ISO 2827 INTERNATIONAL STANDARD Second edition 1988-08-15 INTERNATIONAL ORGANIZATION FOR STANDARDIZATION tso ORGANISATION INTERNATIONALE DE NORMALISATION MEKAYHAPOAHAA OPrAHW3ALMA NO CTAHAAPTW3AMM Photography - Electronic flash equipment Determination of light output and performance Photographie - Flash électronique -- Determination de I'émission lumineuse et des performances Reference number ISO 2827 : 1988 (E) ted without license from IHS Not for Resale ISO 2827 : 1988 (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 the right to be represented on that committee. International organizations, govern- mental 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. 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. They are approved in accordance with ISO procedures requiring at least 75 % approval by the member bodies voting. International Standard ISO 2827 was prepared by Technical Committee ISO/TC 42, Photography. This second edition cancels and replaces the first edition (IS0 2827 : 1973), of which it constitutes a technical revision. Users should note that all International Standards undergo revision from time to time and that any reference made herein to any other International Standard implies its latest edition, unless otherwise stated. International Organization for Standardization, 1988 Printed in Switzerland Not for Resale itted without license from IHS ISO 2827 : 1988 (E) INTERNATIONAL STANDARD Photography - Electronic flash equipment - Determination of light output and performance Scope and field of application 3.5half angle of coverage : The angle between the axis of the reflector and the direction where the luminous intensity falls This International Standard specifies methods of measurement to one half of the value in the axis. and sets standards of performance for light output, angle of coverage, ready indication, recycle time and number of flashes On symmetrically designed reflectors the angle of coverage is for electronic flash equipment of the single flash type, which is equal to twice the half angle of coverage. For flash equipment primarily intended to provide illumination for photography with producing a pattern which deviates significantly from a circle, a cameras in which the contacts that control the flash are closed rectangle within which the luminous intensity does not vary by when the shutter of the camera is fully or nearly fully open. more than ± 50 % from the value on the axis may be specified by two angles in horizontal and vertical directions of the rec- tangle. For large flash sources, for example studio flash 2 References sources, where the dimensions are not smaller than 2 m, the method of specifying angle of coverage is not applicable. Iso 1229, Photography - Expendable photoflash lamps Determination of the light output. IS0 1230, Photography -- Determination of flash guide 3.6 light output (for bare flash tubes) : The light output numbers. measured in two mutually perpendicular equatorial lines around the bare tubes. The cross-line of the planes through the Iso 3028, Photography - Camera flash illuminants -Deter- equatorial lines shall be parallel to the optical axis of the lens of mination of /SO spectral distribution index (ISO/SDI). the camera. ISO 5763, Photography Electronic flash equipment Automatic control of exposure. 3.7 beam light output : The time integral of the luminous intensity of flash equipment in the direction specified by the Definitions axis of the reflector, expressed in candela