Abstract: An inner focus lens includes sequentially from an object side, a first lens group having a positive refractive power; a second lens group having a negative refractive power; and a third lens group having a negative refractive power. The second lens group is moved along an optical axis, whereby focusing from a focus state for an object at infinity to a focus state for a minimum object distance is performed. A lens group configured by a lens other than a lens that is disposed farthest on the object side is moved in a direction orthogonal to the optical axis to shift an image. The inner focus lens satisfies a conditional expression (1) 0.15?(1??p)×?r?4.50, where ?p is transverse magnification of the orthogonally moved lens group and ?r is composite transverse magnification of a lens group disposed farther on an image side than the orthogonally moved lens group.

Abstract: An inner focus lens includes sequentially from an object side, a first lens group having a positive refractive power; a second lens group having a negative refractive power; and a third lens group having a negative refractive power. The second lens group is moved along the optical axis, whereby focusing from a focus state for an object at infinity to a focus state for a minimum object distance is performed. The inner focus lens satisfies a conditional expression (1) ?29.0?f3/f??5.4, where f3 is a focal length of the third lens group at the focus state for an object at infinity and f is a focal length of the optical system overall at the focus state for an object at infinity.

Abstract: An optical system of the present invention includes, in order from an object side: a first lens group G1; a second lens group G2 having positive refractive power; and a third lens group G3 having positive refractive power, wherein the first lens group G1 and the third lens group G3 are fixed in an optical axis direction while the second lens group G2 is moved in an optical axis direction to focus on from an object at infinity to an object at a finite distance, and specified conditions is satisfied.

Abstract: An optical system of the present invention includes, in order from an object side: a first lens group G1; a second lens group G2 having positive refractive power; and a third lens group G3 having positive refractive power, wherein the first lens group G1 and the third lens group G3 are fixed in an optical axis direction while the second lens group G2 is moved in an optical axis direction to focus on from an object at infinity to an object at a finite distance, and specified conditions is satisfied.

Abstract: An inner focus lens includes sequentially from an object side, a first lens group having a positive refractive power; a second lens group having a negative refractive power; and a third lens group having a negative refractive power. The second lens group is moved along the optical axis, whereby focusing from a focus state for an object at infinity to a focus state for a minimum object distance is performed. The inner focus lens satisfies a conditional expression (1) ?29.0?f3/f??5.4, where f3 is a focal length of the third lens group at the focus state for an object at infinity and f is a focal length of the optical system overall at the focus state for an object at infinity.

Abstract: An inner focus lens includes sequentially from an object side, a first lens group having a positive refractive power; a second lens group having a negative refractive power; and a third lens group having a negative refractive power. The second lens group is moved along an optical axis, whereby focusing from a focus state for an object at infinity to a focus state for a minimum object distance is performed. A lens group configured by a lens other than a lens that is disposed farthest on the object side is moved in a direction orthogonal to the optical axis to shift an image. The inner focus lens satisfies a conditional expression (1) 0.15?(1??p)×?r?4.50, where ?p is transverse magnification of the orthogonally moved lens group and ?r is composite transverse magnification of a lens group disposed farther on an image side than the orthogonally moved lens group.

Abstract: A fixed focus lens comprising, sequentially from an object side, a first lens group having a positive refractive power; a second lens group having a negative refractive power; and a third lens group having a positive refractive power. The first lens group includes an aperture stop. The second lens group is configured by a single lens element. During focusing, the second lens group moves along an optical axis and the first lens group and the third lens group are fixed with respect to an imaging plane.

Abstract: A fixed focus lens comprising, sequentially from an object side, a first lens group having a positive refractive power; a second lens group having a negative refractive power; and a third lens group having a positive refractive power. The first lens group includes an aperture stop. The second lens group is configured by a single lens element. During focusing, the second lens group moves along an optical axis and the first lens group and the third lens group are fixed with respect to an imaging plane.

Abstract: An internal focusing lens includes sequentially from an object side, a first lens group having a positive refractive power; a second lens group having a negative refractive power; and a third lens group having a positive refractive power. During focusing, the second lens group is moved along the optical axis and, the first lens group and the third lens group are fixed. The internal focusing lens satisfies a conditional expression (1) 0.31<f1/f<0.58, where f1 is the focal length of the first lens group and f is the focal length of the entire optical system, at infinity focus.

Abstract: A fixed focus lens comprising, sequentially from an object side, a first lens group having a positive refractive power; a second lens group having a negative refractive power; and a third lens group having a positive refractive power. The first lens group includes an aperture stop. The second lens group is configured by a single lens element. During focusing, the second lens group moves along an optical axis and the first lens group and the third lens group are fixed with respect to an imaging plane.

Abstract: An internal focusing lens includes sequentially from an object side, a first lens group having a positive refractive power; a second lens group having a negative refractive power; and a third lens group having a positive refractive power. During focusing, the second lens group is moved along the optical axis and, the first lens group and the third lens group are fixed. The internal focusing lens satisfies a conditional expression (1) 0.31<f1/f<0.58, where f1 is the focal length of the first lens group and f is the focal length of the entire optical system, at infinity focus.

Abstract: A fixed focus lens comprising, sequentially from an object side, a first lens group having a positive refractive power; a second lens group having a negative refractive power; and a third lens group having a positive refractive power. The first lens group includes an aperture stop. The second lens group is configured by a single lens element. During focusing, the second lens group moves along an optical axis and the first lens group and the third lens group are fixed with respect to an imaging plane.