JPH09329828A - Finder device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a small sized finder device capable of easily switching a visual field frame. SOLUTION: A visual field frame display plate 14 and a mask plate 15 with an opening for presenting the visual field frame are arranged in a direction horizontal to a finder optical axis 18 so that they may overlap each other, then, a visual field frame image is projected in a direction orthogonal to the finder optical axis 18. On the projection optical path 19 of the visual field frame image, a half mirror 17 is arranged, and also, a flat/convex lens 23 with a reflection layer 24 is arranged at a position opposite to the visual field frame display plate 14 across the finder optical axis 18. In this case, the visual field frame image projected in the projection optical path 19 is transmitted through the half mirror 17 and made incident on the flat/convex lens 23, then, after the frame image is reflected by the reflection layer 24 toward the half mirror 17, the image is reflected by the half mirror 17 toward an eyepiece 12. The visual field frame image is condensed by the flat/convex lens 23 and made incident on the half mirror 17, then, a visibility with reference to an object image obtained through an objective lens 11 is reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inverted Galileo type finder device.

[0002]

2. Description of the Related Art Inverse Galileo viewfinders make a virtual image of a subject through an objective lens made of a concave lens and an eyepiece lens made of a convex lens, and a visual field frame image is superimposed on the subject image so that the photographing range can be confirmed. It is a thing.
This reverse Galilean viewfinder can increase the viewfinder magnification by the magnifying action of the eyepiece lens.
Moreover, it is used for low-priced cameras because it has advantages such as a bright image and a large field of view despite its simple structure.

There are two types of display methods of the field frame image in the reverse Galileo finder, the bright frame method and the albada method. The bright frame method is
The view field frame placed outside the viewfinder optical path is illuminated by the light taken in from the lighting window, and this view frame image is displayed in the viewfinder view field by combining it with the half mirror placed between the objective lens and the eyepiece lens. . In addition, the Albada method is to form a half mirror on the image side surface of the objective lens, arrange a field frame on the objective lens side of the eyepiece lens, and observe the image of this field frame with the half mirror for observation. Generally, the visual field frame is formed on the object side surface of the eyepiece lens by using a substance having light reflectivity. Since the half mirror and the field frame are arranged between the objective lens and the eyepiece lens in this Albada finder, the entire finder can be made compact.

By the way, in recent years, in order to further expand the attractiveness and enjoyment of print photographs to general users, print photographs having different aspect ratios are provided depending on the type and size of the photographed subject. As a print photograph like this, a standard print (89 mm x 1
27 mm), panoramic prints (89 mm × 252 mm) whose horizontal length is doubled, high-definition prints (89 mm × 158 mm) that approximate the aspect ratio in high-definition television broadcasting, etc. are generally known.

As a method of obtaining a print photograph having a different aspect ratio, the exposure range for the photographic film is limited by a light-shielding member provided on the camera side, and the subject image is formed only within the range defined in a similar shape to the desired print photograph. There is a method of exposing and a method of always exposing the entire exposure screen of the photographic film at the time of shooting, recording the print size data on the photographic film, and processing only the range according to the print size data in the exposure screen. is there. In this way, in a camera that has the function of limiting the exposure range for the photo film or recording the print size data on the photo film, the viewfinder range of the viewfinder is changed corresponding to each size, and the photographer changes the print range. It is desirable to have an accurate grasp.

[0006]

In the above-mentioned camera incorporating the reverse Galilean finder, the print range can be represented by the size of the field frame. Therefore, the field frame of a size corresponding to each size is included in the field of view of the finder. The image may be selectively displayed. However, since the field frame is directly formed on the lens surface of the eyepiece lens in a general Albada finder, the eyepiece lens must be replaced when changing the size of the field frame. For this reason, this viewfinder requires not only the same number of eyepieces as the field frames to be switched, but also the switching mechanism must be built in, which complicates the structure. Moreover, it is necessary to secure a retracting space for the unused eyepiece lens outside the optical path of the finder, resulting in an increase in the size of the finder section. Further, in an albada type finder in which the field frame and the eyepiece are separately provided, the field frame retreat space is also required.

