Real image mode variable magnification finder
AssigneeOlympus Optical Co., Ltd.
InventorShigeru Kato
Life of this patent
Estimating the term…
Abstract
A real image mode variable magnification finder has an objective optical system with positive refracting power, an image erecting optical system, and an ocular optical system with positive refracting power. The objective optical system has a first lens unit with negative refracting power, a second lens unit with negative refracting power, a third lens unit with positive refracting power, and a fourth lens unit with negative refracting power. When the magnification of the finder is changed, at least one lens unit, namely the third lens unit is moved. In this way, the total length of the objective optical system can be reduced, and thus a compact finder is obtained.
Claims14
A real image mode variable magnification finder comprising:
- an objective optical system having positive refracting power;
- an image erecting optical system;
- and
- an ocular optical system having positive refracting power,
- said objective optical system having, in order from an object side, a first lens unit with negative refracting power, a second lens unit having negative refracting power, a third lens unit having positive refracting power, and a fourth lens unit having negative refracting power,
- wherein an object-side surface of said second lens unit is concave toward an object side and has a smallest absolute value of radius of curvature among lens surfaces of said first lens unit, said second lens unit and said third lens unit, and
- wherein when a magnification of said finder is changed, a plurality of lens units including said third lens unit are moved, a distance between said second lens unit and said third lens unit is changed, and a distance between said first lens unit and said second lens unit is changed.
Dependencies are inferred from the claim text.