ASPHERICAL ZOOM LENS

Japanese Patent JPH04275516

A

PURPOSE:To provide the high-performance aspherical zoom lens which is reducible in size and weight with an extremely small number of elements. CONSTITUTION:The aspherical zoom lens consists of a 1st group G1 as a focusing part having positive refracting power, a 2nd group G2 as a variator part which has negative refracting power and varies the power by moving on the optical axis, a 3rd group G3 as a compensator part which holds an image plane moving owing to the movement of the variator part at a constant position about a reference surface, and a relay lens system connected to the power variation system that the 1st, 2nd, and 3rd groups form, and a relay lens system consists of a 4th group G4 composed of a single lens which has an aspherical surface and positive refracting power and a 5th group G5 composed of a negative lens and two biconvex positive lenses at a large interval and satisfies inequalities mentioned below. Namely, 1.8fw