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US 6,014,265 AGranted
Zoom optical system
AssigneeOlympus Optical Co., Ltd.
InventorsShigeru Kato, Masaru Morooka, Seiji Shimizu
Life of this patent
Estimating the term…
Abstract
An optical system composed, in order from the object side, of a first lens unit which has a positive power or is powerless, a second lens unit which has a positive power, a third lens unit which has a positive power and a fourth lens unit which has a negative power, and configured to change its magnification by varying airspaces reserved between the lens unit. The fourth lens unit is composed of a single lens element or the optical system as a whole is composed of lens element in a number not exceeding twice a number of movable lens units. The optical system is composed of a small number of lens elements and compact.
Claims30
A zoom optical system comprising in order from the object side:
- a first lens unit which has a positive power or is powerless;
- a second lens unit which has a positive power;
- a third lens unit which has a positive power;
- and a fourth lens unit which has a negative power, wherein said zoom optical system is configured to change its magnification varying airspaces reserved between the lens units, and wherein said fourth lens unit is composed of a single lens element and satisfies the following condition (8):
- 0.ltoreq.y/f.sub.1 .ltoreq.0.14 (8)
- wherein the reference symbol y represents 1/2 of a diagonal length of an image surface and the reference symbol f.sub.1 designates a focal length of the first lens unit.
3 more elements
A zoom optical system comprising in order from the object side:
- a first lens unit which has a positive power or is powerless;
- a second lens unit which has a positive power;
- a third lens unit which has a positive power;
- and a fourth lens unit which has a negative power, wherein said zoom optical system is configured to change its magnification by varying airspaces reserved between the lens units and satisfy the following conditions (1) and (8):
- 0.03<.SIGMA.D.sub.4 /y<0.25 (1)
- 0.ltoreq.y/f.sub.1 .ltoreq.0.14 (8)
- wherein the reference symbol .SIGMA.D.sub.4 represents a structural length of the fourth lens unit and the reference symbol y designates 1/2 of a diagonal length of an image surface and the reference symbol f.sub.1 denotes a focal length of the first lens unit.
4 more elements
A zoom optical system comprising in order from the object side:
- a first lens unit which has a positive power or is powerless;
- a second lens unit which has a positive power;
- a third lens unit which has a positive power;
- and a fourth lens unit which has a negative power, wherein said zoom optical system is configured to change its magnification by varying airspaces reserved between the lens units, be composed of lens elements in a number not exceeding twice a number of movable lens units and satisfy the following condition (8):
- 0.ltoreq.y/f.sub.1 .ltoreq.0.14 (8)
- wherein the reference symbol y represents 1/2 of a diagonal length of an image surface and the reference symbol f.sub.1 designates a focal length of the first lens unit.
3 more elements
A zoom optical system comprising in order from the object side:
- a first lens unit which has a positive power or is powerless;
- a second lens unit which has a positive power;
- a third lens unit which has a positive power;
- and a fourth lens unit which has a negative power, wherein said zoom optical system is configured to change its magnification by varying airspaces reserved between the lens units, wherein an aperture stop is disposed on the image side of a first lens element of said second lens unit and on the object side of said third lens unit, and wherein said zoom optical system satisfies the following condition (10):
- 0.10.ltoreq.E(W)/f.sub.W .ltoreq.0.30 (10)
- wherein the reference symbol E (W) represents a distance on an optical axis as measured from a vertex of a first surface to an entrance pupil of the optical system at a wide position and the reference symbol f.sub.W designates a focal length of the optical system as a whole at the wide position.
3 more elements
A zoom optical system comprising in order from the object side:
- a first lens unit which has a positive power or is powerless;
- a second lens unit which has a positive power;
- a third lens unit which has a positive power;
- and a fourth lens unit which has a negative power, wherein said zoom optical system is configured to change its magnification by varying airspaces reserved between the lens units, wherein an aperture stop is disposed between the second lens unit and the third lens unit, wherein the second lens unit and the aperture stop are moved as an integral unit for the magnification change, and wherein said zoom optical system satisfies the following condition (8):
- 0.ltoreq.y/f.sub.1 .ltoreq.0.14 (8)
- wherein the reference symbol y represents 1/2 of a diagonal length of an image surface and the reference symbol f.sub.1 designates a focal length of the first lens unit.
3 more elements
A zoom optical system comprising in order from the object side:
- a first lens unit which has a positive power or is powerless;
- a second lens unit which has a positive power;
- a third lens unit which has a positive power;
- and a fourth lens unit which has a negative power, wherein said zoom optical system is configured to change its magnification by varying airspaces reserved between the lens units, wherein an aperture stop is disposed-between the second lens unit and the third lens unit and is moved independently for the magnification change, and wherein said zoom optical system satisfies the following condition (8):
- 0.ltoreq.y/f.sub.1 .ltoreq.0.14 (8)
- wherein the reference symbol y represents 1/2 of a diagonal length of an image surface and the reference symbol f.sub.1 designates a focal length of the first lens unit.
3 more elements
Dependencies are inferred from the claim text.