JPH1144838A - Finder device for camera - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a finder device capable of confirming whether or not a subject intended by a photographer is brought into focus by autofocusing while looking in a finder in a camera provided with a finder system independently of a photographing lens system. SOLUTION: This device is constituted of a virtual image type finder optical system, a real image type range-finder optical system, and a passive system range-finding device 120. The finder optical system is constituted of a 1st objective optical system 10 and an ocular 50; and the range-finder optical system is equipped with a turning mirror 40 and a 2nd objective optical system 20. Luminous flux made incident through the objective optical systems 10 and 20 is synthesized by a half mirror 30, so that the photographer observes a double image at the center of finder visual field. A control circuit 100 obtains the turning angle of the mirror 40 based on a subject distance outputted from the device 120, and controls a mirror driving motor 110 based on the obtained angle. The angle of the mirror 40 is obtained so that the double image may coincide with the subject at a calculated subject distance.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a finder device for a camera, and more particularly to a finder device provided independently of a photographic lens system.

[0002]

2. Description of the Related Art Recent cameras, whether a single-lens reflex camera or a compact camera, generally have an autofocus function. With single-lens reflex cameras, the degree of blurring of the image formed on the focus plate in the viewfinder changes with the focusing of the shooting lens, and as a result of autofocusing, it is determined whether or not the subject is in focus by looking through the viewfinder can do.

On the other hand, in a camera in which the finder system is provided independently of the photographing lens system, means for turning on a lamp in the finder when the subject distance can be detected is provided. When lights up, it is determined that the subject is in focus and the shutter is released.

[0004]

However, in a non-single-lens reflex camera, it is not possible to confirm whether or not the photographer can properly focus on the subject intended by the photographer before photographing. If the camera is set to autofocus without accurately focusing on the subject, or if the subject malfunctions because it is difficult to detect flames or scenery through glass by the distance measurement system, the intended subject will be in focus. There is a problem that does not fit.

That is, since the means such as the lamp in the finder only indicates whether or not the distance measurement has been successful for the subject located in the distance measurement area, the above-mentioned operation by the photographer is performed. In the event of a mistake or malfunction of the distance measurement system, even if you check that the lamp is lit and take a picture, a so-called out-of-focus photograph is taken without focusing on the subject intended by the photographer. The Rukoto.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art. In a camera in which a finder system is provided independently of a photographic lens system, the camera focuses on a subject intended by a photographer by autofocusing. It is an object of the present invention to provide a finder device that allows the user to know whether or not the camera can be adjusted while looking at the finder.

[0007]

To achieve the above object, a finder apparatus according to the present invention has a first objective optical system for forming a virtual image of a subject and a first objective optical system having a predetermined base line length. A second objective optical system that looks at the subject from a direction different from that of the subject and forms a real image of the subject;
An upright optical system for inverting an inverted image formed by the objective optical system to form an erect image, and a part of a visual field formed by a light beam incident through the first objective optical system;
A light beam combining element that forms a double image by superimposing light beams incident through the second objective optical system and the erecting optical system, and an eyepiece optical system that guides the light beam combined by the light beam combining device to the photographer's eyes Light path deflecting means for changing the degree of overlap of the double images along the base line length direction by deflecting the optical path of the second objective optical system, and passive distance measuring means for detecting the distance to the subject; The optical path deflecting means is controlled based on the object distance detected by the distance measuring means so that two object images formed by the light beams incident from the first and second objective optical systems overlap the object at the object distance. And control means for performing the operation.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of a finder device for a camera according to the present invention will be described. FIG. 1 is an explanatory diagram illustrating a configuration of an optical system and a control system of the finder device according to the embodiment. The photographic optical system is provided independently of the finder, and has an autofocus function in which the photographic lens is driven for focusing according to a subject distance signal from a distance measuring device.

The optical system of the double image matching type finder according to the embodiment comprises a virtual image type finder optical system, a real image type rangefinder optical system, and a passive type distance measuring means. The finder optical system includes a first objective optical system 10 for forming a virtual image of a subject and an eyepiece lens (eyepiece optical system) 50, and constitutes an inverse Galilean finder. The first objective optical system 10 includes a negative lens 11 and a positive lens 12.

