Zenith Chronomaster

On 10 January 1969, Zenith unveiled the El Primero in a press conference at Le Locle: an automatic chronograph movement running at 36,000 vph (5 Hz), capable of measuring 1/10-second intervals, and the world's first integrated automatic chronograph (where the chronograph mechanism is built into the base movement rather than added as a module). The launch was a milestone in horological history: in parallel, Heuer-Breitling-Buren-Dubois Dépraz launched the Cal. 11 (modular automatic chronograph) and Seiko launched the Cal. 6139 (also integrated). Industry historians have debated which was technically "first" for decades; all three reached the market within a few weeks of each other.

The original El Primero was the Cal. 3019 PHC, beating at 36,000 vph (vs the standard 21,600 or 28,800 vph of the era) and reading 1/10 of a second on the central chronograph hand. The launch wristwatch, the A386, was a 38mm steel case with a tri-coloured chronograph dial: a grey sub-counter at 3, blue at 6, white at 9, with the small seconds running on the same orange register. The A386 dial layout became the canonical El Primero visual identity that has run through the brand's catalogue for 55+ years.

In 1975, the Quartz Crisis reached its peak. Zenith's American owner (Zenith Radio Corp., then a US conglomerate) ordered the manufacture to stop producing mechanical movements and destroy the El Primero tooling. Charles Vermot, a Zenith production engineer, secretly disobeyed: he hid the El Primero plans, machinery, and tools in a sealed attic at the Le Locle factory. The tooling lay hidden for nine years. In 1984, after Zenith was reacquired by a Swiss owner and Rolex needed a high-quality automatic chronograph for the Daytona ref. 16520, Vermot revealed the hidden tooling. Rolex's Cal. 4030 (the Daytona movement, 1988-2000) was an El Primero-derived movement; the El Primero is the reason the Daytona ref. 16520 "Zenith" exists.

The modern Chronomaster catalogue centres on three primary references. The Chronomaster Original (ref. 03.3200.3600) is a faithful 38mm A386 reissue with the tri-colour dial; the Chronomaster Sport (ref. 03.3100.3600) is a 41mm sport variant with a ceramic bezel marked in 1/10-second graduations and a central chronograph hand that completes one revolution per 10 seconds; the Chronomaster Open shows the El Primero escapement through a dial cut-out. Movement is the modern El Primero 3600, beating at 36,000 vph with 60-hour power reserve. Retail spans approximately USD 9,000 (Original 38mm steel) to USD 11,000 (Sport 41mm) to USD 25,000+ (precious metal variants).