Zoom lens system

A zoom lens system with both zooming and focusing functions, having a plurality of lens groups including at least two focusing lens groups which move by different amounts in zooming or in focusing:

• wherein when a predetermined movement trace for zooming is expressed with a variable of rotation angle of a rotating barrel for defining a displacement amount of a lens group along an optical axis, a movement trace of a first focusing lens group is formed by a combination of a first focus cam with a first compensating zoom cam, a movement trace of a second focusing lens group is formed by a combination of a second focus cam with a second compensating zoom cam, and a movement trace of each movable non-focusing lens group taking no part in focusing is formed by a combination of one of said first and second compensating zoom cams with a zoom cam for said non-focusing lens group.

A zoom lens system with both zooming and focusing functions, having a plurality of lens groups including at least two focusing lens groups which move by different amounts in zooming or in focusing:

• wherein when a predetermined movement trace for zooming is expressed with a variable of rotation angle of a rotating barrel for defining a displacement amount of a lens group along an optical axis, a movement trace of a first focusing lens group is formed by a combination of a first focus cam with a first compensating zoom cam, a movement trace of an n-th focusing lens group is formed by a combination of an n-th focus cam with an n-th compensating zoom cam, and a movement trace of at least one movable non-focusing lens group taking no part in focusing is determined only by a zoom cam for said non-focusing lens group without being combined with any of said first to n-th compensating zoom cams.

A zoom lens system with both zooming and focusing functions, having a plurality of lens groups including at least two focusing lens groups which move by different amounts in zooming or in focusing:

• wherein when a predetermined movement trace for zooming is expressed with a variable of rotation angle of a rotating barrel for defining a displacement amount of a lens group along an optical axis, a movement trace of a first focusing lens group is formed by a combination of a first focus cam with a first compensating zoom cam, a movement trace of a second focusing lens group is formed by a combination of a second focus cam with a second compensating zoom cam, and a movement trace of at least one movable non-focusing lens group taking no part in focusing is determined only by a zoom cam for said non-focusing lens group without being combined with said first compensating zoom cam or with said second compensating zoom cam.