JPH0943669A - Image photographic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve photometric accuracy with simple constitution in an image photographic device such as a single lens reflex camera and a still camera equipped with a video camera. SOLUTION: A half mirror 3 is disposed apart from a shutter curtain 5 in a mirror box 2, and a photometry element 14 is arranged at a position where an angle formed by a line linking the element 14 with the center of an area on the shutter curtain 5 covered as the photometric range of the element 14 at the time of normal photometry with the shutter curtain 5 becomes nearly perpendicular, whereby the same brightness of respective parts is nearly uniformly obtained when the same light quantity per unit area is cast to the respective parts in the case of viewing the photometric range on the shutter curtain 5 from the element 14.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a single-lens reflex camera,
Also, the present invention relates to an image capturing device having functions of both a video camera and a still camera.

[0002]

2. Description of the Related Art FIG. 11 is a schematic configuration diagram of an optical system of a portion centering on a mirror box 2 of a conventional single-lens reflex camera. As shown in this figure, an optical system of a conventional single-lens reflex camera includes an interchangeable lens 1 as a main optical system, a mirror box 2 into which a light beam from a subject enters through the interchangeable lens 1, and a mirror box 2 inside. A mirror 20 rotatably supported around a fulcrum 20b, a film exposure surface 6 on which a light beam from a subject forms an image when the mirror 20 moves in the X direction, and a mirror surface 20a when the mirror 20 moves in the Y direction. And a finder optical system that guides the light flux from the subject reflected by.

Here, the mirror 20 is moving in the Y direction except when the shutter is released. Normally, at this time, the mirror 20 is supported at an angle of 45 ° with respect to the optical axis of the main optical system, and a positioning tool 21 is provided to accurately measure the angle. On the other hand, when the shutter is released, the mirror 20 is flipped up in the X direction.

A shutter curtain 5 is provided on the film exposure surface 6 on the side of the mirror 20. When the shutter is released, the shutter curtain 5 operates in synchronization with the mirror 20 so that the main optical The light flux incident from the system is guided onto the film exposure surface 6. Further, since the film exposure surface 6 is arranged at a predetermined position, the film is positioned by the pressure plate 7 and the film rail 8. The film exposure surface 6, the shutter curtain 5 and the like constitute a silver salt photographic image pickup section.

The distance FBL from the rear flange surface 13 of the lens barrel that houses the interchangeable lens 1 to the film exposure surface 6 is called a flange back, and normally, the interchangeable lens 1 can be shared so that one lens of the same series can be used. The same value is set on the reflex camera.

In this conventional single-lens reflex camera, it is necessary to secure a space for rotating the mirror 20 in the mirror box 2 on the rear side of the lens barrel of the interchangeable lens 1. It is arranged as far as possible from the rear flange surface 13 of the lens barrel. In this case, assuming that the flange back FBL is constant, the mirror 20 moves to the shutter curtain 5.
Will be placed close to.

Another conventional example is a single-lens reflex camera equipped with a fixed half mirror in place of the movable mirror 20. In this type of camera, the luminous flux from the subject incident from the main optical system is divided into two by the half mirror, one luminous flux reaches the silver salt photographic imaging section, and the other luminous flux is guided to the finder optical system. ing. In this case, since the half mirror does not rotate, it can be placed close to the rear flange surface of the lens barrel of the interchangeable lens, but for the purpose of sharing parts with a camera using a movable mirror in the same series, Generally, the half mirror is arranged close to the shutter curtain.

In these single-lens reflex cameras, the primary image plane (the film exposure surface, but the shutter curtain becomes the primary image plane during steady photometry, in order to perform steady photometry or flash light control). In many cases, a photometric element is arranged between the shutter curtain and a mirror or half mirror at a position where it can be directly covered as a photometric range. In this case, whether using a mirror or a half mirror, when the flash is used, the light metering element receives the light reflected by the exposed surface of the film to perform flash dimming.

[0009]

However, the above-mentioned 1
In an eye reflex camera, when a photometric element or a distance measuring element is arranged between the mirror or half mirror and the shutter curtain on the wall surface of the mirror box, the space for arranging these elements is small and it is not possible. Had to be placed.

For this reason, the photometric element should face the area on the primary image surface (film exposure surface or shutter curtain) covered as the photometric range of the photometric element obliquely (that is, from a position close to the primary image plane). become. In this case, as shown in FIG.
When it is arranged at a point P2 closer to the primary image plane 16 than the point P1 on the wall surface of the, the intersection point between the optical axis AX of the light flux reaching the primary image plane 16 and the primary image plane 16 is O, and the straight line OP2 and the primary image. Surface 1
The angle θ2 formed by 6 is smaller than the angle θ1 formed by the straight line OP1 and the primary image plane 16, and the points in the area A1 on the primary image plane 16 and the points in the area A2 reach the photometric element. The difference between the angle formed by the straight line and the primary image plane 16 is the point P1
It is larger than the case in.

Here, the light incident on the primary image surface (film exposure surface or shutter curtain) 16 is diffusely reflected,
The intensity distribution of the irregularly reflected light is anisotropic, and in this case, a larger amount of light is reflected in a direction close to the direction perpendicular to the primary image plane 16. Therefore, when the photometric element is arranged at the point P2, even if the light of the same intensity is incident on the point in the area A1 of the primary image plane 16 and the point in the area A2, the direction of the photometric element from the point in the area A2. The amount of light reflected by is larger than the amount of light from a point in the area A1. And
The difference is greater when the photometric element is placed at the point P2 than when it is placed at the point P1.

At the same time, when a photometric element is arranged at the point P2, the distance from the point in the area A1 to the photometric element is the area A2.
It becomes longer than the distance from the point inside to the photometric element, and the difference is larger than when the photometric element is arranged at the point P1.
Therefore, even if the minute area in the area A1 and the minute area in the area A2 reflect the same amount of light per unit area toward the light measuring element located at the point P2, the light measuring element is The amount of light received from the minute area is larger than the amount of light received from the minute area in the area A1. The difference is larger when the photometric element is arranged at the point P2 than when it is arranged at the point P1.

