JP3486314B2 - Camera viewfinder optical system - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a viewfinder optical system for a single-lens reflex camera which records images in different areas on the surface of the same image pickup device.

[0002]

2. Description of the Related Art Japanese Unexamined Patent Publication (Kokai) No. 5-2280 proposes an image pickup device which visually records an image by combining a photosensitive material layer and a liquid crystal panel. A so-called frame sequential method is suitable for capturing a color image with such an image sensor. That is, the surface of the rectangular image sensor is divided into three regions in the longitudinal direction, and R (red)
A filter, a G (green) filter, and a B (blue) filter are respectively covered on any of the areas. Then, by sequentially arranging the image pickup device and each filter in the photographing optical path and photographing the same object, an image in each primary color can be recorded in each region.

When the aspect ratio of each area (that is, the aspect ratio of a color image obtained by synthesizing the images) is made wide like the Leica plate, by arranging the areas in the vertical direction,
Since the aspect ratio of the image pickup device as a whole can be reduced, the manufacturing cost can be suppressed and the amount of movement of the image pickup device can be reduced. Therefore, in this case, the moving direction of the image pickup device is the vertical direction (the short axis direction of the imaged image).

Various structures are conceivable as a new camera using such an image pickup device, but in view of compatibility with conventional camera systems and variety of photographic expressions, a single lens reflex system with interchangeable lenses is available. It is desirable to collect. In order to be able to observe an erect image of an object in the same direction as the object in this single-lens reflex system, a quick return mirror is placed between the image pickup lens and the image pickup element to make the viewfinder optical axis perpendicular to the shooting optical axis. Along with separating
By disposing an erecting optical system in the middle of the finder optical axis, the finder optical axis must be made parallel to the photographing optical axis and the vertical and horizontal directions of the image must be reversed. Then, in order to observe this image, it is common to place a fine loupe behind the prism.

[0005]

However, the pentaprism generally used as the erecting optical system in the conventional Leica single-lens reflex camera is designed so that the incident light axis (finder optical axis folded back by the quick return mirror) is different from that of the pentaprism. The finder optical axis is reflected so that the outgoing optical axes are orthogonal to each other. Therefore, the finder fine loupe arranged immediately after the pentaprism is located above the film (above in the short axis direction of the imaged image). Therefore, if a pentaprism is incorporated in a camera that uses the above-described image sensor, the moving space of the image sensor and the fine loupe will interfere. On the other hand, to avoid this interference, a quick return mirror,
If the entire finder optical system such as a pentaprism or a fine loupe is moved to the object side, the size of the entire camera becomes large, and the conventional optical lens cannot be used (because the flange back is different). Also, if the fine loupe is placed behind the moving space of the image sensor, the focal length of this fine loupe must be lengthened, so the magnifying power of the finder (defined as 250 / fe).
Fe is not preferable because the focal length of the magnifying glass decreases.

In view of the above-mentioned problems when using a pentaprism, an object of the present invention is to provide an optical system of a single-lens reflex camera which moves an image pickup element in the direction of a finder optical axis bent by a quick mirror. It is possible to prevent the fine loupe from interfering with the moving space of the image sensor without increasing the size of the entire camera and reducing the magnifying power of the viewfinder while maintaining compatibility with the interchangeable lens of It is to provide a finder optical system.

[0007]

The present invention adopts the following means in order to solve the above problems. That is, claim 1
The invention described above is a camera for projecting an object image formed by an imaging optical system onto a surface of an image sensor to record the object image on the image sensor and moving the image sensor in one direction along the surface. In the finder optical system of, by being arranged between the imaging optical system and the imaging element, the photographing optical axis of the imaging optical system,
A reflective optical member that folds back in the moving direction of the image sensor as a finder optical axis, a first reflective surface that folds back the finder optical axis that is folded back by the reflective optical member toward the object side, and a finder optical axis that folds back by the first reflective surface. In a plane parallel to the surface of the image sensor, the second reflective surface that is folded back in a direction orthogonal to the moving direction of the image sensor, and the finder optical axis that is folded back by the second reflective surface is parallel to the photographing optical axis. Porro prism having a third reflecting surface that folds back to the image sensor side, and a finder that is arranged closer to the object side than the end of the first reflecting surface on the image sensor side on the optical axis of the finder that is folded back by the third reflecting surface. And a loupe.

