Imaging lens and imaging apparatus
View Patent ↗An imaging lens consists essentially of six lenses in the following order from the object side: 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. An aperture stop is disposed more toward the object side than the image-side surface of the fourth lens. Conditional expression (4) is satisfied, where f is the focal length of the entire system, and f56 is the combined focal length of the fifth lens and the sixth lens: f 56/ f <−6.4 (4).
1. An imaging lens consisting essentially 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 this order from the object side, wherein
an aperture stop is disposed toward the object side than the image-side surface of the fourth lens,
the Abbe number of the material of the third lens with respect to the d-line is less than or equal to 30, and
the imaging lens satisfies conditional formula (4) below:
f 56/ f<− 6.4 (4),where
f: the focal length of the entire system, and
f56: the combined focal length of the fifth lens and the sixth lens.
2. The imaging lens of claim 1 that satisfies conditional formulas (5-1) and (6) below:
−1.5 <f 34 /f 56<0.0 (5-1)
0.0 <f 34 /f (6),where
f34: the combined focal length of the third lens and the fourth lens, and
f56: the combined focal length of the fifth lens and the sixth lens.
3. The imaging lens of claim 1 , wherein materials of the third lens, the fourth lens, the fifth lens, and the sixth lens are plastics.
4. The imaging lens of claim 3 that satisfies conditional formula (7) below:
2.0 <f 3456 /f (7),where
f3456: the combined focal length of the third lens, the fourth lens, the fifth lens, and the sixth lens.
5. The imaging lens of claim 1 that satisfies conditional formula (8) below:
0.9 <νd 2 /νd 3 (8),where
νd2: the Abbe number of the material of the second lens with respect to the d-line, and
νd3: the Abbe number of the material of the third lens with respect to the d-line.
6. The imaging lens of claim 1 that satisfies conditional formula (9) below:
−2.5 <f 3 /f<− 0.5 (9),where
f: the focal length of the entire system, and
f3: the focal length of the third lens.
7. The imaging lens of claim 1 , wherein the aperture stop is provided between the object-side surface of the second lens and the image-side surface of the fourth lens.
8. The imaging lens of claim 1 that satisfies conditional formula (10) below:
−3.0 <f 3 /f 4<−0.2 (10),where
f3: the focal length of the third lens, and
f4: the focal length of the fourth lens.
9. The imaging lens of claim 1 that satisfies conditional formula (11) below:
0.2 <f 12 /f< 5.0 (11),where
f: the focal length of the entire system, and
f12: the combined focal length of the first lens and the second lens.
10. The imaging lens of claim 1 that satisfies conditional formula (12) below:
( Nd 1 +Nd 2 +Nd 3 +Nd 4 +Nd 5 +Nd 6)/6<1.70 (12),where
Nd1 through Nd6: the refractive indices of the materials of the first lens through the sixth lens with respect to the d-line.
11. The imaging lens of claim 1 , wherein the object-side surface of the fourth lens is an aspherical surface, both of the center and the edge of the effective diameter have positive powers, and the positive power at the edge of the effective diameter is weaker than that of the center.
12. The imaging lens of claim 1 , wherein the Abbe number of the material of the first lens with respect to the d-line is greater than or equal to 40.
13. The imaging lens of claim 1 , wherein the Abbe number of the material of the second lens with respect to the d-line is greater than or equal to 25.
14. The imaging lens of claim 1 , wherein the Abbe number of the material of the fourth lens with respect to the d-line is greater than or equal to 40.
15. The imaging lens of claim 1 , wherein the Abbe number of the material of the fifth lens with respect to the d-line is greater than or equal to 40.
16. The imaging lens of claim 1 , wherein the Abbe number of the material of the sixth lens with respect to the d-line is less than or equal to 32.
17. The imaging lens of claim 1 that satisfies conditional formula (4-1) below:
f 56 /f<− 7.0 (4-1),where
f: the focal length of the entire system, and
f56: the combined focal length of the fifth lens and the sixth lens.
18. The imaging lens of claim 1 that satisfies conditional formula (4-2) below:
f 56 /f<− 7.2 (4-2),where
f: the focal length of the entire system, and
f56: the combined focal length of the fifth lens and the sixth lens.
19. The imaging lens of claim 1 that satisfies conditional formula (4-3) below:
−50.0 <f 56 /f<− 7.2 (4-3),where
f: the focal length of the entire system, and
f56: the combined focal length of the fifth lens and the sixth lens.
20. An imaging apparatus comprising:
an imaging lens of claim 1 .