Imaging lens including seven lenses of ++−++−− or ++−+++− refractive powers
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 with positive refractive power, a fifth lens with positive refractive power, a sixth lens, and a seventh lens with negative refractive power, wherein said first lens has an object-side surface being convex in a paraxial region, said second lens has an image-side surface being convex in a paraxial region, said third lens has an object-side surface being concave in a paraxial region, said fourth lens has an object-side surface being concave in a paraxial region, said sixth lens has an object-side surface being convex in a paraxial region, and said seventh lens has an image-side surface being concave in a paraxial region.
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 with positive refractive power,
a fifth lens with positive refractive power,
a sixth lens, and
a seventh lens with negative refractive power,
wherein said first lens has an object-side surface being convex in a paraxial region, said second lens has an image-side surface being convex in a paraxial region, said third lens has an object-side surface being concave in a paraxial region, said fourth lens has an object-side surface being concave in a paraxial region, said sixth lens has an object-side surface being convex in a paraxial region, and said seventh lens has an image-side surface being concave in a paraxial region.
2. The imaging lens according to claim 1 , wherein an object-side surface of said seventh lens is convex in a paraxial region.
3. The imaging lens according to claim 1 , wherein the following conditional expression (1) is satisfied:
0.02<( D 6/| f 6|)×100<2.55 (1)
where
D6: a thickness along the optical axis of the sixth lens, and
f6: a focal length of the sixth lens.
4. The imaging lens according to claim 1 , wherein the following conditional expression (2) is satisfied:
0.50< f 1/ f< 1.70 (2)
where
f1: a focal length of the first lens, and
f: a focal length of the overall optical system of the imaging lens.
5. The imaging lens according to claim 1 , wherein the following conditional expression (3) is satisfied:
3.75< f 5/ f< 17.50 (3)
where
f5: a focal length of the fifth lens, and
f: a focal length of the overall optical system of the imaging lens.
6. The imaging lens according to claim 1 , wherein the following conditional expression (4) is satisfied:
0.20<( f 1/| f 6|)×100<35.00 (4)
where
f1: a focal length of the first lens, and
f6: a focal length of the sixth lens.
7. The imaging lens according to claim 1 , wherein the following conditional expression (5) is satisfied:
0.60< r 13/ f< 3.50 (5)
where
r13: a paraxial curvature radius of an object-side surface of the seventh lens, and
f: a focal length of the overall optical system of the imaging lens.