| 摘要 |
A zoom lens 1 includes, in the order starting from the object side to the side of an image plane I, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, a third lens group G3 having negative refractive power, and a fourth lens group G4 having positive refractive power. The fourth lens group G4 includes, in the order starting from the side closest to the image plane to the object side, a first positive lens L46, a first negative lens L45, a second negative lens L44 and a second positive lens L43. The fourth lens group G4 has a configuration that satisfies the following conditional expression (1) when νdP1 represents an Abbe number of the first positive lens L46 and νdN1 represents an Abbe number of the first negative lens L45: ;−40<νdP1−νdN1<0 (1) |
| 主权项 |
1. A zoom lens comprising: a first lens group having positive refractive power; a second lens group having negative refractive power; a third lens group having negative refractive power; and a fourth lens group having positive refractive power, the first to fourth lens groups being arranged in the order starting from an object side to an image plane side, wherein
in magnification change, the second and third lens groups are moved so that intervals between the first and second lens groups, between the second and third lens groups and between the third and fourth lens groups are changed, the fourth lens group includes, in the order starting from the side closest to the image plane to the object side, a first positive lens, a first negative lens, a second negative lens and a second positive lens, and when an Abbe number νd is a value obtained by (nd−1)/(ng−nC) where a refractive index relative to d-line is nd, a refractive index relative to g-line is ng, and a refractive index relative to C-line is nC, in terms of a material that forms the lenses, and when the Abbe number of the first positive lens is νdP1 and the Abbe number of the first negative lens is νdN1, the following conditional expression (1) is satisfied:
−40<νdP1−dN1<0 (1) |
