Zoom lens system and imaging apparatus provided with the same

A zoom lens system comprising:

• a first lens group having positive refractive power;
• a second lens group having negative refractive power;
• and a rear group, the first lens group, the second lens group and the rear group being arranged in that order from an object side,
• the second lens group consisting essentially of a second lens group-a having negative refractive power and a second lens group-b having negative refractive power arranged in that order from the object side,
• the second lens group-a consisting essentially of a negative lens and a positive lens arranged in that order from the object side,
• the second lens group-a being configured to move to include a component in a direction vertical to an optical axis of the zoom lens system, and
• the rear lens group consisting essentially of an aperture stop, and at least two lens groups,
• wherein during a change in a focus from a short focal length end to a long focal length end to change a magnification power,
• a distance between the first lens group and the second lens group-a increases,
• a distance between the second lens group-a and the second lens group-b is changeable or stationary,
• a distance between the second lens group-b and the rear lens group decreases, and
• wherein conditional expression (4) below is satisfied:
• 0.01<Da/D2a<0.5 (4)
• where
• Da denotes a distance between the negative lens and the positive lens of the second lens group-a along the optical axis;
• and
• D2a denotes a thickness of the second lens group-a along the optical axis.

A zoom lens system comprising:

• a first lens group having positive refractive power;
• a second lens group having negative refractive power;
• and a rear group, the first lens group, the second lens group and the rear group being arranged in that order from an object side,
• the second lens group consisting essentially of a second lens group-a having negative refractive power and a second lens group-b having negative refractive power arranged in that order from the object side,
• the second lens group-a consisting essentially of a negative lens and a positive lens arranged in that order from the object side,
• the second lens group-a being configured to move to include a component in a direction vertical to an optical axis of the zoom lens system, and
• the rear lens group consisting essentially of an aperture stop, and at least two lens groups,
• wherein during a change in a focus from a short focal length end to a long focal length end to change a magnification power,
• a distance between the first lens group and the second lens group-a increases,
• a distance between the second lens group-a and the second lens group-b is changeable or stationary,
• a distance between the second lens group-b and the rear lens group decreases, and
• the second lens group-a is stationary with respect to the image plane.