| CPC G02B 13/0045 (2013.01) [G02B 9/64 (2013.01)] | 13 Claims |

|
1. An optical imaging system comprising:
a first lens comprising a convex object-side surface and a concave image-side surface;
a second lens comprising a refractive power;
a third lens comprising positive refractive power and a convex object-side surface;
a fourth lens comprising a refractive power;
a fifth lens comprising a refractive power and a concave object-side surface in a paraxial region;
a sixth lens comprising a refractive power; and
a seventh lens comprising a refractive power,
wherein the first to seventh lenses are sequentially disposed in ascending numerical order from an object side toward an imaging plane,
wherein a radius of curvature of an object-side surface of the seventh lens is greater than a radius of curvature of an image-side surface of the sixth lens, and
wherein −5.0<f2/f<−2.0 and 3.0<|f4/f|, where f is a focal length of the optical imaging system, f2 is a focal length of the second lens, and f4 is a focal length of the fourth lens.
|