The present invention relates to an illuminating device for an operating microscope including two observation beam paths for a first observer and two observation beam paths for a second observer. An illuminating system provides two parallel illuminating beam paths and a deflecting device, for deflecting the parallel illuminating beam paths onto an object that is to be observed. The deflecting device includes a first semitransparent deflector element which is associated with a first observation beam path of the first observer and a first observation beam path of the second observer, and a second semitransparent deflector element, which is associated with a second observation beam path of the first observer and a second observation beam path of the second observer. The first illuminating beam path acts exclusively on the first deflector element and the second illuminating beam path acts exclusively on the second deflector element.