US 6,788,474 B2Granted

Zoom image pickup optical system

AssigneeOlympus Corporation

InventorsKouki Hozumi, Yuji Miyauchi

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Abstract

A zoom image pickup optical system including, in order from the object side, a first lens unit having positive refractive power, a second lens unit having negative refractive power, a third lens unit having positive refractive power and a fourth lens unit having positive refractive power, in which at least the second lens unit and the fourth lens units are moved along an optical axis to change a magnification, in which the third lens unit includes at least two lens components, in which the fourth lens unit includes at least two lens components, and in which radii of curvature on at least one of pairs of surfaces of the third lens unit and the fourth lens unit such as an image side surface of a most image side lens component in the third lens unit and an object side surface of a most object side lens component in the fourth lens unit which correspond to each other with regard to an airspace between the third lens unit and the fourth lens unit have different signs.

Claims53

Dependent claims

A zoom image pickup optical system comprising in order from an object side:

a first lens unit having positive refractive power;
a second lens unit having negative refractive power;
a stop;
a third lens unit having positive refractive power;
and
a fourth lens unit having positive refractive power,
wherein at least the second lens unit is moved along an optical axis to change a magnification,
wherein at least one of the third lens unit and the fourth lens unit is moved along the optical axis to change the magnification,
wherein an air space between the first lens unit and the second lens unit is changed during a magnification change,
wherein the stop is kept stationary during the magnification change,
wherein a space between the third lens unit and the fourth lens unit is changed during the magnification change,
wherein said first lens unit comprises, in order from the object side,
a cemented lens component and one lens component,
wherein said third lens unit consists of, in order from the object side,
a single positive lens element having at least one aspherical surface on the object side of the single lens element and a menisucus cemented lens component convex to the object side
wherein said fourth lens unit consists of one positive lens component having at least one aspherical surface on an image side of the positive lens component, and
wherein said zoom image pickup optical system has a zoom ratio of 5 of higher.

14 more elements

A zoom image pickup optical system comprising in order from an object side:

a first lens unit having positive refractive power;
a second lens unit having negative refractive power;
a stop;
a third lens unit having positive refractive power;
a fourth lens unit having positive refractive power,
an optical filter;
and
wherein the first lens unit is kept stationary during a magnification change,
wherein the second lens unit is moved along an optical axis to change a magnification,
wherein at least one of the third lens unit and the fourth lens unit is moved along an optical axis to change the magnification,
wherein a space between the second lens unit and the stop is changed during the magnification change,
wherein a space between the third lens unit and the fourth lens unit is changed during the magnification change,
wherein said first lens unit consists of, in order from the object side,
a cemented lens component and a single lens element,
wherein the second lens unit comprises at least one single negative lens element located on the most object side in the second lens unit and at least one cemented lens component located on the most image side in the second lens unit,
wherein said third lens unit consists of, in order from the object side,
a single biconvex lens element having at least one aspherical surface on the object side of the single lens element and a menisucus cemented lens component convex on the object side,
wherein said fourth lens unit consists of one positive lens component having an aspherical surface located on the most image side surface of the positive lens component, and
wherein said zoom image pickup optical system has a zoom ratio of 8 to 15.

16 more elements

A zoom image pickup optical system comprising in order from an object side:

a first lens unit having positive refractive power;
a second lens unit having negative refractive power,
a stop;
a third lens unit having refractive power;
and
a fourth lens unit having positive refractive power,
wherein at least the second lens unit is moved along an axis magnification, optical to change a
wherein at least one of the third lens unit and the fourth lens unit is moved along an optical axis to change the magnification,
wherein an air space between the first lens unit and the second lens unit is changed during a magnification change,
wherein an air space between the second lens unit and the stop is changed during the magnification change,
wherein a space between the third lens unit and the fourth lens unit is changed during the magnification change,
wherein said first lens unit comprises, in order from the object side,
a cemented lens component and one lens component,
wherein said third lens unit consists of, in order from the object side,
a single positive lens element having at least one aspherical surface on the object side of the single lens element and a menisucus cemented lens component convex on the object side
wherein said fourth lens unit consists of three lens elements, and said fourth lens unit comprises at least one cemented surface, and said fourth lens unit has one aspherical surface disposed on the most image side of said fourth lens unit, and
wherein said zoom image pickup optical system has a zoom ratio of 5 or higher.

14 more elements

A zoom image pickup optical system comprising in order from an object side:

a first lens unit having positive refractive power;
a second lens unit having negative refractive power;
a stop;
a third lens unit having positive refractive power;
a fourth lens unit having positive refractive power,
an optical filter,
wherein the first lens unit is kept stationary during a magnification change,
wherein the second lens unit is moved along an optical axis to change a magnification,
wherein at least one of the third lens unit and the fourth lens unit is moved along the optical axis to change the magnification,
wherein the stop is kept stationary during the magnification change,
wherein a space between the third lens unit and the fourth lens unit is changed during the magnification change,
wherein said first lens unit consists of, in order from the object side,
a cemented lens component and a single lens element,
wherein the second lens unit comprises at least one single negative lens element located on the most object side in the second lens unit and at least ne cemented lens component located on the most image side in the second lens unit,
wherein said third lens unit consists of, in order from the object side,
a single biconvex lens element having at least one aspherical surface on the object side of the single lens element and a menisucus cemented lens component convex on the object side,
wherein said fourth lens unit consists of three lens elements, and said fourth lens unit comprises at least one cemented surface convex to the object side and one aspherical surface disposed on the most image side, and
wherein said zoom image pickup optical system has a zoom ratio of 8 to 15.

15 more elements

Dependencies are inferred from the claim text.