A lens interchangeable digital camera includes an image sensor in which a subject image is formed on an imaging surface through an imaging optical system including a zoom lens and a sensor movement type shake correction mechanism that performs a sensor movement operation of moving the image sensor in a direction to cancel a shake. A zoom operation determination unit determines whether or not a zoom operation in which the zoom lens moves is being performed. In a case where the zoom operation determination unit determines that the zoom operation is being performed, an operation deciding unit prohibits a shift operation which is at least a part of a sensor movement operation which is allowed while the zoom operation is stopped.

An optical system for a microscope for imaging an object includes: a telescope system having an optical correction unit, which is adjustable in order to correct a spherical imaging aberration, and having a zoom optical unit, which is adjustable in order to adapt a magnification of the telescope system to a ratio of two refractive indices, one of which is assigned to an object side and an other of which is assigned to an image side, within a predetermined magnification range. The telescope system is telecentric over an entire magnification range both with respect to the object side and with respect to the image side by the zoom optical unit contained in the telescope system.

The present disclosure is directed to an optical system internally having an intermediate imaging position MI that is conjugate with both of a magnification conjugate point on a magnification side and a reduction conjugate point on a reduction side, the optical system including: a first positive lens group GP1 including a plurality of lens elements and positioned on the magnification side with respect to the intermediate imaging position; a second positive lens group GP2 including a plurality of lens elements and positioned between the first positive lens group GP1 and the intermediate imaging position Ml; and a negative lens group GN including a plurality of lens elements and positioned on the reduction side with respect to the intermediate imaging position MI, wherein, during focusing, the first positive lens group GP1 and the negative lens group GN move in an optical axis direction, and the second positive lens group GP2 is stationary.

An image lens assembly includes, in order from an object side to an image side along an optical path, a first lens group, a second lens group, a third lens group and a fourth lens group. A total number of lens elements in the image lens assembly is seven. The first lens group includes a first lens element with positive refractive power and a second lens element with negative refractive power. Each of the second lens group and the third lens group includes at least one lens element. The fourth lens group includes a seventh lens element. When the image lens assembly is focusing or zooming, a relative position between the first lens group and an image surface is fixed, a relative position between the fourth lens group and the image surface is fixed, and the second lens group and the third lens group move along the optical axis.

The imaging lens consists of, in order from an object side: a first lens group that has a positive refractive power; an aperture stop; a second lens group that has a positive refractive power; and a third lens group. The second lens group consists of two or less lenses, and moves to the object side during focusing from an object at infinity to an object at a closest distance. The third lens group includes, successively in order from at a position closest to an image side, a rear lens group that has a positive refractive power and a vibration reduction lens group that has a negative refractive power. Then, Conditional Expression (1) is satisfied.

1.5<f3ois/f3r<0.85(1)

The imaging lens consists of, in order from an object side: a first lens group that has a positive refractive power; an aperture stop; a second lens group that has a positive refractive power; and a third lens group. The second lens group consists of two or less lenses, and moves to the object side during focusing from an object at infinity to an object at a closest distance. The third lens group includes, successively in order from at a position closest to an image side, a rear lens group that has a positive refractive power and a vibration reduction lens group that has a negative refractive power. Then, Conditional Expression (1) is satisfied.

0.04<D2o/L<0.1(1)

An optical system for a microscope for imaging an object includes: a telescope system having an optical correction unit, which is adjustable in order to correct a spherical imaging aberration, and having a zoom optical unit, which is adjustable in order to adapt a magnification of the telescope system to a ratio of two refractive indices, one of which is assigned to an object side and an other of which is assigned to an image side, within a predetermined magnification range. The telescope system is telecentric over an entire magnification range both with respect to the object side and with respect to the image side by the zoom optical unit contained in the telescope system.

The imaging lens consists of, in order from an object side, a first lens group having a positive refractive power, a second lens group having a positive refractive power, a stop, a third lens group having a negative refractive power, and a fourth lens group. The first lens group has, in order from the object side, a positive single lens, and two or more cemented lenses. The second lens group consists of a positive lens and a negative lens. During image blur correction, only the third lens group moves. A conditional expression relating to the back focal length Bf and the lens system total length TTL is satisfied: 2<TTL/Bf<3.6.

An optical system (ZL(1)) comprises a plurality of lens groups including a first focusing lens group (G2) and a second focusing lens group (G4) that are disposed side by side on an optical axis, and the second focusing lens group (G4) is disposed at a position closer to an image surface than the first focusing lens group (G2). The first focusing lens group (G2) has positive refractive power, and moves toward an object along the optical axis from focusing on an infinite-distance object to focusing on a short-distance object. The second focusing lens group (G4) moves toward the image surface along the optical axis from focusing on the infinite-distance object to focusing on the short-distance object. The optical system (ZL(1)) satisfies the following conditional expression. ?020<?F1/?F2<0.50 where ?F1 is the lateral magnification of the first focusing lens group at the time of focusing on the infinite-distance object, and ?F2 is the lateral magnification of the second focusing lens group at the time of focusing on the infinite-distance object.

In the zoom lens, a first optical system is formed on the magnification side, and a second optical system is formed on the reduction side, with the intermediate image formed between the first optical system and the second optical system. The second optical system consists of, in order from the magnification side, a first lens group that has a positive power, a second lens group that has a positive power, a third lens group that has a positive or negative power, and a fourth lens group that has a positive power. During zooming, the second lens group and the third lens group are moved by changing spacings between the groups adjacent to each other in a direction of an optical axis, and the fourth lens group remains stationary with respect to the reduction side imaging plane.