Imaging lens and imaging apparatus
View Patent ↗The imaging lens consists essentially of a front group that consist essentially of a negative first lens having a meniscus shape with a convex surface toward the object side, a negative second lens and a positive third lens; a stop; a positive rear group that includes a positive lens and a negative lens. When the focal length of the entire system is f, a half angle of view is ω, and the distance from the object-side surface of the first lens to the imaging plane along the optical axis is L, conditional formula (1) below is satisfied: 0.25<2* f *tan(ω/2)/ L <1.00 (1).
1. An imaging lens, consisting of:
a front group which consists of a negative first lens having a meniscus shape with a convex surface toward the object side, a negative second lens, a point along the optical axis at the image-side surface of which is more toward the object side than points on both ends of the effective diameter of the image-side surface, and a positive third lens;
an aperture stop; and
a rear group which is positive as a whole in this order from the object side, wherein
the rear group consists of one positive lens and one negative lens; and
conditional formula (1) below is satisfied:
0.25<2 *f *tan(ω/2)/ L< 1.00 (1),
where
f: the focal length of the entire system
ω: a half angle of view
L: the distance from the object-side surface of the first lens to the imaging plane along the optical axis (back focus corresponds to an air converted length), and
the conditional formula (2) below is satisfied:
−2.0< f 2/ f <−0.5 (2),
where
f 2 : the focal length of the second lens, and
f: the focal length of the entire system.
2. The imaging lens of claim 1 that satisfies conditional formula (3) below:
1.0< f 3/ f< 3.0 (3),
where
f 3 : the focal length of the third lens, and
f: the focal length of the entire system.
3. The imaging lens of claim 1 that satisfies conditional formula (5) below:
−20.0< fN/fP<− 0.9 (5),
where
fN: the focal length of the negative lens of the rear group,
fP: the focal length of the positive lens of the rear group.
4. The imaging lens of claim 1 that satisfies conditional formula (1-1) below:
0.27<2* f *tan(ω/2)/ L< 1.00 (1-1),
where
f: the focal length of the entire system,
ω: a half angle of view
L: the distance from the object-side surface of the first lens to the imaging plane along the optical axis (the back focus corresponds to an air converted length).
5. The imaging lens of claim 1 that satisfies conditional formula (2-1) below:
−1.9< f 2/ f<− 0.7 (2-1),
where
f 2 : the focal length of the second lens, and
f: the focal length of the entire system.
6. The imaging lens of claim 1 that satisfies conditional formula (3-1) below:
1.0< f 3/ f< 2.7 (3-1),
where
f 3 : the focal length of the third lens, and
f: the focal length of the entire system.
7. The imaging lens of claim 1 that satisfies conditional formula (4-1) below:
d 4/ L< 0.06 (4-1),
where
d 4 : the distance from the second lens to the third lens along the optical axis, and
L: the distance from the object-side surface of the first lens to the imaging plane along the optical axis (the back focus corresponds to an air converted length).
8. The imaging lens of claim 1 that satisfies conditional formula (5-1) below:
−9.0< fN/fP<− 1.0 (5-1),
where
fN: the focal length of the negative lens of the rear group, and
fP: the focal length of the positive lens of the rear group.
9. The imaging lens of claim 1 , wherein the third lens is of a shape with a convex surface toward the object side.
10. An imaging apparatus comprising:
the imaging lens of claim 1 .
11. An imaging lens, consisting of:
a front group which consists of a negative first lens having a meniscus shape with a convex surface toward the object side, a negative second lens, a point along the optical axis at the image-side surface of which is more toward the object side than points on both ends of the effective diameter of the image-side surface, and a positive third lens;
an aperture stop; and
a rear group which is positive as a whole in this order from the object side, wherein
the rear group consists of one positive lens and one negative lens; and
conditional formula (1) below is satisfied:
0.25<2 *f *tan(ω/2)/ L< 1.00 (1),
where
f: the focal length of the entire system
ω: a half angle of view
L: the distance from the object-side surface of the first lens to the imaging plane along the optical axis (back focus corresponds to an air converted length), and
the conditional formula (4) below is satisified:
d4/L<0.07 (4),
where
d 4 : the distance from the second lens to the third lens along the optical axis, and
L: the distance from the object-side surface of the first lens to the imaging plane along the optical axis (the back focus corresponds to an air converted length).