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US 5,627,686 AGranted
Large-aperture medium-range telephoto lens system
AssigneeNikon Corporation
InventorKoichi Ohshita
Life of this patent
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AssigneeNikon Corporation
InventorKoichi Ohshita
Estimating the term…
In a large-aperture medium-range telephoto lens system, which includes, in the following order from the object side, a first lens unit having a positive refractive power, a second lens unit having a negative refractive power, and a third lens unit having a positive refractive power, and attains focusing by moving the second and third lens units along the optical axis while the first lens unit is fixed in position, the telephoto lens system satisfies: ______________________________________ 0.8 < f1/f < 1.5 -3.0 < f2/f < -1.0 0.7 < f3/f < 1.0 0.02 < .vertline.x2/x3.vertline. < 0.3 ______________________________________ where f is the focal length of the entire lens system in an infinity in-focus state, f1 is the focal length of the first lens unit, f2 is the focal length of the second lens unit, f3 is the focal length of the third lens unit, x2 is the moving amount of the second lens unit from the infinity in-focus state to a closest distance in-focus state, and x3 is the moving amount of the third lens unit from the infinity in-focus state to the closest distance in-focus state.
A large-aperture medium-range telephoto lens system, which comprises, in the following order from the object side, a first lens unit having a positive refractive power, a second lens unit having a negative refractive power, and a third lens unit having a positive refractive power, and
A large-aperture medium-range telephoto lens system, which comprises, in the following order from the object side, a first lens unit consisting of a positive meniscus lens with a convex surface facing the object side, a second lens unit consisting of a positive meniscus lens with a convex surface facing the object side and a negative meniscus lens with a convex surface facing the object side, and a third lens unit consisting of a positive meniscus lens with a convex surface facing the object side, a biconcave lens, a positive meniscus lens with a concave surface facing the object side, and a biconvex lens, and
A large-aperture medium-range telephoto lens system, which comprises, in the following order from the object side, a first lens unit consisting of a positive meniscus lens with a convex surface facing the object side, a second lens unit consisting of a positive meniscus lens with a convex surface facing the object side and a negative meniscus lens with a convex surface facing the object side, and a third lens unit consisting of a negative meniscus lens with a concave surface facing the object side, a cemented lens of a positive meniscus lens with a concave surface facing the object side and a negative meniscus lens with a concave surface facing the object side, and a biconvex lens, and
A large-aperture medium-range telephoto lens system, which comprises, in the following order from the object side, a first lens unit consisting of a positive meniscus cemented lens of a biconvex lens and a biconcave lens, a second lens unit consisting of a positive meniscus lens with a convex surface facing the object side and a negative meniscus lens with a convex surface facing the object side, and a third lens unit consisting of a positive meniscus lens with a convex surface facing the object side, a biconcave lens, a positive meniscus cemented lens of a biconcave lens and a biconvex lens, and a positive meniscus lens with a convex surface facing the object side, and
Dependencies are inferred from the claim text.