JPH0325423A - Finder for camera - Google Patents

Abstract

PURPOSE:To prevent a finder size from being scaled up by allowing one means to simultaneously correct parallax and diopter. CONSTITUTION:Parallax in macro-photographing when a finder optical system is provided above a photographing optical system arises because an image is formed above a normal image forming position. When a fourth reflecting plane is moved downward so that the image forming position is moved down by as much as the parallax, the parallax arising when photographing can be corrected. On the other hand, the dislocation of diopter can be prevented in such a way that only the length of an optical path between an objective lens 5 and the image forming plane is corrected to correspond with the longer distance. By moving the fourth reflecting plane 4, a distance between a third reflecting plane 3 and the fourth reflecting plane 4 becomes shorter to shorten the length of the optical path. Consequently, the parallax and the dislocation of diopter can be simultaneously corrected by moving the reflecting planes 1 to 4. As a result, the scaling-up of the finder can be prevented.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a camera finder that has a photographic optical system and a finder optical system separately, and more specifically, the present invention relates to a camera finder that has a photographic optical system and a finder optical system, and more specifically, uses a so-called Boro mirror that uses a Boro prism or an equivalent optical system with a reflecting mirror as an image erecting optical system. The present invention relates to a finder which is equipped with means for correcting vararax and diopter deviation that occur in the finder optical system when performing macro photography.

[Prior art and its problems]

Conventionally, in cameras other than single-lens reflex cameras, the finder optical system is generally configured with an optical axis separate from that of the photographic optical system. Therefore, for example, light directed toward the camera from an arbitrary point on the optical axis of the photographic optical system forms an image on the leading axis of the photographic optical system, but forms an image at a position offset from the optical axis in the finder optical system. The amount of deviation in the imaging position, or parallax, is so small that it does not pose a problem when the distance between any one point and the imaging plane is extremely far, but as the distance approaches, it increases and The deviation from the center of the viewfinder field of view also gradually increases. Particularly when performing macro photography, if the field of view remains the same as when taking normal photographs, the screen constructed by the finder will differ from the actual photograph. As one structure for solving this problem, as shown in FIGS. 10A and 10B, a field frame 20 for macro photography is drawn in the viewfinder in addition to the field of view for normal photography. However, even in this case, since it is not possible to see all four corners of the field of view during macro photography, it is very difficult for the photographer to accurately grasp the photographic range. For example, if the photographer is an inexperienced person in operating a camera, the photographer may not even be aware that the shooting range must be aligned with the field of view frame drawn in the viewfinder during macro photography. There is also. In addition, as another configuration for correcting parallax,
One example is a finder optical system with an optical element added. Regarding this, for example, JP-A-62-284
The technology is disclosed in Japanese Patent Application Laid-open No. 336, Japanese Patent Application Laid-open No. 63-52-4, and Japanese Utility Model Application No. 63-70539, etc., all of which place a prism on the objective lens side of the finder optical system. , the refraction of light by this prism is used to correct vararax. On the other hand, in the case of an L-lens reflex camera, the image is always focused on the image forming plate and observed even if the shooting distance changes, so the subject can be seen even in the viewfinder. The image can always be seen in the same position. Therefore, since the distance between the photographer's pupil and the imaging position does not change,
It can be said that the degree of perspective in which an image is visible, that is, the diopter, is always constant. However, in a camera as described above in which a photographing optical system and a finder optical system are provided separately, the viewfinder optical system is generally not changed, so the image forming position changes as the photographing distance changes. In other words, the diopter changes and the image becomes difficult to see. Particularly in extreme cases where the diopter changes greatly, such as when performing macro photography, an in-focus image cannot be seen in the viewfinder. On the other hand, this means that when performing macro photography, it is possible to correct the diopter by changing the finder optical system, but even in that case, it is necessary for the photographer to see the appropriate image. There is still a need to correct parallax. Therefore, if a parallax correction means is provided separately from a means for changing the finder optical system to correct the diopter, there is a problem that the finder becomes larger due to the complicated structure. The present invention has been devised to effectively solve these conventional technical problems. Therefore, its purpose is
In order to prevent the finder from becoming too large, the objective is to simultaneously perform parallax correction and diopter correction using one solution.

