A rotary encoder system for registering the rotary angle position and/or angular speed of a rotary shaft which extends along an axis of rotation, including at least two optical marks at the rotary shaft, an optical sensor with a pixel matrix having pixel points, an imaging device for imaging each mark in a substantially axial direction on the pixel matrix as a mark image, and an evaluation device for reading and evaluating the pixel matrix in order to determine data in relation to the rotary angle position and/or angular speed. Further, the marks, the imaging device and pixel points are embodied in such a way that the mark images on the pixel matrix have at least the area of a pixel point, and the evaluation device is embodied to establish the location of the centroids of the mark images on the pixel matrix.