It shouldn’t surprise you to learn that the Rolex Cosmograph Daytona, arguably one of the most famous and sought-after mechanical chronograph watches in the world, is also chronometer certified. A Rolex Superlative Chronometer watch therefore offers a precision of -2/ +2 seconds per day. A Rolex movement with this title has been certified as a Swiss chronometer by the COSC and then tested a second time by Rolex – after the movement is cased up – using specially developed technology. Arguably the most famous among them is Rolex, which has developed its own Superlative Chronometer certification. Some manufacturers have taken the concept of chronometer certification one step further.
Each watch is tested in five positions and at different temperatures and is certified as having an accuracy of -4/+6 seconds a day. As such, a COSC-certified chronometer denotes a watch whose uncased movement has successfully demonstrated its accuracy and consistency of rate over fifteen days of tests at one of the COSC’s official testing facilities. In Switzerland, the certifying body is called Contrôle Officiel Suisse des Chronomètres, although it’s more commonly known as COSC.
Chronograph iso#
Only mechanisms that have satisfied the criteria for precision of ISO 3159, or its equivalent, are issued with an official chronometer certificate.
Instead, a chronometer is the term used to denote a high-precision watch with a running seconds display whose movement accuracy has been controlled over a period of several days in different positions and at different temperatures by an official neutral body. Omega Globemaster Master Chronometer, Image: Bert BuijsroggeĪ chronometer, on the other hand, is not a complication or an additional function a watch performs, though it very much sounds like one. The top one stops and starts the chronograph mechanism, while the bottom one resets all indicators. There is a pusher on either side of the crown, which sits on the side of the case. The 30-minute counter is shown at 3 o’clock, 12-hour counter at 6 o’clock, and running seconds at 9 o’clock, and there is a central chronograph seconds hand. There are a number of variations of this model, of course, but the majority have a basic 3-6-9 layout for the chronograph displays. Although the dial layouts of chronograph-equipped watches can vary to some degree, there will normally be two sub-counters for the minutes and hours (usually 30 minutes and 12 hours), which totalize the number of revolutions made by the central chronograph hand (which measures seconds).Ī classic example of a simple chronograph is the Omega Speedmaster Professional. In a chronograph, at least one hand can be started, stopped, and returned to zero on demand to measure a duration of time to one fifth, tenth, or even hundredth of a second. You probably know this more commonly as a stopwatch. In this instance, that function is to separately track and indicate elapsed time over defined periods. Rather, a chronograph is an additional function (referred to as a complication in the world of mechanical watches) that a watch indicating hours, minutes, and seconds can perform. The first thing to understand is that a chronograph is not a watch in and of itself. TAG Heuer Carrera Chronograph, Image: Bert Buijsrogge