With this structure, the fine loupe is located closer to the object side than the end of the first reflecting surface on the image pickup device side, that is, the end of the Porro prism on the image pickup device side. Therefore, even if the reflective optical member and the Porro prism are brought close to the image sensor, it is possible to avoid the fine loupe from interfering with the moving space of the image sensor. Therefore, the size of the entire camera does not increase. Moreover, since the fine loupe can be arranged immediately after the third reflecting surface, it is not necessary to increase the focal length of the fine loupe. Therefore, the magnifying power of the fine loupe can be kept high.

The second reflecting surface may be folded back to the right side or the left side when the finder optical axis is viewed from the photographer side. However, when it is folded back to the left side, it is possible to prevent the viewfinder optical axis from interfering with the shutter button or the like arranged in the upper right of the camera in many cases. Further, when folded back to the left side, the viewfinder window is arranged on the left side of the back surface of the camera, so that the nose of the photographer looking into the viewfinder window with his right eye is prevented from interfering with the back surface of the camera. Also, the right hand of the photographer holding the camera is prevented from interfering with the right half of the photographer's face. As a result, the photographer can easily look into the viewfinder window, and at the same time, the camera can be stably held.

Further, the reflection optical system may be one that switches the optical path depending on time, such as a quick return mirror, or may be one that splits the optical path by dividing the light flux in the amount of light like a pellicle mirror.

According to a second aspect of the present invention, the image pickup device according to the first aspect has a rectangular shape whose major axis direction is the moving direction, and a plurality of recording areas for recording the subject images are provided in the image pickup device. It is specified by being formed side by side in the long axis direction.

According to a third aspect of the present invention, the second and third reflecting surfaces of the Porro prism of the first aspect, the finder optical axis folded back by the third reflecting surface defines a moving region of the image pickup device. This is specified by folding back the optical axis of the finder so as to avoid it.

According to a fourth aspect of the present invention, the reflective optical member according to the first aspect is selectively arranged in the photographing optical axis, and transmits through the photographing lens when arranged in the photographing optical axis. The light is reflected toward the Porro prism, and when the light is retracted from the photographing optical axis, the light that has passed through the photographing lens is passed toward the image pickup element to be specified.

According to a fifth aspect of the present invention, the Porro prism of the first aspect has an entrance surface and an exit surface, and a subject image formed on the finder optical axis is outside the exit surface of the Porro prism. It was identified by the placement of a fine loupe for enlargement.

The invention according to claim 6 is specified by the exit surface of the porro prism according to claim 5 being on the object side in the imaging optical axis direction with respect to the edge of the entrance surface on the image sensor side. . According to this structure, even if the fine loupe is arranged immediately after the exit surface, it is possible to prevent the exit surface of the fine loupe from interfering with the moving space of the image sensor, so that the moving space of the image sensor is secured. can do. That is, when the photographer looks into the fine loupe, a space (eye relief) of about 15 to 25 mm is usually placed between the exit surface of the fine loupe and the eyeball, and this space is used as the moving space of the image sensor. As a result, even when the photographer looks directly into the fine loupe, the moving space of the image pickup device can be secured.

When the camera body is projected far behind the fine loupe due to the mechanism for driving the image pickup device, the photographer may not be able to place the eyeball at the eyepoint of the fine loupe. At this time, by using an appropriate relay optical system in which the entrance pupils are substantially aligned with each other, the eye point can be moved backward, and the viewfinder can be easily observed. Even when such a relay optical system is arranged, if the exit surface of the Porro prism is arranged closer to the object side than the edge of the entrance surface on the image sensor side, the movement of the image sensor is not hindered.

