JP3278792B2 - Viewfinder system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a finder system suitable for a photographic camera, a video camera and the like, and more particularly to a finder system which removes a flare component by setting an aperture of an aperture provided in an objective lens. The present invention relates to a finder system that enables observation of an image.

[0002]

2. Description of the Related Art An object image formed on a primary image forming surface by an objective lens using an image inverting optical member as a finder system used in recent photographic cameras and video cameras is converted into an erect real image. There is a real image type finder system in which an object image of a normal image is observed with an eyepiece. As the image inversion optical member, a reflection member such as a prism having a roof reflection surface or a Porro prism is often used.

In a normal finder system, a roof ridge line where a roof surface intersects is set at a position distant from a primary image forming plane formed by an objective lens so that the roof ridge line is largely blurred and inconspicuous when viewed from the eyepiece lens side. ing. In the finder system, a circular or rectangular aperture is provided in the objective lens to shield harmful stray light such as ghost light and flare light. Thereby, a finder image is observed favorably.

[0004]

In a conventional finder system using a roof reflecting surface as an image inverting optical member, a rectangular aperture is provided in an objective lens to shield harmful ghost light and flare light. There are things that are.

However, in such a viewfinder system, when the pupil position for observation, that is, the eye is displaced in the direction perpendicular to the roof ridge line of the roof reflecting surface and observed through the eyepiece, the light beam incident on the pupil is slit by the eye and the rectangular aperture. It is squeezed into a shape. When a light beam narrowed in a slit shape in a direction parallel to the roof ridge passes through the roof ridge, the roof ridge that is usually largely blurred and inconspicuous, that is, an unobservable roof ridge is conspicuous. As a result, there is a problem that good observation of the finder image is hindered.

According to the present invention, in a real image type finder system using an image inverting optical member having a roof reflecting surface for image inversion of an object image formed by an objective lens, the shape of an aperture of an aperture provided in the objective lens is appropriately adjusted. By setting to, harmful ghost light and flare light are effectively shielded, and even if the pupil position for observation is moved up and down on the eyepiece side, a good viewfinder image is observed without observing the roof ridge line. The objective is to provide a finder system that can be used.

[0007]

According to the finder system of the present invention, an object image formed on a predetermined surface by an objective lens having a stop is formed into an erect image by an image inverting optical member having a roof reflecting surface, and the eyepiece is formed by the erect image. In a finder system for observation through a lens, when the optical axis of the finder system is set to the Z axis, and the X and Y axes are set in a section perpendicular to the Z axis, the roof ridge line of the roof reflecting surface is located in the XZ plane; It is characterized in that the aperture of the diaphragm has a continuous or discontinuous repetitive shape in the X-axis direction in the XY plane.

[0008]

FIG. 1 is a perspective view of a main part of a first embodiment of the present invention, and FIG.
3 is a schematic view of a main part when the optical path of the optical system of FIG. 1 is developed, and FIGS. 3 to 5 are enlarged explanatory views of a part of FIG.

In the drawing, L1 is an objective lens such as a single focal length or a zoom lens.

The objective lens L1 of this embodiment has a negative first lens L1, a stop S having an opening of a predetermined shape, and a positive second lens L2 in order from the object side.

LP is an image reversing optical member and has a first prism P1 and a second prism P2. IP is a primary imaging plane, located between the first prism P1 and the second prism P2, and an object image (finder image) is formed by the objective lens L0. A finder field frame, various finder information, and the like are formed on the primary imaging plane IP. The first prism P1 has a plane or an incident surface P1 having a positive refractive power, a reflecting surface P1b for totally reflecting a light beam incident from the incident surface P1, a reflecting surface P1c for reflecting a light beam from the reflecting surface P1b, and a reflecting surface P1c. Outgoing surface P1d on the same plane as the reflecting surface P1b that transmits the light flux.

The second prism P2 totally reflects the light beam from the light-emitting surface P1d of the first prism P1, the light-entering surface P2a, the light-reflecting surface P2b for totally reflecting the light beam from the light-entering surface P2a, and the light beam from the light-reflecting surface 2b. The roof reflecting surface P2c, the incident surface P2a for totally reflecting the light beam from the roof reflecting surface P2c
And a reflecting surface P2d on the same plane, and an emitting surface P2e for emitting a light beam from the reflecting surface P2d.

