Microscope having an objective comprising a focal plane situated in a sample space and an autofocus device comprising - a light modulator configured for producing a light-emitting modulation object which is intensity-modulated periodically along a direction, - an autofocus illumination optical unit (7; 20; 7, 28) imaging the modulation object such that an image of the modulation object is produced in the sample space, - an autofocus camera (16, 18), - an autofocus imaging optical unit (7; 20; 7, 28; 20, 29) imaging the image of the modulation object situated in the sample space onto the autofocus camera (16, 18), - a control device receiving signals of the autofocus camera (16, 18), said control device being configured to ascertain an intensity distribution of the image of the modulation object and to produce therefrom a focus control signal, - wherein the light modulator additionally produces a light-emitting comparison object (R1; G2) that extends along the direction of the modulation object, - wherein the autofocus illumination optical unit (7; 20; 7, 28) also images the comparison object (R1; G2) such that an image of the comparison object (R1; G2) is produced in the sample space, and - wherein the autofocus imaging optical unit (7; 20; 7, 28; 20, 29) also images the image of the comparison object (R1; G2) situated in the sample space onto the autofocus camera (16, 18), characterized in that - the control device is configured to ascertain an intensity distribution of the image of the comparison object (R1; G2) along the direction from the signals of the autofocus camera (16, 18) and to thus correct the intensity distribution of the image of the modulation object with respect to reflectivity variations in the sample space by way of normalization, and - the comparison object has the form of a line or of a rectangular field or has the form of a grating gap, the grating constant of which is below the resolution limit of the autofocus imaging optical unit (7; 20; 7, 28; 20, 29). - a light modulator configured for producing a light-emitting modulation object which is intensity-modulated periodically along a direction, - an autofocus illumination optical unit (7; 20; 7, 28) imaging the modulation object such that an image of the modulation object is produced in the sample space, - an autofocus camera (16, 18), - an autofocus imaging optical unit (7; 20; 7, 28; 20, 29) imaging the image of the modulation object situated in the sample space onto the autofocus camera (16, 18), - a control device receiving signals of the autofocus camera (16, 18), said control device being configured to ascertain an intensity distribution of the image of the modulation object and to produce therefrom a focus control signal, - wherein the light modulator additionally produces a light-emitting comparison object (R1; G2) that extends along the direction of the modulation object, - wherein the autofocus illumination optical unit (7; 20; 7, 28) also images the comparison object (R1; G2) such that an image of the comparison object (R1; G2) is produced in the sample space, and - wherein the autofocus imaging optical unit (7; 20; 7, 28; 20, 29) also images the image of the comparison object (R1; G2) situated in the sample space onto the autofocus camera (16, 18), - the control device is configured to ascertain an intensity distribution of the image of the comparison object (R1; G2) along the direction from the signals of the autofocus camera (16, 18) and to thus correct the intensity distribution of the image of the modulation object with respect to reflectivity variations in the sample space by way of normalization, and - the comparison object has the form of a line or of a rectangular field or has the form of a grating gap, the grating constant of which is below the resolution limit of the autofocus imaging optical unit (7; 20; 7, 28; 20, 29).