Imaging lens and imaging apparatus
View Patent ↗The imaging lens consists essentially of a front group that consists essentially of a negative first lens having a meniscus shape with a convex surface toward the object side, a negative second lens and a positive third lens; a stop; a positive rear group that consists essentially of one positive lens and one negative lens. When the Abbe number with respect to the d-line of the material of the first lens is νd 1 and the refractive index thereof is Nd 1 , conditional formula (1) below is satisfied: 60.0<νd1+26* Nd 1<85.0 (1).
1. An imaging lens consisting of:
a front group which consists of a negative first lens having a meniscus shape with a convex surface toward the object side, a negative second lens, a point along the optical axis at the image-side surface of which is more toward the object side than points on both ends of the effective diameter of the image-side surface, and a positive third lens;
an aperture stop; and
a rear group which is positive as a whole, in this order from the object side, wherein
the rear group consists of one positive lens and one negative lens; and
conditional formula (1) below is satisfied:
60.0<ν d 1+26 *Nd 1<85.0 (1), where
νd1: the Abbe number with respect to the d-line of the material of the first lens, and
Nd1: the refractive index with respect to the d-line of the material of the first lens, and
conditional formula (2) below is satisfied:
0.15< f 3/ L< 0.26 (2), where
f3: the focal length of the third lens, and
L: the distance from the object-side surface of the first lens to the imaging plane along the optical axis (back focus corresponds to an air converted length).
2. The imaging lens of claim 1 , wherein the third lens is of a shape with a convex surface toward the object side.
3. The imaging lens of claim 1 that satisfies conditional formula (3) below:
d 4 /L< 0.07 (3), where
d4: the distance between the second lens and the third lens along the optical axis, and
L: the distance from the object-side surface of the first lens to the imaging plane along the optical axis (the back focus corresponds to an air converted length).
4. The imaging lens of claim 1 that satisfies conditional formulas (8) below:
80.0<ν d 1+35 *Nd 1<96.0 (8), where
νd1: the Abbe number with respect to the d-line of the material of the first lens, and
Nd1: the refractive index with respect to the d-line of the material of the first lens.
5. The imaging lens of claim 1 , wherein the rear group consists of the negative lens and the positive lens in this order from the object side.
6. The imaging lens of claim 1 , wherein the positive lens and the negative lens in the rear group are cemented to each other.
7. The imaging lens of claim 6 , wherein a joint surface of the positive lens and the negative lens is of a shape with a convex surface toward the object side in a paraxial region.
8. The imaging lens of claim 6 , wherein the joint surface of the positive lens and the negative lens is of an aspherical shape in which a refractive power becomes weaker in portions further away from the optical axis.
9. The imaging lens of claim 1 , wherein a specific gravity of the material of the first lens is less than or equal to 4.0.
10. The imaging lens of claim 1 that satisfies conditional formulas (5-1) below:
ν d 3<27 (5-1 ), where
νd3: the Abbe number with respect to the d-line of the material of the third lens.
11. An imaging apparatus comprising:
the imaging lens of claim 1 .
12. An imaging lens consisting of:
a front group which consists of a negative first lens having a meniscus shape with a convex surface toward the object side, a negative second lens, a point along the optical axis at the image-side surface of which is more toward the object side than points on both ends of the effective diameter of the image-side surface, and a positive third lens;
an aperture stop; and
a rear group which is positive as a whole, in this order from the object side, wherein
the rear group consists of one positive lens and one negative lens; and
conditional formula (1) below is satisfied:
60.0<ν d 1+26 *Nd 1<85.0 (1), where
νd1: the Abbe number with respect to the d-line of the material of the first lens, and
Nd1: the refractive index with respect to the d-line of the material of the first lens, and
conditional formula (3) below is satisfied:
d 4 /L< 0.07 (3), where
d4: the distance between the second lens and the third lens along the optical axis, and
L: the distance from the object-side surface of the first lens to the imaging plane along the optical axis (the back focus corresponds to an air converted length).
13. An imaging lens consisting of:
a front group which consists of a negative first lens having a meniscus shape with a convex surface toward the object side, a negative second lens, a point along the optical axis at the image-side surface of which is more toward the object side than points on both ends of the effective diameter of the image-side surface, and a positive third lens;
an aperture stop; and
a rear group which is positive as a whole, in this order from the object side, wherein
the rear group consists of one positive lens and one negative lens; and
conditional formula (1) below is satisfied:
60.0<ν d 1+26 *Nd 1<85.0 (1), where
νd1: the Abbe number with respect to the d-line of the material of the first lens, and
Nd1: the refractive index with respect to the d-line of the material of the first lens,
wherein the rear group consists of the negative lens and the positive lens in this order from the object side.