For these reasons, when the photometric element is arranged at the point P2, even if the area A1 and the area A2 on the primary image plane 16 receive the same amount of light per unit area, they are reflected and reach the photometric element. The amount of light is larger from the area A2 than from the area A1. That is, in this case, the area A2 looks brighter than the area A1 when viewed from the photometric element. Then, the difference between the light amounts becomes larger than that when the photometric element is arranged at the point P1.

Therefore, like a conventional single-lens reflex camera, a mirror or a half mirror is arranged in the mirror box close to the shutter curtain, and a photometric element is arranged between the mirror or the half mirror and the shutter curtain. In that case, there is a problem that accurate photometry cannot be performed over the entire primary image surface (film exposure surface or shutter curtain).

Further, when multi-divisional photometry is performed on the primary image plane, variations in photometric accuracy with respect to each area on the primary image plane will occur for the same reason as above, and in order to eliminate this variation. In this case, it is necessary to correct the detection output of each area on the photometric surface of the photometric element corresponding to each area on the primary image surface.

Further, as shown in FIG. 13, the half mirror 3 is used to divide the light beam incident from the interchangeable lens 1 into two.
In the conventional single-lens reflex camera equipped with, normally, a part of the light flux transmitted through the half mirror 3 is reflected on the primary image plane 16 side of the half mirror 3 and is passed through the convex lens 15a for image formation to the distance measuring element 15. Since a guide mirror (hereinafter referred to as an AF mirror) 4 is provided, a shadow S1 blocked by the AF mirror 4 is formed on the primary image plane 16.

That is, as shown in FIG. 14, on the primary image plane 16 covered by the photometric element 14 as a photometric range, A
The shadow S1 of the F mirror 4 occurs. Moreover, as shown in FIG. 13, since the light flux passing through the half mirror 3 and reaching the primary image plane 16 is gradually expanded, the half mirror 3 is brought closer to the shutter curtain as in a conventional single-lens reflex camera. If it is arranged, the AF mirror 4 becomes larger accordingly, and the area that can be effectively used for photometry on the primary image surface 16 formed on the photometric surface of the photometric element 14 through the convex lens 14a becomes smaller. There was a problem of going down.

At the same time, as shown in FIG. 15, in the conventional image taking apparatus having the half mirror 3 and the AF mirror 4 in the mirror box 2, the half mirror 3 is arranged close to the shutter curtain. And photometric element 14
Since the distance measuring element 15 is arranged in a narrow space between them, a part of the light reflected by the primary image plane 16 is blocked by the AF mirror 4 on the way to the light measuring element 14. For this reason, when the primary image surface 16 is viewed from the photometric element 14, the shadow S2 of the AF mirror 4 is generated in the primary image surface 16, and the area on the primary image surface 16 that can be effectively used for photometry is reduced. There was a problem that the accuracy was lowered.

The present invention has been made in order to solve such a problem, and has a simple structure in an image pickup apparatus having both functions of a single-lens reflex camera, a video camera and a still camera. The purpose is to greatly improve the photometric accuracy.

[0020]

In order to achieve the above object, according to the present invention, a main optical system, a box-shaped chamber into which a light beam from a subject enters through the main optical system, and a fixed support in the box-shaped chamber. A light splitter for splitting a light flux from a subject into a first light flux and a second light flux, and a light splitting member and a light splitting member on one side surface of a box-shaped chamber where the first light flux forms an image. A silver salt photographic first image pickup means having a shutter curtain disposed on the side of the container, and a first light flux disposed between the light splitter and the shutter curtain on the wall surface of the box-shaped chamber to expose the photosensitive member or In an image capturing apparatus equipped with a photometric device that measures light by detecting the amount of light reflected by a shutter curtain, an optical splitter is arranged in a half position with respect to the optical axis of the main optical system. The light sensitive member and the shutter curtain are used as a mirror, and the light of the first light flux is used together. So that the straight line connecting the center of the area on the shutter curtain covered by the photometric means to the photometric means and the angle formed by the shutter curtain is close to vertical. Then, the light splitter is arranged apart from the shutter curtain in the optical axis direction of the first light flux.

According to this structure, for example, when the same amount of light per unit area hits the entire shutter curtain as the first light flux, the brightness of each part of the shutter curtain is almost uniform when viewed from the photometric element. Become.

Further, it is preferable that the above-mentioned image capturing apparatus satisfies the following conditions. a ≧ 3 ^1/2 · F _SL / 2, where a: the distance between the intersection of the light splitting surface of the light splitter and the optical axis of the first light flux and the shutter curtain, F _SL : the above It is the length of the shutter curtain when cut along a plane parallel to the optical axis of the first light flux and the optical axis of the second light flux.

In this case, the distance between the light splitter and the shutter curtain can be surely widened, and the straight line connecting the center of the area on the shutter curtain covered by the photometric means to the photometric means. Since the photometric means can be arranged at a position where the angle formed with the shutter curtain is close to vertical, for example, when the same amount of light per unit area hits the entire shutter curtain as the first light flux, the shutter curtain is seen from the photometric element. The brightness of each part becomes almost uniform.

Further, the second light flux may be guided to the second image pickup means by the relay optical system and used for image pickup.

In this case, after the light incident from the main optical system is split, it is guided to two image pickup means and used independently for image pickup.

Further, the second image pickup means can be of an electrophotographic type.

In this case, for example, video shooting is performed by the second image pickup means.

Further, it is preferable that the reflectance of the surface of the shutter curtain on the side of the light splitter is substantially equal to the reflectance of the surface of the photosensitive member.

Then, the amount of light reflected by the shutter curtain during steady photometry becomes substantially equal to the amount of light reflected by the film exposure surface without the shutter curtain.

