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US 5,966,245 AGranted
Zoom lens system
AssigneeOlympus Optical Co., Ltd.
InventorToshiyuki Nagaoka
Life of this patent
Estimating the term…
Abstract
A zoom lens system composed, in order from the object side, of a first lens unit which has a positive refractive power and is kept stationary during a change of a magnification, a second lens unit which has a negative refractive power and is movable for the change of the magnification, a third lens unit which has a positive refractive power and is kept stationary during the change of the magnification, a fourth lens unit which has a positive refractive power and is movable during the change of the magnification, and a fifth lens unit which has a negative refractive power and is kept stationary during the change of the magnification; and using an aspherical surface or aspherical surfaces in the lens units which are kept stationary during the change of the magnification.
Claims50
A zoom lens system comprising, in order from an object side:
- a first lens unit having a positive refractive power;
- a second lens unit which has a negative refractive power and is moved along an optical axis effecting a change in magnification;
- a third lens unit having a positive refractive power;
- a fourth lens unit which has a positive refractive power and is moved along the optical axis for correcting a deviation of a focal point caused by changing the magnification;
- and
- a fifth lens unit having a negative refractive power,
- wherein said fourth lens unit consists of spherical lens elements and wherein said zoom lens system satisfies condition (1):
- -0.85<f.sub.w /f.sub.2 <-0.25 (1)
- wherein reference symbol f.sub.w represents a focal length of the zoom lens system as a whole at a wide position and reference symbol f.sub.2 designates a focal length of said second lens unit.
6 more elements
A zoom lens system comprising, in order from an object side:
- a first lens unit having a positive refractive power;
- a second lens unit which has a negative refractive power and is moved along an optical axis effecting a change in magnification;
- a third lens unit having a positive refractive power;
- a fourth lens unit which has a positive refractive power and is moved along the optical axis for correcting a deviation of a focal point caused by changing the magnification;
- and
- a fifth lens unit having a negative refractive power,
- wherein said fourth lens unit consists of spherical lens elements and wherein said zoom lens system satisfies condition (3):
- 0. 05<f.sub.w /f.sub.1 <0.22 (3)
- wherein reference symbol f.sub.w represents a focal length of said zoom lens system as a whole at a wide position and reference symbol f.sub.1 designates a focal length of said first lens unit.
6 more elements
A zoom lens system comprising, in order from an object side:
- a first lens unit having a positive refractive power;
- a second lens unit which has a negative refractive power and is moved along an optical axis effecting a change in magnification;
- a third lens unit having a positive refractive power;
- a fourth lens unit which has a positive refractive power and is moved along the optical axis for correcting a deviation of a focal point caused by changing the magnification;
- and
- a fifth lens unit having a negative refractive power,
- wherein said third lens unit consists of, in order from the object side, a positive lens element and a negative lens element,
- said fourth lens unit comprises spherical lens elements,
- said fifth lens unit comprises a single negative meniscus lens component which has a concave surface on the image side, and
- a moving amount of said second lens unit is larger than moving amounts of other said lens units when magnification is changed from a wide position to a tele position.
7 more elements
A zoom lens system comprising, in order from an object side:
- a first lens unit having a positive refractive power;
- a second lens unit which has a negative refractive power and is moved along an optical axis effecting a change in magnification;
- a third lens unit having a positive refractive power;
- a fourth lens unit which has a positive refractive power and is moved along the optical axis for correcting a deviation of a focal point caused by changing the magnification;
- and
- a fifth lens unit having a negative refractive power,
- wherein said third lens unit comprises at least one positive lens element and at least one negative lens element,
- said fourth lens unit comprises spherical lens elements,
- said fifth lens unit comprises a single negative meniscus lens component which has a concave surface on the image side, and satisfying condition (1):
- -0.85<f.sub.w /f.sub.2 <-0.25 (1)
- wherein reference symbol f.sub.w represents a focal length of the zoom lens system as a whole at a wide position and reference symbol f.sub.2 designates a focal length of said second lens unit.
8 more elements
A zoom lens system comprising, in order from an object side:
- a first lens unit having a positive refractive power;
- a second lens unit which has a negative refractive power and is moved along an optical axis effecting a change in magnification;
- a third lens unit having a positive refractive power;
- a fourth lens unit which has a positive refractive power and is moved along the optical axis for correcting a deviation of a focal point caused by changing the magnification;
- and
- a fifth lens unit having a negative refractive power,
- wherein said third lens unit comprises at least one positive lens element and at least one negative lens element,
- said fourth lens unit comprises spherical lens elements,
- said fifth lens unit comprises a single negative meniscus lens component which has a concave surface on the image side, and satisfying condition (3):
- 0. 05<f.sub.w /f.sub.1 <0.22 (3)
- wherein reference symbol f.sub.w represents a focal length of said zoom lens system as a whole at a wide position and reference symbol f.sub.1 designates a focal length of said first lens unit.
