| 摘要 |
PROBLEM TO BE SOLVED: To provide a variable magnification optical system that properly corrects aberration while the entire length is reduced relative to an image height. SOLUTION: The variable optical system with a variable power ratio of 2.5 or more includes, in order from the object side, at least a first lens group of negative refractive power and a second lens group of positive refractive power, and satisfies the following conditional expressions (1) and (2): (1) 0.44≤�fv�/(fw×ft)<SP>1/2</SP>≤0.61 and (2) 0.5≤�fv�/(fw×ft)<SP>1/2</SP>≤1.05, wherein fv is the focal distance of the lens group having a variable power action, f1 is the focal distance of the first lens group, fw is the focal distance of the optical system at a wide angle end, and ft is the focal distance of the optical system at a telephoto end. COPYRIGHT: (C)2011,JPO&INPIT |
