Imaging lens, imaging apparatus and information terminal apparatus
View Patent ↗When an optical image is formed through an imaging lens on an imaging surface that is convex toward a light incident side, the imaging lens is constructed in such a manner that a defocus MTF peak position at an arbitrary image height in a range of from 70% to 100% of a maximum image height of the optical image is located further in a light-traveling direction than a same kind of defocus MTF peak position on an optical axis of the imaging lens.
1. An imaging lens for forming an optical image of an object on an imaging surface that is convex toward a light incident side, wherein a defocus MTF peak position in a sagittal direction or a tangential direction at an arbitrary image height in a range of from 70% to 100% of a maximum image height of the optical image is located further in a light-traveling direction than a same kind of defocus MTF peak position on an optical axis of the imaging lens.
2. An imaging lens, as defined in claim 1 , wherein the defocus MTF peak position in the sagittal direction or the tangential direction at the maximum image height is located further in a light-traveling direction than a same kind of defocus MTF peak position on the optical axis.
3. An imaging lens, as defined in claim 1 , wherein the defocus MTF peak position in the sagittal direction or the tangential direction at 80% of the maximum image height is located further in a light-traveling direction than a same kind of defocus MTF peak position on the optical axis.
4. An imaging lens, as defined in claim 1 , wherein the imaging lens is composed of a first lens having positive power, a second lens, a third lens having positive power and a fourth lens, which are arranged in this order from an object side of the imaging lens, and wherein the following formulas (1) and (2) are satisfied at the same time:
0.49< f 1/ f< 1.0 (1); and
0.5< f 3/ f< 3.0 (2), where
f is the focal length of the entire system of the imaging lens,
f 1 is the focal length of the first lens, and
f 3 is the focal length of the third lens.
5. An imaging lens, as defined in claim 4 , wherein the following formulas (3) and (4) are satisfied at the same time:
0.49< f 1/ f< 0.69 (3); and
0.7< f 3/ f< 2.0 (4).
6. An imaging apparatus comprising:
an imaging lens, as defined in claim 1 ; and
an imaging device having the imaging surface for imaging the optical image formed through the imaging lens.
7. An information terminal apparatus comprising:
the imaging apparatus, as defined in claim 6 .
8. An imaging lens for forming an optical image of an object on an imaging surface that is convex toward a light incident side, wherein defocus MTF peak positions in a sagittal direction or a tangential direction at all of image heights in a range of from 80% to 100% of a maximum image height of the optical image are located further in a light-traveling direction than a same kind of defocus MTF peak position on an optical axis of the imaging lens.
9. An imaging lens, as defined in claim 8 , wherein the imaging lens is composed of a first lens having positive power, a second lens, a third lens having positive power and a fourth lens, which are arranged in this order from an object side of the imaging lens, and wherein the following formulas (1) and (2) are satisfied at the same time:
0.49< f 1/ f< 1.0 (1); and
0.5< f 3/ f< 3.0 (2), where
f is the focal length of the entire system of the imaging lens,
f 1 is the focal length of the first lens, and
f 3 is the focal length of the third lens.
10. An imaging lens, as defined in claim 9 , wherein the following formulas (3) and (4) are satisfied at the same time:
0.49< f 1/ f< 0.69 (3); and
0.7< f 3/ f< 2.0 (4).
11. An imaging apparatus comprising:
an imaging lens, as defined in claim 8 ; and
an imaging device having the imaging surface for imaging the optical image formed through the imaging lens.
12. An information terminal apparatus comprising:
the imaging apparatus, as defined in claim 11 .