Optical imaging system
An optical imaging system includes lenses sequentially disposed from an object side toward an imaging plane. A third lens, a fourth lens, and a fifth lens of the lenses each have a negative refractive power. An F number of the optical imaging system is 1.7 or less.
1. An optical imaging system comprising:
no more than six lenses comprising a first lens having a positive refractive power, a second lens having a positive refractive power, a third lens having a negative refractive power, a fourth lens having a negative refractive power, a fifth lens having a negative refractive power, and a sixth lens having a negative refractive power sequentially disposed from an object side of the optical imaging system toward an imaging plane of the optical imaging system,
wherein an image-side surface of the second lens is convex along an optical axis of the optical imaging system,
an object-side surface of the third lens is convex along the optical axis, and
an F number of the optical imaging system is 1.7 or less.
2. The optical imaging system of claim 1 , wherein an image-side surface of the third lens is concave along the optical axis.
3. The optical imaging system of claim 1 , wherein both surfaces of the fourth lens are concave along the optical axis.
4. The optical imaging system of claim 1 , wherein an object-side surface of the fifth lens is convex along the optical axis, and an image-side surface of the fifth lens is concave along the optical axis.
5. The optical imaging system of claim 1 , wherein an object-side surface of the first lens is convex along the optical axis, and an image-side surface of the first lens is concave along the optical axis.
6. The optical imaging system of claim 1 , wherein an object-side surface of the second lens is convex along the optical axis.
7. The optical imaging system of claim 1 , wherein an object-side surface of the sixth lens is convex along the optical axis, and an image-side surface of the sixth lens is concave along the optical axis.
8. The optical imaging system of claim 1 , wherein the fifth lens has an inflection point formed on an object-side surface of the fifth lens or an image-side surface of the fifth lens.
9. The optical imaging system of claim 1 , wherein the sixth lens has an inflection point formed on an object-side surface of the sixth lens or an image-side surface of the sixth lens.
10. The optical imaging system of claim 1 , wherein the optical imaging system satisfies any one or any combination of any two or more of the following Conditional Expressions:
1.0< f 1/ f< 2.0
0.5< f 2/ f< 2.0
−2.0< f 3/ f<− 1.0
where f represents an overall focal length of the optical imaging system, f1 represents a focal length of the first lens, f2 represents a focal length of the second lens, and f3 represents a focal length of the third lens.
11. The optical imaging system of claim 1 , wherein the optical imaging system satisfies the following Conditional Expression:
0.9< f 1/ f 2<2.0
where f1 represents a focal length of the first lens and f2 represents a focal length of the second lens.
12. The optical imaging system of claim 1 , wherein the optical imaging system satisfies the following Conditional Expression:
−1.2< f 2/ f 3<−0.3
where f2 represents a focal length of the second lens and f3 represents a focal length of the third lens.
13. The optical imaging system of claim 1 , wherein the optical imaging system satisfies one or any combination of any two or more of the following Conditional Expressions:
0.3< R 1/ f
0.7< R 5/ f
10< R 8/ f
where R1 represents a radius of curvature of an object-side surface of the first lens, R5 represents a radius of curvature of an object-side surface of the third lens, R8 represents a radius of curvature of an image-side surface of the fourth lens, and f represents an overall focal length of the optical imaging system.