Imaging lens and imaging apparatus
View Patent ↗An imaging lens consists of, in order from the object side, a negative first lens, a positive second lens, a positive third lens, a negative fourth lens, a positive fifth lens, a positive sixth lens, and a negative seventh lens. When f12 is the combined focal length of the first lens and the second lens, f is the focal length of the entire system, νd7 and νd3 are respectively the Abbe's numbers of the materials of the seventh lens and the third lens with respect to the d line, the following conditional formulae are satisfied: f 12/ f <−3.2 (1) νd7<55 (2) 40<νd3 (3).
1. An imaging lens consisting of, in order from the object side, a first lens having a negative power, a second lens having a positive power, a third lens having a positive power, a fourth lens having a negative power, a fifth lens having a positive power, a sixth lens having a positive power, and a seventh lens having a negative power, wherein
the following conditional formulae are satisfied:
f 12/ f<− 3.2 (1)
νd7<55 (2)
40<νd3 (3)
where,
f12 is the combined focal length of the first lens and the second lens,
f is the focal length of the entire system,
νd7 is the Abbe's number of the material for the seventh lens with respect to the d line, and
νd3 is the Abbe's number of the material for the third lens with respect to the d line.
2. An imaging lens consisting of, in order from the object side, a first lens having a negative power, a second lens having a positive power, a third lens having a positive power, a fourth lens having a negative power, a fifth lens having a positive power, a sixth lens having a positive power, and a seventh lens having a negative power, wherein
the following conditional formulae are satisfied:
f 12/ f<− 3.2 (1)
D 4/ f< 0.39 (4)
where,
f12 is the combined focal length of the first lens and the second lens,
f is the focal length of the entire system, and
D4 is the air space between the second lens and the third lens.
3. An imaging lens consisting of, in order from the object side, a first lens having a negative power, a second lens having a positive power, a third lens having a positive power, a fourth lens having a negative power, a fifth lens having a positive power, a sixth lens having a positive power, and a seventh lens having a negative power, wherein
the following conditional formulae are satisfied:
νd7<55 (2)
−0.93<( R 3+ R 4)/( R 3− R 4) (5)
where,
νd7 is the Abbe's number of the material for the seventh lens with respect to the d line,
R3 is the radius of curvature of the object-side surface of the second lens, and
R4 is the radius of curvature of the image-side surface of the second lens.
4. The imaging lens as defined in claim 2 , wherein the following conditional formula is further satisfied:
40<νd3 (3)
where,
νd3 is the Abbe's number of the material for the third lens with respect to the d line.
5. The imaging lens as defined in claim 1 , wherein the following conditional formula is further satisfied:
25<νd5 (13)
where,
νd5 is the Abbe's number of the material for the fifth lens with respect to the d line.
6. The imaging lens as defined in claim 1 , wherein the following conditional formula is further satisfied:
0.5< f 3/ f< 10 (14)
where,
f3 is the focal length of the third lens, and
f is the focal length of the entire system.
7. The imaging lens as defined in claim 1 , wherein the following conditional formula is further satisfied:
0.5< f 2/ f< 7 (15)
where,
f2 is the focal length of the second lens, and
f is the focal length of the entire system.
8. The imaging lens as defined in claim 1 , wherein the following conditional formula is satisfied:
f 1/ f<− 0.25 (16)
where,
f1 is the focal length of the first lens, and
f is the focal length of the entire system.
9. The imaging lens as defined in claim 1 , wherein the following conditional formula is satisfied:
0.3< f 123/ f< 15 (17)
where,
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 system.
10. The imaging lens as defined in claim 1 , wherein the following conditional formula is further satisfied:
0.5< f 234/ f< 18 (18)
where,
f234 is the combined focal length of the second lens, the third lens, and the fourth lens, and
f is the focal length of the entire system.
11. The imaging lens as defined in claim 1 , wherein the following conditional formula is further satisfied:
0.5< f 12345/ f< 10 (19)
where,
f12345 is the combined focal length of the first lens, the second lens, the third lens, the fourth lens, and the fifth lens, and
f is the focal length of the entire system.
12. The imaging lens as defined in claim 1 , wherein the following conditional formula is further satisfied:
−5.0<( R 14+ R 15)/( R 14− R 15)<−0.01 (8)
where,
R14 is the radius of curvature of the object-side surface of the seventh lens, and
R15 is the radius of curvature of the image-side surface of the seventh lens.
13. The imaging lens as defined in claim 1 , wherein the following conditional formula is further satisfied:
0.4< f 2345/ f< 10 (20)
where,
f2345 is the combined focal length of the second lens, the third lens, the fourth lens, and the fifth lens, and
f is the focal length of the entire system.
14. The imaging lens as defined in claim 1 , wherein the following conditional formula is further satisfied:
0.1< f 3456/ f< 5.0 (21)
where,
f3456 is the combined focal length of the third lens, the fourth lens, the fifth lens, and the sixth lens, and
f is the focal length of the entire system.
15. The imaging lens as defined in claim 1 , wherein the following conditional formula is further satisfied:
−4.0<( R 8+ R 9)/( R 8− R 9)<4.0 (22)
where,
R8 is the radius of curvature of the object-side surface of the fourth lens, and
R9 is the radius of curvature of the image-side surface of the fourth lens.
16. The imaging lens as defined in claim 1 , wherein the following conditional formula is further satisfied:
−3< f/f 45<3 (23)
where,
f45 is the combined focal length of the fourth lens and the fifth lens, and
f is the focal length of the entire system.
17. An imaging apparatus equipped with the imaging lens as defined in claim 1 .
18. An imaging apparatus equipped with the imaging lens as defined in claim 2 .
19. An imaging apparatus equipped with the imaging lens as defined in claim 3 .