| 摘要 |
A zoom lens comprises in order from an object side,
a first lens unit having a positive refractive power,a second lens unit having a negative refractive power, anda third lens unit having a positive refractive power, andthe third unit having a positive refractive power comprises in order from the object side,a first lens component having a positive refractive power, anda second lens component having a negative refractive power in which, a lens having a positive refractive power and a lens having a negative refractive power are cemented, andthe zoom lens satisfies the following conditional expressions (1), (2), and (3);1.4<|f3_2p/f3_2n|<2.6 (1);nd3_2p−nd3_2n≧0 (2);nd3_2n≧1.8 (3) |
| 主权项 |
1. A zoom lens comprising in order from an object side:
a first lens unit having a positive refractive power; a second lens unit having a negative refractive power; and a third lens unit having a positive refractive power, wherein the third lens unit having a positive refractive power comprises in order from the object side, a first lens component having a positive refractive power, a second lens component having a negative refractive power in which, a lens having a positive refractive power and a lens having a negative refractive power are cemented, a third lens component, and a fourth lens component, and the zoom lens satisfies the following conditional expressions (2b) and (4)
nd3_2p−nd3_2n≧−0.2 (2b)Σd3G/ft<0.42 (4) where, nd3_2p denotes a refractive index for a d-line of the lens having a positive refractive power, in the second lens component having a negative refractive power, in the third lens unit having a positive refractive power, and nd3_2n denotes a refractive index for the d-line of the lens having a negative refractive power, in the second lens component having a negative refractive power, in the third lens unit having a positive refractive power, Σd3G denotes a total length (not including an aperture) of the third lens unit, and ft denotes a focal length at a telephoto end of the overall zoom lens system. |
