Abstract: A variable magnification optical system comprises, in order from an object side, a negative first lens group, a positive second lens group, a negative third lens group and a positive fourth lens group. Upon varying a magnification, a distance between the first lens group and the second lens group, a distance between the second lens group and the third lens group, and a distance between the third lens group and the fourth lens group are varied. The first lens group consists of, in order from the object side, a negative lens and a positive lens. The second lens group consists of, in order from the object side, a positive 2a lens group, a positive 2b lens group, and a negative 2c lens group. A downsized system having high optical performance is provided.

Abstract: An optical system used in an optical apparatus, such as a camera 1, is configured to include a plurality of lens groups such that at focusing the distances between the lens groups are varied, that a final lens group disposed closest to an image side of the lens groups includes at least one lens surface having a pole, and that all of the following conditional expressions are satisfied: 0.020<Y/f<0.120??(1) 0.010<Bf/TL<0.150??(2) where Y is image height, f is the focal length of the optical system, TL is the total optical length of the optical system, and Bf is the back focus of the optical system.

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: 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: 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 and an optical apparatus that have favorable imaging performance and a method for manufacturing the optical system are provided. An optical system OL includes, sequentially from an object side, a front group G1 having positive refractive power and a focusing group G2 that performs focusing by moving in an optical axis direction, the front group G1 includes, sequentially from the object side, a first lens L11, a second lens L12, and a third lens L13, and the optical system OL satisfies a condition expressed by an expression below, 0.10<D23/f1<0.75 in the expression, f1: focal length of the front group G1, and D23: distance on an optical axis between the second lens L12 and the third lens L13.

Abstract: A variable magnification optical system comprising, in order from an object side, a first lens group having negative refractive power, a second lens group having positive refractive power, a third lens group having negative refractive power and a fourth lens group having positive refractive power; upon varying a magnification, a distance between the first lens group and the second lens group being varied, a distance between the second lens group and the third lens group being varied, and a distance between the third lens group and the fourth lens group being varied; the first lens group consisting of, in order from the object side, a negative lens and a positive lens; and the second lens group consisting of, in order from the object side, a 2a lens group having positive refractive power, a 2b lens group having positive refractive power, and a 2c lens group having negative refractive power, whereby the variable magnification optical system having high optical performance and being downsized, is provided.