OBJECTIVE Russian patent published in 1998 - IPC

FIELD: optical instrumentation engineering. SUBSTANCE: objective has four groups of lenses the first, second and fourth groups are collecting lenses, and the third group is telescopic optical system of the Galilee type. Second and third groups of lenses are mounted for movement along optical axis. In addition, third group of lenses may be introduced into optical system and removed from it. First group of lenses has three positive components, second group has two positive and one negative components, and fourth group includes two positive components. EFFECT: more efficient construction. 2 cl, 19 dwg