Further, the film format of the first image pickup means can be set to the 135 system.

In this case, the film format of the first image pickup means is widely used.

Further, a mirror arranged on the shutter curtain side of the light splitter for reflecting a part of the first light flux and a light arranged on the wall of the box-shaped chamber for receiving the light reflected by the mirror are measured. Distance measuring means for performing distance measurement can be provided.

In this case, the first light flux obtained by the light splitter is used to perform the photometry and the distance measurement. Further, since the light splitter is arranged away from the shutter curtain, the mirror can be arranged farther from the shutter curtain than in the case of the conventional technique.

Further, the photometric means can be arranged on the wall surface of the box-shaped chamber opposite to the propagation direction of the second light flux.

In this case, since the light splitter is separated from the shutter curtain, the angle formed by the straight line connecting the center of the area on the shutter curtain covered by the photometric means and the photometric means is perpendicular to the shutter curtain. It is easier to arrange the photometric means at a position closer to each other than in the case of the conventional technique.

Further, the photometric means may be arranged on the wall surface of the box-shaped chamber on the side of the propagation direction of the second light flux.

Also in this case, since the light splitter is separated from the shutter curtain, the angle formed by the straight line connecting the center of the area on the shutter curtain covered by the photometric means and the photometric means is perpendicular to the shutter curtain. It is easier to dispose the photometric means at a position closer to the position than in the prior art.
Moreover, in this case, the photometric means is arranged at a position where the light flux from the shutter curtain to the photometric means is not blocked by the mirror.

The photometric means may be arranged on the wall surface of the box-shaped chamber parallel to the optical axes of the first and second light beams.

Also in this case, since the light splitter is separated from the shutter curtain, the angle formed by the straight line connecting the center of the area on the shutter curtain covered by the photometry means and the photometry means is perpendicular to the shutter curtain. It is easier to dispose the photometric means at a position closer to the position than in the prior art.

A pair of photometric means may be arranged on two wall surfaces parallel to the optical axis of the first light flux and the optical axis of the second light flux in the box-shaped chamber.

In this case, each of the photometric elements is located closer to each of the two areas of the shutter curtain divided by the optical axis of the first light flux when viewed from the optical axis direction of the second light flux, and far away. If a part of one of the two areas is covered as a photometric range, the photometric range of each photometric element can be compared to the case where one photometric means is provided on either of the two wall surfaces. The straight line connecting the center of and the photometric element intersects the shutter curtain at a more vertical angle.

The photometric means and the distance measuring means are both arranged on the wall surface of the box-shaped chamber opposite to the propagation direction of the second light flux, and viewed from the optical axis direction of the second light flux. At this time, both may be arranged near the optical axis of the first light flux.

In this case, when viewed from the optical axis direction of the second light flux, the photometric means faces the regions on both sides of the optical axis of the first light flux at the same angle.

Further, at this time, when viewed from the optical axis direction of the second light flux, it is preferable that the distance measuring means and the light measuring means are arranged in this order from the optical splitter toward the shutter curtain.

In this case, the light flux from the shutter curtain to the photometric means can be easily and surely prevented from being blocked by the mirror.

[0046]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment in which the present invention is applied to an image capturing apparatus having both functions of a video camera and a still camera will be described below with reference to the drawings. FIG.
The same components as those according to the related art shown in FIGS. 1 to 4 show the first embodiment. FIG. 1 is a schematic configuration diagram of the entire optical system of the present embodiment. The light flux from the subject that has entered the mirror box 2 through the interchangeable lens 1 as the main optical system reaches the film exposure surface 6 through the shutter curtain 5 by the half mirror 3 arranged in the mirror box 2. The light beam is split into a second light beam that reaches the CCD image sensor 12 via the condenser lens 9, the reflection mirror 10, and the relay lens 11.

The half mirror 3 is formed by depositing a metal oxide on the surface of glass to form a thin film.
In this embodiment, the mirror box 2 is fixedly supported at an angle of 45 ° with respect to the optical axis of the interchangeable lens 1.

Here, the first light flux is used for still photography using a silver salt photographic film, and the silver salt photographic image pickup section for that purpose is composed of a shutter curtain 5, a film exposure surface 6, and the like. Has been done. In this case, the shutter curtain 5 and the film exposure surface 6 are both arranged perpendicularly to the optical axis of the first light flux, and since the film exposure surface 6 is arranged at a predetermined position, the film is formed by the pressure plate 7. It is positioned by the film rail 8.

Also, in the first embodiment, unlike the prior art, the half mirror 3 is arranged close to the rear flange surface 13 of the lens barrel that houses the interchangeable lens 1. Here, the distance from the rear flange surface 13 of the lens barrel to the film exposure surface 6, that is, the flange back FBL, is usually set to the same value in single-lens reflex cameras of the same series so that the interchangeable lens 1 can be shared. Therefore, in this case, the half mirror 3 is arranged at a position away from the shutter curtain 5.

The second light flux reaches the CCD image sensor 12 and is used for electrophotographic video photography. The second light flux forms an aerial image once near the condenser lens 9 on its optical path. Where the general 1
In the case of an eye reflex camera (a camera in which the optical system after the condenser lens 9 of the present embodiment is replaced with a finder optical system), a focusing screen is provided at that position and an image is formed on the focusing screen. Multi-division photometry can be performed by disposing a photometric element on the rear side of the focusing plate in the optical path of the light flux and providing an optical system so that an image projected on the focusing plate can be projected on the photometric surface of the photometric element.

However, in the present embodiment, if the focusing plate is arranged on the optical path of the second light flux, the second light flux becomes diffused light there, and the CCD image sensor 12 cannot perform clear photographing. Not provided. Therefore, in order to perform multi-divisional photometry, the second light flux is not used, but the primary image plane on which the first light flux forms an image (the film exposure surface 6), but during steady photometry approximately the shutter curtain 5 Will be the primary image plane), and a photometric element for multi-division photometry will be arranged at a position where it can cover the photometric range.

