ISO 4238:1976

Cinematography - Optical printing ratios for enlargement and reduction of motion-picture film images - Specifications

Cinématographie — Rapports d'agrandissement et de réduction d'image pour le tirage optique des films cinématographiques — Spécifications

General Information

• Status: Published
• Publication Date: 30-Nov-1976
• ICS: 37.060.20 - Motion picture films. Cartridges
• Technical Committee: ISO/TC 36 - Cinematography
• Drafting Committee: ISO/TC 36/WG 2 - Laboratory and distribution services technology
• Current Stage: 9093 - International Standard confirmed
• Start Date: 10-Jul-2023
• Completion Date: 13-Dec-2025

Overview

ISO 4238:1976 - "Cinematography - Optical printing ratios for enlargement and reduction of motion‑picture film images - Specifications" defines recommended optical printing ratios used when transferring motion‑picture images between film formats. The standard addresses both intermittent and continuous printing operations, provides ratio guidance for common film widths (8 mm, 16 mm, 35 mm, 65/70 mm) and distinguishes anamorphotic and non‑anamorphotic variants. ISO 4238 supplies practical numeric ratios in a table and sets usage notes to minimize picture loss during format conversion.

Key Topics and Requirements

• Scope: Ratios for optical enlargement and reduction when transferring film formats.
• Printing modes: Covers both intermittent printing and continuous printing operations.
• Format coverage: Includes guidance for standard film widths and format pairs commonly used in cinematography (8, 16, 35, 65/70 mm).
• Anamorphic vs non‑anamorphic: Ratios are provided separately for anamorphotic and non‑anamorphotic variants.
• Guidance, not override: Ratios are intended as guidelines and do not supersede image dimensions specified in fundamental ISO cinematography standards.
• Unshrunk film basis: Ratio values are based on the use of unshrunk film; shrinking or dimensional variation must be considered separately.
• Picture‑loss minimization: Recommends choosing enlargement ratios as close as possible to the minimum values in the table for intermittent optical printing, unless original cropping is required.

Applications

Who uses ISO 4238 and why:

• Film laboratories performing optical blow‑ups or reductions during format transfers.
• Post‑production technicians and telecine facilities converting archival or camera originals between formats.
• Cinematographers and restoration specialists planning transfers where image framing and resolution must be preserved.
• Equipment manufacturers designing optical printers and converters to support standard transfer ratios. Practical benefits include standardized expectations for magnification, reduced risk of unintended cropping or resolution loss, and compatibility with established camera and projection image areas.

Related Standards

ISO 4238 is used in conjunction with ISO fundamental cinematography standards that define image areas and apertures:

• ISO 74 - Image area produced by camera aperture (8 mm Type R)
• ISO 466 - Image produced by 16 mm camera aperture
• ISO 2467 - 65/70 mm image area
• ISO 2906 - 35 mm image area
• ISO 3645 - 8 mm Type S camera aperture These references establish the image dimensions that ISO 4238’s printing ratios are intended to support.

Keywords: ISO 4238:1976, optical printing ratios, cinematography standard, film enlargement, film reduction, motion‑picture film, format conversion, anamorphic, intermittent printing, continuous printing.

Standards Content (Sample)

