An imaging lens comprises, in order from an object side: a first lens having a positive refractive power; a second lens having a negative refractive power whose concave surface faces to the object; and a third lens having a positive refractive power and having a meniscus form that has a convex surface, facing to the object, in a portion at and around an optical axis of the imaging lens; wherein the first, second and third lenses have at least one aspheric surface, and wherein the imaging lens satisfies conditional expressions given below: 0.7<f1/f<1.3 (1) 0.3<D2/f<0.5 (2) 1.0<|f2/f|<3.0 (3) 1.2<f3/f<4.0 (4) where f: a focal length of an overall system, f 1: a focal length of the first lens, f 2: a focal length of the second lens, f 3: a focal length of the third lens, and D 2: a spacing, on the optical axis, between the first lens and the second lens.
1. An imaging lens comprising, in order from an object side:
a first lens having a positive refractive power;
a second lens having a negative refractive power whose concave surface faces to the object; and
a third lens having a positive refractive power and having a meniscus form that has a convex surface, facing to the object, in a portion at and around an optical axis of the imaging lens;
wherein the first, second and third lenses have at least one aspheric surface, and
wherein the imaging lens satisfies conditional expressions given below:
0.7<f1/f<1.3 (1)
0.3<D2/f<0.5 (2)
0.21≦D2/f<0.5 (2′)
1.0<|f2/f|<3.0 (3)
1.2<f3/f<4.0 (4)
where
f: a focal length of an overall system,
f 1 : a focal length of the first lens,
f 2 : a focal length of the second lens,
f 3 : a focal length of the third lens, and
D 2 : a spacing, on the optical axis, between the first lens and the second lens.
2. An imaging lens according to claim 1 ,
wherein a conditional expression given below is further satisfied:
20<ν1−ν2 (5)
where
ν1: Abbe number of the first lens, and
ν2: Abbe number of the second lens.
3. An imaging lens according to claim 1 ,
wherein the first lens has: an object-side surface having a convex form in a portion at and around the optical axis; and an image-side surface having all aspheric form and having a positive refractive power increasing as a peripheral portion thereof is neared, and
the second lens has a meniscus form in a portion at and around the optical axis.
4. An imaging lens according to claim 2 ,
wherein the first lens has: an object-side surface having a convex form in a portion at and around the optical axis; and an image-side surface having an aspheric form and having a positive refractive power increasing as a peripheral portion thereof is neared, and
the second lens has a meniscus form in a portion at and around the optical axis.