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,
• the zoom lens system comprises a second lens unit that includes a lens element having a reflecting surface for bending a light beam from an object, and
• the following condition (1) is satisfied:
• 0.50<(C−S)/H<1.00 (1)
• where,
• C is an effective radius of the image side surface of the most object side lens element in the second lens unit that causes an interval between the image side surface of the most object side lens element in the second lens unit and the lens element having a reflecting surface to be equal to a sag of the image side surface of the most object side lens element in the second lens unit
• C=√(2R·dR−dR2),
• S is a sag of the image side surface of the most object side lens element in the second lens unit at height H,
• H is one-half of an optical axial thickness of the lens element having a reflecting surface,
• R is a radius of curvature of the image side surface of the most object side lens element in the second lens unit, and
• dR is an interval between the most object side lens element in the second lens unit and the lens element having a reflecting surface, and wherein
• 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,
• the zoom lens system comprises a second lens unit that includes a lens element having a reflecting surface for bending a light beam from an object, and
• the following condition (1) is satisfied:
• 0.50<(C−S)/H<1.00 (1)
• where,
• C is an effective radius of the image side surface of the most object side lens element in the second lens unit that causes an interval between the image side surface of the most object side lens element in the second lens unit and the lens element having a reflecting surface to be equal to a sag of the image side surface of the most object side lens element in the second lens unit
• C=√{square root over ( )}(2R·dR−dR2),
• S is a sag of the image side surface of the most object side lens element in the second lens unit at height H,
• H is one-half of an optical axial thickness of the lens element having a reflecting surface,
• R is a radius of curvature of the image side surface of the most object side lens element in the second lens unit, and
• dR is an interval between the most object side lens element in the second lens unit and the lens element having a reflecting surface.

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,
• the zoom lens system comprises a second lens unit that includes a lens element having a reflecting surface for bending a light beam from an object, and
• the following condition (1) is satisfied:
• 0.50<(C−S)/H<1.00 (1)
• where,
• C is an effective radius of the image side surface of the most object side lens element in the second lens unit that causes an interval between the image side surface of the most object side lens element in the second lens unit and the lens element having a reflecting surface to be equal to a sag of the image side surface of the most object side lens element in the second lens unit
• C=√{square root over ( )}2R·dR−dR2),
• S is a sag of the image side surface of the most object side lens element in the second lens unit at height H,
• H is one-half of an optical axial thickness of the lens element having a reflecting surface,
• R is a radius of curvature of the image side surface of the most object side lens element in the second lens unit, and
• dR is an interval between the most object side lens element in the second lens unit and the lens element having a reflecting surface.