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US 9,829,681 B2Granted
Optical system and image pickup apparatus including the same
AssigneeCanon Kabushiki Kaisha
InventorTakeo Mori
Life of this patent
Estimating the term…
Abstract
Provided is an optical system, which retains enhanced optical performance at any object distance, and has compact and light-weight focus lens units. Provided is an optical system including a plurality of lens units, in which an interval between adjacent lens units changes during focusing, the optical system including: a positive lens unit arranged closest to an object side; first and second focus lens units having negative refractive powers configured to move during focusing; and an intermediate lens unit having a positive refractive power and arranged between the first and second focus lens units. The first and second focus lens units are configured to move toward an image side during focusing.
Claims11
An optical system including a plurality of lens units, in which an interval between adjacent lens units changes during focusing, the optical system comprising:
- a positive lens unit arranged closest to an object side;
- a first focus lens unit having a negative refractive power configured to move during focusing;
- a second focus lens unit having a negative refractive power configured to move during focusing;
- and
- an intermediate lens unit having a positive refractive power and arranged between the first focus lens unit having the negative refractive power and the second focus lens unit having the negative refractive power,
- wherein the first focus lens unit having the negative refractive power and the second focus lens unit having the negative refractive power are configured to move toward an image side during focusing on from a first object at infinity to a second object at a distance in which an image-to-object ratio is 1,
- wherein the following conditional expressions are satisfied:
- −0.80<mn1/fn1<−0.22;
- and
- −0.80<mn2/fn2<−0.22,
- where fn1 represents a focal length of the first focus lens unit having the negative refractive power, fn2 represents a focal length of the second focus lens unit having the negative refractive power, mn1 represents a movement amount of the first focus lens unit having the negative refractive power during focusing on from the first object at infinity to the second object at a distance at which an image-to-object ratio is 1, and mn2 represents a movement amount of the second focus lens unit having the negative refractive power during the focusing on from the first object at infinity to the second object at a distance at which an image-to-object ratio is 1, wherein a sign of mn1 or mn2 is positive when a position of a corresponding focus lens unit that is in focus on the second object at a distance at which an image-to-object ratio is 1 is closer to the image side than a position of the corresponding focus lens unit that is in focus on the first object at infinity.
8 more elements
An image pickup apparatus, comprising:
- an optical system;
- and
- an image sensor configured to receive an image formed by the optical system,
- wherein the optical system comprises:
- a positive lens unit arranged closest to an object side;
- a first focus lens unit having a negative refractive power configured to move during focusing;
- a second focus lens unit having a negative refractive power configured to move during focusing;
- and
- an intermediate lens unit having a positive refractive power and arranged between the first focus lens unit having the negative refractive power and the second focus lens unit having the negative refractive power, and
- wherein an interval between adjacent lens units changes during focusing, and the first focus lens unit having the negative refractive power and the second focus lens unit having the negative refractive power are configured to move toward an image side during focusing on from a first object at infinity to a second object at a distance in which an image-to-object ratio is 1,
- wherein the following conditional expressions are satisfied:
- −0.80<mn1/fn1 <−0.22;
- and
- −0.80<mn2/fn2 <−0.22,
- where fn1 represents a focal length of the first focus lens unit having the negative refractive power, fn2 represents a focal length of the second focus lens unit having the negative refractive power, mn1 represents a movement amount of the first focus lens unit having the negative refractive power during focusing on from the first object at infinity to the second object at a distance in which an image-to-object ratio is 1, and mn2 represents a movement amount of the second focus lens unit having the negative refractive power during the focusing on from the first object at infinity to the second object at a distance at which an image-to-object ratio is 1, wherein a sign of mn1 or mn2 is positive when a position of a corresponding focus lens unit that is in focus on the second object at a distance at which an image-to-object ratio is 1 is close to the image side than a position of the corresponding focus lens unit that is in focus on the first object at infinity.
12 more elements
Dependencies are inferred from the claim text.