A focusing method is provided for the high speed digitalization of microscope slides using an imaging device, wherein the slide is divided into fields of view according to the imaging device and focusing is performed. During rough focusing, several images are captured within the focus range using large focus steps. On the basis of this set of images the position of the best contrast is determined. Fine focusing is performed by adjusting the focus according to the focus distance already determined for another field of view and by focusing with fine steps. A slide displacing device is provided, which enables the displacement of a slide parallel to the optical axis. The slide displacing device includes slide holding elements affixed to one side of a supporting member having two parallel sides, which are connected by stiffening elements defining at least two parallel planes.