During the last ten years the Max-Planck-Institut fur Astronomie (MPIA) has installed four large telescopes at its observatory on Calar Alto, Spain, which is operated jointly with the Spanish National Commission for Astronomy as the German-Spanish Astronomical Center. Figure 1 shows the domes of the 1.2 m, 2.2 m, and 3.5 m telescopes of Ritchey-Chrétien type and the dome of the Schmidt Telescope. They all are Zeiss telescopes, the former three coming from Oberkochen, the latter one from Jena.