Photographic lens optical system
A photographic lens optical system includes: a first lens having a positive refractive power and a meniscus shape convex toward an object side; a second lens having a negative refractive power and a meniscus shape convex toward the object side; a doublet lens having a positive refractive power and formed by combining a third lens and a fourth lens; a fifth lens having a positive refractive power and a double convex shape; and a sixth lens having a positive refractive power and a double convex shape. The first to sixth lenses are sequentially arranged in a direction from the object side to an image side, and the photographic lens optical system satisfies the following condition: 1.5< Nd 2<1.7 where Nd2 denotes a refractive index of the second lens.
1. A photographic lens optical system comprising:
a first lens having a positive refractive power and a meniscus shape convex toward an object side;
a second lens having a negative refractive power and a meniscus shape convex toward the object side;
a doublet lens having a positive refractive power and formed by combining a third lens and a fourth lens;
a fifth lens having a positive refractive power and a double convex shape; and
a sixth lens having a positive refractive power and a double convex shape,
wherein the first to sixth lenses are sequentially arranged in a direction from the object side to an image side, and the photographic lens optical system satisfies the following condition:
1.5 <Nd 2<1.7
where Nd2 denotes a refractive index of the second lens.
2. The photographic lens optical system of claim 1 , wherein the doublet lens has a concave object-side surface.
3. The photographic lens optical system of claim 2 , wherein the third lens is a double concave lens and the fourth lens is a double convex lens.
4. The photographic lens optical system of claim 1 , wherein the photographic lens optical system satisfies the following condition:
BFL/ f< 1.4
where BFL and f denote a back focal length and a focal length of the photographic lens optical system, respectively.
5. The photographic lens optical system of claim 4 , wherein the doublet lens has a concave object-side surface.
6. The photographic lens optical system of claim 5 , wherein the third lens is a double concave lens and the fourth lens is a double convex lens.
7. The photographic lens optical system of claim 1 , wherein at least one lens of the photographic lens optical system is formed of a plastic material.
8. The photographic lens optical system of claim 7 , wherein the second lens is formed of a plastic material.
9. The photographic lens optical system of claim 8 , wherein the second lens has at least one aspheric surface.
10. The photographic lens optical system of claim 1 , further comprising an aperture stop disposed between the second lens and the third lens.
11. A photographing apparatus comprising:
the photographic lens optical system of claim 1 ; and
an image sensor converting an optical image formed by the photographic lens optical system into an electric signal.