| 摘要 |
An imaging lens includes: a first lens group; an aperture stop; and a second lens group having a positive refractive power, in this order from an object side. The first lens group includes a negative first lens provided most toward the object side. The second lens group includes a positive lens, provided most toward an imaging surface, and a negative lens having a concave surface and an aspherical surface at least toward the object side. The following Conditional Formulae are satisfied:;0.03<(|Sagsp1|−|Sagas1|)/Re1<0.35; and;1.819≦NdAB wherein Sagsp1 is the sag of a reference spherical surface at the edge of the effective diameter of the object side surface of the negative lens, Sagas1 is the sag of the aspherical surface of the lens, Re1 is the effective diameter of the object side surface of the lens, and NdAB is the average refractive index of the positive lens and the negative lens. |
| 主权项 |
1. An imaging lens, substantially consisting of:
a first lens group having a negative or a positive refractive power; an aperture stop; and a second lens group having a positive refractive power, provided in this order from an object side; the first lens group at least including a negative lens provided most toward the object side; the second lens group including a lens A having a positive refractive power, provided most toward the side of an imaging surface, and a lens B having a negative refractive power, an aspherical lens surface at least toward the object side, and a concave surface toward the object side, provided adjacent to and toward the object side of the lens A; the imaging lens satisfying Conditional Formulae (1) and (2) below:
0.03<(|Sagsp1|−|Sagas1|)/Re1<0.35 (1)1.819≦NdAB (2) wherein Sagsp1 is the amount of sag of a reference spherical surface at the edge of the effective diameter of the surface of the lens B toward the object side, Sagas1 is the amount of sag of the aspherical surface of the lens B, Re1 is the effective diameter of the lens surface of the lens B toward the object side, and NdAB is the average refractive index of the lens A and the lens B. |
