Zoom lens system, optical device with the zoom lens system, and method of manufacturing the zoom lens system
AssigneeNikon Corporation
InventorSatoshi Yamaguchi
Life of this patent
Estimating the term…
Abstract
A zoom lens system has a front lens group and a rear lens group along the optical axis and in order from the object side. The rear lens group has a first lens unit having a positive refracting power, a second lens unit having a negative refracting power, and a third lens unit having a positive refracting power. Upon zooming from a wide-angle end state to a telephoto end state, a space between the front lens group and the first lens unit varies, a space between the first lens unit and the second lens unit increases, and a space between the second lens unit and the third lens unit decreases. At least a part of the second lens unit is movable so as to have a component in a direction perpendicular to the optical axis.
Claims10
A zoom lens system comprising a front lens group and a rear lens group arranged along an optical axis and in order from an object side,
- wherein the rear lens group comprises:
- a first lens unit having a positive refracting power;
- a second lens unit having a negative refracting power;
- and
- a third lens unit having a positive refracting power,
- wherein upon zooming from a wide-angle end state to a telephoto end state, a space between the front lens group and the first lens unit varies, a space between the first lens unit and the second lens unit increases from d12w to d12t, and a space between the second lens unit and the third lens unit decreases from d23w to d23t,
- wherein the second lens unit comprises the following units arranged in order from the object side:
- a 2a partial lens unit having a negative refracting power;
- and
- a 2b partial lens unit having a negative refracting power,
- wherein either the 2a partial lens unit or the 2b partial lens unit is movable so as to have a component in a direction perpendicular to the optical axis,
- the zoom lens system satisfying conditions of the following expressions:
- 0.002<(d12t−d12w)/BL<0.110, and
- 0.002<(d23w−d23t)/BL<0.090,
- where BL=fw123×(1−βw123), and
- where fw123 is a composite focal length of the first lens unit, the second lens unit, and the third lens unit in the wide-angle end state and βw123 is a composite magnification of the first lens unit, the second lens unit, and the third lens unit in the wide-angle end state.
A method of manufacturing a zoom lens system, comprising:
- a step of arranging a front lens group and a rear lens group along an optical axis and in order from an object side, the rear lens group comprising a first lens unit having a positive refracting power, a second lens unit having a negative refracting power, and a third lens unit having a positive refracting power, and
- a step of, upon zooming from a wide-angle end state to a telephoto end state, varying a space between the front lens group and the first lens unit, increasing a space between the first lens unit and the second lens unit from d12w to d12t, and decreasing a space between the second lens unit and the third lens unit from d23w to d23t,
- wherein the second lens unit comprises the following units arranged in order from the object side:
- a 2a partial lens unit having a negative refracting power;
- and
- a 2b partial lens unit having a negative refracting power,
- wherein either the 2a partial lens unit or the 2b partial lens unit is movable so as to have a component in a direction perpendicular to the optical axis,
- the zoom lens system satisfying conditions of the following expressions:
- 0.002<(d12t−d12w)/BL<0.110, and
- 0.002<(d23w−d23t)/BL<0.090,
- where BL=fw123×(1−βw123), and
- where fw123 is a composite focal length of the first lens unit, the second lens unit, and the third lens unit in the wide-angle end state and βw123 is a composite magnification of the first lens unit, the second lens unit, and the third lens unit in the wide-angle end state.
Dependencies are inferred from the claim text.