Imaging lens
An imaging lens includes a first lens group and a second lens group, arranged from an object side to an image plane side. The first lens group includes a first lens, a second lens, and a third lens. The second lens group includes a front side lens group and a rear side lens group. The front side lens group includes a fourth lens and a fifth lens. The rear side lens group includes a sixth lens and a seventh lens both having two aspheric surfaces. The imaging lens has a total of seven single lenses. The first to seventh lenses are arranged respectively with a space in between. The third lens has convex surfaces on both sides. The fourth lens has a concave surface on the object side. The fifth lens has a concave surface on the image plane side. The rear side lens group has a specific focal length.
1. An imaging lens comprising:
a first lens group; and
a second lens group, 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, arranged in this order from the object side to the image plane side,
said second lens group includes a front side lens group and a rear side lens group, arranged in this order from the object side to the image plane side,
said front side lens group includes a fourth lens and a fifth lens,
said rear side lens group includes a sixth lens having two aspheric surfaces and a seventh lens having two aspheric surfaces,
said imaging lens has a total of seven single lenses,
said first lens, said second lens, said third lens, said fourth lens, said fifth lens, said sixth lens, and said seventh lens are arranged respectively with a space in between,
said third lens is formed in a shape so that a surface thereof on the object side and a surface thereof on the image plane side are convex near an optical axis thereof,
said fourth lens is formed in a shape so that a surface thereof on the object side is concave near an optical axis thereof,
said fifth lens is formed in a shape so that a surface thereof on the image plane side is concave near an optical axis thereof, and
said rear side lens group has a focal length Fr so that the following conditional expression is satisfied:
1< Fr/f< 10,
where f is a focal length of a whole lens system.
2. The imaging lens according to claim 1 , wherein said fourth lens is formed in the shape so that a surface thereof on the image plane side has a curvature radius R4r so that the following conditional expression is satisfied:
−1.2< R 4 r/f<− 0.3.
3. The imaging lens according to claim 1 , wherein said seventh lens is formed in a shape so that a surface thereof on the image plane side has a curvature radius R7r so that the following conditional expression is satisfied:
0.2< R 7 r/f< 0.6.
4. The imaging lens according to claim 1 , wherein said front side lens group has a focal length Ff so that the following conditional expression is satisfied:
−1.5< Ff/Fr<− 0.1.
5. The imaging lens according to claim 1 , wherein said fifth lens has a focal length f5 so that the following conditional expression is satisfied:
3<| f 5|/ f< 60.
6. An imaging lens comprising:
a first lens group; and
a second lens group, 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, arranged in this order from the object side to the image plane side,
said second lens group includes a front side lens group and a rear side lens group, arranged in this order from the object side to the image plane side,
said front side lens group includes a fourth lens having negative refractive power and a fifth lens,
said rear side lens group includes a sixth lens having two aspheric surfaces and a seventh lens having two aspheric surfaces,
said imaging lens has a total of seven single lenses,
said first lens, said second lens, said third lens, said fourth lens, said fifth lens, said sixth lens, and said seventh lens are arranged respectively with a space in between,
said third lens is formed in a shape so that a surface thereof on the object side and a surface thereof on the image plane side are convex near an optical axis thereof,
said fourth lens is formed in a shape so that a surface thereof on the object side is concave near an optical axis thereof,
said fifth lens has at least one aspheric surface, and
said fifth lens is formed in a shape so that a surface thereof on the image plane side is concave near an optical axis thereof.
7. The imaging lens according to claim 6 , wherein said fourth lens is formed in the shape so that a surface thereof on the image plane side has a curvature radius R4r so that the following conditional expression is satisfied:
−1.2< R 4 r/f<− 0.3,
where f is a focal length of a whole lens system.
8. The imaging lens according to claim 6 , wherein said seventh lens is formed in a shape so that a surface thereof on the image plane side has a curvature radius R7r so that the following conditional expression is satisfied:
0.2< R 7 r/f< 0.6,
where f is a focal length of a whole lens system.
9. The imaging lens according to claim 6 , wherein said front side lens group has a focal length Ff and said rear side lens group has a focal length Fr so that the following conditional expression is satisfied:
−1.5< Ff/Fr<− 0.1.
