Abstract: An objective lens (OL) comprises, disposed in order from an object: a positive lens (L11); a negative meniscus lens (L12) cemented to the positive lens (L11) and having a concave surface facing the object; and a positive meniscus lens (L13) having a concave surface facing the object; wherein the objective lens satisfies following conditional expressions 2.03?n1m?2.30 and 20??1m, where, n1m: a refractive index of the negative meniscus lens (L12) with respect to a d-line, and ?1m: an Abbe number of the negative meniscus lens (L12).

Abstract: An objective lens (OL) comprises, disposed in order from an object: a positive lens (L11); a negative meniscus lens (L12) cemented to the positive lens (L11) and having a concave surface facing the object; and a positive meniscus lens (L13) having a concave surface facing the object; wherein the objective lens satisfies following conditional expressions 2.03?n1m?2.30 and 20??1m, where, n1m: a refractive index of the negative meniscus lens (L12) with respect to a d-line, and ?1m: an Abbe number of the negative meniscus lens (L12).

Abstract: A variable magnification optical system (ZL) comprises a preceding lens group (GA) having negative refractive power and a succeeding lens group (GB) having positive refractive power, which are arranged in order from the object side along an optical axis. The succeeding lens group (GB) has a focusing group (GF) and an image-side group (GC) disposed closer to the image side than the focusing group (GF), the focusing group (GF) moves to the image side along the optical axis from focusing on an object at infinity to focusing on a close-distance object, and the following conditional expression is satisfied. 1.80<fF/fBaw FNow<3.40 where fF is the focal length of the focusing group (GF), fBaw is the focal length in the wide-angle end state of an image-side lens group (GBa) composed of lenses disposed on the image side from the focusing group (GF), and FNow is the F-number of the variable magnification optical system (ZL) in the wide-angle end state.

Abstract: An optical system (LS) has an aperture stop (S), and a positive lens (L4) disposed closer to the object side than the aperture stop (S). The positive lens (L4) satisfies the following conditional expressions. ?0.010<ndP1?(2.015?0.0068×?dP1) 50.00<?dP1<65.00 0.545<?gFP1 ?0.010<?gFP1?(0.6418?0.00168×?dP1) where ndP1 is the refractive index to the d line of the positive lens, ?dP1 is the Abbe number with respect to the d line of the positive lens, and ?gFP1 is the partial dispersion ratio of the positive lens.

Abstract: An optical system (LS) has an aperture stop (S), and a negative lens (L73) disposed closer to the image side than the aperture stop (S) and satisfying the following conditional expressions. ?0.010<ndN2?(2.015?0.0068×?dN2), 50.00<?dN2<65.00, 0.545<?gFN2, ?0.010<?gFN2?(0.6418?0.00168×?dN2) where ndN2 is the refractive index to the d line of the negative lens, ?dN2 is the Abbe number with respect to the d line of the negative lens, and ?gFN2 is the partial dispersion ratio of the negative lens.

Abstract: This optical system (LS) has an aperture diaphragm (S) and a negative lens (L4) disposed closer to an object side than the aperture diaphragm (S) and satisfies the following conditional expression. ?0.010<ndN1?(2.015?0.0068×?dN1), 50.00<?dN1<65.00, 0.545<?gFN1, ?0.010<?gFN1?(0.6418?0.00168×?dN1). Where, ndN1 is a refractive index of the negative lens with respect to a d-line, vdN1 is an Abbe number of the negative lens based on the d-line, and ?gFN1 is a partial dispersion ratio of the negative lens.

Abstract: An optical system (LS) has a lens (L11) that satisfies the following conditional expressions. ?0.010<ndLZ?(2.015?0.0068×?dLZ) 50.00<?dLZ<65.00 0.545<?gFLZ ?0.010<?gFLZ?(0.6418?0.00168×?dLZ) where ndLZ is the refractive index to the d line of the lens, ?dLZ is the Abbe number with respect to the d line of the lens, and ?gFLZ is the partial dispersion ratio of the lens.

Abstract: A magnification-variable optical system having a small size, a wide angle of view, and high optical performance, an optical apparatus including the magnification-variable optical system, and a method for manufacturing the magnification-variable optical system are provided. A magnification-variable optical system ZL used for an optical apparatus such as a camera 1 includes a first lens group G1 having a negative refractive power and including at least two lenses, and a rear group GR including at least one lens group disposed on an image side of the first lens group G1, and is configured so that a distance between lens groups adjacent to each other changes at magnification change and a condition expressed by predetermined condition expressions is satisfied.

Abstract: A magnification-variable optical system having a small size, a wide angle of view, and high optical performance, an optical apparatus including the magnification-variable optical system, and a method for manufacturing the magnification-variable optical system are provided. A magnification-variable optical system ZL used for an optical apparatus such as a camera 1 includes a first lens group G1 having a negative refractive power, and a rear group GR including at least one lens group disposed on an image side of the first lens group G1, and is configured so that a distance between lens groups adjacent to each other changes at magnification change and a condition expressed by predetermined condition expressions is satisfied.

Abstract: The ophthalmic optical system is configured to apply an angular scanning light ray to an eye. M=|?out/?in| is defined, where ?in represents an angle between an incident light ray to the ophthalmic optical system and an optical axis of the ophthalmic optical system, and ?out represents an angle between an exiting light ray exiting from the ophthalmic optical system toward the eye and the optical axis. The ophthalmic optical system satisfies a conditional expression Mpar<Mmax, where Mpar represents M in a case that the incident light ray is a paraxial ray, Mmax represents M in a case that the incident light ray is a ray of a maximum angle of win.

Abstract: An objective lens (OL) comprises, disposed in order from an object: a positive lens (L11); a negative meniscus lens (L12) cemented to the positive lens (L11) and having a concave surface facing the object; and a positive meniscus lens (L13) having a concave surface facing the object; wherein the objective lens satisfies following conditional expressions 2.03?n1m?2.30 and 20??1m, where, n1m: a refractive index of the negative meniscus lens (L12) with respect to a d-line, and ?1m: an Abbe number of the negative meniscus lens (L12).