Imaging lens and imaging apparatus
View Patent ↗An imaging lens is constituted by, in order from the object side to the image side: a first lens having a negative refractive power and a concave surface toward the image side; a second lens having a negative refractive power; a third lens having a positive refractive power and a convex surface toward the image side; a fourth lens having a negative refractive power and a concave surface toward the image side; a biconvex fifth lens which is cemented to the fourth lens; and a sixth lens having a negative refractive power and a concave surface toward the object side. Conditional Formula (1) below is satisfied: −1.05< f 12/ f <−0.8 (1).
1. An imaging lens consisting of, in order from the object side to the image side:
a first lens having a negative refractive power and a concave surface toward the image side;
a second lens having a negative refractive power;
a third lens having a positive refractive power and a convex surface toward the image side;
a fourth lens having a negative refractive power and a concave surface toward the image side;
a biconvex fifth lens which is cemented to the fourth lens; and
a sixth lens having a negative refractive power and a concave surface toward the object side; and
Conditional Formula (1) below being satisfied:
−1.05< f 12/ f<− 0.8 (1)
wherein f12 is the combined focal length of the first lens and the second lens, and f is the focal length of the entire lens system.
2. An imaging lens as defined in claim 1 , in which Conditional Formula (2) below is satisfied:
0.7< f 1/ f 2<2.0 (2)
wherein f1 is the focal length of the first lens, and f2 is the focal length of the second lens.
3. An imaging lens as defined in claim 2 , in which Conditional Formula (2-1) below is satisfied:
0.8< f 1/ f 2<1.2 (2-1).
4. An imaging lens as defined in claim 1 , wherein:
the second lens is of a biconcave shape.
5. An imaging lens as defined in claim 1 , in which Conditional Formula (3) below is satisfied:
−2.8< f 2/ f<− 1.3 (3)
wherein f2 is the focal length of the second lens, and f is the focal length of the entire lens system.
6. An imaging lens as defined in claim 5 , in which Conditional Formula (3-1) below is satisfied:
−2.5< f 2/ f<− 1.5 (3-1).
7. An imaging lens as defined in claim 1 , in which Conditional Formula (4) below is satisfied:
2.5< f 123/ f< 5.0 (4)
wherein f123 is the combined focal length of the first lens, the second lens, and the third lens, and f is the focal length of the entire lens system.
8. An imaging lens as defined in claim 7 , in which Conditional Formula (4-1) below is satisfied:
3.0< f 123/ f< 4.5 (4-1).
9. An imaging lens as defined in claim 1 , in which Conditional Formula (5) below is satisfied:
2.0< r 3 f/f< 6.0 (5)
wherein r3f is the radius of curvature of the surface toward the object side of the third lens, and f is the focal length of the entire lens system.
10. An imaging lens as defined in claim 9 , in which Conditional Formula (5-1) below is satisfied:
2.5< r 36 f< 5.0 (5-1).
11. An imaging lens as defined in claim 1 , in which Conditional Formula (6) below is satisfied:
−2.1< r 3 r/f<− 1.2 (6)
wherein r3r is the radius of curvature of the surface toward the image side of the third lens, and f is the focal length of the entire lens system.
12. An imaging lens as defined in claim 11 , in which Conditional Formula (6-1) below is satisfied:
−2.0< r 3 r/f<− 1.45 (6-1).
13. An imaging lens as defined in claim 1 , in which Conditional Formula (7) below is satisfied:
0.5< r 45/ f< 0.75 (7)
wherein r45 is the radius of surface of the coupling surface between the fourth lens and the fifth lens, and f is the focal length of the entire lens system.
14. An imaging lens as defined in claim 13 , in which Conditional Formula (7-1) below is satisfied:
0.55< r 45/ f< 0.7 (7-1).
15. An imaging lens as defined in claim 1 , in which Conditional Formula (8) below is satisfied:
−5.5< f 6/ f<− 2.5 (8)
wherein f6 is the focal length of the sixth lens, and f is the focal length of the entire lens system.
16. An imaging lens as defined in claim 15 , in which Conditional Formula (8-1) below is satisfied:
−5.0< f 6/ f<− 3.0 (8-1).
17. An imaging lens as defined in claim 1 , in which Conditional Formula (9) below is satisfied:
0.85<max.| f/fx|< 1.2 (9)
wherein f is the focal length of the entire lens system, fx is the focal length of an xth lens, and x is an integer within a range from 1 to 6.
18. An imaging lens as defined in claim 17 , in which Conditional Formula (9-1) below is satisfied:
0.9<max.| f/fx|< 1.1 (9-1).
19. An imaging lens as defined in claim 1 , in which Conditional Formula (1-1) below is satisfied:
−1.0< f 12/ f<− 0.85 (1-1).
20. An imaging apparatus equipped with an imaging lens as defined in claim 1 .