Imaging lens and imaging apparatus including the imaging
View Patent ↗An imaging lens substantially consists of, in order from an object side, five lenses of a first lens that has a positive refractive power and has a meniscus shape which is convex toward the object side, a second lens that has a biconcave shape, a third lens that has a meniscus shape which is convex toward an image side, a fourth lens that has a positive refractive power, and a fifth lens that has a negative refractive power and has at least one inflection point on an image side surface. Further, the imaging lens satisfies a predetermined conditional expression.
1. An imaging lens consisting of, in order from an object side, five lenses of:
a first lens that has a positive refractive power and has a meniscus shape which is convex toward the object side;
a second lens that has a biconcave shape;
a third lens that has a meniscus shape which is convex toward an image side;
a fourth lens that has a positive refractive power; and
a fifth lens that has a negative refractive power and has at least one inflection point on an image side surface,
wherein the following conditional expression (1) is satisfied:
−0.06 <f 1 /f 3<0.4 (1),
where
f 1 is a focal length of the first lens, and
f 3 is a focal length of the third lens.
2. The imaging lens, as defined in claim 1 , wherein the following conditional expression is further satisfied:
−0.65 <f/f 2<−0.2 (2),
where
f is a focal length of a whole system, and
f 2 is a focal length of the second lens.
3. The imaging lens, as defined in claim 1 , wherein the following conditional expression is further satisfied:
−0.2<( R 3 f−R 3 r )/( R 3 f+R 3 r )<0.2 (3),
where
R 3 f is a paraxial radius of curvature of an object side surface of the third lens, and
R 3 r is a paraxial radius of curvature of an image side surface of the third lens.
4. The imaging lens, as defined in claim 1 , wherein the following conditional expression is further satisfied:
−1 <f/f 5<−0.3 (4),
where
f is a focal length of a whole system, and
f 5 is a focal length of the fifth lens.
5. The imaging lens, as defined in claim 1 , wherein the following conditional expression is further satisfied:
1 <f ·tan ω/ R 5 r< 10 (5),
where
f is a focal length of a whole system,
ω is a half angle of view, and
R 5 r is a paraxial radius of curvature of an image side surface of the fifth lens.
6. The imaging lens, as defined in claim 1 , wherein the following conditional expression is further satisfied:
0.8 <f/f 1<1.6 (6),
where
f is a focal length of a whole system, and
f 1 is the focal length of the first lens.
7. The imaging lens, as defined in claim 1 , wherein the following conditional expression is further satisfied:
−0.3 <f/f 3<0.5 (7),
where
f is a focal length of a whole system, and
f 3 is the focal length of the third lens.
8. The imaging lens, as defined in claim 1 , wherein the following conditional expression is further satisfied:
0 <f/f 34<0.7 (8),
where
f is a focal length of a whole system, and
f 34 is a composite focal length of the third lens and the fourth lens.
9. The imaging lens, as defined in claim 1 , wherein the third lens has a positive refractive power.
10. The imaging lens, as defined in claim 1 , wherein the following conditional expression is further satisfied:
0.05 <D 7 /f< 0.3 (9),
where
f is a focal length of a whole system, and
D 7 is a spacing on an optical axis between the third lens and the fourth lens.
11. The imaging lens, as defined in claim 1 , further comprising an aperture stop that is disposed on the object side of an object side surface of the second lens.
12. The imaging lens, as defined in claim 1 , wherein the following conditional expression is further satisfied:
−0.055 <f 1 /f 3<0.3 (1-1),
where
f 1 is the focal length of the first lens, and
f 3 is the focal length of the third lens.
13. The imaging lens, as defined in claim 1 , wherein the following conditional expression is further satisfied:
−0.64 <f/f 2<−0.25 (2-1),
where
f is a focal length of a whole system, and
f 2 is a focal length of the second lens.
14. The imaging lens, as defined in claim 1 , wherein the following conditional expression is further satisfied:
−0.16<( R 3 f−R 3 r )/( R 3 f+R 3 r )<0.15 (3-1),
where
R 3 f is a paraxial radius of curvature of an object side surface of the third lens, and
R 3 r is a paraxial radius of curvature of an image side surface of the third lens.
15. The imaging lens, as defined in claim 1 , wherein the following conditional expression is further satisfied:
−0.8 <f/f 5<−0.35 (4-1),
where
f is a focal length of a whole system, and
f 5 is a focal length of the fifth lens.
16. The imaging lens, as defined in claim 1 , wherein the following conditional expression is further satisfied:
1.3 <f ·tan ω/ R 5 r< 3 (5-1),
where
f is a focal length of a whole system,
ω is a half angle of view, and
R 5 r is a paraxial radius of curvature of an image side surface of the fifth lens.
17. The imaging lens, as defined in claim 1 , wherein the following conditional expression is further satisfied:
1 <f/f 1<1.5 (6-1),
where
f is a focal length of a whole system, and
f 1 is the focal length of the first lens.
18. The imaging lens, as defined in claim 1 , wherein the following conditional expression is further satisfied:
−0.1 <f/f 3<0.4 (7-1),
where
f is a focal length of a whole system, and
f 3 is the focal length of the third lens.
19. The imaging lens, as defined in claim 1 , wherein the following conditional expression is further satisfied:
0 <f/f 34<0.6 (8-1),
where
f is a focal length of a whole system, and
f 34 is a composite focal length of the third lens and the fourth lens.
20. An imaging apparatus comprising:
the imaging lens, as defined in claim 1 .