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US 9,541,746 B2Granted
Optical system and image pickup apparatus having the same
AssigneeCanon Kabushiki Kaisha
InventorTakayoshi Yokoyama
Life of this patent
Estimating the term…
Abstract
An optical system includes, a front lens unit having a positive refractive power, an aperture stop, and a rear lens unit having a positive refractive power, wherein the front lens unit includes an FB lens system, and an FA lens system, the FB and FA lens systems being configured to move appropriately, when shifting a focus from an object at a long distance to an object at a short distance. A focal length fFB of the FB lens system and a focal length f of the entire optical system are appropriately set.
Claims10
An optical system comprising, in order from an object side to an image side:
- a front lens unit having a positive refractive power;
- an aperture stop;
- and
- a rear lens unit having a positive refractive power,
- wherein the front lens unit includes an FB lens system having a negative refractive power, and an FA lens system having a negative refractive power located on the object side relative to the FB lens system, the FB lens system and the FA lens system being configured to move toward the image side and the object side, respectively, when shifting a focus from an object at a long distance to an object at a short distance, or
- the front lens unit includes an FB lens system having a negative refractive power, and an FA lens system having a positive refractive power located on the object side relative to the FB lens system, both the FB lens system and the FA lens system being configured to move toward the image side, respectively, when shifting a focus from an object at a long distance to an object at a short distance, and
- wherein the following conditional expression is satisfied:
- 0.70<|fFB/f|<3.00
- where fFB represents a focal length of the FB lens system, and
- f represents a focal length of the entire optical system.
7 more elements
An image pickup apparatus comprising:
- an optical system;
- and
- a photoelectric conversion element configured to receive light of an image formed by the optical system,
- wherein the optical system includes, from an object side to an image side:
- a front lens unit having a positive refractive power;
- an aperture stop;
- and
- a rear lens unit having a positive refractive power in this order,
- wherein the front lens unit includes an FB lens system having a negative refractive power, and an FA lens system having a negative refractive power located on the object side relative to the FB lens system, both the FB lens system and the FA lens system being configured to move toward the image side and the object side, respectively, when shifting a focus from an object at a long distance to an object at a short distance, or,
- the front lens unit includes an FB lens system having a negative refractive power, and an FA lens system having a positive refractive power located on the object side relative to the FB lens system, the FB lens system and the FA lens system being configured to move toward the image side, respectively, when shifting a focus from an object at a long distance to an object at a short distance, and
- wherein the following conditional expression is satisfied:
- 0.70<|fFB/f|<3.00
- where fFB represents a focal length of the FB lens system, and f represents a focal length of the entire optical system.
10 more elements
Dependencies are inferred from the claim text.