The 50' telescope manufactured in 1908 by Karl Ziess firm, Germany, was delivered to the Crimean Astrophysical Observatory on reparation after the Second War from Germany in return of the blasted 1 m Simeiz telescope. The 50' telescope has very original mechanical construction and two broken Cassegrain foci.

In the beginning of 50-s it has been installed in Nauchny and for a decade it was the largest telescope in the Soviet Union. A wide program of stellar spectra studing has been carried out with this instrument aimed to develop a system of classification of stellar spectra (I.M.Kopylov), to investigate a structure of Be-star (A.A.Boyarchuk), to determine chemical compositions of atmospheres of different types of stars (E.R.Mustel and colleagues). The widest known result obtained with this telescope is the discovery of the volcanic eruption on the Moon detected in 1958 by N.A.Kozyrev.

Now the 50' telescope is used by the Dr.Zhilyaev's team from the Main Astronomical observatory of Academy of Sciences of Ukraine to study the flare activity of red dwarf stars.