Zoom lens
First Claim
1. A zoom lens comprising in order from an object side three optical units movable for zooming, a first optical unit that is negative, a second optical unit that is positive, and a third optical unit that is negative, in which said third optical unit provides a greater amount of the magnification change during zooming than provided by either of the first or the second optical unit and the third optical unit consists of a single negative lens element, and the ratio of powers of said first optical unit to said third optical unit of said zoom lens is between 0.7 and 1.6.
2 Assignments
0 Petitions
Accused Products
Abstract
This invention relates to a compact zoom lens. The zoom lens comprises of small number of elements arranged in three groups. The first group has negative refractive power, the second group has positive refractive power and the third group has negative refractive power. The air space between each of two adjacent groups is made variable to effect zooming.
93 Citations
43 Claims
- 1. A zoom lens comprising in order from an object side three optical units movable for zooming, a first optical unit that is negative, a second optical unit that is positive, and a third optical unit that is negative, in which said third optical unit provides a greater amount of the magnification change during zooming than provided by either of the first or the second optical unit and the third optical unit consists of a single negative lens element, and the ratio of powers of said first optical unit to said third optical unit of said zoom lens is between 0.7 and 1.6.
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15. A zoom lens comprising three optical units movable for zooming, a negative front optical unit, a positive middle optical unit, and a negative rear optical unit, in which said rear optical unit provides a greater amount of the magnification change during zooming than provided by either of the front or the middle optical unit and the front and rear optical units each consists of a single negative lens component, and the ratio of powers of said front optical unit to said rear optical unit is between 0.7 and 1.6 and in which said lens component of said rear optical unit consists entirely of a single negative element in which one surface of said element is aspherical.
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16. A zoom lens comprising three optical units movable for zooming, a negative front optical unit, a positive middle optical unit and a negative rear optical unit, in which said rear optical unit provides a greater amount of the magnification change during zooming than provided by either of the front or the middle optical unit, the ratio of powers of said front optical unit to said rear optical unit is between 0.7 and 1.6 and in which said rear unit consists of a negative lens element and a biconvex positive lens element.
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17. A zoom lens comprising:
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a front lens optical unit of negative power movable along an optical axis for zooming; a middle optical unit including two subunits each of positive power which move unitedly along the optical axis for zooming, one of the two subunits being movable along the optical axis for focusing; a rear optical unit on the image side of the front and middle optical units, the rear optical unit including only one negative element, said negative element being convex to the rear, said rear unit being movable along the optical axis for maintaining a fixed focal plane during zooming.
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18. A zoom lens system comprising three optical units movable for zooming, a negative first optical unit, a positive second optical unit and a negative third optical unit, in which said third optical unit provides a greater amount of the magnification change during zooming than provided by either of the first or the second optical unit and the third optical unit consists of a single negative lens element, and the ratio of powers of said first optical unit to said third optical unit is between 0.7 and 1.6 and wherein the power of the third optical unit relates to the power of the system at the short focal length zoom position, so that:
- ##EQU3## wherein K3 is the power of the 3rd optical unit and Kw is the power of the lens system at the short focal length zoom position.
- View Dependent Claims (19, 20, 21, 22, 23, 24)
- 25. A zoom lens comprising, in order from an object side, three optical units movable for zooming, a first optical unit that is negative, a second optical unit that is positive, and a third optical unit that is negative, in which said third optical unit provides a greater amount of magnification change during zooming than provided by either of the first or the second optical unit and the first optical unit consists of a single negative lens element, and the ratio of powers of said first optical unit to said third optical unit of said zoom lens is between 0.7 and 1.6.
Specification