Optical system, and imaging apparatus incorporating the same

An optical system, comprising, in order from an object side thereof:

• a first lens group that remains fixed,
• an aperture stop,
• a second lens group that remains fixed and has positive refracting power, and
• a third lens group that includes one or a cemented, first lens, is movable and has negative refracting power, wherein:
• the third lens group moves along an optical axis toward an image side thereby implementing focusing from a focusing-on-infinity state to a focusing-on-a-near-distance state, with satisfaction of the following Conditions (1) and (2):
• |f(2+3)g/f1g|<1 (1)
• −6.0<(R3gr+R3gf)/(R3gr−R3gf)<3.5 (2)
• where f(2+3)g is a combined focal length of the second lens group and the third lens group upon focusing on infinity,
• f1g is a focal length of the first lens group,
• R3gr is an axial radius of curvature of a surface in and on the most image side of a negative lens component forming a part of the third lens group, and
• R3gf is an axial radius of curvature of a surface in and on the most object side of the lens component forming a part of the third lens group.