Although not particularly shown, an ND filter and a relay diaphragm are provided near the relay lens 11 on the optical path of the second light flux in order to adjust the amount of light reaching the CCD image sensor 12. .

Further, in the first embodiment, since the photometric element 14 is disposed between the half mirror 3 and the shutter curtain 5 on the wall surface of the mirror box 2, the shutter curtain 5 and the flash are flashed during steady photometry. At the time of dimming, by covering the film exposure surface 6 as a photometric range, multi-division photometry can be performed (of course, it is also possible to perform average photometry or spot photometry). Further, an AF mirror 4 is provided on the shutter screen 5 side of the half mirror 3 and reflects a part of the first light flux to measure the distance.
Distance measurement is performed by leading to 5. The photometric element 1
4. In front of the distance measuring element 15, a convex lens 14 is provided in order to form the light fluxes respectively guided on the light measuring surface and the distance measuring surface.
a and 15a are provided.

In such a structure, if the AF mirror 4 is fixedly supported, a part of the first light flux is AF when the actual exposure on the film exposure surface 6 by the first light flux.
The AF mirror 6 is shaded in the image (primary image formed by the first light flux) that is blocked by the mirror 4 and appears on the film exposure surface 6. Therefore, in the first embodiment, when the shutter is released (that is, when the shutter curtain 5 opens and the film exposure surface 6 is exposed), the AF mirror 4 is retracted from the range through which the first light flux passes by means not shown. Configure to allow.

FIG. 2 shows an example of the photometric surface of the photometric element 14 for multi-division photometry. In this way, the photometric surface has many areas 1
It is divided into 41, and each region 141 is configured to output a voltage according to the amount of light received. Therefore, if the primary image (the image exposed on the film exposure surface 6 or the shutter curtain 5) by the first light flux is projected on this photometric surface, each primary image portion (that is, each object portion) Each time), for example, it is possible to easily perform photometry with drawing weighting.

FIG. 3 shows a portion of the optical system of the first embodiment centered on the mirror box 2 for extraction. In this embodiment, the photometric element 14 is arranged on the wall surface of the mirror box 2 on the side opposite to the propagation direction of the second light flux. The figure shows a state in which the photometric element 14 covers the shutter curtain 5 as a photometric range.

At this time, the film exposure surface 6 is hidden, and the light received by the photometric element 14 is the light reflected by the shutter curtain 5. However, during actual shooting, the film exposure surface 6 (more specifically, shutter speed). (Since the shutter curtain 5 operates in front of the film exposure surface 6 within the time, the film exposure surface 6 and the shutter curtain 5 are partially)
It is exposed to the first light flux.

Therefore, in the first embodiment, the reflectance on the half mirror 3 side of the shutter curtain 5 is made substantially equal to the reflectance on the film exposure surface 6. As a result, the amount of light reflected by the shutter curtain 5 and the amount of light when it is reflected by the film exposure surface 6 without the shutter curtain 5 are substantially equal to each other.
From the amount of light received at 4, the exposure amount of the film exposure surface 6 at the time of actual photographing can be accurately known without any correction, and more accurate photometry can be performed with a simple configuration.

In the first embodiment, since the half mirror 3 is arranged apart from the shutter curtain 5, the photometric element 14
Therefore, the distance measuring element 15 can be arranged with a margin in a wide space between the half mirror 3 and the shutter curtain 5. In particular, the photometric element 14 can be arranged away from the primary image surface (the film exposure surface 6 or the shutter curtain 5) formed by the first light flux.

That is, in FIG. 12, the arrangement position of the photometric element 14 in the case of the single-lens reflex camera according to the prior art is indicated by P.
If the number is 2, the arrangement position of the photometric element 14 in the case of the first embodiment is P1 (position farther from the primary image plane 16 than P2). Therefore, a straight line connecting the center O of the area on the primary image plane 16 (the intersection of the optical axis AX of the first light flux and the primary image plane 16) covered by the photometric range of the photometric element 14 to the photometric element 14 The photometric element 14 can be arranged at a position where an angle θ1 formed by the primary image plane 16 is close to vertical (compared to the angle θ2 in the case of the conventional technique).

Therefore, for the reason described in the description of FIG. 12, when the same amount of light hits the area A1 and the area A2 on the primary image plane 16 per unit area, the difference in the amount of light reflected by them reaches the photometric element 14. Is smaller than in the prior art. That is, in this case, when viewed from the photometric element 14, the brightness of the areas A1 and A2 (compared to the case of the conventional technique) is
It becomes more uniform, and more accurate photometry can be performed over the entire primary image plane 16 with a simple configuration.

When performing multi-divisional photometry on the primary image plane 16, in the prior art, in order to eliminate the variation in photometric accuracy for each area on the primary image plane 16, each photometric plane on the photometric element is eliminated. The correction of weighting the detection output for each region was necessary, but according to the present embodiment, for the same reason as described above, the variation itself is small, and therefore such correction is extremely easy to perform, and in some cases, the correction is performed. No need to correct.

FIG. 4 shows how the AF mirror 4 is shaded on the primary image plane 16 by the first light flux in the first embodiment. In the first embodiment as well as in the prior art, the AF mirror 4 is disposed on the primary image surface 16 side of the half mirror 3 to reflect a part of the light flux transmitted through the half mirror 3 and guide it to the distance measuring element 15. Therefore, the A on the primary image plane 16
There is a shadow S1 blocked by the F mirror 4.

However, in this case, the light flux which has passed through the half mirror 3 and reaches the primary image plane 16 is gradually expanded. In the first embodiment, the half mirror 3 is moved from the primary image plane 16 to the primary image plane 16 as compared with the prior art. Since they are arranged apart from each other, the AF mirror 4 can be arranged apart from the primary image plane 16. Therefore, the AF mirror 4 can be made smaller by that amount, and the part of the area covered by the photometric element 14 as the photometric range is reduced by the AF mirror 4, and the photometric accuracy is improved.