On the other hand, in the finder of the bright frame system, the field frame is incorporated as a single unit, so that it is easy to replace this field frame. However, with this viewfinder, it is difficult to match the diopter of the field frame image to the subject image observed through the viewfinder, and if it is attempted to reduce this, the storage part of the field frame will have a protruding shape, and the entire viewfinder will become large. There are easy drawbacks.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a finder device which is small in size and whose field frame switching operation is easy.

[0009]

In order to achieve the above object, a finder device according to the present invention comprises a field frame display plate on one side of a beam splitter orthogonal to the finder optical axis and a field of view on the other side. An auxiliary optical system having positive power is arranged while reflecting the display light from the frame display plate toward the beam splitter, and the display light from the field frame display plate passes through the beam splitter and enters the auxiliary optical system, The display light that has passed through this auxiliary optical system is reflected by the beam splitter toward the eyepiece lens side. The auxiliary optical system is preferably composed of a plano-convex lens, one surface of which is directed toward the beam splitter and the other surface of which is a flat surface, and a reflective layer formed on the plane of the plano-convex lens.
The convex surface of the plano-convex lens is preferably an aspherical surface. Further, the line width of the line-shaped field frame is widened so that the two field frame images observed by the display light passing through the auxiliary optical system being reflected by the two front and back surfaces of the beam splitter overlap in the line width direction. It is better to

Further, at least two types of field frames are formed on the field frame display plate, and at least two types of openings corresponding to the respective field frames are provided in the light shielding plate between the field frame display plate and the beam splitter. The formed mask plate is arranged, and by the relative movement between the mask plate and the field frame display plate, only the image of the field frame in which any of the apertures matches can be observed together with the subject image. Good.

Further, the visual field frame display plate is composed of a flat light guide having a visual field frame formed on the surface facing the beam splitter and having a light incident surface facing the subject side. It is preferable to form a reflection surface that reflects the external light entering from the incident surface toward the field frame. Also,
The visual field frame display plate is composed of a light shielding plate in which the visual field frame is formed as a light transmitting area, and this light shielding plate is illuminated by external light from the back side and external light passing through the light transmitting area is used as display light for the visual field frame. The colored field frame image may be observed by making the light incident on the beam splitter and providing a coloring member on the back side of the light shielding plate or coloring the plano-convex lens forming the auxiliary optical system.

Further, a flat plate-shaped light guide is provided so as to face the back surface of the field frame display plate, and this light guide takes in external light from a light incident surface directed to the subject side, and at the same time, in the light transmitting area of the light shielding plate. External light may be reflected toward the light transmission region by the reflecting surface formed correspondingly.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows the structure of a finder device according to the present invention. The finder device 10
An objective lens 11 made of a concave lens, an eyepiece lens 12 made of a convex lens, a light guide 13, a field frame display plate 14,
It is composed of a mask plate 15, a visual field frame correction unit 16, and a half mirror 17 as a beam splitter. The objective lens 11 and the eyepiece lens 12 are arranged coaxially,
This constitutes an inverted Galileo finder. The objective lens 11 and the eyepiece lens 12 have an image in the viewfinder field 20 (see FIG. 4) observed through them.
It is configured to have a similar shape to the image formed on the exposure screen of the photographic film.

As shown in FIG. 2, the visual field frame display plate 14 is made of a flat plate having a light shielding property. The field frame display plate 14 has slits 31a, 31b, 32a, 3 extending in the horizontal direction in the figure.
2b and slits 33a, 33b, 34 extending in the vertical direction
a and 34b are formed. Slits 31a, 31
b, 32a, 32b and slits 33a, 33b, 3
4a and 34b are formed so as to define the vertical position and the horizontal position of the three types of visual field frames F _C , F _H , and F _P having different sizes, and as shown in FIG. 31a, 31b and the slits 34a, 34b constitute a field frame F _C having a standard size (hereinafter referred to as C size) with an aspect ratio of 1.4. Also slit 31
High definition size (hereinafter H size) with aspect ratio of 1.8 due to a, 31b and slits 33a, 33b
The field frame F _H (see FIG. 2B) of the slit 32a,
The 32b and the slits 33a and 33b configure a panoramic size (hereinafter referred to as P size) field frame F _P having an aspect ratio of 3.2 (see FIG. 7C).

