Zoom lens

Abstract

Abstract PURPOSE:To obtain a compact zoom lens effectively compensated at its aberration of distortion and comma over the whole power modification range while keeping high modified power by specifying the constitution of a lens group. CONSTITUTION:The zoom lens is formed by a lens group G1 having positive refractive power, a lens group G2 having negative refractive power and lens groups G3, G4 having positive refractive power arranged successively from the object side and power modification is attained by changing the air interval between respective groups. The lens group G4 has negative refractive power when the radiuses of curvature of lens surfaces on the object and image sides are defined as R1 and R2 respectively and includes a meniscus-like lens K42 turning its convex surface to the object side. When it is defined that the shortest and longest focal distances of the whole system are (fw) and (ft), the focal distances of the lens groups G1, G2 are f1 and f2 and the synthetic focal distance of the lens groups G3, G4 when the whole system is in the shortest focal distance state is f34, an objective zoom lens is obtained when 0.25<fw/f1<0.6, 0.25<f2/fw<0.6, 0.15<f34/ft<0.35 and -5.0<(R2+R1)/(R2-R1)<-1.0 are satisfied.

Inventors

• 👤 Kenji Hori
• 👤 健治 堀

Bibliographic Details