Using Kepler's telescope, an image of the lunar surface is observed. In front of the tube lens there is a circular diaphragm of variable diameter. As the aperture diameter increases, the illumination of the Moon image on the retina gradually increases until the aperture diameter exceeds 30 mm. At D > 30 mm, the image brightness does not depend on the aperture value. Taking the pupil diameter of the eye to be 3 mm, determine the magnification of the tube.

Answer. Format gif