Speedmaster Professional Moonwatch

In Context

At 42 mm it is sized to the current mainstream: 40 mm is the median across every watch measured in this catalogue. The case back is closed, so the movement stays out of sight, and the plexiglass crystal scratches easily but polishes back out at home, which sapphire does not. 50 m covers rain and hand-washing comfortably; it is not a watch to swim in.

The movement is hand-wound, so winding it becomes part of the day rather than something the watch does for you. 48 hours of reserve is enough to set it down on Friday evening and find it still running on Monday.

3590.50.00 stands on its own in this catalogue — no other reference here shares its base number. It pairs a black dial with a stainless steel case. Beyond the time it carries a chronograph.

The 861 is the Moonwatch movement of 1969 to 1997. It is the hand-wound chronograph that replaced the column-wheel 321 in the Speedmaster Professional and set the architecture the line kept for fifty years. It powers 15 watches in this library. Built on the Lemania 1873, it switched the chronograph with a cam and lever rather than a column wheel, which was cheaper to make and to service, and coupled it with a horizontal clutch; it beat at 21,600 vph with a 48-hour reserve at 27 mm across, with 17 jewels until 1992 and 18 after. The ref 145.022 that carried it from 1969 flew on the later Apollo missions, and the [1861](/calibers/omega-1861) of 1997 is the same movement with a rhodium-plated finish. The [chronograph piece](/blog/how-a-chronograph-engages-column-wheel-cam-and-clutch) explains the cam-and-clutch family it belongs to. In the library it powers 14 [Speedmaster Moonwatch](/brands/omega/speedmaster) references, the Alaska III and the Apollo editions among them, and one De Ville. 7 are limited editions. The [321](/calibers/omega-321-b) is the Lemania 2310-based movement it replaced, and the [3861](/calibers/omega-3861) the co-axial Master Chronometer that ended the family in 2021.

14 other watches in the library run the Omega 861.

Omega

De Ville Prestige Chronograph Stainless Steel / Silver

4840.21.00 · 36.1 mm

Omega

Speedmaster Professional Moonwatch MIR 365 Stainless Steel

3896.50.00 · 42 mm

Omega

Speedmaster Professional Two Tone Germany

DD 145.0022 · 42 mm

Omega

Speedmaster Professional Stainless Steel / Yellow Gold / Champagne / Bracelet

DD 145.0022 CHAMP · 42 mm