Camera lens

1. A camera lens, comprising, from an object side to an image side: a first lens having a positive refractive power, a second lens having a negative refractive power, a third lens having a positive refractive power and a fourth lens having a negative refractive power, the camera lens satisfying following relational expressions (1) to (6):

0.50 f1/f 0.68   (1)

−1.50 f2/f −1.30   (2)

−0.50 f1/f2 −0.45   (3)

−0.90 ( R 1+ R 2)/( R 1− R 2) −0.60   (4)

0.15 ( R 3+ R 4)/( R 3− R 4) 0.85   (5)

1.10 ( R 7+ R 8)/( R 7− R 8) 3.00   (6),

wherein

f denotes an overall focal length of the camera lens,

f1 denotes a focal length of the first lens,

f2 denotes a focal length of the second lens,

R 1 denotes a curvature radius of an object side surface of the first lens,

R 2 denotes a curvature radius of an image side surface of the first lens,

R 3 denotes a curvature radius of an object side surface of the second lens,

R 2 denotes a curvature radius of an image side surface of the second lens,

R 7 denotes a curvature radius of an object side surface of the fourth lens, and

R 8 denotes a curvature radius of an image side surface of the fourth lens.

2. The camera lens according to claim 1 , wherein:

the camera lens satisfies following relational expressions (7) and (8):

0.65 f3/f 1.80   (7)

2.40 ( R 5+ R 6)/( R 5− R 6) 5.00   (8),

wherein

f3 denotes a focal length of the third lens,

R 5 denotes a curvature radius of an object side surface of the third lens, and

R 6 denotes a curvature radius of an image side surface of the third lens.

3. The camera lens according to claim 1 , wherein:

the camera lens satisfies following relational expression (9):

−1.20 f4/f −0.50   (9),

wherein

f4 denotes a focal length of the fourth lens.