This International Standard applies exclusively to the automatic exposure control built into or coupled with electronic flash equipment. It specifies the methods for measuring the characteristics peculiar to the control such as its accuracy and repeatability. It also lays down the numerical values of the integral of time of the object luminance and of the exposure given to an object by flash equipment with automatic exposure control, as well as the maximum deviation from these nominal values. Furthermore, the measuring conditions are stated under which the adjustment of the automatic exposure control is to be tested. Definitions and measuring methods concerning electronic flash equipment without automatic control of exposure are specified in ISO 2827. It is assumed that when testing the automatic exposure control, the optical axis of the sensor of the control and of the lamp head of the electronic flash equipment are, when fitted to a camera, substantially coincident with that of the taking lens of the camera.