Courtesy Lynx System Developers, Inc., 1/15/2015
A “zero control test” or “zero gun test” is used to check that the automatic timing system starts and captures properly. The zero gun test is required for many official records.
IAAF Photo Finish Guidelines – April 2010
Ensure that the zero gun control is taken on all cameras in use at a rate of 1000 lines per second, and preferably 2000 lines per second, and that the time is read
to a precision of at least 1/1000th of a second and preferably 1/10,000th of a second. Ensure in the case where ammunition is being used that the cursor is not
placed on any minor build up of smoke / flame which would mark the “pre-burn” before the actual explosion producing the “gun sound”. An electronic gun will
produce a clear vertical flash. Check that the resulting times correspond to the requirements of Rule 165.14.
Ensure that a photograph of the test from each camera for each session is produced, suitably labelled and is retained by the IPFJ and given to the Technical
IAAF Rule 165:14 (From IAAF 2010- 2011 Rulebook)
Fully Automatic Photo Finish equipment shall be approved by the IAAF, based upon a test of accuracy made within 4 years prior to the competition. It shall be started automatically from the Starter’s gun, or approved starting apparatus, so that the overall delay between the report from the muzzle and the start of the timing system is constant and less than 1/1000th of a second.
USATF Rule 165:10(a) (From USATF 2009 Rulebook)
The timing equipment must be fully automatic and certified to be accurate prior to the competition. It must be started automatically by the discharge
of the Starter’s pistol or authorized starting device at the instance of the flash/smoke from the charge, and it must record the finish times
automatically when any part of the competitor’s body or torso (as distinguished from the head, neck, arms, hands, legs, or feet) reaches the
perpendicular plane of the nearer edge of the finish line. The overall delay between the report from the pistol or the initial sound of the electronic
tone and the start of the timing system must be constant and less than 1 millisecond.
IAAF Rule 165:19 (From IAAF 2010 -2011 Rulebook) [Zero Gun Test]
The Chief Photo Finish Judge shall be responsible for the functioning of the System. Before the start of the competition, he will meet the technical staff involved and familiarize himself with the equipment. In cooperation with the Track Referee and the Starter, he shall initiate a zero control test, before the beginning of each session, to ensure that the equipment is started automatically by the Starter’s gun within the limit identified in Rule165.14 (i.e. 1/1000th second). He shall supervise the testing of the equipment and ensure that the camera(s) is correctly aligned.