Imaging lens
An imaging lens includes a stop; a first lens having positive refractive power; a second lens having negative refractive power; 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 first lens is formed in a meniscus shape near an optical axis thereof. The third lens is formed in a shape so that a surface thereof directing to the image plane side is concave near an optical axis thereof. The sixth lens is formed in a meniscus shape near an optical axis thereof.
1. An imaging lens comprising:
a stop;
a first lens having positive refractive power;
a second lens having negative refractive power;
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 first lens is formed in a meniscus shape near an optical axis thereof,
said third lens is formed in a shape so that a surface thereof directing to the image plane side is concave near an optical axis thereof, and
said sixth lens is formed in a meniscus shape near an optical axis thereof.
2. 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.
3. The imaging lens according to claim 1 , wherein said second lens has a focal length f 2 and said third lens has a focal length f 3 so that the following conditional expression is satisfied:
0.1< f 2/ f 3<0.6.
4. 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:
1.0< f 4/ f< 3.0,
where f is a focal length of a whole lens system.
5. 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:
−4.0< f 7/ f<− 0.8,
where f is a focal length of a whole lens system.
6. The imaging lens according to claim 1 , wherein said sixth lens and said seventh lens have a composite focal length f 67 so that the following conditional expression is satisfied:
−1.7< f 67/ f<− 0.5,
where f is a focal length of a whole lens system.
7. The imaging lens according to claim 1 , wherein said second lens is disposed away from the third lens by a distance D 23 on an optical axis thereof so that the following conditional expression is satisfied:
0.03< D 23/ f< 0.2,
where f is a focal length of a whole lens system.
8. An imaging lens comprising:
a first lens group;
a second lens group; and
a third lens group having negative refractive power, arranged in this order from an object side to an image plane side,
wherein said first lens group includes a first lens, a second lens, and a third lens,
said second lens group includes a fourth lens and a fifth lens,
said third lens group includes a sixth lens and a seventh lens,
wherein said fifth lens is formed in a meniscus shape near an optical axis thereof,
said seventh lens is formed in a meniscus shape near an optical axis thereof, and
said third lens has an Abbe's number νd 3 so that the following conditional expression is satisfied:
ν d 3<35.
9. The imaging lens according to claim 8 , 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.
10. The imaging lens according to claim 8 , wherein said second lens has a focal length f 2 and said third lens has a focal length f 3 so that the following conditional expression is satisfied:
0.1< f 2/ f 3<0.6.
11. The imaging lens according to claim 8 , wherein said fourth lens has a focal length f 4 so that the following conditional expression is satisfied:
1.0< f 4/ f< 3.0,
where f is a focal length of a whole lens system.
12. The imaging lens according to claim 8 , wherein said seventh lens has a focal length f 7 so that the following conditional expression is satisfied:
−4.0< f 7/ f<− 0.8,
where f is a focal length of a whole lens system.
13. The imaging lens according to claim 8 , wherein said sixth lens and said seventh lens have a composite focal length f 67 so that the following conditional expression is satisfied:
−1.7< f 67/ f<− 0.5,
where f is a focal length of a whole lens system.
14. The imaging lens according to claim 8 , wherein said second lens is disposed away from the third lens by a distance D 23 on an optical axis thereof so that the following conditional expression is satisfied:
0.03< D 23/ f< 0.2,
where f is a focal length of a whole lens system.
15. An imaging lens comprising:
a first lens group;
a second lens group; and
a third lens group having negative refractive power, arranged in this order from an object side to an image plane side,
wherein said first lens group includes a first lens, a second lens, and a third lens,
said second lens group includes a fourth lens and a fifth lens,
said third lens group includes a sixth lens and a seventh lens,
said seventh lens is formed in a meniscus shape near an optical axis thereof,
said seventh lens is formed in a shape so that a surface thereof on the image plane side is aspheric, and
said third lens has an Abbe's number νd 3 so that the following conditional expression is satisfied:
ν d 3<35.
16. The imaging lens according to claim 15 , wherein said second lens has a focal length f 2 and said third lens has a focal length f 3 so that the following conditional expression is satisfied:
0.1< f 2/ f 3<0.6.
17. The imaging lens according to claim 15 , wherein said fourth lens has a focal length f 4 so that the following conditional expression is satisfied:
1.0< f 4/ f< 3.0,
where f is a focal length of a whole lens system.
18. The imaging lens according to claim 15 , wherein said seventh lens has a focal length f 7 so that the following conditional expression is satisfied:
−4.0< f 7/ f<− 0.8,
where f is a focal length of a whole lens system.
19. The imaging lens according to claim 15 , wherein said sixth lens and said seventh lens have a composite focal length f 67 so that the following conditional expression is satisfied:
−1.7< f 67/ f<− 0.5,
where f is a focal length of a whole lens system.
20. The imaging lens according to claim 15 , wherein said second lens is disposed away from the third lens by a distance D 23 on an optical axis thereof so that the following conditional expression is satisfied:
0.03< D 23/ f< 0.2,
where f is a focal length of a whole lens system.