According to a seventh aspect of the invention, the focal length of the fine loupe of the sixth aspect is fe, and the photographic optical axis between the finder optical axis bent by the reflective optical member and the exit surface of the Porro prism is This is specified by satisfying the expression 0 <L1 / fe <0.1 when the deviation amount in the direction is L1. This conditional expression is
The condition of claim 6 is digitized. If the upper limit of this conditional expression is exceeded, the fine loupe may interfere with the image sensor. On the other hand, when the value goes below the lower limit of this conditional expression, the eye point of the fine loupe may enter the moving space of the image sensor, and the photographer may not be able to adjust the pupil to the eye point.

The invention according to claim 8 is specified by the exit surface of the fine loupe according to claim 5 being closer to the object side than the surface of the image pickup device in the photographing optical axis direction. According to this structure, even if the fine loupe is arranged immediately after the exit surface, it is possible to prevent the exit surface of the fine loupe from interfering with the moving space of the image sensor, so that the moving space of the image sensor is secured. can do.

According to a ninth aspect of the invention, the focal length of the fine loupe of the eighth aspect is fe, and the shift amount in the direction of the photographing optical axis between the exit surface of the Porro prism and the surface of the image sensor is L2. In such a case, the expression 0.17 <L2 / fe <0.34 is satisfied, and thus it is specified. This conditional expression is
The condition of claim 8 is digitized. If the upper limit of this conditional expression is exceeded, the eyepoint of the fine loupe may enter the moving space of the image sensor, and the photographer may not be able to adjust the pupil to the eyepoint. On the other hand, if the lower limit of this conditional expression is exceeded, there is a possibility that there will be no space in which the fine loupe can be placed.

According to a tenth aspect of the present invention, the incident surface of the Porro prism of the fifth aspect is more than the lower edge surface of the portion of the Porro prism sandwiched between the second reflecting surface and the third reflecting surface. It is specified by projecting to the reflective optical member side. According to this structure, it is possible to prevent the photographing optical system and the Porro prism from interfering with each other.
That is, according to the configuration of the present invention, the Porro prism is largely projected toward the object side as compared with the penta prism. Since the imaging optical system is arranged on the photographing optical axis side of the projecting end of the Porro prism, the Porro prism may be an obstacle when the detaching and replacing operation of the photographing optical system or the operation of the diaphragm ring. However, if the incident surface is projected in this way,
Since the space between the image pickup optical system and the projecting end of the Porro prism is enlarged, the photographing operation can be smoothly performed.

According to an eleventh aspect of the present invention, the focal length of the fine loupe of the tenth aspect is fe, the lower edge surface of the portion of the Porro prism sandwiched between the second reflecting surface and the third reflecting surface, and the Porro prism. It is specified by satisfying the expression 0.08 <L3 / fe <0.25, where L3 is the distance between the entrance surface of the prism and the entrance surface in the direction of the finder optical axis. . This conditional expression is
The condition of claim 10 is digitized. If the upper limit of this conditional expression is exceeded, the distance on the optical axis of the finder from the focal plane of the finder to the finder loupe becomes too long, and the focal length of the finder loupe must be lengthened, resulting in a reduction in the magnification of the finder. There is a risk.
On the other hand, when the value goes below the lower limit of this conditional expression, the Porro prism and the image pickup optical system are too close to each other, which may hinder the shooting operation.

The twelfth aspect of the invention is specified by the Porro prism of the eleventh aspect being made of a glass material having a refractive index of 1.7 or more. With this configuration, it is possible to prevent the finder magnification from decreasing. That is, according to the description of claim 11, when the Porro prism according to the present invention is adopted, in order to avoid the proximity of the Porro prism and the photographing optical system, an ordinary penta prism (a glass material having a refractive index of about 1.5 is used). Compared with the magnification of a finder that employs an erecting optical system based on the used pentaprism), a reduction in the finder magnification cannot be avoided.
However, if the Porro prism is made of a glass material having a refractive index of 1.7 or more, the viewfinder magnification can be made the same as when a normal penta prism is used even if the condition of claim 11 is satisfied.

