Imaging lens
An imaging lens includes a first lens group and a second lens group, arranged in this order 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 having two aspheric surfaces and a seventh lens 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 and fourth lenses have convex surfaces on the image plane side. The fifth lens has a convex surface on the object 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 has at least one aspheric surface,
said third lens is formed in a shape so that a surface thereof on the image plane side is convex near an optical axis thereof,
said fourth lens is formed in a shape so that a surface thereof on the image plane side is convex near an optical axis thereof,
said fifth lens is formed in a shape so that a surface thereof on the object side is convex 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 the 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 rear side lens group having positive refractive power,
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 has at least one aspheric surface,
said third lens is formed in a shape so that a surface thereof on the image plane side is convex near an optical axis thereof,
said fourth lens is formed in a shape so that a surface thereof on the image plane side is convex near an optical axis thereof,
said fifth lens is formed in a shape so that a surface thereof on the object side is convex near an optical axis thereof, and
said first lens has an Abbe's number νd1 so that the following conditional expression is satisfied:
35<ν vd 1<75.
7. The imaging lens according to claim 6 , wherein said fourth lens is formed in the shape so that the 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 rear side lens group having positive refractive power,
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 image plane side is convex near an optical axis thereof,
said fourth lens is formed in a shape so that a surface thereof on the image plane side is convex near an optical axis thereof,
said fifth lens is formed in a shape so that a surface thereof on the object side is convex near an optical axis thereof, and
said second lens has an Abbe's number νd2 so that the following conditional expression is satisfied:
15<ν d 2<35.
12. The imaging lens according to claim 11 , wherein said fourth lens is formed in the shape so that the 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 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.
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 rear side lens group having positive refractive power,
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 has at least one aspheric surface,
said third lens is formed in a shape so that a surface thereof on the image plane side is convex near an optical axis thereof,
said fourth lens is formed in a shape so that a surface thereof on the image plane side is convex near an optical axis thereof,
said fifth lens is formed in a shape so that a surface thereof on the object side is convex near an optical axis thereof, and
said third lens has an Abbe's number νd3 so that the following conditional expression is satisfied:
35<ν d 3<75.
17. The imaging lens according to claim 16 , wherein said fourth lens is formed in the shape so that the 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.
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,
where f is a focal length of a whole lens system.
19. 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.
20. The imaging lens according to claim 16 , 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.