Calibre 1045 — the Speedmaster's Lemania 5100

In brief

Sinn, Fortis and Tutima all built on the Lemania 5100; the 1045 is Omega's version of it. A sturdy automatic chronograph with a central minute counter, day-date and a fixed 24-hour hand — more functional than elegant, and prized for its reliability.

Short history

Omega put the calibre into the Speedmaster that collectors nickname the "Mark 4.5", references 176.00xx, launched in 1974, and later into the Mark V. The Lemania 5100 base it works from was the same ébauche that Sinn, Fortis and Tutima used.

Watches that used it

• Speedmaster "Mark 4.5" (ref. 176.00xx)
• Speedmaster Mark V