According to a thirteenth aspect of the present invention, a relay optical system is provided behind the fine loupe on the optical axis of the finder of the fifth aspect, with a space for the image pickup element passing between the finder and the emission surface of the fine loupe. It is specified by the arrangement of the system. According to this structure, even if the mechanism for moving the image pickup device is arranged along the image pickup device, the eye point can be set backward, so that the photographer can easily observe the viewfinder image.

According to a fourteenth aspect of the present invention, the focal length of the fine loupe of the thirteenth aspect is fe, and the distance L between the exit surface of the fine loupe and the entrance surface of the relay optical system is L.
4 is specified by satisfying the expression 0.25 <L4 / fe <0.43. This conditional expression is
The condition of claim 13 is digitized. When the value goes below the lower limit of this conditional expression, the distance between the fine loupe and the relay optical system may be too narrow to move the image sensor. On the other hand, if the upper limit of this conditional expression is exceeded, the outer diameter of the fine loupe increases, which may increase the size of the entire camera.

According to a fifteenth aspect of the present invention, in the finder optical system of a camera for recording an object image on a recording medium by projecting the object image formed by the imaging optical system on the surface of the recording medium, the imaging optical system is provided. And a recording medium, and a reflection optical member that is folded back in a direction orthogonal to the optical axis of the image pickup optical system with the image pickup optical axis of the image pickup optical system as a finder optical axis. A first reflecting surface that folds the folded finder optical axis back to the object side in parallel with the optical axis of the imaging optical system;
A second reflecting surface that folds back the finder optical axis that is folded back by the first reflecting surface in a direction orthogonal to a plane that includes the optical axis of the imaging optical system and the finder optical axis that is folded back by the reflecting optical member; An erecting optical system having a third reflecting surface that folds the finder optical axis that is folded back by the second reflecting surface toward the recording medium side in parallel with the photographing optical axis, and a finder light that is folded by the third reflecting surface. And a fine loupe arranged on the object side of an end of the first reflecting surface on the axis side of the image sensor. Thus, the recording medium of the present invention is
The image pickup device is not limited to the image pickup device, and may be, for example, a silver salt roll film for Leica-sized image pickup. Also, the erecting optical system is not limited to the Porro prism,
A reflective optical system in which the first to third reflective surfaces are respectively reflective mirrors may be used.

[0026]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

[0027]

First Embodiment (Imaging Device) First, an imaging device used in each embodiment will be described with reference to FIGS. 2 and 9.

FIG. 9 is a vertical sectional view showing the internal structure of the image pickup device 200. As shown in FIG. 9, the image sensor 2
00 is the electrostatic information recording medium 210 and the charge holding medium 211.
Is equipped with. The electrostatic information recording medium 210 includes the substrate 21.
3, electrode layer 214, inorganic oxide layer 215 and photoconductive layer 2
16 is laminated, and the photoconductive layer 216 is the charge generation layer 21.
7 and the charge transport layer 218 are polymerized. The charge holding medium 211 includes a liquid crystal support 219 and a liquid crystal electrode layer 220.
And a liquid crystal 221 is enclosed between them. The charge transport layer 218 and charge holding medium 211 of the electrostatic information recording medium 210
The liquid crystal support 219 of FIG.

Between the electrode layer 214 and the liquid crystal electrode layer 220, when the image pickup device 200 is mounted on the camera body 100 (see FIG. 2), the control power source 212 on the camera body 100 side selectively selects. The voltage is applied. And
When the electrostatic information recording medium 210 is exposed while a voltage is applied between the electrode layer 214 and the liquid crystal electrode layer 220,
In the electrostatic information recording medium 210, electric charges are generated according to the image. As a result, depending on the distribution of this charge, the liquid crystal 221
The strength of the electric field that acts on the liquid crystal changes, and the orientation of the molecules of the liquid crystal 221 changes. Therefore, when an image is projected on the electrostatic information recording medium 210, the orientation of the molecules of the liquid crystal 221 changes according to the shape of the image.

