Photographic lens
View Patent ↗A photographic lens comprising a first lens having a positive refractive power, a second lens having a negative refractive power, a third lens having a positive refractive power, and a fourth lens having a negative refractive power, wherein the lenses are numbered in order of location from the object, and wherein a surface of the fourth lens toward the object is an aspheric surface having an inflection point.
1. A photographic lens comprising:
a first lens having a positive refractive power;
a second lens having a negative refractive power;
a third lens having a positive refractive power; and
a fourth lens having a negative refractive power, wherein:
the lenses are numbered in order of location from the object,
a surface of the fourth lens toward the object is an aspheric surface having an inflection point; and
the photographic lens satisfies an inequality such that 0.75<f 3 /|f 4 |<1, wherein “f 3 ” and “f 4 ” respectively are focal lengths of the third lens and the fourth lens.
2. The photographic lens of claim 1 , wherein at least one surface of each of the first to fourth lenses is an aspheric surface.
3. The photographic lens of claim 1 , wherein both surfaces of each of the first to fourth lenses are aspheric surfaces.
4. The photographic lens of claim 1 , wherein an aperture stop is disposed between the first lens and the object.
5. The photographic lens of claim 1 , wherein the first lens is a meniscus lens having a convex surface toward the object.
6. The photographic lens of claim 1 , wherein the second lens is a meniscus lens having a convex surface toward the image.
7. The photographic lens of claim 1 , wherein the fourth lens is a meniscus lens having a convex surface toward the image.
8. The photographic lens of claim 1 , satisfying an inequality such that 0.5<f/|f 2 |<1, wherein “f” is a focal length of the overall lens and “f 2 ” is a focal length of the second lens.
9. The photographic lens of claim 1 , satisfying an inequality such that 0.3<f 1 /|f 2 |<0.8, wherein “f 1 ” and “f 2 ” respectively are focal lengths of the first lens and the second lens.
10. The photographic lens of claim 1 , satisfying an inequality such that v 1 -v 2 >15, wherein “v 1 ” and “v 2 ” respectively are the Abbe numbers of the first and second lenses.
11. The photographic lens of claim 10 , satisfying an inequality such that 0.9<v 3 /v 4 <1.1, wherein “v 3 ” and “v 4 ” respectively are the Abbe numbers of the third and fourth lenses.