Optical system
An optical system includes a first lens having negative refractive power and having two concave surfaces, a second lens having positive refractive power, a third lens having refractive power, a fourth lens having refractive power, a fifth lens having refractive power, a sixth lens having refractive power, and a seventh lens having refractive power. The first to seventh lenses are sequentially disposed from an object side.
1. An optical system comprising:
a first lens having negative refractive power and having two concave surfaces;
a second lens having positive refractive power, wherein both surfaces of the second lens are convex;
a third lens having positive refractive power and having meniscus shape in which an object-side surface of the third lens is convex;
a fourth lens having refractive power;
a fifth lens having refractive power;
a sixth lens having refractive power; and
a seventh lens having refractive power,
wherein the first to seventh lenses are sequentially disposed from an object side, the second lens among the first to seventh lenses has a second largest effective radius and
the seventh lens has at least one inflection point formed on at least one of an object-side surface and an image-side surface of the seventh lens.
2. The optical system of claim 1 , wherein the fourth lens has positive refractive power.
3. The optical system of claim 1 , wherein both surfaces of the fourth lens are convex.
4. The optical system of claim 1 , wherein the fifth lens has negative refractive power.
5. The optical system of claim 1 , wherein the fifth lens has a meniscus shape in which an image-side surface of the fifth lens is convex.
6. The optical system of claim 1 , wherein the sixth lens has positive refractive power.
7. The optical system of claim 1 , wherein both surfaces of the sixth lens are convex.
8. The optical system of claim 1 , wherein the seventh lens has negative refractive power.
9. The optical system of claim 1 , wherein the seventh lens has a meniscus shape in which an object-side surface of the seventh lens is convex.
10. The optical system of claim 1 , further comprising a stop disposed between the fourth and fifth lenses.
11. The optical system of claim 1 , wherein the fourth to seventh lenses are provided as plastic lenses.
12. The optical system of claim 1 , wherein all respective surfaces of the first to seventh lenses are aspherical.
13. An optical system comprising:
a first lens having negative refractive power and having two concave surfaces;
a second lens having refractive power;
a third lens having positive refractive power and having meniscus shape in which an object-side surface of the third lens is convex;
a fourth lens having refractive power;
a fifth lens having negative refractive power, wherein the fifth lens has a meniscus shape in which an image-side surface of the fifth lens is convex;
a sixth lens having refractive power; and
a seventh lens having refractive power,
wherein the first to seventh lenses are sequentially disposed from an object side,
the second lens among the first to seventh lenses has a second largest effective radius, and
the seventh lens has at least one inflection point formed on at least one of an object-side surface and an image-side surface of the seventh lens.
14. The optical system of claim 13 , wherein the fourth lens has positive refractive power and two convex surfaces.
15. The optical system of claim 13 , wherein the sixth lens has positive refractive power and two convex surfaces.
16. The optical system of claim 13 , wherein the seventh lens has negative refractive power and has a meniscus shape in which an object-side surface of the seventh lens is convex.
17. The optical system of claim 13 , further comprising a stop disposed between the fourth and fifth lenses.
18. An optical system comprising:
a first lens having negative refractive power and having two concave surfaces;
a second lens having positive refractive power;
a third lens having positive refractive power and having meniscus shape in which an object-side surface of the third lens is convex;
a fourth lens having refractive power;
a fifth lens having refractive power;
a sixth lens having refractive power; and
a seventh lens having negative refractive power,
wherein the first to seventh lenses are sequentially disposed from an object side, the second lens among the first to seventh lenses has a second largest effective radius, and
the seventh lens has at least one inflection point formed on at least one of an object-side surface and an image-side surface of the seventh lens.