[Means to solve the problem]

The camera finder according to the present invention is configured as follows in order to achieve the above-mentioned object. In other words, it is used in a camera equipped with a photographing optical system that can select between a normal photographing position and a macro photographing position, and there are four cameras in the system.
A finder having an image erecting optical system such as a Boro prism composed of a reflective surface or an equivalent optical system composed of a reflecting mirror, and when selecting a normal photographing position of the photographing optical system, While each reflective surface is positioned at its normal position so that the subject is imaged on a predetermined imaging plane, when selecting the macro photography position of the photography optical system, the optical path position of the subject is changed to align the center of the photography range and the viewfinder field of view. A position adjustment mechanism that adjusts the position of each reflective surface so as to correct vararax by aligning the center with the center, and at the same time correct diopter by changing the path length and converging the light beam on the image forming surface. It is equipped with

[Action/effect]

If the photographing optical system or normal photographing position is selected in the above {{3 configuration, each reflective surface in the finder optical system is positioned at the normal position corresponding to the normal photographing position of the photographing optical system by the position adjustment mechanism. do. Therefore, since the subject is imaged on a predetermined imaging plane in this state, the photographer can clearly see an image corresponding to the shooting range. On the other hand, when the photographing optical system selects the macro photographing position, the position of each reflective surface is changed by the position adjustment mechanism. The reflective surfaces of Boro prisms and Porro mirrors can be arranged in various ways, and depending on the configuration, the combination of which reflective surfaces are moved in which direction to correct parallax changes, for example. , as an example, the light entering the camera from the subject on the reflective surface located closest to the subject (this is referred to as the first reflective surface, hereinafter referred to as the second, third, and fourth reflective surfaces toward the photographer). The second reflecting surface is arranged so that the light from the first reflecting surface is refracted to the right as seen from the photographer, and the third reflecting surface is arranged so that the light from the second reflecting surface is refracted to the right. A case will be described in which the fourth reflective surface is arranged so as to refract the light from the third reflective surface upward, and finally, to refract the light from the third reflective surface along the direction from the subject to the camera. Note that the moving direction of the reflective surface should also be changed depending on the positional relationship between the photographing optical system and the finder optical system, but this is also an example, and only the case where the finder optical system is installed above the photographing optical system will be explained. do. In this configuration, for example, if the fourth reflective surface is moved downward, the position of light reflection on this reflective surface also changes downward, and accordingly, the position of the subject image itself moves downward. . Parallax during macro photography when the finder optical system is installed above the photographic optical system is caused by the image being formed above the normal image formation position, so the amount of parallax is determined according to the parallax. By moving the fourth reflective surface downward so as to lower the image formation position by the same amount, it is possible to correct the vararax that may occur during photographing. On the other hand, visual shift is caused by the distance from the objective lens to the image formation position becoming longer as the object approaches the camera, resulting in the object image being formed at a position shifted from the original image formation plane. occurs. Therefore, the occurrence of the deviation is
This can be prevented by changing only the optical path length between the objective lens and the image forming surface to match the increased distance without changing the position of the image forming surface. Here, by moving the fourth reflective surface as described above, the distance between the third reflective surface and the fourth reflective surface becomes closer. In other words, the optical path length is shortened. However, for example, if the second and third reflective surfaces are moved downward at the same time,
Only the distance between the objective lens and the imaging plane can be extended without changing the imaging position. Therefore, it is possible to correct the diopter by changing the optical path length shortened by the movement of the fourth reflective surface described above to an appropriate length. As explained above, according to the above configuration, balarax and diopter deviation can be corrected at the same time by moving each reflecting surface. Therefore, since there is no need to provide separate correction means for variation and diopter, there is no need to increase the size of the viewfinder that allows you to clearly see an appropriate image corresponding to the shooting range, and it is not necessary to use either of these correction means. It can be made as compact as a finder with only one.