The rangefinder optical system includes a second objective optical system 20 for forming a real image of a subject by a light beam reflected by the rotating mirror 40, a condenser lens 23, and a relay lens 24. The second objective optical system 20 includes a negative lens 21 and a positive lens 22. The second objective optical system 20 differs from the first objective optical system 10 with a predetermined base line length by viewing a subject via the rotating mirror 40. Look at the subject from the direction. The inverted image formed by the second objective optical system 20 is re-imaged by the relay lens 24, which is an erecting optical system, to be an erect image. The range of the image formed by the rangefinder optical system is limited only to the central portion of the finder field of view by a stop (not shown) arranged near the image plane IM of the second objective optical system 20.

A light beam incident through the first and second objective optical systems 10 and 20 is converted into a half mirror 30 as a light beam combining element disposed between the first objective optical system 10 and the eyepiece 50. Are synthesized by First objective optical system 10
Incident on the finder cover the entire area of the finder field of view, a part of which passes through the half mirror 30, and is guided to the photographer's eye via the eyepiece lens 50. On the other hand, a light beam incident from the second objective optical system 20 has a transmission range limited to a central portion in the finder visual field by a stop, and a part of the light beam is reflected by the half mirror 30 and is reflected by the photographer's eye through the eyepiece lens 50. Incident on. Therefore, the photographer can use the two objective optical systems 10 and 20 for the range in the center of the viewfinder.
Observes a double image formed by the light beam incident through the first objective optical system 10, and observes a non-overlapping image formed by the light beam incident through the first objective optical system 10. Can be.

The degree of overlap of the double images is changed by changing the angle of the rotating mirror 40 according to the output of the distance measuring device 120. The angle of the rotating mirror 40 is controlled by a mirror driving motor 110 which is a stepping motor. These rotating mirror 40 and mirror drive motor 110 are
By deflecting the optical path of the second objective optical system 20, that is, by tilting the optical axis Ax2 of the second objective optical system 20 with respect to the optical axis Ax1 of the first objective optical system 10,
It functions as an optical path deflecting unit that changes the overlapping state of the double images along the base line length direction. As the optical path deflecting means, in addition to using the above-mentioned rotating mirror 40, at least a part of the lens of the second objective optical system 20 is decentered in a direction perpendicular to the optical axis of the second objective optical system 20. A variable apex prism may be used.

The passive distance measuring means includes, for example, a pair of imaging lenses arranged in parallel, and a pair of line sensors provided corresponding to the respective imaging lenses. The distance to the target subject is determined based on the phase difference between the subject images to be formed. The control circuit 10
0 is a rotation mirror 40 based on the determined subject distance.
Is obtained. The angle of the rotation mirror 40 is formed by a light beam incident on the subject at the calculated subject distance from the first and second objective optical systems 10 and 20.
The two subject images coincide within the double image forming range, that is, the optical axis Ax1 of the first objective optical system 10 and the optical axis Ax2 of the second objective optical system intersect at the detected subject distance. Asked to do so. The control circuit 100 controls the mirror drive motor 110 so that the turning mirror 40 is set to the obtained turning angle.

The subject distance information output from the distance measuring device 120 is generally used by an autofocus device that automatically focuses the photographing lens on the subject. In this embodiment, as described above, the rotating mirror 40 is used. The subject distance information is also used as information for determining the rotation angle.
Thus, it is possible to know whether or not the subject intended by the photographer is focused by the autofocus while looking through the viewfinder. That is, according to the finder device of the embodiment, since the rotating mirror 40 is controlled so that the image of the subject to be measured for distance is observed in the same manner within the double image forming range, it is possible for the photographer to If the subject is the intended subject, it can be determined that the intended subject can be focused by autofocusing. If the image of the intended subject is double-shifted in the double image display area and observed twice, it is measured as the intended subject. It can be seen that the subject to be distanced is different. Therefore, when the image of the intended subject is double-observed, the photographing lens can be focused on the intended subject by re-measuring the distance until the image of the intended subject is observed.

Further, in this embodiment, a frame display means 80 for displaying a bright frame in the field of view is provided, and the finder optical system is configured as a lighting type bright frame finder. The frame display means 80 is provided with a second half mirror 83 for displaying light, which is transmitted through a frame mask 81 and a condenser lens 82 from a lighting window provided in the middle of a window for capturing a light beam into each of the objective optical systems 10 and 20, and a display half mirror 83. Objective optical system 2
The light beam incident through the light source 0 is synthesized.

The frame mask 81 is formed by forming a linear transparent portion for displaying a bright frame (optical image frame) on an opaque plate, and is formed with the image plane IM of the second objective optical system 20. They are arranged at optically conjugate positions. The display light combined by the display half mirror 83 disposed between the condenser lens 23 and the relay lens 24 is:
The light beam is reflected by the half mirror 30 together with the light beam entering through the second objective optical system 20 and enters the eyepiece 50.
The photographer sets the frame mask 8 in the field of view including the above-described double image.
1 can be seen in a superimposed manner.

