Imaging lens
An imaging lens includes a first lens having positive refractive power; a second lens; a third lens; a fourth lens having positive refractive power; a fifth lens; a sixth lens; and a seventh lens, arranged in this order from an object side to an image plane side. The sixth lens is formed in a shape so that a surface thereof on the image plane side has a positive curvature radius. The seventh lens is formed in a shape so that a surface thereof on the image plane side and a surface thereof on the object side are aspheric. The imaging lens has a specific angle of view.
1. An imaging lens comprising:
a first lens having positive refractive power;
a second lens;
a third lens;
a fourth lens having positive refractive power;
a fifth lens;
a sixth lens; and
a seventh lens, arranged in this order from an object side to an image plane side,
wherein said sixth lens is formed in a shape so that a surface thereof on the image plane side has a positive curvature radius,
said seventh lens is formed in a shape so that a surface thereof on the image plane side and a surface thereof on the object side are aspheric; and
said imaging lens has an angle of view 2ω so that the following conditional expression is satisfied:
80°≤2ω.
2. The imaging lens according to claim 1 , wherein said third lens is disposed away from the fourth lens by a distance D 34 on an optical axis so that the following conditional expression is satisfied:
0.05< D 34/ f< 0.2,
where f is a focal length of a whole lens system.
3. The imaging lens according to claim 1 , wherein said first lens has a focal length f 1 so that the following conditional expression is satisfied:
0.5< f 1/ f< 2.0,
where f is a focal length of a whole lens system.
4. The imaging lens according to claim 1 , wherein said first lens has a focal length f 1 and said second lens has a focal length f 2 so that the following conditional expression is satisfied:
−4< f 2/ f 1<−0.5.
5. The imaging lens according to claim 1 , wherein said first lens has a focal length f 1 and said third lens has a focal length f 3 so that the following conditional expression is satisfied:
0.5< f 3/ f 1<4.
6. The imaging lens according to claim 1 , wherein said fourth lens has a focal length f 4 and said fifth lens has a focal length f 5 so that the following conditional expression is satisfied:
−8< f 4/ f 5<−1.5.
7. The imaging lens according to claim 1 , wherein said fourth lens has a focal length f 4 so that the following conditional expression is satisfied:
2< f 4/ f< 15,
where f is a focal length of a whole lens system.
8. The imaging lens according to claim 1 , wherein said seventh lens has a focal length f 7 so that the following conditional expression is satisfied:
−8< f 7/ f<− 1,
where f is a focal length of a whole lens system.
9. The imaging lens according to claim 1 , wherein said second lens has an Abbe's number νd 2 so that the following conditional expression is satisfied:
20<ν d 2<35.
10. The imaging lens according to claim 1 , wherein said fifth lens has an Abbe's number νd 5 so that the following conditional expression is satisfied:
20<ν d 5<35.
11. An imaging lens comprising:
a first lens having positive refractive power;
a second lens;
a third lens;
a fourth lens having positive refractive power;
a fifth lens;
a sixth lens; and
a seventh lens, arranged in this order from an object side to an image plane side,
wherein said sixth lens is formed in a shape so that a surface thereof on the object side and a surface thereof on the image plane side have positive curvature radii,
said seventh lens is formed in a shape so that a surface thereof on the image plane side and a surface thereof on the object side are aspheric; and
said fourth lens has a focal length f 4 so that the following conditional expression is satisfied:
2< f 4/ f< 15,
where f is a focal length of a whole lens system.
12. The imaging lens according to claim 11 , wherein said third lens is disposed away from the fourth lens by a distance D 34 on an optical axis so that the following conditional expression is satisfied:
0.05< D 34/ f< 0.2.
13. The imaging lens according to claim 11 , wherein said first lens has a focal length f 1 so that the following conditional expression is satisfied:
0.5< f 1/ f< 2.0.
14. The imaging lens according to claim 11 , wherein said first lens has a focal length f 1 and said second lens has a focal length f 2 so that the following conditional expression is satisfied:
−4< f 2/ f 1<−0.5.
15. The imaging lens according to claim 11 , wherein said first lens has a focal length f 1 and said third lens has a focal length f 3 so that the following conditional expression is satisfied:
0.5< f 3/ f 1<4.
16. The imaging lens according to claim 11 , wherein said fifth lens has a focal length f 5 so that the following conditional expression is satisfied:
−8< f 4/ f 5<−1.5.
17. The imaging lens according to claim 11 , wherein said seventh lens has a focal length f 7 so that the following conditional expression is satisfied:
−8< f 7/ f<− 1.
18. The imaging lens according to claim 11 , wherein said second lens has an Abbe's number νd 2 so that the following conditional expression is satisfied:
20<ν d 2<35.
19. The imaging lens according to claim 11 , wherein said fifth lens has an Abbe's number νd 5 so that the following conditional expression is satisfied:
20<ν d 5<35.
20. The imaging lens according to claim 11 , wherein said imaging lens has an angle of view 2ω so that the following conditional expression is satisfied:
80°2ω.