As shown in FIG. 3, the mask plate 15 is made of a light-shielding flat plate and is arranged so as to overlap with the field frame display plate 14. The mask plate 15 has openings 41 to 43 extending in a direction parallel to the slits 31a, 31b, 32a, 32b of the field frame display plate 14 (X direction in the drawing), and slits 33a,
Openings 44 and 45 extending in a direction parallel to 33b, 34a and 34b (Y direction in the drawing) and a notch 46 are formed.

The mask plate 15 has a C size display position where the field frame display plate 14 and the lower left corner of the drawing overlap each other (see FIG. 7A) and an H size display position where the lower right corner overlaps with each other (see the same drawing (B)). )) And a P size display position where the upper left corner overlaps with each other (see (C) in the figure). Then, when the mask plate 15 is in the C size display position, the openings 41, 42, 44 and 45 respectively have slits 31 a and 31 of the field frame display plate 14.
The field frame F _C is exposed so as to face b, 34a, and 34b.
Further, when the mask plate 15 is in the H size display position, the openings 41, 42, 44 and the notches 46 face the slits 31a, 31b, 33a, 33b and the field frame F.
_{When the H} is exposed and the P size display position is set, the opening 4
1, 43, 44 and the notch 46 are slits 32a,
The field frame F _P is exposed so as to face 32b, 33a, and 33b. The mask plate 15 is provided so as to be movable only in two directions of the X direction in the drawing and the Y direction perpendicular to the X direction based on the H size display position. When it is moved from a certain state in the X direction, it reaches the C size display position, and when it is moved from the H size display position in the Y direction, it reaches the P size display position.

In FIG. 1, the visual field frame display plate 14 and the mask plate 15 are arranged in a direction horizontal to the finder optical axis 18, and the projection optical path 19 of the visual field frame image is orthogonal to the finder optical axis 18. ing.

The light guide 13 receives the light incident through the daylighting window 22 formed in the camera body 21 from the view frame display plate 1.
It is for guiding to the back surface of No. 4, and is fitted into the lighting window 22. The light guide 13 is made of a red translucent material, and its light emission surface 13a is a diffusion surface. Then, the field frame display plate 14 is formed by the light transmitted through the light guide 13.
Of the three types of field frames F _C , F _H , and F _{P in} the projection optical path 19, and the field plate display plate 14 and the mask plate 1
An image of what corresponds to the relative position with respect to 5 is projected.

The field frame correction section 16 is formed by vapor-depositing a light-reflecting substance such as aluminum on the flat surface 23b of the plano-convex lens 23 having a positive refractive power to form the reflection layer 24. The convex surface 23a of the plano-convex lens 23 is formed as an aspherical surface. The field frame correction unit 16 places the convex surface 23a of the plano-convex lens 23 on the field frame display plate 14 side on the projection optical path 19 of the field frame image and at a position facing the field frame display plate 14 with the finder optical axis 18 interposed therebetween. It is placed in the state of facing.

The half mirror 17 has a finder optical axis 1
8 and the projection optical path 19 are arranged so as to intersect with each other, and the incident light is transmitted in a straight traveling direction, and a part thereof is reflected in a direction perpendicular to the transmission direction. This half mirror 17
The first surface 17a is positioned between the objective lens 11 and the field frame display plate 14, and the second surface 17b is positioned between the eyepiece 12 and the field frame correction unit 16.

Next, the operation of the above configuration will be described. The subject light that has passed through the objective lens 11 passes through the half mirror 17, enters the eyepiece lens 12, and heads for the pupil position E.

On the other hand, when the field frame display plate 14 is illuminated by the light that has entered through the daylighting window 22 and has passed through the light guide 13, a field frame image is projected in the projection optical path 19. At this time, for example, when the mask plate 15 is in the H size display position, the mask plate 1 is placed in the slits 31a, 31b, 33a, 33b forming the four sides of the field frame F _H of the field frame display plate 14.
5, the openings 41, 42, 44 and the notch 46 face each other,
Since the plate surface of the mask plate 15 faces the slits 32a, 32b, 34a, 34b, an image of the H-size field frame F _H is projected in the projection optical path 19. In addition, since the light guide 13 is made of a red translucent material, the field frame image projected by the illumination light that has passed through the light guide 13 is also red light.