Here, the roof reflecting surface P2c has its roof ridge line D located in a plane including the optical axis Z of the finder system (in the XZ plane). The light beam emitted from the emission surface P2e of the second prism P2 is incident on the eyepiece LE. Q is a pupil position for observation.

In this embodiment, the object image formed on the primary image plane IP by the objective lens L0 is inverted by the image inverting optical member LP into an erect image. And the eyepiece L from the pupil position Q
The object image (finder image) of the erect erect image is observed through E.

Next, prior to describing the features of the shape of the aperture of the aperture S of the present embodiment, a conventional aperture will be described. Conventionally, a rectangular aperture as shown in FIG. 6 has been used as an aperture provided in an objective lens in order to shield harmful stray light without shielding a finder image observation light flux.

For this reason, in a finder system using a roof reflecting surface as an image inverting optical member, when the observation pupil position is shifted in a direction perpendicular to the roof ridge line (Y-axis direction), the luminous flux for the finder observation is transmitted between the eye and the stop S. The light is restricted by the aperture and narrowed down to a narrow slit-like light beam.

At this time, when a light beam narrowed in a narrow slit shape in a direction parallel to the roof ridge passes through the roof ridge, the roof ridge which is normally not greatly blurred and cannot be observed becomes noticeable.

Therefore, in the present invention, the shape of the opening of the stop S is set as follows, thereby shielding harmful stray light and preventing the roof ridge line from being observed even if the pupil position for observation is moved up and down. And a good finder image is observed.

Now, as shown in FIG. 1, the optical axis direction is the Z axis, and the X and Y axes are set in a plane perpendicular to the Z axis. The roof ridge line D of the roof reflection surface P2c is located in the XZ plane.
The aperture of the stop S has a continuous or discontinuous repetitive shape such as a waveform, a comb shape, and a sawtooth shape in the X-axis direction symmetrically with respect to the X-axis in the XY plane.

FIG. 3 to FIG. 5 are explanatory views of Embodiments 1 to 3 of the aperture of the stop applicable to this embodiment.

In this embodiment, the shape of the opening of the stop S is shown in FIG.
5 to thereby effectively shield stray light such as harmful ghosts and flares without deteriorating the performance of the finder image, and move the pupil position Q in the vertical direction (Y-axis direction). Even when it is shaken, the roof edge D is effectively prevented from being blurred and observed.

In this embodiment, the aperture shape of the stop S is X
It is not necessary to be strictly symmetrical about the axis, and it is sufficient that the roof ridgeline D is not observed when the pupil is moved in the vertical direction.

[0023]

According to the present invention, as described above, a real image type finder system using an image inversion optical member having a roof reflection surface is provided in an objective lens for image inversion of an object image formed by an objective lens. By properly setting the shape of the aperture of the aperture, harmful ghost light and flare light are effectively blocked, and even if the pupil position for observation is moved up and down on the eyepiece side, the roof ridge line is not observed A finder system capable of observing an excellent finder image can be achieved.

[Brief description of the drawings]

FIG. 1 is a perspective view of a main part of a first embodiment of the present invention.

FIG. 2 is an explanatory diagram when an optical path of the optical system of FIG. 1 is developed.

FIG. 3 is an explanatory view of Embodiment 1 of the aperture according to the present invention.

FIG. 4 is an explanatory view of a diaphragm according to a second embodiment of the present invention;

FIG. 5 is an explanatory diagram of Embodiment 3 of the diaphragm according to the present invention.

FIG. 6 is an explanatory view of an aperture of a conventional diaphragm.

[Explanation of symbols]

 L0 Objective lens LP Image reversing optical member LE Eyepiece Q Pupil position S Aperture P1 First prism P2 Second prism D Dach ridge

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G03B 13/02-13/28

Claims (3)

(57) [Claims] 1. A viewfinder system wherein an object image formed on a predetermined surface by an objective lens having an aperture is formed into an erect image by an image inverting optical member having a roof reflection surface, and the erect image is observed through an eyepiece. Set the optical axis of the viewfinder system to Z
When the X and Y axes are set in a section perpendicular to the axis and the Z axis, the roof ridge line of the roof reflecting surface is located in the XZ plane, and the aperture of the diaphragm is continuous or discontinuous in the X axis direction in the XY plane. A finder system characterized by having a repeating shape of. 2. The finder system according to claim 1, wherein a repetitive shape of the aperture of the diaphragm is a wave shape, a comb shape, or a sawtooth shape. 3. A finder system according to claim 1 or 2.
Camera.