====== Omega 861 ======
{{wst>image_cr|Lemania|1873}}

**Calibre 861** is a [[manual winding]] [[chronograph]] movement from [[Omega]] produced since [[1968]].

===== History =====
[[Lemania]] created [[Lemania 1872|a family]] of [[cam switching]] [[chronograph]] movements in the 1960s just as chronograph watches were becoming more popular in the mass market. The [[Lemania 1873|Lemania Calibre 1873]] was part of a family of similar 12 [[ligne]] movements, running at 21,600 A/h and lacking modern features like [[hacking seconds]] or [[automatic winding]]. In [[1968]], [[Omega]] selected the Lemania 1873 as the basis for their **Cal. 861**, used in the [[Omega Speedmaster Professional]] line of watches. These feature a 30 minute chronograph counter at 3 00, a 12 hour counter at 6 00, and [[small seconds]] at 9 00.

The Omega 861 (and similar **Cal. 863**) differ from the Lemania base mainly in decoration. They used 17 [[jewel]]s through [[1992]] before being reissued and updated with 18 jewels in [[1993]]. **Cal. 1861** and **1863** are [[rhodium]] plated. Cal. 863 and 1863 differ in decoration as well They feature more elaborate finishing for use in watches with [[display caseback]]s.

===== Movement Family =====
  * Cal. 860 (1968-) - 17 jewels, no 12 hour counter
    * Cal. 861 (1968-1992) - 17 jewels
    * Cal. 862 (1968-) - 21 jewels
    * Cal. 863 (1980-1987) - [[Rose gold]] plated and decorated, 21 jewels
    * Cal. 865 (1967-1968) - 17 jewels, [[monopusher]], no counters
    * Cal. 866 (1968-1992) - [[Moon phase indicator]] at 12 00 and [[date]]
    * Cal. 910 (1969-1971) - Adds 24-hour [[second timezone]] set by pusher
      * Cal. 911 (1971-1972) - [[Small seconds]]
    * Cal. 920 (1968-1970) - [[Monopusher]] with no counters, date
    * Cal. 930 (1969-1970) - [[Bullhead]] version
  * Cal. 861 (1992-1996) - 18 jewels
    * Cal. 863 (1993-1996) - [[Yellow gold]] plated and decorated, 21 jewels
    * Cal. 864 (1992) - [[Chronometer]] rated
    * Cal. 866 (1985-1988) - [[Moon phase indicator]] at 12 00 and [[date]]
    * Cal. 867 (1992-1994) - [[Skeletonized]] by [[Armin Strom]], 21 jewels
  * Cal. 1861 (1996-) - [[Rhodium]] plating, 18 jewels
    * Cal. 1863 (1994-) - [[Gold plated]] and decorated
    * Cal. 1866 (1999-) - [[Moon phase indicator]] at 12 00 and [[date]]
      * Cal. 3604 A (2003) - [[Skeletonized]] Cal. 1866
  * [[Omega 3861|Cal. 3861]] (2019-present) - [[Co-axial]] escapement, [[silicon]] balance spring, [[anti-magnetic]], [[chronometer]] rated


<WRAP ud ud_mov>

**Description:**
  * [[Manual winding]] movement, [[chronograph]]

**Functions:**
  * Hours, Minutes
  * [[Small seconds]] at 9 00
  * [[Chronograph]] 30 minutes counter at 3 00, 12 hour counter at 6 00

**Data:**
  * 12 [[ligne]]s
  * D 27 mm, H 6.87 mm
  * 17 or 18 [[jewels]]
  * 21,600 A/h
  * Power reserve 40 Hours

**Production period:**
  * [[1968]]-Present
</WRAP>
===== External Links =====
  * [[http://www.chronomaddox.com/moonwatch_cal_background.html|Speedmaster "Moonwatch" Movements: Background information]]
  * [[http://www.omega-addict.com/movement.html|Omega Movements]]


{{tag>Movements Lemania_calibres Manual_winding_movements Chronograph_movements Omega_chronograph_calibres}}