Optical imaging system
An optical imaging system includes a first lens having negative refractive power, a second lens having negative refractive power, a third lens, a fourth lens, a fifth lens, a sixth lens, and a seventh lens. The first to seventh lenses are sequentially disposed from an object side toward an image side. The third lens, the fourth lens, the sixth lens, and the seventh lens are formed of plastic, and the first lens, the second lens, and the fifth lens are formed of glass.
1. An optical imaging system comprising:
a first lens comprising negative refractive power;
a second lens comprising refractive power;
a third lens comprising positive refractive power, a convex object-side surface and a convex image-side surface;
a fourth lens comprising negative refractive power;
a fifth lens comprising refractive power;
a sixth lens comprising refractive power; and
a seventh lens comprising negative refractive power,
wherein the first to seventh lenses are sequentially disposed from an object side toward an image side,
wherein n3<1.64 is satisfied, where n3 is a refractive index of the third lens,
wherein TTL/(2*IMGH)<3.0 is satisfied, where TTL is a distance from an object-side surface of the first lens to an imaging plane of an image sensor, and IMGH is a half of a diagonal length of the imaging plane of the image sensor, and
wherein 0.02<f/f3<0.65 is satisfied, where f3 is a focal length of the third lens, and f is an overall focal length of the optical imaging system.
2. The optical imaging system of claim 1 , wherein −0.5<f/f4<−0.1 is satisfied, where f4 is a focal length of the fourth lens.
3. The optical imaging system of claim 1 , wherein 0.25<f/f6<0.65 is satisfied, where f6 is a focal length of the sixth lens.
4. The optical imaging system of claim 1 , wherein −0.5<f/f7<−0.1 is satisfied, where f7 is a focal length of the seventh lens.
5. The optical imaging system of claim 1 , wherein n4<1.64 is satisfied, where n4 is a refractive index of the fourth lens.
6. The optical imaging system of claim 1 , wherein n6<1.535 is satisfied, where n6 is a refractive index of the sixth lens.
7. The optical imaging system of claim 1 , wherein n7<1.64 is satisfied, where n7 is a refractive index of the seventh lens.
8. The optical imaging system of claim 1 , wherein the first lens has a convex object-side surface and a concave image-side surface.
9. The optical imaging system of claim 1 , wherein the second lens has a concave object-side surface and a concave image-side surface.
10. The optical imaging system of claim 1 , wherein the fourth lens has a concave object-side surface and a concave image-side surface.
11. The optical imaging system of claim 1 , wherein the fifth lens has a convex object-side surface and a convex image-side surface.
12. The optical imaging system of claim 1 , wherein the sixth lens has a convex object-side surface and a convex image-side surface.
13. The optical imaging system of claim 1 , wherein the seventh lens has a concave object-side surface and a convex image-side surface.
14. The optical imaging system of claim 1 , wherein the second lens has negative refractive power.
15. The optical imaging system of claim 1 , wherein the fifth lens has positive refractive power.
16. The optical imaging system of claim 1 , wherein the sixth lens has positive refractive power.
17. An optical imaging system comprising:
a first lens comprising negative refractive power;
a second lens comprising refractive power;
a third lens comprising positive refractive power, a convex object-side surface and a convex image-side surface;
a fourth lens comprising negative refractive power;
a fifth lens comprising refractive power;
a sixth lens comprising refractive power; and
a seventh lens comprising negative refractive power,
wherein the first to seventh lenses are sequentially disposed from an object side toward an image side,
wherein n3<1.64 is satisfied, where n3 is a refractive index of the third lens,
wherein TTL/(2*IMGH)<3.0 is satisfied, where TTL is a distance from an object-side surface of the first lens to an imaging plane of an image sensor, and IMGH is a half of a diagonal length of the imaging plane of the image sensor, and
wherein −0.5<f/f7<−0.1 is satisfied, where f7 is a focal length of the seventh lens, and f is an overall focal length of the optical imaging system.