A microscope including an illumination objective with a first optical axis, embodied to produce a light sheet, and a detection objective with a second optical axis, embodied to detect light coming from the specimen plane. The illumination objective and the detection objective are aligned relative to one another and the specimen plane so that the first and second optical axes intersect in the specimen plane and include a substantially right angle therebetween. The optical axes each include an angle which differs from zero with a reference axis directed orthogonal to the specimen plane. An overview illumination apparatus for wide-field illumination of the specimen plane, includes an illumination optical unit with a third optical axis. The characterizing feature is that the detection objective is provided to detect both light from the light sheet and light from the illumination optical unit. A method is also provided for operating a light sheet microscope.