The interesting experiments for investigation of image formation in optical microscopes have been done by E. Abbe, A. Porter and L. Mandelshtam. These experiments have become the classical ones and they are widely used for explanation of Fourier optics. The principal disadvantage of them is difference in optical schemes for observation of object images and their spatial spectrums. The proposed optical setup makes possible demonstration of two stages of image formation – obtaining a spatial spectrum and composing a magnified object image – together in one plane. This setup contains two imaging channels separated by a beam splitter after a microscope objective. The first one forms a magnified object image, the second one – an image of a spatial spectrum. These images may be observed on a screen, via eyepieces or using image sensors. Any occluding of spectrum zones becomes visible and it leads to the corresponded changes in an object image. This optical setup would be useful for optical education and research.