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 the object 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 is convex toward the object side, and a fifth lens that has a negative refractive power and has at least one inflection point on an image side surface.
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 the object 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 is convex toward the object side; and
a fifth lens that has a negative refractive power and has at least one inflection point on an image side surface.
2. The imaging lens, as defined in claim 1 , wherein the following conditional expression is further satisfied:
−2< f/f 345<−0.25 (1), where
f is a focal length of a whole system, and
f345 is a composite focal length of the third to fifth lenses.
3. The imaging lens, as defined in claim 1 , wherein the following conditional expression is further satisfied:
0.2<( R 4 f+R 3 r )/( R 4 f−R 3 r )<1.6 (2), where
R3r is a paraxial radius of curvature of an image side surface of the third lens, and
R4f is a paraxial radius of curvature of an object side surface of the fourth lens.
4. The imaging lens, as defined in claim 1 , wherein the following conditional expression is further satisfied:
−0.5< f 1/ f 3<1 (3), where
f1 is a focal length of the first lens, and
f3 is a focal length of the third lens.
5. The imaging lens, as defined in claim 1 , wherein the following conditional expression is further satisfied:
−0.5<( R 3 f−R 3 r )/( R 3 f+R 3 r )<0.3 (4), where
R3f is a paraxial radius of curvature of an object side surface of the third lens, and
R3r is a paraxial radius of curvature of the image side surface of the third lens.
6. 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 (5), where
f is a focal length of a 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.
7. The imaging lens, as defined in claim 1 , wherein the following conditional expression is further satisfied:
−2< f/f 5<−0.2 (6), where
f is a focal length of a whole system, and
f5 is a focal length of the fifth lens.
8. The imaging lens, as defined in claim 1 , wherein the following conditional expression is further satisfied:
0.8< f/f 1<2.5 (7), where
f is a focal length of a whole system, and
f1 is a focal length of the first lens.
9. The imaging lens, as defined in claim 1 , wherein the following conditional expression is further satisfied:
−0.8< f/f 3<0.3 (8), where
f is a focal length of a whole system, and
f3 is a focal length of the third lens.
10. 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.
11. The imaging lens, as defined in claim 1 , wherein the third lens has a positive refractive power.
12. The imaging lens, as defined in claim 1 , wherein the third lens has a negative refractive power.
13. The imaging lens, as defined in claim 1 , wherein the following conditional expression is further satisfied:
−1.8< f/f 345<−0.3 (1-1), where
f is a focal length of a whole system, and
f345 is a composite focal length of the third to fifth lenses.
14. The imaging lens, as defined in claim 1 , wherein the following conditional expression is further satisfied:
0.25<( R 4 f+R 3 r )/( R 4 f−R 3 r )<1.3 (2-1), where
R3r is a paraxial radius of curvature of the image side surface of the third lens, and
R4f is a paraxial radius of curvature of the object side surface of the fourth lens.
15. The imaging lens, as defined in claim 1 , wherein the following conditional expression is further satisfied:
−0.4< f 1/ f 3<0.3 (3-1), where
f1 is a focal length of the first lens, and
f3 is a focal length of the third lens.
16. The imaging lens, as defined in claim 1 , wherein the following conditional expression is further satisfied:
−0.4<( R 3 f−R 3 r )/( R 3 f+R 3 r )<0.15 (4-1), where
R3f is a paraxial radius of curvature of the object side surface of the third lens, and
R3r is a paraxial radius of curvature of the image side surface of the third lens.
17. The imaging lens, as defined in claim 1 , wherein the following conditional expression is further satisfied:
0.7< 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
R5r is a paraxial radius of curvature of the image side surface of the fifth lens.
18. The imaging lens, as defined in claim 1 , wherein the following conditional expression is further satisfied:
−1.5 <f/f 5<−0.4 (6-1), where
f is a focal length of a whole system, and
f5 is a focal length of the fifth lens.
19. The imaging lens, as defined in claim 1 , wherein the following conditional expression is further satisfied:
1< f/f 1<2 (7-1), where
f is a focal length of a whole system, and
f1 is a focal length of the first lens.
20. An imaging apparatus comprising:
the imaging lens, as defined in claim 1 .