Zoom lens system
AssigneeMinolta Co., Ltd.
InventorsTetsuya Arimoto, Mamoru Terada, Takashi Okada, Kenji Konno, Tetsuo Kohno, Kazuhiko Ishimaru
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Abstract
A zoom lens system has, from the object side, a first lens unit having a optical power, a second lens unit having a negative optical power a third lens unit having a positive optical power, and a succeeding lens unit. The first and the third lens units monotonically move toward the object side during zooming from the shortest focal length condition to the longest focal length condition. A number of predetermined conditions are disclosed which can be satisfied to ensure a high quality, compact zoom lens for a digital camera.
Claims24
A zoom lens system, comprising from an object side:
- a first lens unit having a positive optical power;
- a second lens unit having a negative optical power;
- a third lens unit having a positive optical power;
- and
- a succeeding lens unit,
- wherein the first lens units and the third lens unit monotonically move toward the object side during zooming from a shortest focal length condition to a longest focal length condition, and
- wherein the following conditions are satisfied:
- 0.7 < m1 Z < 3.0 1 < max ( T1 , T2 , T3 , T4 ) f w < 4
- where
- Ti is an axial thickness of the i-th lens unit and max(T1,T2,T3,T4) is a maximum value thereof,
- m1 is a movement amount (mm) of the first lens unit during zooming from the shortest focal length condition to the longest focal length condition,
- fw is an overall focal length of the zoom lens system at the shortest focal length condition, and
- Z is a zoom ratio (the focal length at the shortest focal length condition/a focal length at the longest focal length condition).
A zoom lens system for forming an image of an object on a solid state imaging device, comprising, from an object side:
- a first lens unit having a positive optical power;
- a second lens unit having a negative optical power;
- a third lens unit having a positive optical power;
- and
- a succeeding lens unit;
- and
- a filter including an optical low-pass filter,
- wherein the first lens unit and the third lens unit monotonically move toward the object side during zooming from a shortest focal length condition to a longest focal length condition, and
- wherein the following conditions are satisfied:
- 0.7 < m1 Z < 3.0 1 < max ( T1 , T2 , T3 , T4 ) fw < 4
- where
- Ti is an axial thickness of the i-th lens unit and max(T1,T2,T3,T4) is a maximum value thereof,
- m1 is a movement amount (mm) of the first lens unit during zooming from the shortest focal length condition to the longest focal length condition,
- fw is an overall focal length of the zoom lens system at the shortest focal length condition, and
- Z is a zoom ratio (the focal length at the shortest focal length condition/a focal length at the longest focal length condition).
An imaging apparatus comprising:
- a solid state imaging device;
- a zoom lens system for forming an image of an object on the solid state imaging device, the zoom lens system comprising, from an object side:
- a first lens unit having a positive optical power;
- a second lens unit having a negative optical power;
- a third lens unit having a positive optical power;
- and
- a succeeding lens unit;
- and
- a filter including an optical low-pass filter,
- wherein the first lens unit and the third lens unit monotonically move toward the object side during zooming from a shortest focal length condition to a longest focal length condition, and
- wherein the following conditions are satisfied:
- 0.7 < m1 Z < 3.0 1 < max ( T1 , T2 , T3 , T4 ) fw < 4
- where
- Ti is an axial thickness of the i-th lens unit and max(T1,T2,T3,T4) is a maximum value thereof,
- m1 is a movement amount (mm) of the first lens unit during zooming from the shortest focal length condition to the longest focal length condition,
- fw is an overall focal length of the zoom lens system at the shortest focal length condition, and
- Z is a zoom ratio (the focal length at the shortest focal length condition/a focal length at the longest focal length condition).
Dependencies are inferred from the claim text.