Imaging lens
There is provided an imaging lens with excellent optical characteristics which satisfies demand of wide field of view, low profile and low F-number. An imaging lens comprises, in order from an object side to an image side, a first lens with positive or negative refractive power in a paraxial region, a second lens with positive or negative refractive power in a paraxial region, a third lens with positive refractive power in a paraxial region, a fourth lens with negative refractive power in a paraxial region, a fifth lens with positive refractive power in a paraxial region, a sixth lens with positive refractive power in a paraxial region, and a seventh lens with negative refractive power.
1. An imaging lens comprising in order from an object side to an image side,
a first lens with positive or negative refractive power in a paraxial region,
a second lens with positive or negative refractive power in a paraxial region,
a third lens with positive refractive power in a paraxial region,
a fourth lens with negative refractive power in a paraxial region,
a fifth lens with positive refractive power in a paraxial region,
a sixth lens with positive refractive power in a paraxial region, and
a seventh lens with negative refractive power,
wherein an image-side surface of said first lens is convex in the paraxial region, an object-side surface of said second lens is convex in the paraxial region, and an image-side surface of said sixth lens is concave in the paraxial region, and
wherein the following conditional expressions (4) and (5) are satisfied:
0.10<vd6/vd7<0.60 (4)
0.20<( D 1 /|f 1|)×100<7.50 (5)
where
vd6: an abbe number at d-ray of the sixth lens,
vd7: an abbe number at d-ray of the seventh lens,
D1: a thickness of the first lens along the optical axis, and
f1: a focal length of the first lens.
2. The imaging lens according to claim 1 , wherein an object-side surface of said first lens is concave in the paraxial region.
3. The imaging lens according to claim 1 , wherein an object-side surface of said fourth lens is concave in the paraxial region.
4. The imaging lens according to claim 1 , wherein an image-side surface of said fourth lens is convex in the paraxial region.
5. The imaging lens according to claim 1 , wherein an object-side surface of said sixth lens is convex in the paraxial region.
6. The imaging lens according to claim 1 , wherein the following conditional expression (1) is satisfied:
0.10<( T 1/TTL)×100<0.45 (1)
where
T1: a distance along the optical axis from an image-side surface of the first lens to an object-side surface of the second lens, and
TTL: a total track length.
7. The imaging lens according to claim 1 , wherein the following conditional expression (2) is satisfied:
10.00< T 2/ T 4 (2)
where
T2: a distance along the optical axis from an image-side surface of the second lens to an object-side surface of the third lens, and
T4: a distance along the optical axis from an image-side surface of the fourth lens to an object-side surface of the fifth lens.