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

A zoom optical system comprising a plurality of lens groups, wherein

• upon zooming, distances between adjacent lens groups change,
• the zoom optical system comprises:
• a focusing lens group that moves upon focusing;
• and a cylindrical member to which a driving apparatus for moving the focusing lens group is fixed,
• upon zooming, the cylindrical member moves,
• the focusing lens group is relatively movable with respect to the cylindrical member by the driving apparatus,
• an amount of movement of a lens disposed to an object side or an image side of the focusing lens group upon zooming is different from the amount of movement of the cylindrical member upon zooming, and
• the zoom optical system satisfies the following conditional expression:
• −1.000<dA/dB<2.000
• where dA:
• an amount of movement of the focusing lens group with respect to an image surface upon zooming from a wide-angle end state to a telephoto end state (a sign of the amount of movement toward an object is assumed to be +, and a sign of the amount of movement toward an image is assumed to be −), and
• dB:
• an amount of movement of the cylindrical member with respect to the image surface upon zooming from the wide-angle end state to the telephoto end state (a sign of the amount of movement toward the object is assumed to be +, and a sign of the amount of movement toward the image is assumed to be −).

A method for manufacturing a zoom optical system comprising a plurality of lens groups, the method comprising:

• arranging the lens groups in a lens barrel such that:
• upon zooming, distances between adjacent lens groups change, and
• the method further comprising at least one of the following features A or B,
• the feature A including:
• configuring the zoom optical system to comprise a focusing lens group that moves upon focusing and an image-side lens group disposed adjacent to an image side of the focusing lens group, and
• satisfying the following conditional expression:
• 0.000<dL0t/dL1t<1.000
• where dL0t:
• a distance on an optical axis between the focusing lens group and the image-side lens group upon focusing on an infinity object in a telephoto end state, and
• dL1t:
• a distance on the optical axis between the focusing lens group and the image-side lens group upon focusing on a short-distance object in the telephoto end state,
• the feature B including:
• configuring the zoom optical system to comprise a focusing lens group that moves upon focusing and a cylindrical member to which a driving apparatus for moving the focusing lens group is fixed,
• the cylindrical member moving upon zooming,
• the focusing lens group being relatively movable with respect to the cylindrical member by the driving apparatus,
• an amount of movement of a lens disposed to an object side or an image side of the focusing lens group upon zooming being different from the amount of movement of the cylindrical member upon zooming, and
• the following conditional expression being satisfied:
• −1.000<dA/dB<2.000
• where dA:
• an amount of movement of the focusing lens group with respect to an image surface upon zooming from a wide-angle end state to a telephoto end state (a sign of the amount of movement toward an object is assumed to be +, and a sign of the amount of movement toward an image is assumed to be −), and
• dB:
• an amount of movement of the cylindrical member with respect to the image surface upon zooming from the wide-angle end state to the telephoto end state (a sign of the amount of movement toward the object is assumed to be +, and a sign of the amount of movement toward the image is assumed to be −).