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Omega 501

Probable

One of the calibers behind the first Seamaster 300. The 500 series is a family of closely related movements distinguished mainly by calendar work and jewel count, and the family members are frequently confused with one another in listings; read the caliber number stamped on the movement rather than inferring it from the reference.

Specifications

Movement manufacturer
Omega
Production
1956–1963
Frequency
19,800 vph (2.75 Hz)
Jewels
20
Winding
automatic
Complications
Centre seconds

Architecture

Automatic with a full rotor and Omega's own going train, from the 500 series that replaced the earlier bumper automatics. Centre seconds, no date on the 501 itself.

Service practice

Sixty-year-old automatic winding assemblies are routinely rebuilt with later parts from within the same family. A 500-series movement carrying a mixture of period-correct components is a service history, not a finding against the watch.

Related calibers

References using this caliber

Provenance of this record

Sources & Evidence

Primary sourceManufacturer archive

OMEGA Vintage Database

OMEGA SA

Accessed
2026-08-18

Cited for

This referenceProbable
View source ↗
Secondary sourceCollector research

Ranfft Watch Movement Archive

Dr. Roland Ranfft (archived and maintained by volunteers)

Accessed
2026-08-18

Cited for

This referenceProbable
View source ↗

Last verified: Not yet reviewed