Zoom lens, optical apparatus and method for manufacturing zoom lens

A method for manufacturing a zoom lens by disposing, in order from an object, a first lens group having negative refractive power, a second lens group having positive refractive power, and a third lens group having positive refractive power,

• the method comprising disposing the first to third lens groups such that, upon zooming from a wide-angle end state to a telephoto end state, at least the first lens group and the second lens group move along an optical axis so that a distance between the first lens group and the second lens group decreases, and a distance between the second lens group and the third lens group increases,
• the lens closest to the object in the second lens group being a positive single lens,
• the object side lens surface of the positive single lens being an aspherical surface of which radius of curvature increases in a direction from the optical axis to the periphery of the lens, and
• the following conditional expression being satisfied:
• 0.018<X×Ymax/(fw×TLw)<0.040
• where X denotes a sag within an effective diameter on the object side lens surface of the positive lens, Ymax denotes a maximum image height of the zoom lens in the wide-angle end state, fw denotes a focal length of the zoom lens in the wide-angle end state, and TLw denotes a total length of the zoom lens in the wide-angle end state.

A zoom lens comprising, in order from an object:

• a first lens group having negative refractive power;
• a second lens group having positive refractive power;
• and a third lens group having positive refractive power,
• upon zooming from a wide-angle end state to a telephoto end state, at least the first lens group and the second lens group moving along an optical axis so that a distance between the first lens group and the second lens group decreases, and a distance between the second lens group and the third lens group increases,
• the lens closest to the object in the second lens group being a positive lens,
• the object side lens surface of the positive lens being an aspherical surface of which radius of curvature increases in a direction from the optical axis to the periphery of the lens,
• the following conditional expression being satisfied:
• 0.018<X×Ymax/(fw×TLw)<0.040
• where X denotes a sag within an effective diameter on the object side lens surface of the positive lens, Ymax denotes a maximum image height of the zoom lens in the wide-angle end state, fw denotes a focal length of the zoom lens in the wide-angle end state, and TLw denotes a total length of the zoom lens in the wide-angle end state, and
• the following conditional expression being satisfied:
• 0.70<f2F/f2<1.20
• where f2F denotes a focal length of the positive lens closest to the object in the second lens group, and f2 denotes a focal length of the second lens group.

A method for manufacturing a zoom lens by disposing, in order from an object, a first lens group having negative refractive power, a second lens group having positive refractive power, and a third lens group having positive refractive power,

• the method comprising disposing the first to third lens groups such that, upon zooming from a wide-angle end state to a telephoto end state, at least the first lens group and the second lens group move along an optical axis so that a distance between the first lens group and the second lens group decreases, and a distance between the second lens group and the third lens group increases,
• the lens closest to the object in the second lens group being a positive lens,
• the object side lens surface of the positive lens being an aspherical surface of which radius of curvature increases in a direction from the optical axis to the periphery of the lens,
• the following conditional expression being satisfied:
• 0.018<X×Ymax/(fw×TLw)<0.040
• where X denotes a sag within an effective diameter on the object side lens surface of the positive lens, Ymax denotes a maximum image height of the zoom lens in the wide-angle end state, fw denotes a focal length of the zoom lens in the wide-angle end state, and TLw denotes a total length of the zoom lens in the wide-angle end state, and the following conditional expression being satisfied:
• 0.70<f2F/f2<1.20
• where f2F denotes a focal length of the positive lens closest to the object in the second lens group, and f2 denotes a focal length of the second lens group.