ISO 10157-1991 PDF

Full title and description

ISO 10157:1991 — Photography — Flash exposure meter — Requirements. This International Standard specifies requirements for photoelectric flash exposure meters used in still photography, defining performance, measurement and environmental test criteria for instruments that measure the time integral of luminance or illuminance produced by brief light sources (electronic flash) and indicate the exposure-related value or f-number needed for correct film exposure.

Abstract

ISO 10157:1991 sets out technical and metrological requirements for flash exposure meters: the quantity measured (time integral of luminance or illuminance), calibration and reference conditions, required measurement ranges and scales, accuracy tolerances, and environmental/mechanical tests to verify reliable operation under specified conditions. It is a short (concise) standard intended to provide manufacturers and test laboratories with a clear baseline for design, testing and conformity assessment of flash metering devices.

General information

• Status: Published (International Standard; confirmed as current in ISO systematic review processes).
• Publication date: 20 June 1991.
• Publisher: International Organization for Standardization (ISO).
• ICS / categories: 37.040.10 — Photographic equipment; ISO/TC 42 (Photography).
• Edition / version: Edition 1 (1991).
• Number of pages: 5.

Key bibliographic and lifecycle details above are recorded on the ISO bibliographic entry and complementary national/retailer records.

Scope

This International Standard applies to photoelectric flash exposure meters that measure the time integral of the luminance or illuminance of a photographic object illuminated by a short-duration light source (electronic flash). It covers meters that indicate the measured time integral or a corresponding number (for example a recommended f‑number) for correct exposure at a given film speed and that also evaluate any continuous light present in addition to the flash. The scope includes definitions, reference conditions, required measurement ranges and environmental/mechanical tests for performance verification.

Key topics and requirements

• Measurement principle: integration of flash-generated luminance or illuminance (lux·s or cd·s·m⁻²) and presentation as time integral, exposure value or f‑number.
• Calibration and reference conditions: specified calibration sources and correlated colour temperature (reference illumination conditions) for verification.
• Performance limits: required accuracy/tolerance limits across the specified measurement range and specified film-speed reference points.
• Timing and gating: requirements for integration (gate) time and storage/readout times where applicable.
• Spectral response and acceptance angle: guidance on spectral response consistency across visible wavelengths and on acceptance-angle / field-of-view specification.
• Environmental and mechanical tests: temperature, humidity, vibration and shock/drop tests drawn from referenced IEC and ISO test methods to ensure reliable operation.

The list above summarizes the principal technical elements and test requirements normally specified or referenced by the text of ISO 10157:1991.

Typical use and users

Primary users are manufacturers of photographic exposure meters and electronic flash systems, calibration and test laboratories, product compliance engineers, and standards bodies. Typical uses include product design specifications, factory testing and calibration procedures, quality assurance, and conformity assessment for photographic flash metering devices.

Related standards

Standards commonly referenced with ISO 10157:1991 include ISO 2720 (general-purpose photographic exposure meters — guide to product specification) and relevant IEC test standards for environmental and safety testing (examples: IEC 68‑2‑6 for vibration and IEC 348 for safety of electronic measuring apparatus). National and sectoral standards on exposure meters or camera metering may also be related.

Keywords

flash exposure meter; exposure meter; flash metering; photographic metrology; luminance time integral; illuminance time integral; calibration; ISO 10157:1991; ISO/TC 42; photographic equipment.

FAQ

Q: What is this standard?

A: ISO 10157:1991 is an International Standard titled "Photography — Flash exposure meter — Requirements" that specifies requirements and test conditions for photoelectric flash exposure meters used in still photography.

Q: What does it cover?

A: It covers the measurement principle (time integral of luminance or illuminance), calibration/reference conditions, measurement ranges and accuracy tolerances, timing/gating and readout behavior, spectral and angular response considerations, and environmental/mechanical tests to verify reliable operation.

Q: Who typically uses it?

A: Manufacturers of photographic light meters and flash units, calibration and test laboratories, product QA teams and conformity assessors, and standards organizations involved in photographic instrument specifications.

Q: Is it current or superseded?

A: The ISO bibliographic record indicates ISO 10157:1991 remains published and has been through ISO periodic review cycles; the ISO catalogue shows the standard was confirmed in the ISO review process (last confirmed in 2021). Users should check current ISO catalogue entries or national standards bodies for any more recent revisions or related replacements before assuming suitability for regulatory conformity.

Q: Is it part of a series?

A: ISO 10157:1991 is a standalone technical standard within the photographic equipment subject area (ICS 37.040.10) and is related by subject matter to other ISO standards on exposure meters and photographic instrument test methods (for example ISO 2720). It is not presented as a numbered multi‑part series.

Q: What are the key keywords?

A: Flash exposure meter, exposure metering, time integral, luminance, illuminance, calibration, photographic metrology, ISO 10157:1991.