VARIABLE MAGNIFICATION OPTICAL SYSTEM AND IMAGING APPARATUS

摘要

A variable magnification optical system includes, in order from the object side: a positive first lens group, which is fixed when changing magnification; a negative second lens group that moves from the object side to the image side when changing magnification from the wide angle end to the telephoto end; and a rearward lens group having a positive refractive power throughout the entire variable magnification range that includes at least one lens group that moves when changing magnification. The first lens group includes, in order from the object side, a positive first lens group front group, a positive first lens group middle group, and a first lens group rear group constituted by a negative lens. The first lens group front group and first lens group middle group include cemented lenses formed by cementing a negative lens and a positive lens, provided in this order from the object side, together.

主权项

1. A variable magnification optical system consisting of, in order from the object side to the image side:
a first lens group having a positive refractive power, which is fixed with respect to an image formation plane when changing magnification; a second lens group having a negative refractive power that moves from the object side to the image side when changing magnification from the wide angle end to the telephoto end; and a rearward lens group having a positive refractive power throughout the entire variable magnification range that includes at least one lens group that moves when changing magnification, the distance between the rearward lens group and the second lens group changing when changing magnification; the first lens group consisting of, in order from the object side to the image side, a first lens group front group having a positive refractive power, a first lens group middle group having a positive refractive power, and a first lens group rear group having a negative refractive power; the first lens group front group consisting of a cemented lens formed by cementing a negative lens and a positive lens, provided in this order from the object side to the image side, together, the coupling surface of this cemented lens being convex toward the object side, and the surface most toward the object side within the first lens group front group being convex; the first lens group middle group consisting of a cemented lens formed by cementing a negative lens and a positive lens, provided in this order from the object side to the image side, together, the coupling surface of this cemented lens being convex toward the object side, and the surface most toward the object side within the first lens group middle group being convex; the first lens group rear group consisting of one negative lens; and Conditional Formula (1) below being satisfied:
−50