The present disclosure relates to a rotary adjuster, including: a housing, a rotary knob mounted in a rotatable manner about a rotation axis (A) on the housing; an optical detection device for detecting a rotary position of the rotary knob and a coding shutter moving synchronously with the rotary knob, wherein the detection device has an optical transmitter and an array of optical receivers, and wherein the coding shutter and the detection device are designed to detect the rotary position of the rotary knob by means of the number of the receivers of the array illuminated by the transmitter and/or by means of an illumination intensity of one or more receivers of the array.