Lens system and optical device having the same
First Claim
Patent Images
1. An imaging lens system for imaging an object onto image taking means, the imaging lens system comprising:
- a plurality of lenses and a stop, wherein a diffractive surface is present in the imaging lens system, the imaging lens system moving the whole or part of the imaging lens system during focusing for a distance to an object from an infinity side to a near side and satisfying the following conditions;
|β
|≧
0.5,
|Δ
S/f|≧
1.0, where β
is a maximum imaging magnification, Δ
S is a maximum moving distance of the whole or part of the imaging lens system during focusing from an object at infinity to an object at a near distance, and f is a focal length of the entire imaging lens system.
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Abstract
A lens system has a plurality of lenses, a stop, and a diffractive surface, the entire lens system moves during focusing, and the lens system satisfies the condition of β≧0.5, where β is a maximum photographic magnification.
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Citations
6 Claims
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1. An imaging lens system for imaging an object onto image taking means, the imaging lens system comprising:
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a plurality of lenses and a stop, wherein a diffractive surface is present in the imaging lens system, the imaging lens system moving the whole or part of the imaging lens system during focusing for a distance to an object from an infinity side to a near side and satisfying the following conditions;
|β
|≧
0.5,
|Δ
S/f|≧
1.0,where β
is a maximum imaging magnification, Δ
S is a maximum moving distance of the whole or part of the imaging lens system during focusing from an object at infinity to an object at a near distance, and f is a focal length of the entire imaging lens system. - View Dependent Claims (2, 3, 4, 5)
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6. An imaging lens system for imaging an object onto image taking means, the imaging lens system comprising:
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from an object side to an image side, two optical elements having positive optical powers, an optical element having negative optical power, a stop, an optical element having negative optical power, and two optical elements having positive optical powers, wherein an optical surface of an optical element of the aforementioned six optical elements is a diffractive surface, the imaging lens system moving the whole or part of the imaging lens system during focusing for a distance to an object from an infinity side to a near side and satisfying the following condition;
|β
|≧
0.5,where β
is a maximum imaging magnification.
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Specification