The field frame image projected in the projection optical path 19 is
The light passes through the half mirror 17 and enters the plano-convex lens 23 of the field frame correction unit 16. When the field frame image is incident from the convex surface 23a side of the plano-convex lens 23 and reaches the flat surface 23b, the flat surface 2
It is reflected by the reflection layer 24 formed on 3b, and again the convex surface 23
It is emitted from a toward the half mirror 17. The field frame image emitted from the plano-convex lens 23 is the half mirror 1.
It is reflected by 7 toward the eyepiece 12 side. And Figure 4
As shown in (B), the objective lens 11 and the eyepiece lens 12
An image of the H-sized field frame F _H is displayed in the finder field 20 observed through.

At this time, the optical path of the field frame image is the half mirror 1.
The optical path length of the visual field frame image becomes longer by the amount of the return because it is folded back once between 7 and the reflective layer 24. Further, since the plano-convex lens 23 has a positive refracting power, the field frame image is condensed and enters the half mirror 17, and the diopter between the subject image and the field frame image observed through the objective lens 11 is increased. It will be reduced.

If the field frame display plate 14 and the field frame correction section 16 are arranged close to the finder optical axis 18, the finder device 10 can be made compact. In this case, since the optical path length of the field frame image becomes short, it is necessary to make the positive refractive power of the plano-convex lens 23 stronger in order to reduce the diopter of the field frame image with respect to the subject image.
However, when the positive refracting power of the plano-convex lens 23 is increased, the chromatic aberration of magnification due to the plano-convex lens 23 is increased, and the field frame image toward the pupil position E is blurred. The chromatic aberration of magnification can be corrected by separating the plano-convex lens 23 into two lenses, but this method is preferable because the finder device becomes large as the number of constituent parts increases, and the cost increases. Absent. Therefore, the light guide 13 is made of a coloring material, and the visual field frame image is colored light so that the blurring of the visual field frame image can be made inconspicuous. In addition, the convex surface 23 of the plano-convex lens 23
By forming a into an aspherical surface, it is possible to correct the curvature of field to a good state and suppress an increase in distortion.

Further, in the visual field frame image projected in the projection optical path 19 and reflected by the reflective layer 24, not all of the light flux is reflected by the second surface 17b of the half mirror 17 toward the eyepiece 12 side. Actually, a part of the light flux goes straight to the first surface 17a side of the half mirror 17, and is reflected to the eyepiece 12 side by the inner surface of the first surface 17a. Therefore, the two images of the clear visual field frame image reflected by the second surface 17b of the half mirror 17 and the blurred visual field frame image reflected by the first surface 17a are shifted to the pupil position E. It will be. However, the slits 31a, 31b, 32a, 32b, 33a, 33b, 3 formed in the field frame display plate 14
By widening the widths of the field frame images 4a and 34b to widen the line widths of the field frame images, the two field frame images have overlapping portions with each other, and the double display of the field frame images can be made inconspicuous. .

When the field frame image displayed in the finder field 20 is changed to the C size field frame F _C , the mask plate 15 is slid to the C size display position. At this time, as shown in FIG.
Since only two display positions of the H size display position and the C size display position are defined with respect to the direction, only the switching between the two display positions is performed in the movement operation of the mask plate 15 in the X direction. Therefore, the moving distance required for switching between the H size display position and the C size display position of the mask plate 15 can be increased, so that the switching between the display positions can be reliably performed and the mask plate 15 can be switched at each display position. Positioning accuracy when positioning is high.

When the mask plate 15 moves to the C size display position, an image of the C size field frame F _C is projected in the projection optical path 19. Then, as shown in FIG. 4A, an image of a C size field frame F _C is displayed in the finder field 20.

