Zoom optical system, optical device and method for manufacturing the zoom optical system

The method for manufacturing a zoom optical system comprising in order from an object side, a first lens group having positive refractive power, a front-side lens group, an intermediate lens group having positive refractive power, and a rear-side lens group, wherein

• the front-side lens group is composed of one or more lens groups and has a negative lens group,
• the intermediate lens group is composed of one or more lens groups,
• at least part of the intermediate lens group is a focusing lens group,
• the rear-side lens group is composed of one or more lens groups, and
• lenses are arranged in a lens barrel in a manner that upon zooming, the first lens group is moved with respect to an image surface, a distance between the first lens group and the front-side lens group is changed, a distance between the front-side lens group and the intermediate lens group is changed, and a distance between the intermediate lens group and rear-side lens group is changed,
• a vibration-proof lens group that is disposed closer to an image than the focusing lens group, and is configured to be movable with a displacement component in a direction orthogonal to an optical axis, and
• the following conditional expression is satisfied:
• −15.00<fV/fRF<10.000
• where, fV denotes a focal length of the vibration-proof lens group, and
• fRF denotes a focal length of a lens group closest to an object in the rear-side lens group.