Imaging lens and imaging apparatus
View Patent ↗An imaging lens consists of a negative first lens, a positive second lens, a negative third lens, a positive fourth lens, a positive fifth lens, and a negative sixth lens in order from the object side. The Abbe number of the material of the sixth lens with respect to the d-line is less than or equal to 30. When the radius of curvature of the object side surface of the third lens is taken as R 3 F, the radius of curvature of the image side surface of the third lens is taken as R 3 R, and the Abbe number of the material of the third lens with respect to the d-line is taken as νd 3 , the following conditional expressions are satisfied: 1.35<( R 3 F+R 3 R )/( R 3 F−R 3 R )<6.0 (1) ν d 3<30.0 (2).
1. An imaging lens, consisting of a first lens having a negative power, a second lens having a positive power, a third lens having a negative power, a fourth lens having a positive power, a fifth lens having a positive power, and a sixth lens having a negative power, in order from the object side, wherein:
the Abbe number of the material of the sixth lens with respect to the d-line is less than or equal to 30; and
the following conditional expressions are satisfied:
1.35<( R 3 F+R 3 R )/( R 3 F−R 3 R )<6.0 (1)
ν d 3<30.0 (2)
where:
R 3 F is the radius of curvature of the object side surface of the third lens;
R 3 R is the radius of curvature of the image side surface of the third lens; and
νd 3 is the Abbe number of the material of the third lens with respect to the d-line.
2. The imaging lens of claim 1 , wherein the following conditional expression is satisfied:
1.0< f 2/ f (4)
where:
f 2 is the focal length of the second lens; and
f is the focal length of the entire system.
3. The imaging lens of claim 2 , wherein the following conditional expression is further satisfied:
1.1< f 2/ f< 6.0 (4-2)
where:
f 2 is the focal length of the second lens; and
f is the focal length of the entire system.
4. The imaging lens of claim 1 , wherein the following conditional expression is satisfied:
1.0< f 4/ f (5)
where:
f 4 is the focal length of the fourth lens; and
f is the focal length of the entire system.
5. The imaging lens of claim 4 , wherein the following conditional expression is further satisfied:
1.1< f 4/ f< 5.0 (5-2)
where:
f 4 is the focal length of the fourth lens; and
f is the focal length of the entire system.
6. The imaging lens of claim 1 , wherein the following conditional expression is satisfied:
0.15<ν d 4/ν d 5<3.0 (6)
where:
νd 4 is the Abbe number of the material of the fourth lens with respect to the d-line; and
νd 5 is the Abbe number of the material of the fifth lens with respect to the d-line.
7. The imaging lens of claim 1 , wherein a material having a negative temperature coefficient of refractive index, dn/dt is used for a lens having a positive power in the lens system.
8. The imaging lens of claim 1 , wherein the following conditional expression is satisfied:
1.5< f 34/ f< 5.0 (7)
where:
f 34 is the combined focal length of the third lens and the fourth lens; and
f is the focal length of the entire system.
9. The imaging lens of claim 8 , wherein the following conditional expression is further satisfied:
1.7< f 34/ f< 4.7 (7-1)
where:
f 34 is the combined focal length of the third lens and the fourth lens; and
f is the focal length of the entire system.
10. The imaging lens of claim 8 , wherein the following conditional expression is further satisfied:
1.8< f 34/ f< 3.9 (7-3)
where:
f 34 is the combined focal length of the third lens and the fourth lens; and
f is the focal length of the entire system.
11. The imaging lens of claim 1 , wherein the following conditional expression is satisfied:
0.3<ν d 1/ν d 2<2.5 (8)
where:
νd 1 is the Abbe number of the material of the first lens with respect to the d-line; and
νd 2 is the Abbe number of the material of the second lens with respect to the d-line.
12. The imaging lens of claim 11 , wherein the following conditional expression is further satisfied:
0.4<ν d 1/ν d 2<1.8 (8-2)
where:
νd 1 is the Abbe number of the material of the first lens with respect to the d-line; and
νd 2 is the Abbe number of the material of the second lens with respect to the d-line.
13. The imaging lens of claim 1 , wherein the following conditional expression is further satisfied:
1.35<( R 3 F+R 3 R )/( R 3 F−R 3 R )<3.3 (1-2)
where:
R 3 F is the radius of curvature of the object side surface of the third lens; and
R 3 R is the radius of curvature of the image side surface of the third lens.
14. The imaging lens of claim 1 , wherein the following conditional expression is further satisfied:
1.4<( R 3 F+R 3 R )/( R 3 F−R 3 R )<2.20 (1-3)
where:
R 3 F is the radius of curvature of the object side surface of the third lens; and
R 3 R is the radius of curvature of the image side surface of the third lens.
15. The imaging lens of claim 1 , wherein the following conditional expression is further satisfied:
ν d 3<20.0 (2-2)
where,
νd 3 is the Abbe number of the material of the third lens with respect to the d-line.
16. An imaging apparatus equipped with the imaging lens of claim 1 .
17. An imaging lens, consisting of a first lens having a negative power, a second lens having a positive power, a third lens having a negative power, a fourth lens having a positive power, a fifth lens having a positive power, and a sixth lens having a negative power, in order from the object side, wherein:
the Abbe number of the material of the sixth lens with respect to the d-line is less than or equal to 30; and
the following conditional expression is satisfied:
1.35<( R 3 F+R 3 R )/( R 3 F−R 3 R )<2.20 (1-1)
where:
R 3 F is the radius of curvature of the object side surface of the third lens; and
R 3 R is the radius of curvature of the image side surface of the third lens.
18. An imaging lens, consisting of a first lens having a negative power, a second lens having a positive power, a third lens having a negative power, a fourth lens having a positive power, a fifth lens having a positive power, and a sixth lens having a negative power, in order from the object side, wherein the following conditional expressions are satisfied:
ν d 3<20.0 (2-2)
f 3/ f<− 1.4 (3)
where:
νd 3 is the Abbe number of the material of the third lens with respect to the d-line;
f 3 is the focal length of the third lens; and
f is the focal length of the entire system.
19. The imaging lens of claim 18 , wherein the following conditional expression is further satisfied:
−5< f 3/ f<− 1.6 (3-4)
where:
f 3 is the focal length of the third lens; and
f is the focal length of the entire system.