Like the Nomos Beta and Delta, the Zeta uses a date wheel mounted outside the movement rather than stacked between the bottom plate and the dial. This allows the movement to be just as thin as the non-date Epsilon version.
The first self-winding movement by Nomos
Epsilon (without date) or Zeta (with date) is the first self-winding movement from Nomos. Because of the creation of this movement, Nomos can truly be called a manufacture, since it was completely designed, developed, and built in-house.
This calibre includes a large 31 mm central rotor which moves around the edge of the movement, allowing it to remain quite thin. It includes a bi-directional winding system. The balance wheel is very large, a traditional watchmaking technique to increase accuracy.
Zeta version 2
The first version of the Epsilon movement had 24 jewels. In May 2007, Nomos switched to a new version with 26 jewels. One wheel in the automatic winding system was set in two extra jewels, allowing better winding efficiency and durability thanks to reduced friction.