When the field frame image displayed in the finder field 20 is changed to the P size field frame F _P , first, the mask plate 15 is slid in the X direction shown in FIG. 3 to display the H size display position. Return to. After that, when the mask plate 15 is moved in the Y direction shown in FIG. 3 to be positioned at the P size display position, an image of the P size field frame F _P is projected in the projection optical path 19 (FIG. 4C. )reference). Even in this case, since the operation of moving the mask plate 15 in the Y direction only switches between the H size display position and the P size display position, the movement of the mask plate 15 required to switch between the two positions. The distance can be increased.

Table 1 below shows lens data of the optical system provided between the projection position of the field frame image and the pupil position in the finder device 10. The surface number i is a number given to the lens surface of each optical system in order from the projection position of the field frame image, and the surface distance d represents the lens thickness or the air distance between the next surface (unit: mm). ).

[0031]

[Table 1]

The aspherical surface of the plano-convex lens 23 has a conditional expression X = ch ² / [1 + √ {1- (1 + K) c ² h ² }] +.
It is formed to satisfy Ah ⁴ + Bh ⁶ + Ch ⁸ + Dh ¹⁰ . In the equation, c represents the reciprocal of the radius of curvature (= 1 / R), and h represents the height of the light beam from the optical axis. Further, the aspherical surface coefficients are as follows. K = 1.710571 A = -0.667167E-4 B = 0.117930E-5 C = -0.138846E-7 D = 0.000000

Next, another example of the structure of the finder apparatus of the present invention will be described with reference to FIGS. The same members as those of the finder device shown in FIG. 1 are designated by common reference numerals. In FIG. 5, the finder device 50 includes an objective lens 11, an eyepiece lens 12, a light guide 51, a field frame display plate 14, a mask plate 15, a field frame correction unit 16, and a half mirror 17. The finder device 50 has a daylighting window 52 formed above the objective lens 11, and is incorporated in a camera body 53 in which illumination light is incident from the subject side.

The light guide 51 is formed in a long shape so as to face both the daylighting window 52 and the back surface of the field frame display plate 14. As shown by the diagonal lines in FIGS. 6 and 7,
The light guide 51 includes the slit 3 of the field frame display plate 14.
1a, 31b, 32a, 32b, and 33a, 34
The inclined surface 5 inclined at an angle of 45 ° with respect to the light incident surface 51a is provided at a position facing each of a, 33b, and 34b.
5a to 55d, 56a, 56b are formed. Reflective layers 57a-57d, 58a, 58b are formed on the inclined surfaces 55a-55d, 56a, 56b by vapor-depositing a light-reflective substance such as aluminum. Further, the light guide 51 is provided with a light transmitting surface 54a on a surface facing the slits 31a, 31b, 32a, 32b and 33a, 34a, 33b, 34b of the field frame display plate 14, respectively. 54a
The light incident surface 51a is a flat surface, and the outer peripheral surface 54b except the light transmitting surface 54a and the light incident surface 51a is a diffusion surface (see FIG. 8). In addition, the incident light is inclined surfaces 55a to 55a.
In the case of total reflection at d, 56a and 56b, the inclined surface 5
5a to 55d, 56a and 56b are provided with reflective layers 57a to 57.
d, 58a, 58b may not be formed.

As shown in FIG. 8, the light entering the light guide 51 from the light incident surface 51a is diffused while being repeatedly reflected on the outer peripheral surface 54b. Then, the reflective layer 57a-
The light flux reflected by 57d, 58a, and 58b and passing through the light transmitting surface 54a is applied to the back surface of the field frame display plate 14. At this time, the reflective layers 57a to 57d, and 5
8a and 58b are slits 31a, 31b, 32a, 32b, 33a and 33b formed in the field frame display plate 14.
Since it is formed at a position facing 34a, 34b,
The field frame display plate 14 includes slits 31a, 31b, 32a,
Only the peripheral portions of 32b, 33a, 33b, 34a, 34b are illuminated. The illumination light projects a field frame image having a size corresponding to the relative position between the field frame display plate 14 and the mask plate 15 into the projection optical path 19.

