Real-image zoom viewfinder and imaging apparatus

Abstract

A zoom viewfinder substantially consists of, in order from the object side: a variable-magnification objective lens system substantially consisting of a first lens group that includes a negative first-group first lens and a reflective member arranged in this order from the object side, a positive second lens group that is moved during magnification change, and a positive third lens group that is moved during magnification change; an erect optical system having a reflective surface for converting an inverted image into an erect image; and a positive eyepiece lens system, wherein conditional expressions (1), (2A) and (3) below are satisfied:

1.5<U2/U1<3.0  (1),

1.76≦|f2/f1|<2.0  (2A) and

1.0<f3/f2<5.0  (3).

Description

TECHNICAL FIELD[0001]The present invention relates to a real-image zoom viewfinder and an imaging apparatus which can provide a good viewfinder image by appropriately setting a variable-magnification objective lens system, an erect optical system and an eyepiece lens system.BACKGROUND ART[0002]Conventionally, real-image zoom viewfinders that are configured to form a vertically and horizontally inverted real image using an objective lens having a positive refractive power, convert the real image into an erect image using an erecting prism that is formed by a combination of one or more prisms, and enlarge the erect image using an eyepiece lens having a positive refractive power are known. Further, imaging apparatuses equipped with such a real-image zoom viewfinder are also known.[0003]As an example of an objective lens forming such a real-image zoom viewfinder, one substantially includes, in order from the object side, a first lens group having a negative refractive power, a second le...

AI Technical Summary

Benefits of technology

[0021]In other words, the above-described configuration allows bending an optical path of light from a position where the light is reflected by the reflective member to a position where the light is reflected by the reflective surface of the erect optical system into a direction orthogonal to the imaging direction so as to provide a longer optical path length in the direction orthogonal to the imaging direction and a shorter optical path length in the imaging direction, thereby allowing reducing the optical path length in the imaging direction without reducing the entire optical path length of the light traveling through the real-image zoom viewfinder. In this manner, the thickness reduction of the real-image zoom viewfinder in the imaging direction is achieved without degrading the optical performance for example, with ensuring a zoom ratio of around 4:1).

[0022]Further, since the first lens that is disposed on the object side of the reflective member and the eyepiece lens system that is disposed on the image side of the erect optical system are optical systems corresponding to the thickness of the real-image zoom viewfinder and these optical systems are fixed during magnification change, the thickness reduction of the real-image zoom viewfinder in the imaging direction can be achieved with higher certainty.

Problems solved by technology

The real-image viewfinder disclosed in Patent Document 1, however, has a problem that the thickness reduction while ensuring a zoom ratio of around 4:1 is difficult to be achieved since the length in the thickness direction of a camera is a sum of thicknesses of the objective lens, the prism and the eyepiece lens.

However, it is still difficult to achieve sufficient thickness reduction since a significant thickness is required to dispose two lens groups including the first lens group and the second lens group, which are disposed on the object side of the third lens group for bending the optical path and are arranged in the imaging direction.

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