Imaging lens
There is provided an imaging lens with excellent optical characteristics which satisfies demand of a low profile and a low F-number. An imaging lens comprises in order from an object side to an image side, a first lens with positive refractive power, a second lens with positive refractive power, a third lens with negative refractive power, a fourth lens, a fifth lens with positive refractive power, a sixth lens with positive or negative refractive power, and a seventh lens with negative refractive power, wherein said first lens is formed in a meniscus shape having an object-side surface being convex in a paraxial region, said second lens has an image-side surface being concave in a paraxial region, said sixth lens has an image-side surface being concave in a paraxial region, and said seventh lens has an image-side surface being concave in a paraxial region, and predetermined conditional expressions are satisfied.
1. An imaging lens comprising, in order from an object side to an image side,
a first lens with positive refractive power,
a second lens with positive refractive power,
a third lens with negative refractive power,
a fourth lens,
a fifth lens with positive refractive power,
a sixth lens with positive or negative refractive power, and
a seventh lens with negative refractive power,
wherein said imaging lens is configured with only seven lenses, said first lens is formed in a meniscus shape having an object-side surface being convex in a paraxial region, said second lens has an image-side surface being concave in a paraxial region, said sixth lens has an image-side surface being concave in a paraxial region, and said seventh lens has an image-side surface being concave in a paraxial region, and the following conditional expression (1) is satisfied:
3.85<| r 13/ r 14| (1)
where
r13: a paraxial curvature radius of an object-side surface of the seventh lens, and
r14: a paraxial curvature radius of the image-side surface of the seventh lens.
2. The imaging lens according to claim 1 , wherein an object-side surface of said third lens is convex in a paraxial region.
3. The imaging lens according to claim 1 , wherein the following conditional expression (2) is satisfied:
13.00< vd 6<34.00 (2)
where
vd6: an abbe number at d-ray of the sixth lens.
4. The imaging lens according to claim 1 , wherein the following conditional expression (3) is satisfied:
−3.50< f 2/ f 7<−0.50 (3)
where
f2: a focal length of the second lens, and
f7: a focal length of the seventh lens.
5. The imaging lens according to claim 1 , wherein the following conditional expression (4) is satisfied:
0.00< f 1/| f 6|<0.30 (4)
where
f1: a focal length of the first lens, and
f6: a focal length of the sixth lens.
6. The imaging lens according to claim 1 , wherein the following conditional expression (5) is satisfied:
0.02< r 12/| r 13|<0.35 (5)
where
r12: a paraxial curvature radius of an image-side surface of the sixth lens, and
r13: a paraxial curvature radius of an object-side surface of the seventh lens.
7. The imaging lens according to claim 1 , wherein the following conditional expression (6) is satisfied:
0.15< D 4/ T 4<1.05 (6)
where
D4: a thickness along an optical axis of the fourth lens, and
T4: a distance along an optical axis from an image-side surface of the fourth lens to an object-side surface of the fifth lens.