In the above-mentioned structure, the widely used 135 system is adopted as the film format of the silver salt photographic image pickup portion of the first embodiment. 135
The film exposure area of the system is 3 for normal shooting.
The size is 6.0 mm x 24.0 mm, and 3 for panoramic shooting.
It is 6.0 mm × 15.0 mm.

As a film format, 16: 9, which is proposed in Japanese Patent Laid-Open No. 7-84309,
It is also possible to use a film system having three formats of 2: 3 and 1: 3. This is because the exposure area is smaller than that of the film of the 135 system, and the size of the mirror box becomes smaller in a camera corresponding to this, so the half mirror should be arranged away from the shutter curtain as in the present embodiment. Therefore, widening the space between the half mirror and the shutter curtain is advantageous because the photometry element and the distance measurement element can be arranged with a margin.

Here, how far the half mirror 3 can be separated from the shutter curtain 5 will be described. FIG.
FIG. 3 is a schematic view of the mirror box 2 viewed from a direction perpendicular to the optical axes of the first light flux and the second light flux in order to show how much the half mirror 3 can be moved within the mirror box 2. In this case, the half mirror 3 is arranged at an angle of 45 ° with respect to the first light flux.

Here, F _BL is the flange back (that is, the distance between the flange surface 13 and the film exposure surface 6), κ
Is the distance between the flange surface 13 and the objective side surface of the shutter curtain 5, F _SL is the distance in a plane parallel to the paper surface of the film exposure surface (generally the short side length of the film exposure surface), and S _L is the film exposure surface. 6 is the distance between the shutter curtain 5 and the objective side surface. Note that the up, down, left, and right directions referred to in the description of FIG. 5 below refer to the up, down, left, and right directions in the figure. Further, the center and the lower end of the objective side surface of the shutter curtain 5 are O and P, respectively.

Then, when the half mirror 3 is brought close to the flange surface 13 until its lower end comes into contact, the lower end, the center and the upper end of the half mirror 3 become K ₁ , L ₁ and M ₁ , respectively. At this time, the left end and the right end of the primary image 17 formed by the second light flux become I ₁ and J ₁ , respectively. Further, when the half mirror 3 is brought close to the shutter curtain 5 at its upper end, the lower end, center and upper end of the half mirror 3 are
These are K ₂ , L ₂ and M ₂ , respectively, and the left and right ends of the primary image plane of the second light flux are I ₂ and J ₂ , respectively.

Therefore, the distance between the intersection of the light splitting surface of the half mirror 3 and the optical axis of the first light beam and the side surface of the objective of the shutter curtain 5 (that is, the center of the half mirror 3 and the point O in FIG. 5). Distance) is a, the movable amount of a is the distance L ₁ L _2, that is, the distance K ₁ K ₂ , and the distance K ₂ P is F.
Considering that it is equal to _SL , (amount of movement of a) = κ−F _SL (1) In this range, when the lower end of the half mirror 3 moves from K ₁ to K _{2 and} at the same time the upper end moves from M ₁ to M ₂ , the left end of the primary image 17 by the second light flux is from I ₁ to I ₂ , and Its right edge moves from J ₁ to J ₂ .

The minimum value amin and the maximum value amax of a are
They are as follows; amin = (distance OL2) = F _SL / 2 (2), amax = amin + (movable amount of a) = κ-F _SL / 2 (3).

By the way, when a is made too large to approach amax, the lower end of the half mirror 3 comes too close to the flange surface 13 and, for example, when a lens or the like is provided on the shutter curtain 5 side of the flange surface 13, It is not preferable because the primary image 17 due to the second light flux is shaded, and as a result, there is a portion that is not visible during imaging with the second light flux. On the other hand, if a is made smaller, the position of the photometric element disposed between the half mirror 3 and the shutter curtain 5 will be closer to the shutter curtain 5, and as described above, the photometric accuracy will be impaired.

In fact, in the prior art, there is no one in which a is increased, and as a result, a problem is likely to occur in the photometric accuracy of the photometric element. Therefore, in the first embodiment of the present invention, the following range is specifically set as the range of a: 3 ^1/2 · F _SL / 2 <a <κ−F _SL / 2 (= amax) ... …(Four).

By setting a in this range, the distance between the half mirror 3 and the shutter curtain 5 can be increased more reliably, and the photometric element can be arranged away from the shutter curtain 5. Since the angle between the line connecting the photometric element and the point O and the shutter curtain 5 is close to vertical,
For the reasons already described, accurate photometry can be performed over the entire shutter curtain 5.

The lower end, the center and the upper end of the half mirror 3 when K is the lower limit of the equation (4) are K ₃ and L ₃ respectively.
And When M _3, which is (distance PL ₃₎ = (distance L ₃ M ₂₎ = (Distance _{PM 2) = F SL ...... (} 5). Further, the possible range of the half mirror 3 according to the equation (4) is a parallelogram K ₁ K ₃ M ₃ M ₁ shown by the diagonal lines, and correspondingly, the possible presence of the primary image 17 by the second light flux is The range is
It becomes a parallelogram I ₁ I ₃ J ₃ J ₁ shown by hatching.

Next, the second embodiment will be described with reference to FIG. This figure is a block diagram of the optical system of the portion centering on the mirror box 2 in the present embodiment, and shows a state in which the photometric element 14 covers the shutter curtain 5 as a photometric range. The configuration of the entire optical system according to the present embodiment is the same as that of the first embodiment shown in FIG. 1 except for the arrangement position of the distance measuring element, and therefore the description thereof will be omitted. 2 and 5 are also used in the same manner as in the first embodiment, the description thereof will be omitted.

