A condenser arrangement for brightfield illumination and/or darkfield illumination for optical microscopes comprises in a housing basic optics having at least one lens, at least one front optics which can be inserted into the illumination beam path in front of the basic optics, and means for inserting the front optics into the illumination beam path of the microscope. A first swiveling arm and a second swiveling arm are swivelably arranged at the housing of the condenser. The first swiveling arm carries first front optics with a high aperture for brightfield illumination and the second swiveling arm carries second front optics for darkfield illumination. The two swiveling arms are arranged at a defined distance from the shared basic optics of the condenser in direction of the optical axis of the illumination beam path. An aperture iris diaphragm is provided on the object side in front of the basic optics and is opened when the cardioid optics are inserted. Further, a darkfield slide with an annular mirror element is provided on the object side at the housing. Operator's controls serve to swivel the two swiveling arms for moving the darkfield slide and for adjusting the aperture iris diaphragm.