Image forming lens system and image pickup apparatus using the same

Patent metadata

Field	Value
Publication number	US-2016306186-A1
Application number	US-201615189439-A
Country	US
Kind code	A1
Filing date	Jun 22, 2016
Priority date	Nov 27, 2013
Publication date	Oct 20, 2016
Grant date	—

Abstract

An image forming lens system includes a front lens unit having a positive refractive power, and a rear lens unit, and does not include any other lens unit. The front lens unit includes a first lens unit having a positive refractive power and a second lens unit having a negative refractive power. Each of the first lens unit and the second lens unit includes a positive lens and a negative lens. The second lens unit is a focusing lens unit. The rear lens unit includes a positive lens and a negative lens. The second lens unit is the only lens unit that moves, in the front lens unit, and the following conditional expressions (1) and (2′) are satisfied:
0.5< f FF /f<1.65   (1)

0≦| f/r G2b |<6.5   (2′)

First claim

What is claimed is:

1 . An image forming lens system comprising in order from an object side to an image side along an optical axis:
a front lens unit having a positive refractive power; and a rear lens unit, wherein the image forming lens system does not include any other lens unit on the optical axis, and the front lens unit includes in order from the object side to the image side, a first lens unit having a positive refractive power, and a second lens unit having a negative refractive power, and each of the first lens unit and the second lens unit includes a positive lens and a negative lens, and the second lens unit is a focusing lens unit, and the focusing lens unit moves toward an image side along the optical axis at the time of focusing operation from an object at infinity to an object at a close distance, and the second lens unit is the only lens unit that moves, in the front lens unit, and the rear lens unit includes an image-motion correcting lens unit, and a first predetermined lens unit which is disposed on the object side of the image-motion correcting lens unit, immediately before the image-motion correcting lens unit, and the image-motion correcting lens unit moves in a direction different from a direction of the optical axis to reduce an image motion due to shaking of the image forming lens system, and the first predetermined lens unit has a refractive power having a sign different from a sign of a refractive power of the image-motion correcting lens unit, and the following conditional expressions (1) and (2′) are satisfied:
0.5< f FF /f< 1.65   (1)

0≦| f/r G2b |<6.5   (2′)

where, f FF denotes a focal length of the front lens unit at the time of focusing at an object at infinity, f denotes a focal length of the image forming lens system at the time of focusing at an object at infinity, and r G2b denotes a paraxial radius of curvature of a lens surface on the object side of the second lens unit, immediately before the object.

2 . An image forming lens system comprising in order from an object side to an image side along an optical axis:
a front lens unit having a positive refractive power; and a rear lens unit, wherein the image forming lens system does not include any other lens unit on the optical axis, and the front lens unit includes in order from the object side to the image side, a first lens unit having a positive refractive power, and a second lens unit having a negative refractive power, and each of the first lens unit and the second lens unit includes a positive lens and a negative lens, and the second lens unit is a focusing lens unit, and the focusing lens unit moves toward an image side along the optical axis at the time of focusing operation from an object at infinity to an object at a close distance, and the second lens unit is the only lens unit that moves, in the front lens unit, and the rear lens unit includes an image-motion correcting lens unit, and a second predetermined lens unit which is disposed immediately after the image-motion correcting lens unit, and the image-motion correcting lens unit moves in a direction different from a direction of the optical axis to reduce an image motion due to shaking of the image forming lens system, and the second predetermined lens unit has a refractive power having a sign different from a sign of a refractive power of the image-motion correcting lens unit, and the following conditional expressions (1) and (2′) are satisfied:
0.5< f FF /f< 1.65   (1)

0≦| f/r G2b |<6.5   (2′)

where, f FF denotes a focal length of the front lens unit at the time of focusing at an object at infinity, f denotes a focal length of the image forming lens system at the time of focusing at an object at infinity, and r G2b denotes a paraxial radius of curvature of a lens surface on the object side of the second lens unit, immediately before the object.

3 . An image forming lens system comprising in order from an object side to an image side along an optical axis:
a front lens unit having a positive refractive power; and a rear lens unit, wherein the image forming lens system does not include any other lens unit on the optical axis, and the front lens unit includes in order from the object side to the image side, a first lens unit having a positive refractive power, and a second lens unit having a negative refractive power, and each of the first lens unit and the second lens unit includes a positive lens and a negative lens, and the second lens unit is a focusing lens unit, and the focusing lens unit moves toward an image side along the optical axis at the time of focusing operation from an object at infinity to an object at a close distance, and the second lens unit is the only lens unit that moves, in the front lens unit, and the rear lens unit includes an image-motion correcting lens unit, and a first predetermined lens unit which is disposed on the object side of the image-motion correcting lens unit, immediately before the image-motion correcting lens unit, and a second predetermined lens unit which is disposed on the image side of the image-motion correcting lens unit, immediately after the image-motion correcting lens unit, and the image-motion correcting lens unit moves in a direction different from a direction of the optical axis to reduce an image motion due to shaking of the image forming lens system, and each of the first predetermined lens unit and the second predetermined lens unit has a refractive power having a sign different from the sign of the refractive power of the image-motion correcting lens unit, and the following conditional expressions (1) and (2′) are satisfied:
0.5< f FF /f< 1.65   (1)

0≦| f/r G2b |<6.5   (2′)

where, f FF denotes a focal length of the front lens unit at the time of focusing at an object at infinity, f denotes a focal length of the image forming lens system at the time of focusing at an object at infinity, and r G2b denotes a paraxial radius of curvature of a lens surface on the object side of the second lens unit, immediately before the object.

4 . An image forming lens system comprising in order from an object side to an image side along an optical axis:
a front lens unit having a positive refractive power; and a rear lens unit, wherein the image forming lens system does not include any other lens unit on the optical axis, and the front lens unit includes in order from the object side to the image side, a first lens unit having a positive refractive power, and a second lens unit having a negative refractive power, and each of the first lens unit and the second lens unit includes a positive lens and a negative lens, and the second lens unit is a focusing lens unit, and the focusing lens unit moves toward an image side along the optical axis at the time of focusing operation from an object at infinity to an object at a close distance, and the second lens unit is the only lens unit that moves, in the front lens unit, and the rear lens unit includes an image-motion correcting lens unit having a negative refractive power and a positive lens, and the image-motion correcting lens unit moves in a direction different from a direction of the optical axis to reduce an image motion due to shaking of the image forming lens system, and the following conditional expressions (1) and (2′) are satisfied:
0.5< f FF /f< 1.65   (1)

0≦| f/r G2b |<6.5   (2′)

where, f FF denotes a focal length of the front lens unit at the time of focusing at an object at infinity, f denotes a focal length of the image forming lens system at the time of focusing at an object at infinity, and r G2b denotes a paraxial radius of curvature of a lens surface on the object side of the second lens unit, immediately before th

Assignees

• Olympus Corp

Inventors

• Fujikura Takashi
• Ichikawa Keisuke
• Kawamura Kazuteru

Classifications

• H04N23/80

  Camera processing pipelines; Components thereof · CPC title

• H04N5/23229

  Electricity · mapped topic

• G02B15/173

  arranged +-+ · CPC title

• H04N5/2254

  Electricity · mapped topic

• G02B9/60

  having five components only · CPC title