As shown in FIG. 6, in the second embodiment, the photometric element 14 and the convex lens 14a for projecting the primary image of the first luminous flux on its photometric surface are used to propagate the second luminous flux of the mirror box 2. It is arranged on the wall on the direction side. Also,
The half mirror 3 is arranged apart from the shutter curtain 5. However, in this case, as compared with the first embodiment, it is possible to easily and surely prevent the light flux reaching the photometric element 14 from the shutter curtain 5 from being blocked by the AF mirror 4, so that the photometric accuracy is improved accordingly. be able to.

Next, a third embodiment will be described with reference to FIGS. 7 and 8. The configuration of the entire optical system according to the present embodiment is the same as that of the first embodiment shown in FIG. 1 except for the arrangement positions of the distance measuring element and the photometric element, and therefore the description thereof will be omitted. 2 and 5 are also used in the same manner as in the first embodiment, the description thereof will be omitted. Here, FIG. 7 and FIG. 8 respectively show the optical system of the portion centering on the mirror box 2 in the present embodiment viewed from a direction perpendicular to the optical axes of the first light flux and the second light flux. 6A and 6B are configuration diagrams in which the same portion is viewed from the optical axis direction of the second light flux, and both show a state in which the photometric element 14 covers the shutter curtain 5 as a photometric range.

As shown in FIG. 7, in the third embodiment, the first
As in the embodiment, the photometric element 14 and the distance measuring element 15 are
Both are arranged on the wall surface of the mirror box 2 opposite to the propagation direction of the second light flux. However, unlike the first embodiment, when viewed from the optical axis direction of the second light flux, the distance measuring element 15, from the half mirror 3 toward the shutter curtain 5,
The photometric elements 14 are arranged in this order. With this arrangement, as compared with the first embodiment, the shutter curtain 5 to the photometric element 14 are compared.
Since it is possible to easily and surely prevent the light flux reaching the above from being blocked by the AF mirror 4, it is possible to improve the photometric accuracy accordingly.

In this case, the photometric element 14 is attached to the shutter curtain 5.
When it is arranged away from the second light flux, the distance measuring element 15 is located closer to the interchangeable lens 1 side than the AF mirror 4 when viewed from the optical axis direction of the second light flux, so that the AF mirror 4 changes the first light flux to the first light flux. The second light flux is configured to be reflected in a direction inclined to the interchangeable lens 1 side with respect to the optical axis. At the same time, since the location of the distance measuring element 15 is narrowed, the light flux reflected by the AF mirror 4 passes through the convex lens 15a and then is reflected by the reflecting mirror 15b to reach the distance measuring surface of the distance measuring element 15. There is.

At this time, as shown in FIG. 8, the photometric element 14 and the distance measuring element 15 (in the figure, the convex lenses 14a, 1a placed in front of the photometric element 14 and the distance measuring element 15 respectively)
5a) is arranged so as to be near the optical axis of the first light flux when viewed from the optical axis direction of the second light flux. As a result, when viewed from the optical axis direction of the second light flux, the photometric element 14 faces the regions on both sides of the optical axis of the first light flux at the same angle. When the same amount of light hits the area, the amount of light reflected by them reaches the photometric element 14 becomes equal. Therefore, more accurate photometry can be performed over the entire shutter curtain 5.

Finally, the fourth embodiment will be described with reference to FIGS. 9 and 10. The configuration of the entire optical system according to the present embodiment is the same as that of the first embodiment shown in FIG. 1 except for the arrangement positions of the distance measuring element and the photometric element, and therefore the description thereof will be omitted. 2 and 5 are also used in the same manner as in the first embodiment, the description thereof will be omitted. here,
9 and 10 are configuration diagrams in which the optical system of the portion centering on the mirror box 2 in the present embodiment is viewed from a direction perpendicular to the optical axes of the first light flux and the second light flux. , And the same portion viewed from the optical axis direction of the second light flux, both showing a state in which the photometric element 14 covers the shutter curtain 5 as a photometric range.

As shown in FIGS. 9 and 10, in the fourth embodiment, the distance measuring element 15 is arranged on the wall surface of the mirror box 2 opposite to the propagation direction of the second light beam. The elements 14 and 14 are arranged in pairs on two wall surfaces parallel to the optical axis of the first light flux and the optical axis of the second light flux. Each of the photometric elements 14 and 14 is located near and away from each of the two areas of the shutter curtain 5 divided by the optical axis of the first light flux when viewed from the optical axis direction of the second light flux. A part of the other area is covered as a photometric range.

By configuring and arranging the photometric elements 14 and 14 in this way, a straight line connecting the center of the photometric range of each photometric element 14 and the photometric element 14 is formed.
On the other hand, since they intersect at an angle close to vertical (compared with the case of the related art or the first to third embodiments), for example, the same light amount per unit area over the entire photometric range of each photometric element 14. When it hits, the brightness of each part of the photometric range becomes more uniform when viewed from the photometric element 14. Therefore, by cooperating the two photometric elements 14, 14, more accurate photometry can be performed over the entire area of the shutter curtain 5.

In the fourth embodiment, the photometric element is the first
A pair is provided on two wall surfaces that are parallel to the optical axis of the luminous flux and the optical axis of the second luminous flux, and the number is one, and the pair is provided on either of the two wall surfaces. You can also do it. In that case, the center of the photometric range becomes the center of the shutter curtain, and the straight line connecting the center of the photometric range and the photometric element should intersect the shutter curtain at a smaller angle than when two above-mentioned photometric elements are arranged. However, by arranging the half mirror away from the shutter curtain, the angle becomes closer to vertical than in the case of the conventional technology. Accurate photometry can be performed.

[0086]

As described above, according to the first aspect of the present invention, for example, when the same amount of light per unit area hits the entire shutter curtain as the first light flux, the shutter is seen from the photometric element. Since the brightness of each part of the curtain becomes nearly uniform, it is possible to perform more accurate photometry over the entire shutter curtain with a simple configuration. In addition, when performing multi-division photometry, it is extremely easy to perform correction by weighting the detection output of each area on the photometric surface of the photometric element in order to eliminate variations in photometric accuracy for each area on the shutter curtain. There is no need to correct in some cases.

