BS ISO 2721:2013

Foreword
Introduction
1 Scope
2 Normative references
3 Terms and definitions
4 Specific requirements
5 Calibration of the exposure controls
6 Acceptance angles of the photoelectric system
Annex A (normative) - Measurement of light exposure in
        the focal plane and calibration of measuring
        instrument
Annex B (normative) - Size of measuring area
Annex C (normative) - Performance test
Bibliography

Describes the exposure at the focal plane of film-based cameras for values of two exposure parameters, i.e. field luminance and film speed, and also describes methods of evaluating other photometric characteristics, such as the acceptance angles of the photoelectric system.

This International Standard specifies the exposure at the focal plane of film-based cameras for values of two exposure parameters, i.e. field luminance and film speed, and also describes methods of evaluating other photometric characteristics, such as the acceptance angles of the photoelectric system.

This International Standard applies to automatic exposure control systems which are built into film-based cameras or coupled with them to regulate the exposure in the focal plane as a function of the several exposure parameters. The mechanism can control either the focal-plane illuminance or the exposure-time interval or both. Pointer (or needle) matching systems are included in this International Standard even though they are not fully automatic. This standard is not applicable to digital cameras.