Image lens system
An image lens system includes, in order from an object side to an image side, a first lens element with negative refractive power including a concave image-side surface; a second lens element with positive refractive power including a convex object-side surface; a third lens element with negative refractive power including an object-side surface and a concave image-side surface, the object-side surface and the image-side surface being aspheric; a fourth lens element with positive refractive power including a convex object-side surface and a convex image-side surface; and a fifth lens element with negative refractive power including a convex object-side surface and a concave image-side surface, the object-side surface and the image-side surface being aspheric, the fifth lens element having at least one inflection point.
1. An image lens system comprising, in order from an object side to an image side:
a first lens element with negative refractive power comprising a concave image-side surface;
a second lens element with positive refractive power comprising a convex object-side surface;
a third lens element with negative refractive power comprising an object-side surface and a concave image-side surface, the object-side surface and the image-side surface being aspheric;
a fourth lens element with positive refractive power comprising a convex object-side surface and a convex image-side surface; and
a fifth lens element with negative refractive power comprising a convex object-side surface and a concave image-side surface, the object-side surface and the image-side surface being aspheric, the fifth lens element having at least one inflection point;
the image lens system satisfying the following condition:
0 ≦R 6 |R 5 |<1.0
wherein R 5 is the curvature radius of the object-side surface of the third lens element, and R 6 is the curvature radius of the image-side surface of the third lens element.
2. The image lens system according to claim 1 , wherein the image lens system satisfies the following condition:
| R 6 /R 7 |<0.9
wherein R 6 is the curvature radius of the image-side surface of the third lens element, and R 7 is the curvature radius of the object-side surface of the fourth lens element.
3. The image lens system according to claim 2 , wherein the second lens element comprises an image-side surface, and the image lens system satisfies the following condition:
0 ≦R 3 /|R 4 |≦1.0
wherein R 3 is the curvature radius of the object-side surface of the second lens element, and R 4 is the curvature radius of the image-side surface of the second lens element.
4. The image lens system according to claim 2 , wherein the image lens system satisfies the following condition:
0.3< R 2 /T 12 <1.6
wherein R 2 is the curvature radius of the image-side surface of the first lens element, and T 12 is the axial distance between the first lens element and the second lens element.
5. The image lens system according to claim 2 , wherein the image lens system satisfies the following condition:
1.5<( V 4 +V 3 )/( V 4 −V 3 )<3.0
wherein V 3 is the Abbe number of the third lens element, and V 4 is the Abbe number of the fourth lens element.
6. The image lens system according to claim 2 , wherein the object-side surface of the third lens element is convex.
7. The image lens system according to claim 1 , wherein the image lens system satisfies the following condition:
0<( R 7 +R 8 )/( R 7 −R 8 )<1.0
wherein R 7 is the curvature radius of the object-side surface of the fourth lens element, and R 8 is the curvature radius of the image-side surface of the fourth lens element.
8. The image lens system according to claim 7 , wherein the image lens system satisfies the following condition:
1.7<( R 9 +R 10 )/( R 9 −R 10 )<5.3
wherein R 9 is the curvature radius of the object-side surface of the fifth lens element, and R 10 is the curvature radius of the image-side surface of the fifth lens element.
9. The image lens system according to claim 7 , wherein at least two of the first lens element, the second lens element, the third lens element, the fourth lens element and the fifth element are made of plastic.
10. The image lens system according to claim 7 , wherein the image lens system satisfies the following condition:
80(degrees;deg.)<FOV<160(deg.)
wherein FOV is the maximal field of view in the image lens system.
11. The image lens system according to claim 7 , wherein the first lens element comprises an object-side surface and the image lens system satisfies the following condition:
0.15 <Dr 5 r 10 /TD< 0.40
wherein Dr 5 r 10 is the axial distance between the object-side surface of the third lens element and the image-side surface of the fifth lens element, and TD is the axial distance between the object-side surface of the first lens element and the image-side surface of the fifth lens element.
12. The image lens system according to claim 1 , wherein the image lens system satisfies the following condition:
0.3 <f/f 12 <1.0
wherein f is the focal length of the image lens system, and f 12 is the composite focal length of the first lens element and the second lens element.
13. The image lens system according to claim 1 , wherein the image lens system satisfies the following condition:
0 <f 12 /f 345 <1.0
wherein f 12 is the composite focal length of the first lens element and the second lens element, and f 345 is the composite focal length of the third lens element, the fourth lens element and the fifth lens element.
