Imaging lens and imaging apparatus
View Patent ↗An imaging lens includes, in order from an object side, a first lens having a negative power and including a concave image-side surface, a second lens having a positive power, a stop, a third negative lens, which is a biconcave lens, a fourth lens having a positive power, and a fifth lens having a positive power and including a convex image-side surface. The imaging lens satisfies the following conditional expressions: 0.18<( D 4+ D 5)/ f <0.44, and 0.18< D 1/ f where f denotes a focal length of an entire lens system, D 1 denotes a thickness of a center of the first lens, D 4 denotes a distance from an image-side surface of the second lens to the stop on an optical axis, and D 5 denotes a distance from the stop to an object-side surface of the third lens on the optical axis.
1. An imaging lens comprising:
a first lens that has a negative power and includes a concave surface facing an image side;
a second lens having a positive power;
a stop;
a third negative lens that is a biconcave lens;
a fourth lens having a positive power; and
a fifth lens that has a positive power and includes a convex surface facing the image side,
wherein the first to fifth lenses are arranged in this order from the object side, and
the imaging lens satisfies the following conditional expressions:
0.18<( D 4 +D 5)/ f< 0.44, and
0.18 <D 1 /f
where f denotes a focal length of an entire lens system, D 1 denotes a thickness of a center of the first lens, D 4 denotes a distance from an image-side surface of the second lens to the stop on an optical axis, and D 5 denotes a distance from the stop to an object-side surface of the third lens on the optical axis.
2. The imaging lens according to claim 1 ,
wherein the second lens is a biconvex lens, and
an absolute value of a curvature radius of an object-side surface of the second lens is smaller than that of a curvature radius of the image-side surface of the second lens.
3. The imaging lens according to claim 1 ,
wherein the fourth lens is a meniscus lens or a plano-convex lens having a convex surface facing the image side.
4. The imaging lens according to claim 1 ,
wherein the fifth lens is a biconvex lens.
5. The imaging lens according to claim 1 ,
wherein the imaging lens satisfies the following conditional expression:
ν2<39
where ν 2 denotes the Abbe number of the second lens at the d-line.
6. The imaging lens according to claim 1 ,
wherein the imaging lens satisfies the following conditional expression:
16.0 mm<L<27.0 mm
where L denotes a distance from a top of an object-side surface of the first lens to an image formation surface.
7. The imaging lens according to claim 1 ,
wherein the imaging lens satisfies the following conditional expression:
5.0 mm<f<9.0 mm
where f denotes the focal length of the entire lens system.
8. The imaging lens according to claim 1 ,
wherein the imaging lens satisfies the following conditional expression:
0.2 <D 2 /f< 0.7
where f denotes the focal length of the entire lens system, and D 2 denotes an air space between the first lens and the second lens.
9. The imaging lens according to claim 1 ,
wherein the imaging lens satisfies the following conditional expression:
0.5 <Bf/f< 1.5
where f denotes the focal length of the entire lens system, and Bf denotes an air equivalent distance from a top of an image-side surface of the fifth lens to an image formation surface.
10. The imaging lens according to claim 1 ,
wherein the imaging lens satisfies the following conditional expression:
−2.2 <f 1 /f<− 1.2
where f denotes the focal length of the entire lens system, and f 1 denotes a focal length of the first lens.
11. The imaging lens according to claim 1 ,
wherein the imaging lens satisfies the following conditional expression:
0.8 <f 345 /f
where f denotes the focal length of the entire lens system, and f 345 denotes a composite focal length of the third to fifth lenses.
12. The imaging lens according to claim 1 ,
wherein the imaging lens satisfies the following conditional expression:
0.30 <|R 6 /R 7|<1.50
where R 6 denotes a curvature radius of the object-side surface of the third lens, and R 7 denotes a curvature radius of an image-side surface of the third lens.
13. The imaging lens according to claim 1 ,
wherein ν 1 is equal to or greater than 40, and ν 4 and ν 5 are equal to or greater than 35 where ν 1 denotes the Abbe number of the first lens at the d-line, ν 4 denotes the Abbe number of the fourth lens at the d-line, and ν 5 denotes the Abbe number of the fifth lens at the d-line.
14. The imaging lens according to claim 1 ,
wherein the imaging lens satisfies the following conditional expression:
0.3 <|f 12 /f 345|<1.4
where f 12 denotes a composite focal length of the first and second lenses, and f 345 denotes a composite focal length of the third to fifth lenses.
15. An imaging apparatus comprising the imaging lens according to claim 1 .
16. An imaging lens comprising:
a first lens that has a negative power and includes a concave surface facing an image side;
a second lens having a positive power;
a stop;
a third negative lens that is a biconcave lens;
a fourth lens having a positive power; and
a fifth lens that has a positive power and includes a convex surface facing an image side,
wherein the first to fifth lenses are in order from the object side, and
the imaging lens satisfies the following conditional expressions:
1.81≦N2<1.92, and
25<ν2<38
where N 2 denotes a refractive index of the second lens at a d-line, and ν 2 denotes the Abbe number of the second lens at the d-line.