【Example】

An embodiment of the present invention shown in FIGS. 1 to 9 will be described in detail below. First, the schematic structure of the finder optical system according to this embodiment will be explained based on FIG. As shown,
In this optical system, a first reflective surface l constituting a bolo mirror is located at a position closer to the object of the objective lens 5, and second, third, and fourth reflective surfaces 2, 3 are located at positions closer to the photographer than the objective lens 5. .4
are arranged so that the normal line of each reflective surface forms an angle of 45° with respect to the optical axis. Further, at a position closer to the photographer on the fourth reflective surface, there is a field frame 6 whose interior is an image forming surface 21.
is located. Although not shown, an objective window is disposed further toward the subject than the first reflective surface l, and an eyepiece is disposed further toward the photographer than the field frame 6. In this configuration, when the photographing optical system is first selected at the normal photographing position, the light from one point on the photographing optical axis enters almost along the optical axis 7 of the finder optical system, and after that, each reflecting surface The beam is refracted along the optical axis, and an image is formed approximately at the center of the imaging plane 21. Therefore, in this case,
The center of the shooting range and the center of the viewfinder field of view almost coincide. Next, changes in the optical path when each reflective surface 1, 2, 3.4 is moved in various directions will be explained using FIGS. 2 to 5. Figures 2 and 3 are explanatory diagrams showing the optical path when the second and third reflective surfaces are viewed from the photographer's side, and Figures 4 and 5 show the viewfinder optical system from the side toward the optical axis. FIG. 3 is an explanatory diagram showing an optical path when viewed at right angles. In these figures, the state of each reflective surface before movement is shown by a thick broken line, the state after movement is shown by a thick solid line, the optical path before movement is shown by a thin broken line, and the optical path after movement is shown by a thin dashed line. Figure 2 shows 2. A state in which the third reflecting surface 2.3 is simultaneously moved downward is shown. As is clear from the figure, each reflective surface 2.3 is moved downwardly by 1>. By moving by the amount indicated by 212, the entire optical path is expanded. Therefore, if the subject position does not change, the imaging position moves perpendicularly from the predetermined imaging plane 21 forward by an amount indicated by 2 (b). The figure shows a state in which the reflecting surfaces 2 and 3 have been moved to the right as viewed from the photographer's side by the amounts indicated by the respective marks.As shown in the figure, the optical path before entering the second reflecting surface 2 and , the optical path length after being reflected by the third reflective surface 3 is shortened by h. On the other hand, the optical path length between the second reflective surface 2 and the third reflective surface 3 is 2
+2. Since the light is elongated, the amount of shortening and the amount of elongation cancel each other out, and the overall optical path length does not change. Therefore, the image is focused on a predetermined image forming plane 21, but as is clear from the figure, the image forming position is 2 horizontally laterally than the image forming position in normal shooting.
(.Changes. Figure 4 shows a state in which the fourth reflective surface 4 is moved downward by an amount indicated by Q. As shown in the figure, the reflected light emitted from the fourth reflective surface 4 is Since the reflecting surface 4 moves downward by an amount of Q compared to before the movement, the imaging position is also shifted to the imaging surface 21.
Move by 123 above. However, in this case, since the distance between the third reflective surface 3 and the fourth reflective surface 4 becomes closer, the optical path from the objective lens 5 to the imaging surface 21 is also shortened by Q. Therefore, if the distance between the object and the objective lens 5 does not change from the normal photographing state, the imaging position moves to a position Q far behind the imaging plane 21. FIG. 5 shows a state in which the first reflecting surface l has been moved downward by an amount indicated by Q4. As shown in the figure, the position at which light is reflected on the l-th reflective surface l moves forward compared to before the reflective surface l was moved. When the reflected light passes through the second and third reflective surfaces 2.3 and is reflected by the fourth reflective surface 4, the position of the reflected light moves downward by 124 degrees compared to before the movement. Therefore, similarly to the case where the fourth reflective surface 4 explained above is moved downward, the imaging position moves Q4 downward on the imaging surface 21. In this case, since the optical path length between the objective lens 5 and the image forming surface 21 does not change before and after the movement of the reflecting surface l, the subject image will be focused on the image forming surface 21. In this way, by moving each reflecting surface in an appropriate direction, the image forming position can be moved on the image forming surface 21, before and after the image forming surface 21, or by a combination of these. You can also move it in different directions. Next, as for the positional relationship between the finder optical system 9 and the photographing optical system 8, when the finder optical system 9 is arranged laterally with respect to the photographing optical system 8 as shown in FIG. 6, for example,
Alternatively, it may be placed upward as shown in Fig. 7, or diagonally upward as shown in Fig. 8. However, parallax and diopter deviation caused by these arrangements are as described above. This can be corrected by combining the movements of reflective surfaces. This will be explained below. First, a case where the finder optical system 9 is arranged side by side with the photographing optical system 8 as shown in FIG. 6 will be described. Parallax during macro photography occurs in the direction connecting the centers of the optical sleeves of each optical system, so in this case it occurs in the lateral direction. However, in order to correct this vararax, as explained in FIG. All you have to do is move it by half the amount of deviation from the center of . Furthermore, the deviation in diopter caused by the approach of the subject can be eliminated by increasing the optical path length from the objective lens 5 to the imaging plane 21, so as explained in FIG.
