Imaging lens
There is provided a compact imaging lens configured to properly correct aberrations. The imaging lens includes, in order from an object side to an image side, a first lens L 1 having negative refractive power, a second lens L 2 having negative refractive power, a third lens L 3 having positive refractive power, a fourth lens L 4 , a fifth lens L 5 , a sixth lens L 6 , a seventh lens L 7 , and an eighth lens L 8 having negative refractive power. The eighth lens L 8 has an aspheric image-side surface having at least one inflection point.
1. An imaging lens forming an image of an object on an image sensor and comprising, in order from an object side to an image side,
a first lens having negative refractive power,
a second lens having negative refractive power,
a third lens having positive refractive power,
a fourth lens,
a fifth lens,
a sixth lens,
a seventh lens, and
an eighth lens having negative refractive power,
wherein said second lens has a convex object-side surface on a paraxial region,
said eighth lens has an aspheric image-side surface having at least one inflection point,
said eighth lens has a meniscus shape comprising a concave image-side surface on a paraxial region, and
the following conditional expression is satisfied:
0.1< R 8 r/f< 0.6
where
f: a focal length of the overall optical system of the imaging lens, and
R8r: a curvature radius of an image-side surface of the eighth lens.
2. The imaging lens according to claim 1 , wherein the following conditional expression is satisfied:
0.15< f 3/ f< 0.95
where
f: a focal length of the overall optical system of the imaging lens, and
f3: a focal length of the third lens.
3. The imaging lens according to claim 1 , wherein the following conditional expression is satisfied:
0.03< D 45/ f< 0.30
where
f: a focal length of the overall optical system of the imaging lens, and
D45: a distance along the optical axis between the fourth lens and the fifth lens.
4. The imaging lens according to claim 1 , wherein the following conditional expression is satisfied:
−7.0< f 8/ f<− 0.3
where
f: a focal length of the overall optical system of the imaging lens, and
f8: a focal length of the eighth lens.
5. The imaging lens according to claim 1 , wherein the following conditional expression is satisfied:
10< vd 1<35
35< vd 2<85
where
vd1: an abbe number at d-ray of the first lens, and
vd2: an abbe number at d-ray of the second lens.