INTERNATIONAL STANDARD
INTERNATIONAL ORGANIZATION FOR STANDARDIZATION l MEXk’LIYHAPOJHAII OPI-AHM3AUMJl no CTAHAAPTM3AUMM~ORGANISATION INTERNATIONALE DE NORMALISATION
Optical printing ratios for enlargement
Cinematography -
and reduction of motion-picture film images - Specifications
@in@matographie - Rapports d Iagrandissemen t et de kduction d ‘image pour ie tirage op tique des films
cinema tographiques - Spkifica tions
First edition - 1976-12-15
UDC 778.588.3 Ref. No. ISO 4238-1976 (E)
: cinematography, motion-picture film, photographic images, printing, magnification, ratios.
Descriptors
Price based on 2 pages
FOREWORD
ISO (the International Organization for Standardization) is a woridwide federation
of national Standards institutes (ISO Member Bodies). The work of developing
International Standards is carried out through ISO Technical Committees. Every
Member Body interested in a subject for which a Technical Committee has been set
up 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.
Draft International Standards adopted by the Technical Committees are circulated
to the Member Bodies for approval before their acceptance as International
Standards by the ISO Council.
International Standard ISO 4238 was drawn up by Technical Committee
and was circulated to the Member Bodies in
ISO/TC 36, Cinematography,
October 1975.
lt has been approved by the Member Bodies of the foilowing countries :
Austria Italy Spain
Belgium Japan Sweden
Canada Korea, Rep. of Switzerland
Czechosiovakia Mexico Turkey
Denmark Netherlands United Kingdom
France Poland U.S.A.
Germany Romania U.S. R.
India South Africa, Rep. of
No Member Body expressed disapproval of the document.
0 International Organkation for Standardkation, 1976 l
Printed in Switzerland
INTERNATIONAL STANDARD ISO 4238-1976 (E)
- Optical printing ratios for enlargement
Cinematography
and reduction of motion-picture film images - Specifications
1 SCOPE AND FIELD OF APPLICATION 3 SPECI FICATIONS
This International Standard specifies the required ratios for
Optical enlargement and reduction of motion-picture f
...

NORME INTERNATIONALE
INTERNATIONAL ORGANIZATION FOR STANDARDIZATION l MEWlYHAPOAHAII OPI-AHM3AUMII l-I0 CTAHAAPTM3AUMM .ORGANISATION INTERNATIONALE DE NORMALISATION
Rapports d’agrandissement et de
Cinématographie -
réduction d’image pour le tirage optique des films
cinématographiques - Spécifications
Optical printing ratios for enlargement and reduction of motion-picture film images -
Cinema tograph y -
Speci fica tions
Prem ière édition - 1976-I 2-15
Réf. no : ISO 4238-1976 (F)
CDU 778.588.3
Descripteurs : cinématographie, film cinématographique, image photographique, tirage, agrandissement, proportion.
Prix basé sur 2 pages
AVANT-PROPOS
L’ISO (Organisation Internationale de Normalisation) est une fédération mondiale
d’organismes nationaux de normalisation (Comités Membres KO). L’élaboration des
Normes Internationales est confiée aux Comités Techniques ISO. Chaque Comité
Membre intéressé par une étude a le droit de faire partie du Comité Technique
correspondant. Les organisations internationales, gouvernementales et non
gouvernementales, en liaison avec I’ISO, participent également aux travaux.
Les Projets de Normes Internationales adoptés par les Comités Techniques sont’
soumis aux Comités Membres pour approbation, avant leur acceptation comme
Normes Internationales par le Conseil de I’ISO.
La Norme Internationale ISO 4238 a été établie par le Comité Technique
ISO/TC 36, Cinématographie, et a été soumise aux Comités Membres en
octobre 1975.
Elle a été approuvée par les Comités Membres des pays suivants :
France Royaume-Uni
Afrique du Sud, Rép. d’
Al lemagne Inde Suède
Italie Suisse
Autriche
Tchécoslovaquie
Belgique Japon
Mexique Turquie
Canada
U. R.S.S.
Corée, Rép. de Pays-Bas
Pologne U.S.A.
Danemark
Roumanie
Espagne
Aucun Comité Membre n’a désapprouvé le document.
0 Organisation lnternatjonale de Normalisation, 1976 l
Imprimé en Suisse
ISO 4238-1976 (F)
NORME INTERNATIONALE
Cinématographie - Rapports d’agrandissement et de
réduction d’image pour le tirage optique des films
cinématographiques - Spécifications
1 OBJET ET.DOMAINE D’APPLICATION
3 SPËCI FICATIONS
La présente Norme Internationale spécifie les rapports
d’agrandissement et de réduction d’image nécessaires au
3.1 Les rapports d’agrandissement ou de réduction
tirage optique des films cinématographiques lors des
optique doivent être comme spécifiés dans le tableau.
opérations de tirage intermittent ou continu pour la
conversion d’un format de
...