Here, if only one reflecting surface is formed on the light guide and the reflecting surface reflects the light incident from the subject side to illuminate the entire surface of the field frame display plate,
The thickness of the light guide must be thicker than the length of the view frame display plate in the finder optical axis direction. Therefore, not only the light guide becomes large, but also the lighting window formed in the camera body must be made large. In this regard, since the light guide 51 forms the reflective layer only at the position facing the slit formed in the field frame display plate,
The area of each reflective layer can be reduced, and the thickness of the light guide can be suppressed.

In each of the above embodiments, an example in which the light guide and the field frame display plate are provided separately has been described. However, a field frame is formed on the light exit surface of the light guide, and parts other than this field frame are formed. The transmission of light may be limited. As a method of limiting the light transmission of the light guide, for example, a light-shielding substance may be vapor-deposited on a portion other than the visual field frame to form the light-shielding layer. Further, a light-shielding member formed by punching a pattern of the field frame on a plate material having a light-shielding property may be embedded in the light guide by an insert molding method. According to this embodiment, since the light guide and the field-of-view frame display plate are integrated, the number of components is reduced and the finder device can be downsized.

Further, in the above-mentioned embodiment, the visual field frame correction unit has the light reflection layer formed on the plane of the plano-convex lens.
In the finder device of the present invention, since the optical path of the field frame image is folded back between the field frame correction unit and the half mirror, and the field frame image is condensed and incident on the half mirror, the field frame correction unit is provided. It may be composed of a positive lens having a positive refracting power and a plate-shaped reflector. In this case, the reflector is arranged on the side not facing the half mirror of the positive lens. Also,
The reflecting plate curved in a concave shape may be arranged with the concave surface facing the half mirror side. Further, the member used as the beam splitter that reflects a part of the incident light and transmits the rest of the light flux is not limited to the half mirror, and it is also possible to utilize the surface reflection of the plane parallel plate, whereby the finder device can be used. It is possible to reduce the price.

In the above embodiment, the light guide is made of a coloring material in order to make the field frame image colored light. However, the light guide surface of the light guide has a light-transmitting paint. May be applied to form a colored layer. Further, since the visual field frame image may be colored light before reaching the eyepiece lens, the optical system of the visual field frame correction unit may be made of a coloring material, or a colored layer may be formed on the lens surface.
Further, the color to be colored is not limited to red, and any color may be used as long as it can make the bleeding of the field frame image caused by the chromatic aberration of the magnification of the optical system inconspicuous.

Further, if each member for displaying the field frame image in the field of view of the finder is unitized with the finder lens, the finder device can be easily handled.

Further, the present invention can of course be applied to a finder device incorporated in a camera having an interchangeable photographing lens. In this case, a visual field frame may be formed according to the type of the photographing lens so that the size of the visual field frame can be switched each time the photographing lens is replaced.

[0042]

As described above, according to the present invention, the field frame image is projected so as to be orthogonal to the finder optical axis, passes through the finder optical axis, and then is folded back to the finder optical axis side by the auxiliary optical system. Since it is reflected toward the eyepiece lens by the beam splitter, the optical path length of the field frame image becomes longer by the amount of the turnaround between the auxiliary optical system and the beam splitter. Further, since the auxiliary optical system is given a positive power, the field frame image folded by the auxiliary optical system is condensed and incident on the beam splitter. With these, if the refractive power of the auxiliary optical system is adjusted according to the optical path length of the field frame image,
The diopter between the subject image and the field frame image can be reduced regardless of the projection position of the field frame image. Therefore, even if the projection position of the view frame image is brought as close as possible to the viewfinder optical axis, the view frame image can be observed in the viewfinder field without causing diopter with the subject image. It is possible to configure a compact finder device without causing the projection.

Further, a visual field frame display plate integrally formed with a plurality of visual field frames and a mask plate having an opening for exposing each visual field frame are arranged in an overlapping manner, and the visual field frame display plate and the mask plate are provided. By changing the field of view frame that is exposed by relative movement between and, when switching the field of view frame image displayed in the viewfinder field, slide one of the field of view frame display plate and the mask plate. It only needs to be done, and the switching operation is easy.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a configuration of a finder device of the present invention.

