Imaging lens and imaging apparatus
View Patent ↗An imaging lens is provided and includes: in order from the object side, a first lens having a concave surface on an image side thereof; a second lens of a negative lens having a concave surface on the image side and having at least one aspheric surface; a third lens having at least one aspheric surface; and a fourth lens of a positive lens having a convex surface on the image side and having at least one aspheric surface. A stop is disposed between the third lens and the fourth lens. In addition, assuming that a focal length of the whole system is f and a focal length of the first lens L 1 is f 1 , the following Conditional Expression (1) is satisfied. 15.0<| f 1/ f| (1)
1. An imaging lens comprising: in order from an object side thereof,
a first lens having a concave surface on an image side thereof;
a second lens of a negative lens having a concave surface on the image side and having at least one aspheric surface;
a third lens having at least one aspheric surface;
a stop;
a fourth lens of a positive lens having a convex surface on the image side and having at least one aspheric surface,
wherein the following Conditional Expression (1) is satisfied:
15.0 <|f 1 /f| (1)
wherein f represents a focal length of the imaging lens, and f1 represents a focal length of the first lens.
2. The imaging lens according to claim 1 , wherein the following Conditional Expression (2) is satisfied:
N1≦1.7 (2)
wherein N 1 represents a refractive index of the first lens at the d-line.
3. The imaging lens according to claim 1 , wherein the following Conditional Expression (3) is satisfied:
ν1<60 (3)
wherein ν1 represents an Abbe number of the first lens at the d-line.
4. The imaging lens according to claim 1 , wherein the following Conditional Expression (4) is satisfied:
0.2 <|f 12 /f 34|<1.0 (4)
wherein f12 represents a composite focal length of the first lens and the second lens, and f34 represents a composite focal length of the third lens and the fourth lens.
5. The imaging lens according to claim 1 , wherein the following Conditional Expression (5) is satisfied:
5.0 <|f 1 /f 2| (5)
wherein f2 represents a focal length of the second lens.
6. The imaging lens according to claim 1 , wherein the second lens has an image side surface having a negative power at a center thereof and a smaller negative power at an effective diameter edge thereof than that at the center.
7. The imaging lens according to claim 1 , wherein the following Conditional Expression (6) is satisfied:
2.0 <|RX 4 |/|R 4| (6)
wherein |R 4 | represents an absolute value of a radius of curvature at a center of an image side surface of the second lens, and |RX 4 | represents an absolute value of a radius of curvature of at an effective diameter edge of the image side surface of the second lens.
8. The imaging lens according to claim 1 , wherein the following Conditional Expression (7) is satisfied:
8.0 <L/f< 13.0 (7)
wherein L represents a distance on an optical axis from an object side surface of the first lens to an imaging plane of the imaging lens.
9. The imaging lens according to claim 1 , wherein the following Conditional Expression (8) is satisfied:
1.0 <Bf/f< 2.5 (8)
wherein Bf represents a distance on an optical axis from an image side surface of a lens closest to the image side to the imaging plane of the imaging lens.
10. The imaging lens according to claim 1 , wherein the following Conditional Expression (9) is satisfied:
0.9 <D 1 (9)
wherein D 1 represents a center thickness of the first lens.
11. An imaging apparatus comprising an imaging lens according to claim 1 .