BS ISO 516:2019 pdf download – Camera shutters – Timing – General definition and mechanical shutter measurements
This document provides a uniform basis for determining the exposure times for all types of shutters used in still cameras and contains suitable definitions of the terms used.
It specifies the exposure-time markings for all types of shutters and their tolerances.
The characteristics of all types of mechanical shutters, which are mounted in still cameras and affect the control of exposure, motion-stopping ability and synchronization with a photoflash light source are also defined.
The tolerances specified are the target values for the shutter performance that can be expected to give good results. They are not intended for application as a general inspection standard in controlling the performance of mechanical shutters, since tolerances may vary with the feature and price class of camera tested.
Test methods are described for routine manufacturing testing and quality control. These test methods require access to the focal plane of the camera and can therefore not be applied to assembled digital still cameras.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
ISO Online browsing platform: available at
IEC Electropedia: available at
front shutter
any shutter in the vicinity of the lens
Note 1 to entry: The front shutter can be in front of, behind or between the lens elements and can consist of rotating discs, rotating slats, sliding blades, oscillating blades, etc. Programmed shutters are also included.
Note 2 to entry: The common characteristic for the front shutter is that the entire picture area is exposed almost simultaneously.
Note 3 to entry: When the shutter and diaphragm are located too far apart, both exposure and shutter speed may vary at different points in the picture area.
focal-plane shutter
any shutter in the vicinity of the focal plane
Note 1 to entry: The focal-plane shutter can consist of fixed or variable slit curtains, rotating discs, sliding blades, etc.
Note 2 to entry: The essential feature of the focal-plane shutter is that the picture area is exposed incrementally,in such a way that the time required to expose the entire picture area is greater than the exposure time of any one point.
effective time
best measure of the amount of light falling on the picture area.BS ISO 516 pdf download.