Variable magnification optical system, optical apparatus, and method for manufacturing variable magnification optical system

A method for manufacturing a variable magnification optical system, wherein

• the variable magnification optical system comprises:
• a first lens group having a negative refractive power;
• a second lens group having a positive refractive power disposed closer to an image side than the first lens group;
• an intermediate lens group disposed closer to the image side than the second lens group;
• and
• a vibration-reduction lens group disposed closer to the image side than the intermediate lens group and arranged to be movable so as to have a movement component in a direction orthogonal to an optical axis,
• the system performs varying magnification by changing at least a distance between the first lens group and the second lens group and a distance between the second lens group and the intermediate lens group, and
• the method comprises at least one of the following features (A) and (B):
• (A) configuring the intermediate lens group to have one or more positive components and one or more negative lens components, and arranging the respective lens groups in a lens barrel so as to satisfy the following conditional expression:
• 2.500<β(Gn)t<50.000
• where
• β(Gn)t:
• an imaging magnification of the intermediate lens group in a telephoto end state;
• (B) providing an image-side lens group having the strongest positive refractive power among lens groups which are disposed closer to the image side than the vibration-reduction lens group and have positive refractive power, the image-side lens group being arranged such that a distance between the image-side lens group and the vibration-reduction lens group changes upon varying magnification, and arranging the respective lens groups in a lens barrel so as to satisfy the following conditional expressions:
• 2.500<β(Gn)t<50.000
• 0.400<f(RP)/(FP)<2,000
• where
• β(Gn) an imaging magnification of the intermediate lens group in a telephoto end state,
• f(RP):
• a focal length of the image-side lens group, and
• f(FP) a composite focal in the wide-angle end state, of lenses disposed closer to the image side than the first lens group and disposed closer to the object side than the intermediate lens group.

A variable magnification optical system comprising:

• a first lens group having a negative refractive power;
• a second lens group having a positive refractive power disposed closer to an image side than the first lens group;
• an intermediate lens group disposed closer to the image side than the second lens group;
• and
• a vibration-reduction lens group disposed closer to the image side than the intermediate lens group and configured to be movable so as to have a movement component in a direction orthogonal to an optical axis, wherein
• the system performs varying magnification by changing at least a distance between the first lens group and the second lens group and a distance between the second lens group and the intermediate lens group,
• the system includes an image-side lens group having the strongest positive refractive power among lens groups which are disposed closer to the image side than the vibration-reduction lens group and have positive refractive power,
• a distance between the image-side lens group and the vibration-reduction lens group changes upon varying magnification, and
• the system satisfies the following conditional expressions:
• 2.500<β(Gn)t<50.000
• 0.400<f(RP)/f(FP)<2.000
• where
• β(Gn)t:
• an imaging magnification of the intermediate lens group in a telephoto end state,
• f(RP):
• a focal length of the image-side lens group, and
• f(FP):
• a composite focal length, in the wide-angle end state, of lenses disposed closer to the image side than the first lens group and disposed closer to the object side than the intermediate lens group.