10. The imaging lens according to claim 6 , wherein said fifth lens has a focal length f5 so that the following conditional expression is satisfied:
3<| f 5|/ f< 60,
where f is a focal length of a whole lens system.
11. An imaging lens comprising:
a first lens group; and
a second lens group, 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, arranged in this order from the object side to the image plane side,
said second lens group includes a front side lens group and a rear side lens group, arranged in this order from the object side to the image plane side,
said front side lens group includes a fourth lens and a fifth lens,
said rear side lens group includes a sixth lens having two aspheric surfaces and a seventh lens having two aspheric surfaces,
said imaging lens has a total of seven single lenses,
said first lens, said second lens, said third lens, said fourth lens, said fifth lens, said sixth lens, and said seventh lens are arranged respectively with a space in between,
said third lens is formed in a shape so that a surface thereof on the object side and a surface thereof on the image plane side are convex near an optical axis thereof,
said fourth lens is formed in a shape so that a surface thereof on the object side is concave near an optical axis thereof,
said fifth lens is formed in a shape so that a surface thereof on the image plane side is concave near an optical axis thereof, and
said front side lens group has a focal length Ff and said rear side lens group has a focal length Fr so that the following conditional expression is satisfied:
−1.5< Ff/Fr<− 0.1.
12. The imaging lens according to claim 11 , wherein said fourth lens is formed in the shape so that a surface thereof on the image plane side has a curvature radius R4r so that the following conditional expression is satisfied:
−1.2< R 4 r/f<− 0.3,
where f is a focal length of a whole lens system.
13. The imaging lens according to claim 11 , wherein said seventh lens is formed in a shape so that a surface thereof on the image plane side has a curvature radius R7r so that the following conditional expression is satisfied:
0.2< R 7 r/f< 0.6,
where f is a focal length of a whole lens system.
14. The imaging lens according to claim 11 , wherein said rear side lens group has the focal length Fr so that the following conditional expression is satisfied:
1< Fr/f< 10,
where f is a focal length of a whole lens system.
15. The imaging lens according to claim 11 , wherein said fifth lens has a focal length f5 so that the following conditional expression is satisfied:
3<| f 5|/ f< 60,
where f is a focal length of a whole lens system.
16. An imaging lens comprising:
a first lens group; and
a second lens group, 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, arranged in this order from the object side to the image plane side,
said second lens group includes a front side lens group and a rear side lens group, arranged in this order from the object side to the image plane side,
said front side lens group includes a fourth lens and a fifth lens,
said rear side lens group includes a sixth lens having two aspheric surfaces and a seventh lens having two aspheric surfaces,
said imaging lens has a total of seven single lenses,
said first lens, said second lens, said third lens, said fourth lens, said fifth lens, said sixth lens, and said seventh lens are arranged respectively with a space in between,
said third lens is formed in a shape so that a surface thereof on the object side and a surface thereof on the image plane side are convex near an optical axis thereof,
said fourth lens is formed in a shape so that a surface thereof on the object side is concave near an optical axis thereof,
said fifth lens is formed in a shape so that a surface thereof on the image plane side is concave near an optical axis thereof, and
said fifth lens has a focal length f5 so that the following conditional expression is satisfied:
3<| f 5|/ f< 60,
where f is a focal length of a whole lens system.
17. The imaging lens according to claim 16 , wherein said fourth lens is formed in the shape so that a surface thereof on the image plane side has a curvature radius R4r so that the following conditional expression is satisfied:
−1.2< R 4 r/f<− 0.3.
18. The imaging lens according to claim 16 , wherein said seventh lens is formed in a shape so that a surface thereof on the image plane side has a curvature radius R7r so that the following conditional expression is satisfied:
0.2< R 7 r/f< 0.6.
19. The imaging lens according to claim 16 , wherein said rear side lens group has a focal length Fr so that the following conditional expression is satisfied:
1< Fr/f< 10.
20. The imaging lens according to claim 16 , wherein said front side lens group has a focal length Ff and said rear side lens group has a focal length Fr so that the following conditional expression is satisfied:
−1.5< Ff/Fr<− 0.1.