Hands-On – Zenith Defy El Primero 21 – From a 10th to a 100th of a Second (Video, Specs & Price)

By rolex
April 7, 2021
8 min read

Back in 1969, Zenith presented a development that would later become a symbol, being both one of the primary automatic chronograph developments, and being the twentieth century’s lord of accuracy, beating at 5Hz and being exact to a 10th of a second. Its name: the El Primero. At Baselworld, the Le Locle-based manufacture has given this fast-beating motor a 21st century appeal: 50Hz recurrence, accuracy to 100th of a second, present day look, open-worked development. Here is the Zenith Defy El Primero 21… and it’s fast, very fast.

The story of the Zenith El Primero has almost become legend. When we talk about symbols in watchmaking, more often than not we allude to watches overall. The El Primero is one of only a handful few famous developments. It was launched in 1969, as one of the absolute first (if not the principal) automatic chronograph developments, and already showed impressive architecture – completely integrated chronograph with central rotor and section wheel, far from a last-minute patch-up work. Be that as it may, what made it so special, even in today’s creation, was its high-recurrence, beating not at 3Hz or 4Hz, like most different chronographs, but rather at 5Hz/36,000vph – meaning it was able to indicate the 10th of a second. All things considered, for Zenith, this was certainly way too twentieth century and the manufacture concluded that for Baselworld 2017, the symbol expected to go into the 21st century, with something other than an update. And now, you probably thought about why it is named the Zenith Defy El Primero 21.

Zenith Defy El Primero 21 – From 5Hz to 50Hz

5hz… something that watchnerds know to be something beyond a number. 5hz means greater accuracy and the ability to time occasions with a higher exactness. 5Hz means 10 beats each second (recall: 1Hz is one oscillation, so actually 2 beats) and that allows you to measure to the 10th of a second, and not to the 6th of a second as with a 3Hz watch or to the 8th of a second as with a 4Hz watch. Other than the higher exactness, a measurement to the 10th of a second is basically more sound with our idea of time. The other added-value of the 5Hz recurrence is the ability to achieve a superior chronometry (on paper, the faster a regulator beats, the more exact it can be) and the super-smooth run of the second hand.

With the Zenith Defy El Primero 21, it’s small upgrades that have been made as well as a massive technical achievement. The 50Hz frequency is not new in watchmaking, yet it has mainly be seen on concept watches or very good quality pieces (think TAG Heuer Mikrograph for instance…) Here, Zenith carries the ultra-high-beat to another level, appropriately evaluated (below $10k) and meant to be delivered on a large scale. Technically, the Zenith Defy El Primero 21 beats multiple times more each second, gives an indication multiple times more exact (presently to the 100th of a second) and can makes its second hand run faster too… to put it plainly, watch this video and you’ll understand the idea of fast and smooth.

In terms of display, Zenith had to adapt the El Primero to this new idea of the super-fast central hand (which revolves around the dial once each second). The original 1969 El Primero (as well as most of its present day iterations) utilizes a tri-subcounter display, with central second hand, 12-hour counter at 6, 30-minute counter at 3 and small second at 9. On the Zenith Defy El Primero 21, we have a 100th of a second hand on the central axis, however the second counter is as yet required. In this manner, the new display comprise of a 30-minute counter still at 3, a 60-second counter at 6 and a small second actually placed at 9. Presently comes the topic of the mechanics behind this ultra-fast display.

Zenith Defy El Primero 21 – Dual-balance architecture

Those who know somewhat about watchmaking realize that having a watch running constantly with a 50Hz recurrence would be very problematic (gigantic energy utilization, parts that will wear extremely fast…) This is the reason, as the vast majority of the chronographs using a ultra-high-recurrence, the Zenith Defy El Primero 21 is based on a dual-balance architecture. As such, the timekeeping part of the watch (the indication of the hours, minutes and seconds) is regulated by the usual 5Hz/36,000vph of the El Primero. This means that the watch keeps its 50h force save and its ability to be chronometer guaranteed by the COSC. The base development itself remains rather equal to the 1969 form, with automatic twisting with central rotor.

