Lens system and image pickup device equipped with the same

Patent metadata

Field	Value
Publication number	US-2016306148-A1
Application number	US-201615134632-A
Country	US
Kind code	A1
Filing date	Apr 21, 2016
Priority date	Mar 10, 2011
Publication date	Oct 20, 2016
Grant date	—

Abstract

A lens system, from an object side to an image side in the following order, includes; an object-side lens group that is disposed closest to the object side and having positive refractive power; a focusing lens group that moves during a focusing operation and having negative refractive power; a third lens group; a wobbling lens group that vibrates in an optical axis direction; and an image-side lens group that is disposed closest to the image side.

First claim

1 - 22 . (canceled)

23 . A lens system, from an object side to an image side in the following order, comprising:
an object-side lens group that is disposed closest to the object side and having positive refractive power, a focusing lens group that moves during a focusing operation and having negative refractive power, a third lens group, a wobbling lens group that vibrates in an optical axis direction,
and
an image-side lens group that is disposed closest to the image side.

24 . The lens system according to claim 23 ,
wherein the object-side lens group includes four lenses.

25 . The lens system according to claim 24 ,
wherein the four lenses in the object-side lens group are three lenses having positive refractive power and one lens having negative refractive power.

26 . The lens system according to claim 24 ,
wherein the four lenses in the object-side lens group are, from the object side in the following order, a lens having positive refractive power, a lens having positive refractive power, a lens having negative refractive power,
and
a lens having positive refractive power.

27 . The lens system according to claim 23 ,
wherein during the focusing operation, the object-side lens group remains fixed.

28 . The lens system according to claim 23 ,
wherein the focusing lens group includes, from the object side in the following order, a lens having negative refractive power, a lens having negative refractive power,
and
a lens having positive refractive power.

29 . The lens system according to claim 23 ,
wherein the focusing lens group includes, from the object side in the following order, a lens having negative refractive power,
and
a cemented lens including a lens having negative refractive power and a lens having positive refractive power.

30 . The lens system according to claim 23 ,
wherein the third lens group includes a cemented lens.

31 . The lens system according to claim 23 ,
wherein the wobbling lens group comprises a single lens or a cemented lens.

32 . The lens system according to claim 23 ,
wherein the image-side lens group includes a cemented lens.

33 . The lens system according to claim 32 ,
wherein the cemented lens is positioned closest to the object side of the image-side lens group.

34 . The lens system according to claim 23 ,
wherein the following conditional expression (1) is satisfied:
0.03 <Dwob /( DF 1+ DF 2)<0.15  (1)

where
Dwob is a thickness on the optical axis of the wobbling lens group,
DF 1 is a thickness on the optical axis of the focusing lens group,
and
DF 2 is a thickness on the optical axis of the third lens group.

35 . The lens system according to claim 23 ,
wherein the third lens group has positive refractive power,
and
the following conditional expressions (2) and (3) are satisfied:
−0.78< fF 1 /fobj<− 0.4  (2)

−1.3< fF 1/ fF 2<−0.80  (3)

where
fobj is a focal distance of the object-side lens group,
fF 1 is a focal distance of the focusing lens group,
and
fF 2 is a focal distance of the third lens group.

36 . The lens system according to claim 23 ,
wherein the following conditional expressions (4) and (5) are satisfied:
|(100×( y 1′− y 1)/ y 1|<0.107  (4)

|(100×( y 0.7′− y 0.7)/ y 0.7|<0.107  (5)

where
y 1 is a maximum height of image on an image plane,
y 0 . 7 is 0.7 times the maximum height of image y 1 ,
y 1 ′ is a light-beam height at a location where a main light beam having the same angle of view as an image-taking angle of view, which extends to the image height y 1 during focusing at infinity, crosses the image plane at a time when a defocus amount of Δs occurs during focusing at infinity as the wobbling lens group moves relative to an object at infinity,
y 0 . 7 ′ is a light-beam height at a location where a main light beam having the same angle of view as an image-taking angle of view, which extends to the image height y 0 . 7 during focusing at infinity, crosses the image plane at a time when a defocus amount of Δs occurs during focusing at infinity as the wobbling lens group moves relative to an object at infinity,
Δs is 8*the maximum height of image y 1 /1000,
and
y 1 , y 0 . 7 , y 1 ′, y 0 . 7 ′ and Δs are all given in millimeters.

37 . The lens system according to claim 23 ,
wherein: the third lens group has positive refractive power, the wobbling lens group has negative refractive power, a lateral magnification of the wobbling lens group is greater than 1,
and
the following conditional expressions (6), (7) and (8) are satisfied:
0.48 <fobj/finf< 0.8  (6)

0.4< fF 2 /finf< 0.5  (7)

0.2 <|fwob|/finf< 2.5  (8)

where
fobj is a focal distance of the object-side lens group,
fF 2 is a focal distance of the third lens group,
fwob is a focal distance of the wobbling lens group, and finf is a focal distance of the lens system during focusing at infinity.

38 . The lens system according to claim 23 ,
wherein the object-side lens group and the image-side lens group remain fixed.

39 . The lens system according to claim 23 ,
wherein the third lens group has positive refractive power.

40 . The lens system according to claim 23 ,
wherein: the third lens group has positive refractive power, an aperture diaphragm is disposed between the focusing lens group and the third lens group,
and
when focusing is carried out from a remote distance to a short distance, the focusing lens group moves to the image side.

41 . The lens system according to claim 23 ,
wherein: the lens system substantially consists of, from the object side in the following order, the object-side lens group, the focusing lens group, the third lens group, the wobbling lens group, and the image-side lens group.

42 . The lens system according to claim 40 ,
wherein the aperture diaphragm is fixed in position between the focusing lens group and the third lens group, and the following conditional expression (9) is satisfied:
0.2<| M 1 F|/|M 2 F|< 2.0  (9)

where
M 1 F is a maximum traveling amount of the focusing lens group,
and
M 2 F is a maximum traveling amount of the third lens group.

43 . The lens system according to claim 40 ,
wherein the following conditional expression (10) is satisfied:
0.003 <|Mwob|/|M 1 F|+|M 2 F|< 0.1  (10)

where
M 1 F is a maximum traveling amount of the focusing lens group,
M 2 f is a maximum traveling amount of the third lens group, and
Mwob is a maximum traveling amount of the wobbling lens group.

44 . The lens system according to claim 23 ,
wherein the following conditional expression (11) is satisfied:
0.09 <Lbf/L total<0.2  (11)

where
Lbf is a distance on an optical axis from a lens surface closest to the image side to the image plane in air of the lens system,
and
Ltotal is Llens+Lbf where Llens is a distance on the optical axis from a lens surface closest to the object side to a lens surface closest to the image side in the lens system.

45 . The lens system according to claim 23 ,
wherein: during a focusing operation, the focusing lens group and the third lens group move such that a focus state

Assignees

• Olympus Corp

Inventors

• Hara Kento

Classifications

• G02B9/60

  having five components only · CPC title

• G02B9/64

  having more than six components · CPC title

• G02B9/36

  arranged + -- + · CPC title

• G02B9/62

  having six components only · CPC title

• G02B15/173 Primary

  arranged +-+ · CPC title