Starting the chronograph of the Zenith Defy El Primero by pressing the large rectangular pusher at 2 o’clock comes with a huge surprise: a long, thin hand spins around the dial at lightning speed. It only needs 1 second for each rotation. And inside the titanium case, the mechanism that makes this possible hums along at this high-speed pace, with an oscillating system that beats at a rate of 360,000 vph. This permits the measurement and display of 1/100-second intervals: 360,000 vph equals 100 beats per second, with as many steps by the hand in the same time interval.

The 1/100-second measurement is precisely displayed on the raised dial ring where it can be easily read. If the pusher at 2 o?clock is pressed again, the central chronograph hand stops immediately and shows the fractions of a second indicated by the elegant sword-shaped hand. Cleanly applied numerals in 10-digit increments mark 1/10 seconds, and intervening index lines show 1/100 seconds. The full seconds time unit is displayed on a counter at 6 o?clock. So, for example, you can read 24 seconds, 7/10 of a second, and 3/100 of a second: 24.73. But by exposing the balance wheel, the otherwise easy-to-read lapsed seconds is interrupted by a concave section in the circle between seconds 40 to 52. If the elapsed seconds hand stops in this area, it?s harder to read the result because of the distorted line markers.

Due to the high frequency of the chronograph, the small elapsed seconds hand also appears to mo...