It is sufficient to move the second reflective surface 2 and the third reflective surface 3 downward by half the amount of the shift. That is, the balarax and diopter deviation that occur in this arrangement are caused by the second reflecting surface 2.
This can be corrected by simultaneously moving the third reflecting surface 3 and the third reflecting surface 3 obliquely downward. Next, if the finder optical system 9 is placed above the photographing optical system 8 as shown in FIG. 7, parallax will occur in the vertical direction. Therefore, in order to correct this balarax and diopter at the same time, for example, as shown in FIG. The diopter can be corrected by moving the third reflective surface 2.3 downward. In addition, as shown in Figure 4, the diopter can be corrected by moving the fourth reflecting surface 4, but in that case, the balax is also corrected at the same time, so the overcorrection or lack of correction can be corrected by the first reflection. It can also be compensated for by moving the surface l. Conversely, by moving the fourth reflecting surface 4, balax is corrected, and at the same time, over-correction or under-correction of the corrected diopter is corrected by moving the second reflecting surface 2 and the third reflecting surface 3 in the vertical direction. It may be corrected. Further, when the finder optical system 9 is disposed diagonally above the photographing optical system 8 as shown in FIG. 8, balax also occurs in the diagonal direction. Therefore, the balax in this case can be corrected by moving the image vertically and horizontally simultaneously, so the lth reflective surface! Alternatively, vertical correction by moving the fourth reflecting surface 4 in the vertical direction and horizontal correction by moving the second and third reflecting surfaces 2.3 in the horizontal direction may be combined. The diopter correction is the second step. This can be done by moving the third reflective surface 2.3 downward. Here, an example of a position adjustment mechanism for moving each reflective surface 1.2, 3.4 will be explained using FIG. 9. FIG. 9 is an exploded perspective view of the position adjustment mechanism. As shown in the figure, the first reflective surface 1 and the fourth reflective surface 4 are each composed of a reflective pin, and the second reflective surface 2 and the third reflective surface 3 are composed of a prism 10. This prism 10 is held by a holding frame l1, and the holding frame l1 is configured to be movable along a guide member l2 fixed to the camera body by being combined therewith, and is also fixed to the camera body. The first pin held by the first pin 13
It is urged downward by a spring 14. On the other hand, when the normal photographing position of the photographing optical system is selected, the holding frame 1l is pressed upward from the lower end side by a lever 19 biased by the second spring l7 with the second bottle l8 as a fulcrum, thereby A reflective surface 2.3 is positioned at a position corresponding to the position. Furthermore, since the angle of the lever l9 changes with the rotation of the eccentric cam l6 connected to the motor l5, if the tip of the lever is moved downward by the rotation of the motor 15, the prism 10 will move diagonally downward along the guide member l2. Moving. Therefore, according to this structure, the parallax and diopter deviation that occur when macro photography is performed with a camera in which the finder optical system 9 is placed next to the photographic optical system 8 as shown in FIG. Simultaneous correction becomes possible by the action already explained. In addition, each optical system 8.9
Depending on the arrangement, it may be necessary to move the first reflecting surface l and the fourth reflecting surface 4, but even in that case, these reflecting surfaces can be easily moved by using a similar mechanism. In this way, in the above configuration, balax and diopter correction can be performed simultaneously by moving each reflecting surface. Also,
Since the correction is performed by combining the movements of the respective reflecting surfaces, the amount of movement of each of the reflecting surfaces can be smaller than, for example, when correction is made by extending the objective lens. Therefore, it is possible to miniaturize a finder that can clearly see the field of view within an appropriate range regardless of the photographing position of the photographic optical system.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing the general structure and optical path of a finder according to an embodiment of the present invention, and FIGS.
An explanatory diagram showing the optical path when the third reflective surface is viewed from the photographer's side. Figures 4 and 5 are explanatory diagrams showing the optical path when the finder optical system is viewed from the side at right angles to the optical axis. , 6th
8 are layout diagrams showing various positional relationships of the finder optical system with respect to the photographing optical system, FIG. 9 is an exploded perspective view showing the position adjustment Il & side of the reflecting surface, and FIGS. 10A and 10.
FIG. B is an explanatory diagram showing a conventional viewfinder field frame. l...First reflective surface, 2...Second reflective surface, 3...Third reflective surface, 4...Fourth reflective surface, 5...Objective lens,
6... Viewing frame, 7... Finder optical axis, 8...
Photographing optical system, 9... Fangoo optical system, lO... Prism, l1... Holding frame, l2... Guide member, l
3... Lth bottle, 14... First spring, 15... Motor, 16... Eccentric cam, l7... Second spring, l8
...Second bottle, l9...Lever patent applicant Minolta Camera Co., Ltd. Agent
Person Patent attorney Aoyama Ao (and other names) Figure 2 Bird Figure 3

Claims (1)

[Claims] (1) An image erecting optical system installed in a camera equipped with a photographing optical system that can select between a normal photographing position and a macro photographing position, and consisting of four reflecting surfaces (1, 2, 3, 4) within the system. When selecting the normal photographing position of the photographing optical system, each of the reflecting surfaces (1, 2, 3, 4) is set to the normal position in order to form an image on a predetermined imaging plane (21). On the other hand, when selecting the macro photography position of the photography optical system,
Parallax is corrected by changing the optical path position of the subject exiting from the final reflective surface to match the center of the photographic range with the center of the viewfinder field of view, and at the same time by changing the optical path length to direct the light flux to the imaging surface ( In order to correct the diopter by converging the reflection surface (1, 2, 3)
, 4) position adjustment mechanisms (11, 12, 13)
, 14, 15, 16, 17, 18, 19).