2A and 2B are schematic diagrams showing the configuration of the field frame display plate shown in FIG. 1, where FIG. 2A is a C size field frame formed on the field frame display plate, and FIG. 2B is an H size field frame. , (C) respectively represent P-sized field frames.

FIG. 3 is an explanatory diagram showing the relationship between the relative position of the visual field frame display plate and the mask plate and the exposed visual field frame. FIG. 3A shows a state in which the mask plate is in the C size display position. ) Represents the state in the H size display position, and (C) represents the state in the P size display position.

4A and 4B are explanatory diagrams of a field frame image displayed in the field of view of the finder, where FIG. 4A is a C size field frame image, FIG. 4B is an H size field frame image, and FIG. The respective field frame images of are shown.

FIG. 5 is an explanatory view showing another configuration example of the finder device of the present invention.

FIG. 6 is a perspective view of the light guide shown in FIG.

FIG. 7 is an explanatory diagram showing a relative positional relationship between the light guide and the field frame display plate of FIG.

FIG. 8 is an explanatory diagram showing a lighting state of the visual field frame display plate by the light guide of FIG. 6;

[Explanation of symbols]

10,50 Finder device 11 Objective lens 12 Eyepiece 13,51 Light guide 14 Field frame display plate 15 Mask plate 17 Half mirror 18 Finder optical axis 19 Projection optical path 20 Finder field of view 22,52 Daylighting window 23 Plano-convex lens 23a Convex surface 23b Plane 24 , 57a to 57d, 58a, 58b Reflective layers F _C , F _H , F _P

Claims (8)

[Claims] 1. A field frame display plate having a beam splitter for reflecting a part of an incident light beam and transmitting the remaining light beam between an objective lens and an eyepiece lens, and forming a field frame corresponding to a photographing range. In the finder device that allows the field light image to be observed together with the subject image by reflecting the display light from the beam splitter toward the eyepiece lens, one side that sandwiches the beam splitter orthogonal to the finder optical axis. In the field frame display plate, the auxiliary optical system having a positive power while reflecting the display light from the field frame display plate toward the beam splitter on the other side,
The display light from the field frame display plate passes through the beam splitter and enters the auxiliary optical system, and the display light passing through the auxiliary optical system is reflected by the beam splitter toward the eyepiece side. Finder device to do. 2. The auxiliary optical system is composed of a plano-convex lens, one surface of which is directed toward the beam splitter and whose other surface is a flat surface, and a reflective layer formed on the flat surface. The finder device according to claim 1. 3. The finder device according to claim 2, wherein the convex surface is an aspherical surface. 4. The line width of the line-shaped field frame is widened,
4. The display field images, which have passed through the auxiliary optical system, are reflected by the front and back surfaces of the beam splitter so that two field frame images observed are overlapped in the line width direction. Finder device described above. 5. At least two types of field frames are formed on the field frame display plate, and at least two types of openings corresponding to the respective field frames are formed in the light shielding plate between the field frame display plate and the beam splitter. The mask plate having the above-mentioned structure is arranged, and by the relative movement between the mask plate and the field frame display plate, only the image of the field frame in which any one of the apertures matches is observed together with the subject image. The finder device according to any one of claims 1 to 4, wherein: 6. The field frame display plate comprises a plate-shaped light guide having a field frame formed on a surface facing a beam splitter, and a light incident surface facing a subject side. 6. The finder device according to claim 1, further comprising a reflecting surface that reflects external light entering from the incident surface toward the field frame. 7. The visual field frame display plate comprises a light-shielding plate in which the visual field frame is formed as a light-transmitting region, and the light-shielding plate is illuminated with external light from the back side to prevent external light passing through the light-transmitting region. While being incident on the beam splitter as display light of the field frame, a colored field frame image can be observed by providing a coloring member on the back side of the light shielding plate or coloring the plano-convex lens. Claims 2 to 5 characterized
The finder device according to any one of 1. 8. A flat plate-shaped light guide is provided so as to face the back surface of the field frame display plate, and the light guide takes in external light from a light incident surface directed to the subject side and the light transmission area of the light shielding plate. 8. The finder device according to claim 7, wherein external light is reflected toward the light transmitting region by a reflecting surface formed corresponding to the above.