Zenith Defy El Primero 21 Review

Zenith's El Primero was one of the earliest automatic chronograph movements, released in 1969. It disappeared from the market during the heyday of quartz watches, but has since made a comeback. It continues to refine to this day, while retaining the basic design from 50 years ago. In 2017, the El Primero Caliber 9004 was released, which features a separate chronograph gear train, beating at 36 vph, enabling time measurement to 1/100th of a second. This time, we'd like to review the Defy El Primero 21, which is equipped with this El Primero movement.

Zenith "Defy El Primero 21"

　Pressing the large rectangular pusher at 2 o'clock to start the Defy El Primero 21 chronograph is a real eye-opener. The slender hand rotates around the dial at lightning speed, taking just one second per revolution. The titanium case houses the mechanical mechanism that makes this high speed possible, its dedicated chronograph gear train beating at 360,000 vibrations per hour, enabling it to measure elapsed times to within one-hundredth of a second. 360,000 vibrations per hour means 100 vibrations per second, which translates to multiple steps for each elapsed time hand.

　The hundredths of a second are precisely displayed on a ring around the outer edge of the dial for easy visibility. Pressing the pusher at 2 o'clock again instantly stops the central chronograph hand, and an elegant sword-shaped hand indicates the seconds. Clear applied indices at the tens mark tenths of a second, while the indices between mark hundredths of a second.

　The dial showing the elapsed seconds is located at 6 o'clock. If the time is read as 24 seconds, 7/10ths, or 3/100ths, it is 24.73 seconds. While the dial showing the elapsed seconds is certainly designed for legibility, it is forced to have a recessed shape between 40 and 52 seconds, as if obstructed by the protruding balance. If the elapsed seconds hand stops in this position, the distorted linear index makes it difficult to read.

　Because it's a high-frequency chronograph, the chronograph seconds hand also moves very quickly. In contrast, the hand displaying the elapsed minutes moves only once per minute. This display is located at 3 o'clock and is a standard 30-minute counter. The chronograph's power is sufficient to run for approximately 50 seconds without additional winding. It takes 25 full turns of the crown to fully wind the barrel.

　As mentioned above, this fascinating mechanism is driven by a dedicated chronograph gear train, which also has its own barrel and regulator. The so-called standard gear train, which drives the hour, minute, and second hands, operates at 36,000 vibrations per hour, just like other previous El Primero calibers.

　While a normal time display movement can be manually wound by turning the crown clockwise or automatically wound by the rotor, the chronograph mechanism only requires manual winding. The power reserve indicator at 12 o'clock is convenient when using the stopwatch function. In this test, we measured a power reserve of approximately 54 minutes (53 minutes 55.12 seconds) when fully wound. The movement of the watch itself has a power reserve of over 50 hours.

　Another key feature is that the watch and chronograph movement are separate, allowing the watch to be stopped while the chronograph is running. Regardless of whether this situation will arise in everyday life, the addition of a hacking function, a much-requested addition in the long history of El Primero, is worthy of note. Unfortunately, the Defy El Primero 21, the watch we tested, was unable to take advantage of this feature. The small seconds, displayed by three propeller-shaped hands at 9 o'clock, did not allow for accurate time adjustment. However, the non-skeletonized dial version with a "normal" small seconds hand allows for accurate time adjustment. In this model, the stop-seconds counter is round, making it easier to read.

Testing the Zenith Defy El Primero 21

　Measurements were taken using a timing machine. When fully wound, the deviation was just +0.4 seconds per day. After 24 hours (without rewinding), the deviation was +2 seconds per day. Because the chronograph is separate from the normal gear train, it does not affect the normal gear train even when the chronograph is running, resulting in stable readings.

　The El Primero 9004 is made up of 203 parts, 75 fewer than the original El Primero. It features a patented chronograph design with a column wheel, a unique start mechanism, and a patented reset mechanism with three heart cams that allows all the displays to be reset in sync, a functional process similar to starting and stopping a chronograph.

　The movement's escapement is made of silicon, which is less susceptible to temperature changes. Furthermore, silicon is a non-magnetic material, so in theory it has high magnetic resistance. However, this point could not be actually verified this time. When the watch was placed in a 1000 gauss magnetic field using a horseshoe-shaped magnet that emits strong magnetic force, a slight effect was observed on the measured values. The time clearly advanced, but did not come to a halt. As for the chronograph function, although the amplitude decreased, it continued to operate. When removed from the magnetic field, the value returned to its original value after a while, but repeated exposure to a magnetic field did not return it to its original value, and in this test the result was more than 20 seconds per day (*Khronos Japan does not recommend this type of testing.).

The design of the Zenith Defy El Primero 21

　While the design reflects the company's long history, Zenith offers the El Primero in a titanium case. Zenith founder Georges Favre-Jacot named his first machined pocket watch, created in 1880, "Defi." This striking timepiece was reborn in the late 1960s as the "Defy" wristwatch collection (the spelling change was likely intended to appeal to the international market). In keeping with the Defy philosophy of taking on challenges, the watch retains its robust appearance, featuring a refined oval case middle smoothly transitioning to short lugs, brushed surfaces and beveled edges, compact and perfectly responsive chronograph pushers, a robust and easy-to-operate crown, and water resistance to 100 meters.

　Despite its large case size, the Defy sits comfortably on the wrist thanks to its compact case shape and angled strap attachment point. Unfortunately, the case doesn't fit under a shirt cuff, and the single-sided titanium folding clasp leaves a mark on the wrist with its hinge, creating sharp edges against the cuff. However, the side pushers and lugs on the leather or rubber strap certainly contribute to the watch's comfort and ease of use.

The skeletonized version of the Defy El Primero 21, with its boldly stripped-back dial, showcases the structure, technology, and design of the El Primero 9004 at its finest. For customers who don't like the skeletonized design, Zenith also offers a model with a more classic silver-colored dial. Surprisingly, the skeletonized version tested here was highly legible despite its many apertures. The time is displayed by luminous faceted hands. The hour markers around the outer edge of the dial stand out brightly, making it easy to read even in the dark.

　The hands and markers are faithful to the El Primero's historical signature. The two circular chronograph counters are also color-coded blue and gray, a nod to the historical tradition. The Zenith star at the tip of the central chronograph hand represents a turning point for the brand, since measuring hundredths of a second was impossible before the Defy.