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US 9,823,452 B2Granted
Zoom lens and image pickup apparatus using the same
AssigneeOlympus Corporation
InventorsTakashi Fujikura, Keisuke Takada
Life of this patent
Estimating the term…
Abstract
A zoom lens comprising in order from an object side, a first lens unit having a negative refractive power, a second lens unit having a negative refractive power, a lens unit having a positive refractive power, and a rearmost lens unit having a negative refractive power, and the rearmost lens unit is positioned nearest to an image in the plurality of lens units, and at the time of zooming, distances between the lens units in the plurality of lens units change. Moreover, an image pickup apparatus includes the zoom lens, and an image pickup element having an image pickup surface.
Claims18
A zoom lens comprising in order from an object side:
- a first lens unit having a negative refractive power;
- a second lens unit having a negative refractive power;
- a lens unit having a positive refractive power;
- and
- a rearmost lens unit having a negative refractive power, wherein
- the total number of lens units in the zoom lens is four, and
- at the time of zooming, distances between the lens units change, and
- at the time of focusing from an infinite object point to an object point at a short distance, only the second lens unit moves, and
- the second lens unit comprises one negative lens, and
- the total number of lenses in the second lens unit is one, and
- the negative lens is a meniscus lens having a convex surface directed toward an image side, and
- at the time of focusing from the infinite object point to an object point at a short distance, the negative lens moves toward the object side, and
- the following conditional expressions are satisfied:
- 2.00<|St|<8.00
- −6.00<(rff+rfb)/(rff−rfb)<−1.00
- where,
- St=(1−β2t×β2t)×βct×βct,
- β2t denotes a lateral magnification of the second lens unit,
- βct denotes a combined lateral magnification of all the lens units positioned on the image side of the second lens unit,
- both β2t and βct are a lateral magnification at the time of focusing on the infinite object point at a telephoto end,
- rff denotes a radius of curvature of an object-side lens surface of the negative lens, and
- rfb denotes a radius of curvature of an image-side lens surface of the negative lens.
19 more elements
A zoom lens comprising in order from an object side:
- a first lens unit having a negative refractive power;
- a second lens unit having a negative refractive power;
- a lens unit having a positive refractive power;
- and
- a rearmost lens unit having a negative refractive power, wherein
- the total number of lens units in the zoom lens is four, and
- at the time of zooming, distances between the lens units change, and
- at the time of focusing from an infinite object point to an object point at a short distance, only the second lens unit moves, and
- the following conditional expressions are satisfied:
- 2.00<|St|<8.00
- 0.30<D1L/D1a<4.00
- where,
- St=(1−β2t×β2t)×βct×βct,
- β2t denotes a lateral magnification of the second lens unit,
- βct denotes a combined lateral magnification of all the lens units positioned on the image side of the second lens unit,
- both β2t and βct are a lateral magnification at the time of infinite object point focusing at a telephoto end,
- D1L denotes a sum total of a lens thickness on an optical axis of the first lens unit, and
- D1a denotes a sum total of an air space on the optical axis in the first lens unit.
15 more elements
A zoom lens comprising in order from an object side:
- a first lens unit having a negative refractive power;
- a second lens unit having a negative refractive power;
- a lens unit having a positive refractive power;
- and
- a rearmost lens unit having a negative refractive power, wherein
- the total number of lens units in the zoom lens is four, and
- at the time of zooming, distances between lens units change, and
- the following conditional expressions are satisfied:
- −5.50<f2/fw<−1.00
- 0.30<D1L/D1a<4.00
- where,
- f2 denotes a focal length of the second lens unit,
- fw denotes a focal length of the overall zoom lens system at a wide angle end,
- D1L denotes a sum total of a lens thickness on an optical axis of the first lens unit, and
- D1a denotes a sum total of an air space on the optical axis in the first lens unit.
12 more elements
A zoom lens comprising in order from an object side:
- a first lens unit having a negative refractive power;
- a second lens unit having a negative refractive power;
- a lens unit having a positive refractive power;
- and
- a rearmost lens unit having a negative refractive power, wherein
- the total number of lens units in the zoom lens is four, and
- at the time of zooming, distances between the lens units change, and
- a lens nearest to an image in the rearmost lens unit, and the first lens unit, satisfy the following conditional expressions:
- −3.00<(r1f+r1b)/(r1f−r1b)<−0.30
- |r1f|<|r1b|
- 0.30<D1L/D1a<4.00
- where,
- r1f denotes a radius of curvature of an object-side lens surface of a lens positioned nearest to the image in the rearmost lens unit,
- r1b denotes a radius of curvature of an image-side lens surface of a lens positioned nearest to the image in the rearmost lens unit,
- D1L denotes a sum total of a lens thickness on an optical axis of the first lens unit, and
- D1a denotes a sum total of an air space on the optical axis in the first lens unit.
13 more elements
A zoom lens comprising in order from an object side:
- a first lens unit having a negative refractive power;
- a second lens unit having a negative refractive power;
- a lens unit having a positive refractive power;
- and
- a rearmost lens unit having a negative refractive power, wherein
- the zoom lens further includes an aperture stop, and
- the total number of lens units in the zoom lens is four, and
- the lens unit having a positive refractive power is a third lens unit, and
- spaces between lenses in the third lens unit are kept unchanged during zooming, and
- the rearmost lens unit is a fourth lens unit, and
- the aperture stop is disposed in the third lens unit, and
- the zoom lens includes at least one aspheric lens, and
- at the time of zooming, distances between the lens units change, and
- the following conditional expression is satisfied:
- 0.30<D1L/D1a<4.00
- where,
- D1L denotes a sum total of a lens thickness on an optical axis of the first lens unit, and
- D1a denotes a sum total of an air space on the optical axis in the first lens unit.
15 more elements
Dependencies are inferred from the claim text.