The present invention is not limited to the above embodiment, and the following modifications are possible. Instead of the distance measuring means for directly obtaining the subject distance as in the embodiment, a focus detecting means for detecting the in-focus state of the photographing optical system can be used. In this case, the control circuit can determine the subject distance based on the defocus amount detected by the focus detection unit, the current focus position of the photographing lens, and the focal length of the photographing lens.

Further, when the photographing optical system is constituted by a variable-magnification lens such as a zoom lens, it is preferable that the first and second objective optical systems 10 and 20 are also constituted as a variable-magnification optical system. In this case, the magnification of the first objective optical system 10 is changed according to the change in the focal length of the photographing optical system, and the second magnification is made equal to the magnification of the first objective optical system 10.
It is desirable to provide a magnification changing means for changing the magnification of the objective optical system 20.

[0019]

As described above, according to the present invention, a double image can be used as a means for confirming an autofocus function, and even in a camera in which a finder system is provided independently of a photographic lens system. Since it is possible to know whether or not the subject intended by the photographer is in focus before photographing, it is possible to prevent a photographing error relating to focusing in advance.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of an optical system and a control system showing an embodiment of a finder device for a camera according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 1st objective optical system 20 2nd objective optical system 30 Half mirror (light beam combining means) 40 Rotating mirror (optical path deflecting means) 50 Eyepiece 80 Frame display means 100 Control circuit 110 Mirror drive motor 120 Distance measuring device

Claims (11)

[Claims] In a finder device of a camera provided independently of a photographing optical system, a first objective optical system for forming a virtual image of a subject and a first objective optical system having a predetermined base length are provided. A second objective optical system for viewing the subject from different directions and forming a real image of the subject; and erecting optics for forming an erect image by inverting an inverted image formed by the second objective optical system. By superimposing a light beam incident through the second objective optical system and the erecting optical system on a part of a field formed by a light beam incident through the first objective optical system. A light beam combining element that forms a double image; an eyepiece optical system that guides a light beam combined by the light beam combining element to a photographer's eye; and the double image by deflecting an optical path of the second objective optical system. The overlap condition of the baseline An optical path deflecting unit that changes along the long direction; a passive distance measuring unit that detects a distance to the subject; and a subject located at the subject distance based on the subject distance detected by the distance measuring unit. A finder device for a camera, comprising: control means for controlling the optical path deflecting means so that two subject images formed by light beams incident from the first and second objective optical systems overlap. 2. The finder device for a camera according to claim 1, wherein the light beam combining element is disposed between the first objective optical system and the eyepiece optical system. 3. The camera viewfinder device according to claim 1, further comprising a frame display means for displaying a bright frame in the field of view, and configured as a lighting type bright frame finder. 4. The frame display means combines light incident through a lighting window and transmitted through a frame mask with a light beam incident through the first objective lens or the second objective lens by a half mirror. The viewfinder device for a camera according to claim 2, wherein: 5. The viewfinder device for a camera according to claim 4, wherein said half mirror is disposed between said second objective optical system and said light beam combining means. 6. The camera viewfinder apparatus according to claim 4, wherein said frame mask is disposed at a position optically equivalent to an image forming plane of said second objective optical system. The eyepiece optical system 7. The camera viewfinder apparatus according to claim 1, further comprising a frame display means for displaying an optical image frame in the field of view, and configured as an albada-type bright frame finder. . 8. The magnification of the first objective optical system is changed in accordance with a change in the focal length of the photographing optical system, and the second objective optical system is made equal to the magnification of the first objective optical system. 2. The camera viewfinder device according to claim 1, further comprising a magnification changing means for changing a magnification of the system. 9. The camera viewfinder device according to claim 1, wherein said optical path deflecting unit includes a turning mirror and a mirror driving unit for turning said turning mirror. 10. The optical path deflecting means, wherein at least a part of the lens of the second objective optical system is decentered in a direction perpendicular to the optical axis of the second objective optical system. Item 2. A viewfinder device for a camera according to Item 1. 11. A focus detecting means for detecting a focus state of the photographing optical system in place of the distance measuring means, wherein the control means controls an object distance based on a defocus amount detected by the focus detecting means. 2. The camera viewfinder device according to claim 1, wherein