an image pick - up apparatus including an image sensor with a matrix of radiation - sensitive elements , notably a ccd image sensor , is provided with a control circuit for selecting gate electrodes as collecting gate electrodes or as isolating gate electrodes by application of an electric potential of suitable polarity . groups of collecting gate electrodes are separated from one another by isolating gate electrodes . the surface area of such a group of collecting gate electrodes co - determines the modulation transfer function and hence the spatial resolution of the image sensor ; this surface area , and hence the spatial resolution , can be adjusted by adjustment of the electric potentials . notably the spatial resolution can be rendered dependent on the different modes of operation of the image pick - up apparatus , for example when the image pick - up apparatus forms part of an x - ray examination apparatus which is suitable for fluoroscopy as well as for making x - ray images . furthermore , the spatial resolution can be adjusted so that it differs in different directions . in the case of an image pick - up apparatus including a plurality of image sensors , each of which picks up the same image , be it with a shift relative to one another , an image is composed from the images supplied by the various image sensors . differentiation of the spatial resolutions of the images constituting the composite image enables a spatial resolution in the composite image to be achieved which is the same and higher in all directions .