Imaging lens including eight lenses of -+-++++-, -+-+++--, -+-++-+-, -+-++---, -+-+-++-, -+-+-+--, -+-+----, -+--+++-, -+--++--, -+--+-+-, -+--+---, -+---++-, -+---+--, -+----+-, or -+-+0-+- refractive powers
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 positive refractive power, a third lens L 3 having negative 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 positive refractive power,
a third lens having negative refractive power,
a fourth lens,
a fifth lens,
a sixth lens,
a seventh lens, and
an eighth lens having negative refractive power,
wherein said eighth lens has an aspheric image-side surface having at least one inflection point, and
the following conditional expression is satisfied:
−4.0< R 4 f/f<− 0.4
where f: a focal length of the overall optical system of the imaging lens, and
R4f: a curvature radius of an object-side surface of the fourth lens.
2. The imaging lens according to claim 1 , wherein the following conditional expression is satisfied:
−10.0< f 1/ f 2<−2.0
where
f1: a focal length of the first lens, and
f2: a focal length of the second lens.
3. The imaging lens according to claim 1 , wherein the following conditional expression is satisfied:
−10.0< f 3/ f<− 2.0
where
f: a focal length of the overall optical system of the imaging lens, and
f3: a focal length of the third lens.
4. The imaging lens according to claim 1 , wherein the following conditional expression is satisfied:
12<| f 5|/ f
where
f: a focal length of the overall optical system of the imaging lens, and
f5: a focal length of the fifth lens.