Imaging lens and imaging apparatus equipped with the imaging lens
View Patent ↗An imaging lens consisting essentially of, in order from the object side, a first lens having a negative refractive power with the object side surface having a concave shape, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, and a seventh lens having a negative refractive power with the image side surface having a concave shape with at least one inflection point, in which an aperture stop is provided between the first lens and the fifth lens, and the imaging lens satisfies predetermined conditional expressions. One of the second lens and the third lens has a positive refractive power and the other has a negative refractive power, and one of the fifth lens and the sixth lens has a positive refractive power and the other has a negative refractive power.
1. An imaging lens consisting of seven lenses, composed of, in order from the object side, a first lens having a negative refractive power with the object side surface having a concave shape, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, and a seventh lens having a negative refractive power with the image side surface having a concave shape with at least one inflection point located radially inward of the intersection between the image side surface and the principal ray of the maximum angle of view, wherein:
an aperture stop is provided between the first lens and the fifth lens;
one of the second lens and the third lens has a positive refractive power and the other of the second lens and the third lens has a negative refractive power;
one of the fifth lens and the sixth lens has a positive refractive power and the other of the fifth lens and the sixth lens has a negative refractive power;
and the following conditional expressions are satisfied:
30<ν P 1−ν N 1<50 (1)
30<ν P 2−ν N 2<50 (2)
where
νP1 is the Abbe number of either one of the second lens and the third lens having a positive refractive power with respect to the d-line;
νN1 is the Abbe number of either one of the second lens and the third lens having a negative refractive power with respect to the d-line;
νP2 is the Abbe number of either one of the fifth lens and the sixth lens having a positive refractive power with respect to the d-line; and
νN2 is the Abbe number of either one of the fifth lens and the sixth lens having a negative refractive power with respect to the d-line.
2. The imaging lens of claim 1 , wherein the aperture stop is located between the third lens and the fourth lens, or between the fourth lens and the fifth lens.
3. The imaging lens of claim 1 , wherein the fifth lens has a negative refractive power and the sixth lens has a positive refractive power.
4. The imaging lens of claim 1 , wherein the following conditional expression is further satisfied:
0< f/f 67<2 (3)
where:
f is the focal length of the entire system; and
f67 is the combined focal length of the sixth lens and the seventh lens.
5. The imaging lens of claim 1 , wherein the sixth lens has a biconvex shape.
6. The imaging lens of claim 1 , wherein the seventh lens has a biconcave shape.
7. The imaging lens of claim 1 , wherein the second lens has a positive refractive power and the third lens has a negative refractive power.
8. The imaging lens of claim 1 , wherein the following conditional expression is further satisfied:
0< f/f 12<2 (4)
where:
f is the focal length of the entire system; and
f12 is the combined focal length of the first lens and the second lens.
9. The imaging lens of claim 1 , wherein the following conditional expression is further satisfied:
0.1< D 2/( f ·tan ω)<0.3 (5)
where:
D2 is the distance between the first lens and the second lens on the optical axis;
f is the focal length of the entire system; and
ω is the maximum half angle of view when an object at infinity is in focus.
10. The imaging lens of claim 1 , wherein the following conditional expression is further satisfied:
−2< f/f 1<0 (6)
where:
f is the focal length of the entire system; and
f1 is the focal length of the first lens.
11. The imaging lens of claim 1 , wherein the following conditional expression is further satisfied:
−3< f/f 7<0 (7)
where:
f is the focal length of the entire system; and
f7 is the focal length of the seventh lens.
12. The imaging lens of claim 1 , wherein the fourth lens has a positive refractive power.
13. The imaging lens of claim 1 , wherein the object side surface of the first lens has at least one inflection point located radially inward of the intersection between the object side surface and the principal ray of the maximum angle of view.
14. The imaging lens of claim 1 , wherein the following conditional expression is further satisfied:
30<ν P 1−ν N 1<40 (1-1).
15. The imaging lens of claim 1 , wherein the following conditional expression is further satisfied:
30<ν P 2−ν N 2<40 (2-1).
16. The imaging lens of claim 4 , wherein the following conditional expression is further satisfied:
0< f/f 67<1 (3-1)
where:
f is the focal length of the entire system; and
f67 is the combined focal length of the sixth lens and the seventh lens.
17. The imaging lens of claim 8 , wherein the following conditional expression is further satisfied:
0< f/f 12<1 (4-1)
where:
f is the focal length of the entire system; and
f12 is the combined focal length of the first lens and the second lens.
18. The imaging lens of claim 10 , wherein the following conditional expression is further satisfied:
−1< f/f 1<0 (6-1)
where:
f is the focal length of the entire system; and
f1 is the focal length of the first lens.
19. The imaging lens of claim 11 , wherein the following conditional expression is further satisfied:
−2.5< f/f 7<−1 (7-1)
where:
f is the focal length of the entire system; and
f7 is the focal length of the seventh lens.
20. An imaging apparatus equipped with the imaging lens of claim 1 .