According to the present invention, the distance between the light splitter and the shutter curtain can be surely widened, and the center of the area on the shutter curtain covered by the photometric range of the photometric means and the photometric means. The photometric means can be placed at a position where the straight line connecting the lines with the shutter curtain is close to vertical.
For example, when the same amount of light per unit area strikes the entire shutter curtain as the first light flux, the brightness of each part of the shutter curtain becomes nearly uniform when viewed from the photometric element.
Therefore, more accurate photometry can be reliably performed over the entire shutter curtain with a simple configuration.

According to the third aspect, the light incident from one main optical system is split and then guided to two image pickup means to be independently used for image pickup. It is possible to configure an image capturing device that includes a means unit and an image pickup unit of a method different from that.

According to claim 4, in the second image pickup means,
For example, video shooting can be performed, and when used together with the first imaging means, a simultaneous shooting mode in which a video movie and a silver salt picture can be taken simultaneously, a silver salt shooting mode in which a silver salt picture can be taken, a video shooting mode in which a video movie can be taken, It is possible to set and use a still video shooting mode or the like that can shoot video still images.

According to the present invention, since the amount of light reflected by the shutter curtain during steady photometry is substantially equal to the amount of light reflected by the film exposure surface without the shutter curtain, the shutter curtain is displayed during steady photometry. From the amount of light reflected by the photometering device and received by the photometric element, the exposure amount of the film exposure surface at the time of actual photographing can be accurately known without any correction, and more accurate photometry can be performed with a simple configuration.

According to the sixth aspect, the format of the film by the first image pickup means is widely used, and the silver salt photograph can be picked up by using an easily available film.

According to the seventh aspect, since the distance measurement is performed together with the light measurement using the first light flux obtained by the light splitter, an additional optical system is provided outside the main optical system to perform the distance measurement. No need to provide. Further, since the light splitter is arranged away from the shutter curtain, the mirror can be arranged farther from the shutter curtain than in the case of the conventional technique. In that case, the mirror can be made smaller, and the portion of the area covered by the photometric means as the photometric range that is kicked by the mirror is reduced, so that photometric accuracy is improved.

According to the eighth aspect, since the light splitter is separated from the shutter curtain, the center of the area on the shutter curtain covered as the photometric range of the photometric means and the photometric means are more than those in the prior art. It becomes easy to dispose the photometric means at a position where the connecting straight line and the shutter curtain form an angle close to vertical. Therefore, for example, when the same amount of light per unit area hits the entire shutter curtain as the first light flux, the brightness of each part of the shutter curtain becomes close to uniform as seen from the photometric element. More accurate photometry is possible over the entire shutter curtain.

According to the ninth aspect, since the light splitter is separated from the shutter curtain, the center of the area on the shutter curtain covered as the photometric range of the photometric means and the photometric means are more provided than in the case of the prior art. It becomes easy to dispose the photometric means at a position where the connecting straight line and the shutter curtain form an angle close to vertical. Therefore, for example, when the same amount of light per unit area hits the entire shutter curtain as the first light flux, the brightness of each portion of the shutter curtain becomes close to uniform as seen from the photometric element. More accurate photometry is possible over the entire shutter curtain. Moreover, since the light measuring means is arranged at a position where the light flux from the shutter curtain to the light measuring means is not blocked by the mirror,
The photometric accuracy can be improved accordingly.

According to the tenth aspect of the present invention, since the light splitter is separated from the shutter curtain, it is more difficult than the prior art.
It becomes easy to dispose the photometric means at a position where the straight line connecting the center of the area on the shutter curtain covered as the photometric range of the photometric means and the photometric means forms an angle near the vertical with the shutter curtain. Therefore, for example, when the same amount of light per unit area hits the entire shutter curtain as the first light flux, the brightness of each part of the shutter curtain becomes close to uniform as seen from the photometric element. More accurate photometry is possible over the entire shutter curtain.

According to the eleventh aspect, each photometric element is closer to each of the two regions of the shutter curtain divided by the optical axis of the first light flux when viewed from the optical axis direction of the second light flux. The entire area and a part of the far area are covered as a photometric range.
Compared with the case of 0, the angle formed by the shutter curtain and the straight line connecting the center of the photometric range of each photometric element and the photometric element becomes closer to vertical. Therefore, for example, when the same amount of light per unit area hits the entire shutter curtain as the first light flux, the brightness of each part of the shutter curtain becomes more uniform as viewed from the photometric element, so that a simple configuration is achieved. With, you can perform more accurate photometry over the entire shutter curtain.

According to the twelfth aspect, when viewed from the optical axis direction of the second light flux, the photometric means faces the regions on both sides of the optical axis of the first light flux at the same angle.
For example, when the same amount of light hits each area per unit area, the amount of light reflected by them reaches the photometric means becomes equal. Therefore, more accurate photometry can be performed over the entire shutter curtain.

According to the thirteenth aspect, the light flux from the shutter curtain to the photometric means can be easily and surely prevented from being blocked by the mirror. Therefore, the area that can be effectively used as the photometric range in the entire shutter curtain is increased accordingly, and the photometric accuracy is improved.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an entire optical system of a still camera with a video camera according to a first embodiment.

FIG. 2 is a diagram showing an example of a photometric surface of a photometric element for multi-division photometry.

FIG. 3 is a schematic configuration diagram of a portion centering on a mirror box 2 of the optical system of the first embodiment.

FIG. 4 is a diagram showing how the shadow of the AF mirror is generated on the primary image plane by the first light flux in the first embodiment.

FIG. 5 is a schematic view of the mirror box viewed from a direction perpendicular to the optical axes of the first light flux and the second light flux in order to show how much the half mirror can be moved within the mirror box.

