| 摘要 |
PROBLEM TO BE SOLVED: To provide a variable-magnification optical system having compact size and low in cost and has high optical performance which gains a high-quality image, while maintaining a large aperture ratio and a high variable magnification ratio. SOLUTION: The variable-magnification optical system includes a first lens group G1 having negative refractive power; a diaphragm; and a second lens group G2 having positive refractive power, these being sequentially arranged in this order from an object side. The system changes interval in an optical axial direction between the first lens group G1 and the second lens group G2 to perform variable magnification and moves the first lens group G1 in the optical axial direction to conduct the correction of an image plane position which is associated with the variable magnification. The first lens group G1 is constituted of three lenses, that is, a meniscus-shaped negative lens L1, a positive lens L2 and a negative lens L3, the lenses being arranged sequentially in this order from the object side. The variable-magnification optical system is constituted so that it satisfies a conditional expression (1), which relates to the lens face S6 on the image side of the negative lens L3 of the first lens group G1. COPYRIGHT: (C)2011,JPO&INPIT |
