| 摘要 |
<p>[Problem] To provide a variable magnification optical system which has a variable magnification of approximately 3X, including wide-angle to telephoto regions, which can be constituted inexpensively and in a compact manner, and which assures high high optical performance while having a large lens diameter. [Solution] The variable magnification optical system comprises: a first lens group (G1) having a negative refractive power; an aperture; and a second lens group (G2) having a positive refractive power. When varying the magnification from the wide angle end to the telephoto end, the gap between the first lens group (G1) and second lens group (G2) in the direction of the optical axis is reduced. The aperture is fixed with respect to the image surface while varying magnification, and the first lens group (G1) comprises, in order from the object side, a positive lens (L1), a negative lens (L2), a negative lens (L3) and a positive meniscus lens (L4) having the protruding surface facing the object side. A predetermined conditional expression concerning the average Abbe number in the d line of the positive meniscus lens (L4) and the positive lens (L1) of the first lens group (G1), the focal length of the entire system at the wide-angle end, and the focal length of the negative lens (L2), is satisfied.</p> |
