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 biconcave shape, a third lens that has a meniscus shape which is convex toward the object side, a fourth lens that has a meniscus shape which is convex toward the image side; and a fifth lens that has a negative refractive power and has at least one inflection point on an image side surface. Further, the following conditional expression (1) is satisfied. 1.4< f/f 1<4 (1)
1. An imaging lens substantially 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 the object side;
a fourth lens that has a meniscus shape which is convex toward an image side; 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:
1.4 <f/f 1<4 (1), where
f is a focal length of a whole system, and
f1 is a focal length of the first lens, and
wherein the following conditional expression (3) is further satisfied:
0.78 <f/f 12<2.5 (3), where
f12 is a composite focal length of the first lens and the second lens.
2. The imaging lens, as defined in claim 1 , wherein the following conditional expression is further satisfied:
−3 <f/f 2<−0.85 (2), where
f2 is a focal length of the second lens.
3. The imaging lens, as defined in claim 1 , wherein the fourth lens has a positive refractive power.
4. The imaging lens, as defined in claim 1 , wherein the following conditional expression is further satisfied:
−2 <f/f 345<0 (4), where
f345 is a composite focal length of the third to fifth lenses.
5. The imaging lens, as defined in claim 1 , wherein the following conditional expression is further satisfied:
−0.5 <f 1 /f 3<0.4 (5), where
f3 is a focal length of the third lens.
6. The imaging lens, as defined in claim 1 , wherein the following conditional expression is further satisfied:
−1<( R 3 f−R 3 r )/( R 3 f+R 3 r )<1.2 (6), 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 an image side surface of the third lens.
7. The imaging lens, as defined in claim 1 , wherein the following conditional expression is further satisfied:
−4 <f/f 5<−0.2 (7), where
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:
0.5 <f ·tan ω/ R 5 r <10 (8), where
ω is a half angle of view, and
R5r is a paraxial radius of curvature of the image side surface of the fifth lens.
9. The imaging lens, as defined in claim 1 , wherein the following conditional expression is further satisfied:
−0.9 <f/f 3<0.7 (9), where
f3 is a focal length of the third lens.
10. The imaging lens, as defined in claim 1 , wherein the following conditional expression is further satisfied:
0.05 <D 7 /f< 0.2 (10), where
D7 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:
1.5 <f/f 1<3.5 (1-1).
13. The imaging lens, as defined in claim 1 , wherein the following conditional expression is further satisfied:
−2.5 <f/f 2<−0.9 (2-1), where
f2 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:
0.8 <f/f 12<2 (3-1), where
f12 is a composite focal length of the first lens and the second lens.
15. The imaging lens, as defined in claim 1 , wherein the following conditional expression is further satisfied:
−1.5 <f/f 345<−0.05 (4-1), where
f345 is a composite focal length of the third to fifth lenses.
16. The imaging lens, as defined in claim 1 , wherein the following conditional expression is further satisfied:
−0.4 <f 1 /f 3<0.2 (5-1), where
f3 is a focal length of the third lens.
17. The imaging lens, as defined in claim 1 , wherein the following conditional expression is further satisfied:
−0.6<( R 3 f−R 3 r )/( R 3 f+R 3 r )<1 (6-1), 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.
18. The imaging lens, as defined in claim 1 , wherein when a composite refractive power of the first to third lenses is positive, the following conditional expression is further satisfied:
−3 <f/f 5<−0.4 (7-1), where
f5 is a focal length of the fifth lens.
19. An imaging apparatus comprising:
the imaging lens, as defined in claim 1 .
20. An imaging lens substantially 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 the object side;
a fourth lens that has a meniscus shape which is convex toward an image side; 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:
1.4 <f/f 1<4 (1), where
f is a focal length of a whole system, and
f1 is a focal length of the first lens, and
wherein the following conditional expression (4) is further satisfied:
−2 <f/f 345<0 (4), where
f345 is a composite focal length of the third to fifth lenses.
21. An imaging lens substantially 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 the object side;
a fourth lens that has a meniscus shape which is convex toward an image side; 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:
1.4 <f/f 1<4 (1), where
f is a focal length of a whole system, and
f1 is a focal length of the first lens, and
wherein the following conditional expression (5-1) is further satisfied:
−0.4 <f 1 /f 3<0.2 (5-1), where
f3 is a focal length of the third lens.