A conception of an adaptive telescope optical system with the segmented primary spherical mirror having a diameter of 10 m is proposed. The system consists of four mirrors. The first two mirrors form a strictly afocal system with angular magnification of 4.2X. The second convex aspherical mirror has a diameter of 2.34 m. The next two mirrors, having diameters 2.52 and 0.51 m, respectively, form a focusing system with a focal length of 23.77 m. The focal length of entire system is 100 m; the length is 13.5 m, the angular field is 10 arcmin, its theoretical resolution is 0.1 arcsec. Alternatives for the main system arising due to changing of shape and relative position of mirrors of the focusing system are considered.