Dual aperture lens
First Claim
Patent Images
1. A variable aperture lens system having a variable effective aperture and a plurality of components, said lens system comprising:
- a fixed aperture stop located inside the lens system,a variable aperture stop variable between at least wide and narrow positions and located outside the lens system,the lens system is being generally of the double Gauss type and including a central air space with first and second negative doublets, concave to the central air space; and
the powers and spacings of the components with respect to the aperture stops being such that the effective aperture of the lens system is defined by the fixed aperture stop for a first wide effective aperture when the variable aperture stop is in its wide position and the effective aperture of the lens system is defined by the variable aperture stop when the variable aperture stop is in its narrow position.
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Abstract
A variable aperture lens has a fixed aperture stop inside the lens and a variable aperture stop located outside the lens. When the lens is operated at its widest effective aperture, the effective aperture is defined by the fixed aperture stop. When it is operated at its narrowest effective aperture, the effective aperture is defined by the variable aperture stop. This permits highest corrections for the widest aperture but with a lens that is free of the cleaning and other difficulties of a variable interior aperture.
39 Citations
6 Claims
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1. A variable aperture lens system having a variable effective aperture and a plurality of components, said lens system comprising:
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a fixed aperture stop located inside the lens system, a variable aperture stop variable between at least wide and narrow positions and located outside the lens system, the lens system is being generally of the double Gauss type and including a central air space with first and second negative doublets, concave to the central air space; and the powers and spacings of the components with respect to the aperture stops being such that the effective aperture of the lens system is defined by the fixed aperture stop for a first wide effective aperture when the variable aperture stop is in its wide position and the effective aperture of the lens system is defined by the variable aperture stop when the variable aperture stop is in its narrow position. - View Dependent Claims (2, 3, 4, 5, 6)
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Specification