Imaging lens and imaging apparatus including the imaging lens
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 negative refractive power and has a meniscus shape which is concave toward an image side, a third lens that has a meniscus shape which is convex toward the 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 predetermined conditional expressions.
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 negative refractive power and has a meniscus shape which is concave toward an image side;
a third lens that has a meniscus shape which is convex toward the 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 expressions (1) and (2-1) are satisfied:
−0.65 <f 1 /f 5<−0.05 (1),
and
−0.09 <f/f 3<0.05 (2-1),
where
f is a focal length of a whole system,
f1 is a focal length of the first lens,
f3 is a focal length of the third lens, and
f5 is a focal length of the fifth lens.
2. The imaging lens, as defined in claim 1 , wherein the following conditional expression is further satisfied:
−0.25 <f/f 2<0 (5),
where
f is the focal length of the whole system, and
f2 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:
0.5 <f ·tan ω/ R 5 r <10 (6),
where
f is the focal length of the whole system,
ω is a half angle of view, and
R5r is a paraxial radius of curvature of the image side surface of the fifth lens.
4. The imaging lens, as defined in claim 1 , wherein the following conditional expression is further satisfied:
0.05 <D 7 /f< 0.2 (7),
where
f is the focal length of the whole system, and
D 7 is a spacing on an optical axis between the third lens and the fourth lens.
5. The imaging lens, as defined in claim 1 , wherein the following conditional expression is further satisfied:
−1< f/f 5<0 (8),
where
f is the focal length of the whole system, and
f5 is the focal length 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 (9),
where
f is the focal length of the whole system, and
f1 is the focal length of the first lens.
7. 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.
8. The imaging lens, as defined in claim 1 , wherein the following conditional expression is further satisfied:
−0.6< f 1/ f 5<−0.08 (1-1),
where
f1 is the focal length of the first lens, and
f5 is the focal length of the fifth lens.
9. The imaging lens, as defined in claim 1 , wherein the following conditional expression is further satisfied:
−1<( R 1 r−R 2 f )/( R 1 r+R 2 f )<−0.5 (3-1),
where
R1r is a paraxial radius of curvature of an image side surface of the first lens, and
R2f is a paraxial radius of curvature of an object side surface of the second lens.
10. The imaging lens, as defined in claim 1 , wherein the following conditional expression is further satisfied:
0< f/f 4<0.22 (4-1),
where
f is the focal length of the whole system, and
f4 is a focal length of the fourth lens.
11. The imaging lens, as defined in claim 1 , wherein the following conditional expression is further satisfied:
−0.2 <f/f 2<0 (5-1),
where
f is the focal length of the whole system, and
f2 is a focal length of the second lens.
12. The imaging lens, as defined in claim 1 , wherein the following conditional expression is further satisfied:
0.8 <f ·tan ω/ R 5 r< 2 (6-1),
where
f is the focal length of the whole system,
ω is a half angle of view, and
R5r is a paraxial radius of curvature of the image side surface of the fifth lens.
13. The imaging lens, as defined in claim 1 , wherein the following conditional expression is further satisfied:
0.08 <D 7 /f< 0.15 (7-1),
where
f is the focal length of the whole system, and
D 7 is a spacing on an optical axis between the third lens and the fourth lens.
14. The imaging lens, as defined in claim 1 , wherein the following conditional expression is further satisfied:
−0.8 <f/f 5<−0.1 (8-1),
where
f is the focal length of the whole system, and
f5 is the focal length of the fifth lens.
15. The imaging lens, as defined in claim 1 , wherein the following conditional expression is further satisfied:
0.9 <f/f 1<1.4 (9-1),
where
f is the focal length of the whole system, and
f1 is the focal length of the first lens.
16. An imaging apparatus comprising:
the imaging lens, as defined in claim 1 .
17. 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 negative refractive power and has a meniscus shape which is concave toward an image side;
a third lens that has a meniscus shape which is convex toward the 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 expressions (1) and (2) are satisfied:
−0.65< f 1/ f 5<−0.05 (1),
and
−0.1< f/f 3<1 (2),
where
f is a focal length of a whole system,
f1 is a focal length of the first lens,
f3 is a focal length of the third lens, and
f5 is a focal length of the fifth lens, and
wherein the following conditional expression is further satisfied:
−2<( R 1 r−R 2 f )/( R 1 r+R 2 f )<−0.45 (3),
where
R1r is a paraxial radius of curvature of an image side surface of the first lens, and
R2f is a paraxial radius of curvature of an object side surface of the second lens.
18. An imaging apparatus comprising:
the imaging lens, as defined in claim 17 .
19. 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 negative refractive power and has a meniscus shape which is concave toward an image side;
a third lens that has a meniscus shape which is convex toward the 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 expressions (1) and (2) are satisfied:
0.65< f 1/ f 5<−0.05 (1),
and
−0.1< f/f 3<1 (2),
where
f is a focal length of a whole system,
f1 is a focal length of the first lens,
f3 is a focal length of the third lens, and
f5 is a focal length of the fifth lens, and
wherein the following conditional expression is further satisfied:
0< f/f 4<0.23 (4),
where
f4 is a focal length of the fourth lens.
20. An imaging apparatus comprising:
the imaging lens, as defined in claim 19 .