An apparatus for detecting movements of a sample with respect to an objective includes imaging optics which include the objective, which have an image plane and which are configured to image light from at least one reference object that is connected to the sample arranged in front of the objective into reference object images in the image plane. The apparatus further includes a camera which is arranged in the image plane of the imaging optics and which is configured to record the reference object images at consecutive points in time, and an optical device arranged between the objective and the camera in a plane that is Fourier-conjugated with respect to the image plane. The optical device is configured to mask out low spatial frequencies of reference object images which the imaging optics image into the image plane.