US 5,970,266 A · Real image mode variable magnification finder

Abstract

A real image mode variable magnification finder includes an objective system having a positive refracting power, an image erecting optical system for erecting an image formed by the objective system, and an eyepiece system having a positive refracting power. The objective system is composed of a first lens unit of a negative biconcave lens, a second lens unit of a positive lens, and a third lens unit of a positive meniscus lens with a convex surface directed toward the image side. The first lens unit is fixed and the second and third lens units are moved along the optical axis, thereby changing the magnification of the finder. In this way, the real image mode variable magnification finder of wide-angle design can be provided which is compact in size, has a high variable magnification ratio, and exhibits excellent performance for correction for aberration.

Claims6

Dependent claims

A real image mode variable magnification finder comprising, in order from an object side:

an objective system having a positive refracting power;
an image erecting optical system for erecting an image formed by said objective system;
and
an eyepiece system having a positive refracting power,
said objective system including, in order from said object side:
a first lens unit of a negative biconcave lens;
a second lens unit of a positive lens;
and
a third lens unit of a positive meniscus lens with a convex surface directed toward an image side,
said first lens unit being fixed and said second lens unit and said third lens unit being moved along an optical axis, thereby changing a magnification of said finder.

7 more elements

Dependencies are inferred from the claim text.

Real image mode variable magnification finder

Life of this patent

Real image mode variable magnification finder

Life of this patent

Abstract

Claims6