Omega
Omega cal 1861
Swiss lever · introduced 1968
Beat rate
21,600 vph
Power reserve
48h
Jewels
18
Introduced
1968
Escapement
Swiss lever
Derived from the Lemania 1873, the cal 1861 is the rhodium-plated 1996 evolution of the cal 861, and it remained in the standard Moonwatch Professional until 2021. Its lever escapement, cam-actuated chronograph, and lateral clutch are traditional but robustly proven. The cam replaced the column wheel of the earlier cal 321 in 1968, a simplification made for serviceability and mass production. The movement was chosen for its resistance to vacuum and temperature extremes, not for precision timekeeping metrics.
Specifications
Beats per hour
21,600
Jewels
18
Power reserve
48h
Diameter
28.0mm
Height
6.4mm
Escapement
Swiss lever
Introduced
1968
Finishing
Commercial
Service interval
8 years
Service cost tier
Mid-range
Complications
chronographmanual wind
Known service issues
- Chronograph return-to-zero mechanism wear on heavily used examples
- Cam and operating levers require careful inspection at service; wear here is a common culprit for start/stop timing issues
Notable in
- Omega Speedmaster Professional Moonwatch 3570.50
- Omega Speedmaster Professional 145.0022
- Omega Speedmaster Apollo 11 50th Anniversary (1861 version)
Buying advice
Practical guides for buying a watch with this caliber on the pre-owned market: