Zoom lens system, lens barrel, imaging device and camera

A lens barrel for holding an imaging optical system that forms an optical image of an object, wherein

• the imaging optical system is a zoom lens system comprising a plurality of lens units each composed of at least one lens element, in which
• an interval between at least any two lens units among the lens units is changed so that an optical image of an object is formed with a continuously variable magnification,
• any one of the lens units, any one of the lens elements, or alternatively a plurality of adjacent lens elements that constitute one lens unit move in a direction perpendicular to an optical axis,
• the zoom lens system, in order from the object side to the image side, comprises:
• a first lens unit having positive optical power;
• a second lens unit that includes a lens element having a reflecting surface for bending a light beam from an object and that has negative optical power;
• a third lens unit having positive optical power;
• and
• a fourth lens unit having positive optical power, and
• the following condition (1) is satisfied:
• 1.00<−(1−m2T)×m3T×m4T<2.00 (1)
• (where, Z=fT/fW>3.90)
• in which,
• m2T is a magnification of the second lens unit at a telephoto limit in a case that the shooting distance is infinity,
• m3T is a magnification of the third lens unit at a telephoto limit in a case that the shooting distance is infinity,
• m4T is a magnification of the fourth lens unit at a telephoto limit in a case that the shooting distance is infinity,
• fW is a focal length of the entire zoom lens system at a wide-angle limit, and
• fT is a focal length of the entire zoom lens system at a telephoto limit), and wherein
• in an imaging state, the first lens unit is held in a manner movable in a direction of the light beam from the object, and
• in an accommodated state, the lens element having a reflecting surface escapes to an escape position different from a position located in the imaging state.

An imaging device capable of outputting an optical image of an object as an electric image signal, comprising:

• an imaging optical system that forms the optical image of the object;
• and
• an image sensor that converts the optical image formed by the imaging optical system into the electric image signal, wherein
• the imaging optical system is a zoom lens system comprising a plurality of lens units each composed of at least one lens element, in which
• an interval between at least any two lens units among the lens units is changed so that an optical image of an object is formed with a continuously variable magnification,
• any one of the lens units, any one of the lens elements, or alternatively a plurality of adjacent lens elements that constitute one lens unit move in a direction perpendicular to an optical axis,
• the zoom lens system, in order from the object side to the image side, comprises:
• a first lens unit having positive optical power;
• a second lens unit that includes a lens element having a reflecting surface for bending a light beam from an object and that has negative optical power;
• a third lens unit having positive optical power;
• and
• a fourth lens unit having positive optical power, and
• the following condition (1) is satisfied:
• 1.00<−(1−m2T)×m3T×m4T<2.00 (1)
• (where, Z=fT/fW>3.90)
• in which,
• m2T is a magnification of the second lens unit at a telephoto limit in a case that the shooting distance is infinity,
• m3T is a magnification of the third lens unit at a telephoto limit in a case that the shooting distance is infinity,
• m4T is a magnification of the fourth lens unit at a telephoto limit in a case that the shooting distance is infinity,
• fW is a focal length of the entire zoom lens system at a wide-angle limit, and
• fT is a focal length of the entire zoom lens system at a telephoto limit.

A camera for converting an optical image of an object into an electric image signal and then performing at least one of displaying and storing of the converted image signal, comprising:

• an imaging device including an imaging optical system that forms the optical image of the object and an image sensor that converts the optical image formed by the imaging optical system into the electric image signal, wherein
• the imaging optical system is a zoom lens system comprising a plurality of lens units each composed of at least one lens element, in which
• an interval between at least any two lens units among the lens units is changed so that an optical image of an object is formed with a continuously variable magnification,
• any one of the lens units, any one of the lens elements, or alternatively a plurality of adjacent lens elements that constitute one lens unit move in a direction perpendicular to an optical axis,
• the zoom lens system, in order from the object side to the image side, comprises:
• a first lens unit having positive optical power;
• a second lens unit that includes a lens element having a reflecting surface for bending a light beam from an object and that has negative optical power;
• a third lens unit having positive optical power;
• and
• a fourth lens unit having positive optical power, and
• the following condition (1) is satisfied:
• 1.00<−(1−m2T)×m3T×m4T<2.00 (1)
• (where, Z=fT/fW>3.90)
• in which,
• m2T is a magnification of the second lens unit at a telephoto limit in a case that the shooting distance is infinity,
• m3T is a magnification of the third lens unit at a telephoto limit in a case that the shooting distance is infinity,
• m4T is a magnification of the fourth lens unit at a telephoto limit in a case that the shooting distance is infinity,
• fW is a focal length of the entire zoom lens system at a wide-angle limit, and
• fT is a focal length of the entire zoom lens system at a telephoto limit.