| CPC G02B 15/12 (2013.01) [G02B 13/001 (2013.01)] | 15 Claims |

|
1. A converter optical system comprising:
a first lens having positive refractive power and a concave image-side surface;
a second lens having negative refractive power;
a third lens having positive refractive power;
a fourth lens having a refractive power and a concave image-side surface; and
a fifth lens having a convex object-side surface,
wherein the first to fifth lenses are sequentially disposed in numerical order from the first lens to the fifth lens from an object side of the converter optical system to an image side of the converter optical system,
a thickness of the first lens is greater than a thickness of the fifth lens,
the first to fifth lenses are the only lenses that have refractive power in the converter optical system,
f-number <2.0, where f-number is an f-number of the converter optical system,
a radius of curvature of an object-side surface of the first lens is greater than a radius of curvature of an object-side surface of the second lens, and
1000<f/D, where f is an overall focal length of the converter optical system and D is a distance from an object-side surface of the first lens to an image-side surface of the fifth lens.
|