8 more elements
A zoom lens system comprising, in order from an object side:
- a first lens unit having a positive refractive power;
- a second lens unit which has a negative refractive power and is moved along an optical axis effecting a change in magnification;
- a third lens unit having a positive refractive power;
- a fourth lens unit which has a positive refractive power and is moved along the optical axis for correcting a deviation of a focal point caused by changing the magnification;
- and
- a fifth lens unit having a negative refractive power,
- wherein said third lens unit comprises at least one positive lens element and at least one negative lens element,
- said fourth lens unit comprises spherical lens elements,
- said fifth lens unit comprises a single negative meniscus lens component which has a concave surface on the image side, and satisfying condition (1-1):
- -0. 65<f.sub.w /f.sub.2 <-0.35 (1-1)
- wherein reference symbol f.sub.w represents a focal length of the zoom lens system as a whole at a wide position and reference symbol f.sub.2 designates a focal length of said second lens unit.
8 more elements
A zoom lens system comprising, in order from an object side:
- a first lens unit having a positive refractive power;
- a second lens unit which has a negative refractive power and is moved along an optical axis effecting a change in magnification;
- a third lens unit having a positive refractive power;
- a fourth lens unit which has a positive refractive power and is moved along the optical axis for correcting a deviation of a focal point caused by changing the magnification;
- and
- a fifth lens unit having a negative refractive power,
- wherein said third lens unit comprises at least one positive lens element and at least one negative lens element,
- said fourth lens unit comprises spherical lens elements,
- said fifth lens unit comprises a single negative meniscus lens component which has a concave surface on the image side, and satisfying condition (3-1):
- 0.07<f.sub.w /f.sub.1 <0.16 (3-1)
- wherein reference symbol f.sub.w represents a focal length of said zoom lens system as a whole at a wide position and reference symbol f.sub.1 designates a focal length of said first lens unit.
8 more elements
A zoom lens system comprising, in order from an object side:
- a first lens unit having a positive refractive power;
- a second lens unit which has a negative refractive power and is moved along an optical axis effecting a change in magnification;
- a third lens unit having a positive refractive power;
- a fourth lens unit which has a positive refractive power and is moved along the optical axis for correcting a deviation of a focal point caused by changing the magnification;
- and
- a fifth lens unit having a negative refractive power,
- wherein said third lens unit comprises at least one positive lens element and at least one negative lens element,
- said fourth lens unit comprises spherical lens elements,
- said fifth lens unit comprises a single negative meniscus lens component which has a concave surface on the image side, and satisfying condition (4):
- 0. 08<f.sub.w /f.sub.3 <0.2 (4)
- wherein reference symbol f.sub.3 represents a focal length of the third lens unit and reference symbol f.sub.w designates a focal length of the zoom lens system as a whole at a wide position.
8 more elements
A zoom lens system comprising, in order from an object side:
- a first lens unit having a positive refractive power;
- a second lens unit which has a negative refractive power and is moved along an optical axis effecting a change in magnification;
- a third lens unit having a positive refractive power;
- a fourth lens unit which has a positive refractive power and is moved along the optical axis for correcting a deviation of a focal point caused by changing the magnification;
- and
- a fifth lens unit having a negative refractive power,
- wherein said third lens unit comprises at least one positive lens element and at least one negative lens element,
- said fourth lens unit comprises spherical lens elements,
- said fifth lens unit comprises a single negative meniscus lens component which has a concave surface on the image side, and satisfying condition (5):
- 3. 2<f.sub.t /f.sub.4 <5.0 (5)
- wherein reference symbol f.sub.4 represents a focal length of the fourth lens unit and reference symbol f.sub.t designates a focal length of the zoom lens system as a whole at the tele position.
8 more elements
A zoom lens system comprising, in order from an object side:
- a first lens unit having a positive refractive power;
- a second lens unit which has a negative refractive power and is moved along an optical axis effecting a change in magnification;
- a third lens unit having a positive refractive power;
- a fourth lens unit which has a positive refractive power and is moved along the optical axis for correcting a deviation of a focal point caused by changing the magnification;
- and
- a fifth lens unit having a negative refractive power,
- wherein said third lens unit comprises at least one positive lens element and at least one negative lens element,
- said fourth lens unit comprises spherical lens elements,
- said fifth lens unit comprises a single negative meniscus lens component which has a concave surface on the image side, and satisfying condition (6):
- -5.0<f.sub.t /f.sub.5 <-1.0 (6)
- wherein reference symbol f.sub.5 represents a focal length of the fifth lens unit and reference symbol f.sub.t designates a focal length of the zoom lens system as a whole at the tele position.
8 more elements
Dependencies are inferred from the claim text.