Since the liquid crystal 221 is a memory type liquid crystal made of smectic liquid crystal, when the voltage of the control power supply 212 is removed after the orientation of the molecule is changed according to the shape of the image, the state of the molecule is changed. The image is recorded while being maintained as it is. Therefore, by illuminating the liquid crystal 221 with illumination light by a known method, the recorded image can be read out visually. The liquid crystal 22
The image recorded in No. 1 is erased by heating the liquid crystal 221 to a predetermined temperature using a heating device (not shown), and in that case, the same recording medium becomes reusable.

As shown in FIG. 2, the planar shape of the image pickup device 200 is a rectangular shape, and the first shape is along the long axis direction.
-Third recording areas 201, 202, 203 are partitioned. Each of these recording areas 201, 202, and 203 is set in a laterally wide shape with its short side oriented in the major axis direction of the image sensor 200. (Still Video Camera) The configuration of the still video camera according to the first embodiment for performing color image pickup using the image pickup device 200 described above will be described below.

FIG. 1 is a perspective view of the still video camera as seen obliquely from above and front, and FIG. 2 is a perspective view of the still video camera as seen from obliquely below rear. As shown in FIG. 1, the still video camera includes a camera body 100.
And an interchangeable lens 130.

A lens mount 101 for mounting the interchangeable lens 130 is formed substantially at the center of the front surface of the camera body 100. This lens mount 101
A detachment button 102 that is pressed down when detaching the interchangeable lens 130 is provided on the side of the lens mount 10.
A window 103 for white balance adjustment is provided on the upper left side of 1. In addition, a strobe shoe 104 for mounting a strobe is provided substantially at the center of the upper surface of the camera body 100. A release button 105 is provided on the side of the strobe shoe 104. In addition, a communication connector 106 for transmitting image data to an external computer or the like is provided on the side surface of the camera body 100.

A finder window 110 is provided on the upper rear surface of the camera body 100. This window 1
Below 10, a mode setting switch 111, a drive switch 112, an AV / TV switch 113, an EF switch 114, and a white balance switch 115 are arranged side by side in the vertical direction (short axis direction of the captured image). . This mode setting switch 111 is used for the camera body 10
This is a switch for setting the shooting mode of 0. The drive switch 112 is, for example, a switch for starting a self-timer. The AV / TV switch 113 is a switch that is pressed when selecting either the aperture priority mode or the shutter speed priority mode. The EF switch 114 is a switch that is pressed when correcting the Ev value. The white balance switch 115 is a switch operated when performing white balance adjustment.

A liquid crystal display section 116 for displaying the operation mode of the camera and the like is provided on the rear surface of the camera body 100 and beside each of the switches 111 to 115. Below the liquid crystal display unit 116, the mode indicator 1
17 and a scan start button 118 are arranged side by side in a substantially horizontal direction. This mode indicator 1
Reference numeral 17 denotes a light emitting unit that lights up in different colors depending on the operation mode of the camera. Also, scan start button 11
A switch 8 is pressed in a scan mode for reading an image recorded on the image sensor 200. Below the scan start button 118, a power switch 119 that is a slide switch is provided. The power is switched from off to on according to the slide position of the power switch 119, and the operation mode of the camera is switched between the shooting mode and the scan mode by further slide.

A slot 120 for inserting the image pickup device 200 into the camera body 100 is formed at the center of the lower surface of the camera body 100. In addition, between the front side edge of the lower surface of the camera body 100 and the slot 120,
A dial 121 for mounting the image pickup device 200 in the camera body 100 is provided. This dial 121
An eject button 122 for ejecting the image sensor 200 from the slot 120 is provided next to the.
In addition, a screw hole 123 for fixing the camera body 100 to a tripod (not shown) and a lid 124 for opening and closing a battery storage portion for storing a battery (not shown) are provided on the back side of the lower surface of the camera body 100. , Respectively.

Next, the camera body 100 and the interchangeable lens 1
The internal structure of 30 will be described with reference to FIG. Figure 3
6 is a block diagram showing the internal structure of the interchangeable lens 130 when it is mounted on the lens mount 101 of the camera body 100. FIG.