FIG. 6 is a schematic configuration diagram of a portion centering on a mirror box 2 of the optical system of the second embodiment.

FIG. 7 is a schematic configuration diagram of an optical system of a portion centered on a mirror box in the third embodiment as viewed from a direction perpendicular to an optical axis of a first light flux and an optical axis of a second light flux.

8 is a schematic configuration diagram in which the same portion as FIG. 7 is viewed from the optical axis direction of the second light flux.

FIG. 9 is a schematic configuration diagram of an optical system of a portion centering on a mirror box in the fourth embodiment as viewed from a direction perpendicular to an optical axis of a first light flux and an optical axis of a second light flux.

FIG. 10 is a schematic configuration diagram of the same portion as FIG. 9 viewed from the optical axis direction of the second light flux.

FIG. 11 is a schematic configuration diagram of an optical system of a part centering on a mirror box of a conventional single-lens reflex camera.

FIG. 12 shows how the angle formed by a straight line connecting the photometric element and the intersection of the optical axis of the first light flux and the primary image plane changes depending on the arrangement position of the photometric element in the mirror box. Fig.

FIG. 13 is a diagram showing how a shadow of an AF mirror is generated on a primary image plane by a first light flux in a conventional image capturing apparatus.

FIG. 14 is a diagram showing the shadow of the AF mirror generated on the primary image plane by the first light flux by the action of FIG.

FIG. 15 is a diagram showing a state in which the light reflected by the first light flux on the primary image plane and reaching the photometric element is blocked by the AF mirror in the conventional image capturing apparatus.

16 is a diagram showing the shadow of the AF mirror generated in the primary image plane viewed by the photometric element by the action of FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Interchangeable lens (main optical system) 2 Mirror box (box-shaped chamber) 3 Half mirror (light splitter) 4 AF mirror 5 Shutter curtain (a part of first imaging means) 6 Film exposure surface (of first imaging means) Part, photosensitive member 7 Pressure plate (part of first imaging means) 8 Film rail (part of first imaging means) 9 Condenser lens (part of second imaging means) 10 Reflecting mirror (of second imaging means) 11) Relay lens (a part of the second image pickup means) 12 CCD image sensor (a part of the second image pickup means) 13 Flange surface 14 Photometric element (photometric means) 15 Distance measuring element (distance measuring means) 16 First Primary image plane by the second luminous flux 17 Primary image plane by the second luminous flux

Claims (13)

[Claims] 1. A main optical system, a box-shaped chamber into which a light beam from a subject enters through the main optical system, and a light beam from the subject that is fixedly supported in the box-shaped chamber and is a first light beam. Second
Beam splitter for splitting into a light beam, a photosensitive member disposed on one side surface of the box-shaped chamber to form an image of the first light beam, and a shutter curtain disposed on the light splitter side of the photosensitive member. And a first image pickup means of a silver salt photographic system, which is arranged between the light splitter and the shutter curtain on the wall surface of the box-shaped chamber, and the first light flux is generated by the photosensitive member or the shutter curtain. In an image capturing apparatus including a photometric unit that measures the amount of reflected light, the light splitter is a half mirror arranged so as to form a predetermined angle with respect to the optical axis of the main optical system. Both the photosensitive member and the shutter curtain are arranged perpendicular to the optical axis of the first light flux, and the center of the area on the shutter curtain covered as the photometric range of the photometric means and the photometric The straight line connecting the means is The image is characterized in that the light splitter is arranged apart from the shutter curtain in the optical axis direction of the first light flux so that the photometric means can be arranged at a position where the angle formed with the shutter curtain is close to vertical. Imaging device. 2. The image capturing apparatus according to claim 1, wherein the following conditions are satisfied: a ≧ 3 ^1/2 · F _SL / 2, where a: a light splitting surface of the light splitter and the first light flux. Distance between the intersection of the optical axes of the above and the shutter curtain, F _SL : of the shutter curtain when cut by a plane parallel to the optical axes of the first light flux and the second light flux. Is the length. 3. The image photographing device according to claim 1, wherein the second light flux is guided to a second image pickup means by a relay optical system and is used for image pickup. 4. The image capturing apparatus according to claim 3, wherein the second image pickup means is an electrophotographic system. 5. The image capturing device according to claim 1, wherein the reflectance of the surface of the shutter curtain on the side of the light splitter is substantially equal to the reflectance of the surface of the photosensitive member. . 6. The film format of the first imaging means is a 135 system.
The image capturing device according to any one of 1. 7. A mirror disposed on the shutter curtain side of the light splitter for reflecting a part of the first light flux, and a mirror disposed on the wall surface of the box-shaped chamber and reflected by the mirror. 7. The image capturing apparatus according to claim 1, further comprising a distance measuring unit that receives light to perform distance measurement. 8. The image according to claim 1, wherein the photometric means is disposed on a wall surface of the box-shaped chamber opposite to a propagation direction of the second light flux. Imaging device. 9. The image capturing device according to claim 1, wherein the photometric means is disposed on a wall surface of the box-shaped chamber on the propagation direction side of the second light flux. . 10. The light metering means is arranged on a wall surface of the box-shaped chamber parallel to the optical axes of the first light flux and the second light flux. Item 7. The image capturing device according to any one of items 7. 11. The photometric means comprises two parallel optical axes of the first light flux and the second light flux of the box-shaped chamber.
The image capturing device according to any one of claims 1 to 7, which is arranged in a pair on one wall surface. 12. The light measuring means and the distance measuring means are both disposed on the wall surface of the box-shaped chamber opposite to the propagation direction of the second light flux, and the light of the second light flux is provided. The image capturing apparatus according to claim 7, wherein both of them are arranged near an optical axis of the first light flux when viewed from the axial direction. 13. When viewed from the optical axis direction of the second light flux, from the light splitter toward the shutter curtain,
The image capturing apparatus according to claim 12, wherein the distance measuring unit and the photometric unit are arranged in this order.