speeds will provide correct exposures for average scenes with exposure meters con forming to ISO 2720 or ISO 2721 when the film is processed as specified in ISO 6.
ISO 6 specifies the method for determining the ISO speed of black-and-white negative camera films used for pictorial still photography.
ISO 6 applies to films processed in conventional chemicals and equipment, but also to those processed using special procedures such as those involving activators or heat for development
ISO 6 does not apply to motion- picture, aerial photography, graphic arts, radiographic or micrographic applications, nor to negatives produced in diffusion transfer systems.
2 Normative references
The following standards contain provisions which, through reference in this text, constitute provisions of ISO 6. At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on ISO 6 are encouraged to investigate the possibility of applying the most recent editions of the standards indicated below. Members of IC and ISO maintain registers of currently valid International Standards.
ISO 5-2:1991, Photography Density measurements
— Part 2: Geometric conditions for transmission density.
ISO 5-3:1984, Photography — Density measurements
— Part 3: Spectral conditions.
ISO 75891 984, Photography — Illuminants for sensitome try — Specifications for daylight and incandescent tungsten.
3 Definitions
For the purposes of ISO 6, the following definitions apply.
3.1 exposure, H: The time integral of illuminance on the film, measured in lux seconds.
Amounts of exposure are often expressed in logarithmic terms (‘09in11)•
3.2 sp..d: A quantitative measure of the response of the photographic material to radiant energy for the specified conditions of exposure, processing and image measurement.
4 Sampling and storage
In determining the ISO speed of a product, it is important that the evaluated samples yield the average results obtained by users. This will require evaluating several different batches periodically under the conditions specified in ISO 6. Prior to evaluation, the samples shall be stored according to the manufacturers’ recommendations for a length of time to simulate the average age at which the product is normally used. Several independent evaluations shall be made to ensure the proper calibration of equipment and processes. The basic objective in selecting and storing samples as described above is to ensure the film characteristics are representative of those obtained by a photographer at the time of use.
5 Test method
5.1 Principle
Samples are exposed and processed as specified below. Density measurements are obtained from the resultant images to produce a sensitometric curve from which values are taken and used to determine ISO speed.
5.2 Safelights
To eliminate the possibility of unintentional exposure to radiation affecting the sensitometric results1 all films shall be handled in complete darkness during sample preparation and processing.
5.3 Exposure
5.3.1 CondItioning of specimens
During exposure, the specimens shall be kept at a temperature of 23 °C ± 2 °C and a relative humidity of(50±5)%.
5.3.2 Type of sensitometer
The sensitometer shall be a non-intermittent, illuminance-scale type.
5.3.3 Radiant energy quality
The appropriate illuminant for the particular film type being exposed shall conform to the specifications given in ISO 7589. ISO speed may be determined using ISO sensitometric daylight, studio tungsten or photoflood illuminants. Since the speed of filmlprocess combinations will depend on the type of illuminant used for determining ISO speed, the illuminant should be specified in use instructions.
5.3.4 Filters
ISO speed shall be specified for use without a filter in front of the camera lens. If film is used with a colour filter in front of the camera lens, an “equivalent” speed number can be used to determine the exposure of the film with the filter. ISO speed does not apply to the filtered conditions.
5.3.5 Modulation
The total range of spectral diffuse transmission density of each area of the light modulator throughout the wavelength interval from 400 nm to 700 nm shall not exceed 5 % of the average density obtained over the same interval or a value of 0,03, whichever is greater. In the interval from 360 nm to 400 nm, 10 % of this same average density, or a value of 0,06, whichever is greater, shell not be exceeded.
If stepped increments are used, the base 10 logarithm of the exposure increment shall not be greater than 0,20. The width and length of a single step shall be adequate to obtain a uniform density within the reading aperture specified for densitometry.
If a continuous variable modulator is used. the base 10 logarithm of the change in exposure with distance along the test strip shall be uniform and not be greater than 0,04 per millimetre.
Since ISO speed is dependent on the exposing and processing conditions, these should be indicated when quoting ISO speed values.
6.3 Accuracy
The calibration of the equipment and processes involveri in determining film speed shall be adequate to ensure that the error in log,0 Hm is less than 0,05.
7 Product marking and labelling
Speed of a product, determined in accordance with this International Standard and expressed on the scales of table 1, may be designated ISO speed and denoted in one of the following forms:
a) by its arithmetic speed , e.g. ISO 100;
b) by its logarithmic speed, e.g. ISO 21°;
c) by both its arithmetic and its logarithmic speed.
e.g. ISO 100/21°.
However, since the speed is dependent on the illuminant, exposure time and process used, these conditions should be clearly indicated whenever practical when quoting values to avoid misinterpretation.