Imaging lens and imaging apparatus
View Patent ↗An imaging lens consists essentially of a front-group consisting of a first lens having a negative meniscus shape with its convex surface facing an object side, a second lens having negative refractive power, a third lens having positive refractive power, a fourth lens having a negative meniscus shape with its concave surface facing an image side and a fifth lens having positive refractive power, and the front-group having positive refractive power as a whole, a stop, and a rear-group consisting of a sixth lens having positive refractive power and a seventh lens having a negative meniscus shape with its concave surface facing the object side, and the rear-group having positive refractive power as a whole, in this order from the object side. A predetermined conditional formula about a combined focal length of the first lens and the second lens, and a focal length of an entire system is satisfied.
1. An imaging lens consisting essentially of:
a front group consisting of a first lens having a negative meniscus shape with its convex surface facing an object side, a second lens having negative refractive power, a third lens having positive refractive power, a fourth lens having a negative meniscus shape with its concave surface facing an image side and a fifth lens having positive refractive power, and the front group having positive refractive power as a whole;
a stop; and
a rear group consisting of a sixth lens having positive refractive power and a seventh lens having a negative meniscus shape with its concave surface facing the object side, and the rear group having positive refractive power as a whole, in this order from the object side,
wherein the following conditional formula (1) is satisfied:
0.6<| f 12|/ f< 1.5 (1), where
f12: a combined focal length of the first lens and the second lens, and
f: a focal length of an entire system.
2. The imaging lens, as defined in claim 1 , wherein the following conditional formula (1-1) is satisfied:
0.7<| f 12|/ f< 1.3 (1-1), where
f12: a combined focal length of the first lens and the second lens, and
f: a focal length of an entire system.
3. The imaging lens, as defined in claim 1 , wherein the following conditional formula (1-2) is satisfied:
0.8<| f 12|/ f< 1.2 (1-2), where
f12: a combined focal length of the first lens and the second lens, and
f: a focal length of an entire system.
4. The imaging lens, as defined in claim 1 , wherein the following conditional formula (2) is satisfied:
1.3< fa/f< 1.9 (2), where
fa: a focal length of the front group, and
f: a focal length of an entire system.
5. The imaging lens, as defined in claim 1 ,
wherein the following conditional formula (2-1) is satisfied:
1.4< fa/f< 1.8 (2-1), where
fa: a focal length of the front group, and
f: a focal length of an entire system.
6. The imaging lens, as defined in claim 1 , wherein the following conditional formula (3) is satisfied:
0.5< fa/f 5<1.4 (3), where
fa: a focal length of the front group, and
f5: a focal length of the fifth lens.
7. The imaging lens, as defined in claim 1 , wherein the following conditional formula (3-1) is satisfied:
0.7< fa/f 5<1.3 (3-1), where
fa: a focal length of the front group, and
f5: a focal length of the fifth lens.
8. The imaging lens, as defined in claim 1 , wherein the following conditional formula (3-2) is satisfied:
0.8< fa/f 5<1.2 (3-2), where
fa: a focal length of the front group, and
f5: a focal length of the fifth lens.
9. The imaging lens, as defined in claim 1 , wherein the following conditional formula (4) is satisfied:
vd 3<26.0 (4), where
vd3: an Abbe number of the third lens for d-line.
10. The imaging lens, as defined in claim 1 , wherein the following conditional formula (4-1) is satisfied:
vd 3<23.0 (4-1), where
vd3: an Abbe number of the third lens for d-line.
11. The imaging lens, as defined in claim 1 , wherein the following conditional formula (5) is satisfied:
3.5< L/Rr 1<9.0 (5), where
L: a length from a vertex of an object-side surface of the first lens to a paraxial image formation position determined by the first lens through the seventh lens, and
Rr1: a paraxial curvature radius of an image-side surface of the first lens.
12. The imaging lens, as defined in claim 1 , wherein the following conditional formula (5-1) is satisfied:
4.0< L/Rr 1<7.0 (5-1), where
L: a length from a vertex of an object-side surface of the first lens to a paraxial image formation position determined by the first lens through the seventh lens, and
Rr1: a paraxial curvature radius of an image-side surface of the first lens.
13. The imaging lens, as defined in claim 1 , wherein the following conditional formula (6) is satisfied:
3.5< L/Rr 2<10.0 (6), where
L: a length from a vertex of an object-side surface of the first lens to a paraxial image formation position determined by the first lens through the seventh lens, and
Rr2: a paraxial curvature radius of an image-side surface of the second lens.
14. The imaging lens, as defined in claim 1 , wherein the following conditional formula (6-1) is satisfied:
4.5< L/Rr 2<9.0 (6-1), where
L: a length from a vertex of an object-side surface of the first lens to a paraxial image formation position determined by the first lens through the seventh lens, and
Rr2: a paraxial curvature radius of an image-side surface of the second lens.
15. The imaging lens, as defined in claim 1 , wherein the following conditional formula (7) is satisfied:
0.4< f 5/ f 6<1 (7), where
f5: a focal length of the fifth lens, and
f6: a focal length of the sixth lens.
16. The imaging lens, as defined in claim 1 , wherein the following conditional formula (7-1) is satisfied:
0.55< f 5/ f 6<0.85 (7-1) where
f5: a focal length of the fifth lens, and
f6: a focal length of the sixth lens.
17. An imaging apparatus comprising:
the imaging lens, as defined in claim 1 , mounted thereon.