Imaging lens system and imaging device comprising seven lenses of −−++−+-refractive powers
To provide a vehicle-mounted wide-angle lens that simultaneously achieves a high resolution necessary for sensing, a size small enough to be mounted on a vehicle, and a low price. An imaging lens includes, sequentially from the object side, a first lens having a negative power and being concave on the image side, a second lens having a negative power and being concave on the image side, a third lens having a positive power and being convex on the object side, an aperture stop, a fourth lens having a positive power and being convex on the image side, a fifth lens, a sixth lens whose object side is bonded to the image side of the fifth lens and a seventh lens having a negative power and being convex on the image side, and the fourth lens is an aspheric glass lens.
1. An imaging lens comprising exactly seven lenses, the imaging lens including, sequentially from an object side:
a first lens having a negative power and being concave on an image side;
a second lens having a negative power and being concave on the image side;
a third lens having a positive power and being convex on an object side;
an aperture stop;
a fourth lens having a positive power and being convex on the image side;
a fifth lens;
a sixth lens whose object side is bonded to the image side of the fifth lens; and
a seventh lens being convex on the image side,
wherein expressions (1) and (2) are satisfied:
−3.0< f 5/ f<− 2.2 (1).
2.8< f 4/ f< 3.5 (2).
where a focal length of the fifth lens is f5, a focal length of the fourth lens is f4 and a focal length of an entire lens optical system is f.
2. The imaging lens according to claim 1 , wherein the fourth lens is an aspheric lens.
3. The imaging lens according to claim 1 , wherein the fourth lens has the highest power out of lenses having a positive power among the first lens to the seventh lens.
4. The imaging lens according to claim 1 , wherein the image side of the fifth lens and the object side of the sixth lens each have an aspheric shape.
5. The imaging lens according to claim 1 , wherein the second lens, the third lens, the fifth lens, the sixth lens and the seventh lens are plastic lenses.
6. An imaging device comprising:
an imaging lens system according to claim 1 ;
a flat-plate cover glass placed on an object side of the imaging lens system; and
an image sensor placed at an image location of the imaging lens system.