14. An image lens system comprising, in order from an object side to an image side:
a first lens element with negative refractive power comprising a concave image-side surface;
a second lens element with positive refractive power comprising a convex object-side surface;
a third lens element with negative refractive power comprising an object-side surface and a concave image-side surface, the object-side surface and the image-side surface being aspheric;
a fourth lens element with positive refractive power comprising a convex image-side surface; and
a fifth lens element with negative refractive power comprising a convex object-side surface and a concave image-side surface, the fifth lens element being made of plastic, the object-side surface and the image-side surface being aspheric, the fifth lens element having at least one inflection point;
the image lens system satisfying the following condition:
0 ≦R 6 /|R 5 |<1.0;
0.5(millimeters;mm)< f /tan(HFOV)<3.0(mm)
wherein R 5 is the curvature radius of the object-side surface of the third lens element, R 6 is the curvature radius of the image-side surface of the third lens element, f is the focal length of the image lens system, and HFOV is a half of the maximal field of view in the image lens system.
15. The image lens system according to claim 14 , wherein the image lens system satisfies the following condition:
0.30 <f/f 12 <1.0
wherein f is the focal length of the image lens system, and f 12 is the composite focal length of the first lens element and the second lens element.
16. The image lens system according to claim 14 , wherein the image lens system satisfies the following condition:
0 <f 12 /f 345 <1.0
wherein f 12 is the composite focal length of the first lens element and the second lens element, and f 345 is the composite focal length of the third lens element, the fourth lens element and the fifth lens element.
17. The image lens system according to claim 14 , wherein the object-side surface of the third lens element is convex.
18. The image lens system according to claim 14 , wherein the second lens element comprises an image-side surface and the image lens system satisfies the following condition:
0 ≦R 3 /|R 4 |≦1.0
wherein R 3 is the curvature radius of the object-side surface of the second lens element, and R 4 is the curvature radius of the image-side surface of the second lens element.
19. The image lens system according to claim 14 , wherein the fourth lens element comprises an object-side surface and the image lens system satisfies the following condition:
| R 6 /R 7 |<0.9
wherein R 6 is the curvature radius of the image-side surface of the third lens element, and R 7 is the curvature radius of the object-side surface of the fourth lens element.
20. The image lens system according to claim 14 , wherein the image lens system satisfies the following condition:
1.5<( V 4 +V 3 )/( V 4 −V 3 )<3.0
wherein V 3 is the Abbe number of the third lens element, and V 4 is the Abbe number of the fourth lens element.
21. An image lens system comprising, in order from an object side to an image side:
a first lens element with negative refractive power comprising a concave image-side surface;
a second lens element with positive refractive power comprising a convex object-side surface;
a third lens element with negative refractive power comprising a convex object-side surface and a concave image-side surface, the object-side surface and the image-side surface being aspheric;
a fourth lens element with positive refractive power comprising a convex image-side surface; and
a fifth lens element with negative refractive power comprising a convex object-side surface and a concave image-side surface, the fifth lens element being made of plastic, the object-side surface and the image-side surface being aspheric, the fifth lens element having at least one inflection point;
the image lens system satisfying the following condition:
0 ≦R 6 /|R 5 |<1.0
wherein R 5 is the curvature radius of the object-side surface of the third lens element, and R 6 is the curvature radius of the image-side surface of the third lens element.
22. The image lens system according to claim 21 , wherein fourth lens element comprises an object-side surface and the image lens system satisfies the following condition:
0<( R 7 +R 8 )/( R 7 −R 8 )<1.0
wherein R 7 is the curvature radius of the object-side surface of the fourth lens element, and R 8 is the curvature radius of the image-side surface of the fourth lens element.
23. The image lens system according to claim 21 , wherein the fourth lens element comprises an object-side surface and the image lens system satisfies the following condition:
| R 6 /R 7 |<0.9
wherein R 6 is the curvature radius of the image-side surface of the third lens element, and R 7 is the curvature radius of the object-side surface of the fourth lens element.
24. The image lens system according to claim 21 , wherein the second lens element comprises an image-side surface and the image lens system satisfies the following condition:
0 ≦R 3 /|R 4 |≦1.0
wherein R 3 is the curvature radius of the object-side surface of the second lens element, and R 4 is the curvature radius of the image-side surface of the second lens element.
25. The image lens system according to claim 21 , wherein the image lens system satisfies the following condition:
0.30 <f/f 12 <1.0
wherein f is the focal length of the image lens system, and f 12 is the composite focal length of the first lens element and the second lens element.
26. The image lens system according to claim 21 , wherein the image lens system satisfies the following condition:
0 <f 12 /f 345 <1.0
wherein f 12 is the composite focal length of the first lens element and the second lens element, and f 345 is the composite focal length of the third lens element, the fourth lens element and the fifth lens element.