Optical imaging system
An optical imaging system includes a first lens having a positive refractive power, an object-side surface wherein an object-side surface of the first lens is convex and an image-side surface of the first lens is concave, a second lens having a negative refractive power, wherein an image-side surface of the second lens is concave, a third lens having a negative refractive power, a fourth lens having a positive refractive power, and a fifth lens having a negative refractive power, wherein the first to fifth lenses are sequentially disposed from an object side toward an imaging plane.
1. An optical imaging system comprising:
a first lens comprising a positive refractive power, wherein an object-side surface of the first lens is convex;
a second lens comprising a negative refractive power, wherein an image-side surface of the second lens is concave;
a third lens comprising refractive power, wherein an object-side surface of the third lens is convex;
a fourth lens comprising refractive power, wherein an object-side surface of the fourth lens is concave; and
a fifth lens comprising refractive power, wherein an object-side surface of the fifth lens is concave and an image-side surface of the fifth lens is convex in a paraxial portion,
wherein the first to fifth lenses are sequentially disposed from an object side of the optical imaging system, towards an imaging plane
where 0.70<TTL/f<1.1, in which TTL is a distance of the object-side surface of the first lens to the imaging plane, and f is an overall focal length of the optical imaging system, and
a focal length f1 of the first lens is in a range of 2.50 to 3.00.
2. The optical imaging system of claim 1 , wherein an image-side surface of the third lens is concave.
3. The optical imaging system of claim 1 , where 20<FOV<35, in which FOV is a half of a field of view of the optical imaging system.
4. The optical imaging system of claim 1 , where 0.16<R 1 /f<2.0, in which R 1 is a radius of curvature of the object-side surface of the first lens, and f is an overall focal length of the optical imaging system.
5. The optical imaging system of claim 1 , wherein one of the first through fifth lenses has a meniscus shape.
6. The optical imaging system of claim 1 , wherein one of the first through fifth lenses has an aspherical shape.
7. The optical imaging system of claim 1 , where 1.10<TTL/ImgH, in which TTL is a distance of the object-side surface of the first lens to the imaging plane, and ImgH is ½ of a diagonal length of the imaging plane.
8. The optical imaging system of claim 1 , further comprising:
a stop located adjacent to the object-side surface of the first lens.