Yet, the chronograph part is currently constrained by a second balance, this time running at 50Hz/360,000vph. Imagine this watch as prepared with two autonomous “gear boxes”: one for the time and the other for the chronograph. Each has its own transmission and escapement framework and there is no coupling grasp. In fact, the new Defy El Primero 21 has two barrels, and the winding crown presently works in both directions: clockwise for the chronograph, counterclockwise for the watch. 25 turns of the crown are sufficient to obtain a 100% charge of the chronograph barrel. The rotor, with a star-shaped openworked oscillating weight, handles the single direction automatic twisting of the watch work. Because of the great frequency, energy utilization is multiple times higher than in the original development and accordingly, there’s only a 50-minute autonomy for the 100th of a second chronograph (yet for the chronograph just, as the watch will in any case run). The remaining energy of the chronograph area is indicated by a gauge at 12 on the dial.

The second novelty comes from the material utilized for the balance-springs. Subsequently of running at such a high-recurrence, standard materials can’t be utilized here. The balance-springs are made of Carbon-Matrix Carbon Nanotube composite (new patented material), more resistant to wear and insensitive to temperature and the impact of magnetic fields (past 15,000 Gauss). While the escapement controlling timekeeping is classically located on the dial side of the development, the second and smaller regulating organ is placed on the movement side, and consequently easily obvious through the caseback of both versions.

The strength of this new Defy El Primero 21 isn’t specifically in its recurrence or its architecture (already found in the past) yet clearly on the industrialization cycle. In fact, not just has Zenith made this innovation accessible , yet it has also considered the development in view of mass-creation. While more complex mechanical capacities are performed, a smaller number of parts are engaged with the development – from 278 for a standard El Primero 400 to just 203 on account of the Zenith Defy El Primero 21. The development is also thicker, yet not that much – 7.9 mm thick rather than the original 6.50 mm.

Zenith Defy El Primero 21 – A modernized look

This is the place where you can clearly see the Biver-influence (J.C. Biver was as of late appointed break CEO of the brand). Disregard the 38mm case with faceted drags and the 1960s look of the El Primero. It’s not just the development that’s going into the 21st century, yet also the look of the watch. The Zenith Defy El Primero 21 is based on a monobloc 44mm case (marginally tonneau-shaped) with a profoundly raised round bezel and integrated carries with straps blending elastic and leather – all of that is very suggestive of late Hublot and TAG Heuer watches. However, the DNA of the brand isn’t lost and we can in any case perceive the Zenith flair in this watch. One thing to note is the actual comfort of the Zenith Defy El Primero 21: light because of the grade 5 titanium or ceramicised-aluminum case, large yet profoundly wearable even on small wrists, thanks to well-shaped straps.

The dials are also in the vein of the Zenith creation, regardless of whether we take a gander at the standard adaptation with silver and black dial – where we can easily perceive the style of Zenith, with the classical files, hands and textual styles and marginally overlapping sub-dials – or on the skeletonized variants, something that has been utilized by the brand for certain years already – this rendition even dares to pick up two of the tones – blue and anthracite gray – of the legendary 1969 chronograph.


This new Zenith Defy El Primero 21 addresses another era for the Le Locle-based brand, which has been something of a sleeping beauty for certain years now. There’s a massive technical potential taken cover behind the blocks of this manufacture and this new watch demonstrates that greetings tech can be combined with a reasonable cost, as this 50Hz watch can be purchased for USD 10,600 (non-skeletonized/titanium rendition), USD 11,600 (skeletonized/titanium form) or USD 12,600 (skeletonized/black ceramicised-aluminum variant). The overall present day style anyway will remain a matter of personal taste.  www.zenith-watches.com .