System control circuit 3 in FIG.
00 is composed of a microcomputer and controls the entire camera body 100. The system control circuit 300 includes an exposure control circuit 332 and a light source 34.
0, element moving circuit 353, image pickup element driving circuit 333, element reading circuit 354, filter moving circuit 350, amplifier 355, A / D conversion circuit 356, interface circuit 3
58, the image processing circuit 357, the operation unit 360, and the display unit 116 are connected. A photometric sensor 324, a mirror drive circuit 330, and a shutter drive circuit 331 are connected to the exposure control circuit 332. The element reading circuit 354 is also connected with the line sensor 346, the element moving circuit 353, and the amplifier 355. The amplifier 355 also includes the A / D conversion circuit 35 described above.
6 is connected. The A / D conversion circuit 356 has
Further, the above-mentioned image processing circuit 357 is connected. The interface circuit 358 described above is also connected to the image processing circuit 357.

On the other hand, inside the interchangeable lens 130, a photographic optical system 301 composed of a plurality of lens groups and a diaphragm 302 for narrowing the photographic light flux passing through the image capturing optical system 301 are built in. There is. Inside the camera body 100, at the position behind (on the image side of) the photographing optical system 301, the photographing light flux is allowed to pass through at the retracted position shown by the dotted line in FIG. 3 and the descending position shown by the solid line in FIG. At, a quick return mirror 320 is provided as a reflective optical member that reflects the photographing light beam upward at a right angle. Further behind the quick return mirror 320 is a shutter 321 that allows a photographing light flux to pass by being released for a predetermined time during photographing.
It is provided. The shape of the opening (aperture) when the shutter 321 is released is in the horizontal direction (direction orthogonal to the paper surface of FIG. 3) compared to the vertical direction (vertical direction in FIG. 3).
Is a long and wide rectangular shape.

The quick return mirror 320 is driven by the mirror drive circuit 330, and the shutter 321 is driven by the shutter drive circuit 331. Further, the mirror drive circuit 330 and the shutter drive circuit 331 are
Each is controlled by the exposure control circuit 332. That is, the exposure control circuit 332 is the system control circuit 300.
When a shooting operation instruction is received from the camera, an appropriate shutter speed for performing appropriate exposure is calculated based on the light amount signal (reflecting subject brightness and aperture value) input from the light receiving element 324, and then the mirror drive circuit. Move the quick return mirror 320 from the lowered position to the retracted position with respect to 330,
Next, for the shutter drive circuit 331, the shutter 321
Open and close 3 times according to the appropriate shutter speed,
Next, the quick return mirror 320 is returned from the retracted position to the lowered position with respect to the mirror drive circuit 330.

Behind the shutter 321, the image pickup device 200 inserted from the slot 120 is arranged with the color filter 310 interposed therebetween. The image pickup device 200 is movable in the vertical direction with its long axis oriented in the vertical direction of the camera body 100. This image sensor 20
An elevating mechanism for moving 0 in the vertical direction will be described with reference to FIGS. 4 and 5. 4 is a side view showing a state in which the lifting mechanism is viewed from the same direction as FIG. 3, and FIG.
It is a top view which shows the state which looked at this raising / lowering mechanism from the upper side. In addition, in FIGS. 4 and 5, the color filter 3 is used.
The illustration of 10 is omitted.

In FIG. 4, the mounting mechanism 600 provided near the bottom of the camera body 100 mounts the image pickup device 200 inserted from the slot 120 on the image pickup device holding member 401 or the recording member holding member 401. The recording member 200 is a mechanism for ejecting the recording member 200 into the slot 120, and includes a dial 121 or an eject button 122.
It is composed of members that operate according to the operation.

The image pickup device holding member 401 is a vertically long rectangular transparent member, and the image pickup device 200 is mounted on the surface thereof.
The image sensor holding member 401 includes a pair of shafts 40.
3,404 penetrates parallel to the surface. These shafts 403 and 404 are vertically extended inside the camera body 100 such that the surface of the image sensor holding member 401 is orthogonal to the optical axis of the photographing optical system 301 (photographing optical axis l ₁ ). . As a result, the image sensor holding member 401
Is the shaft 40 inside the camera body 100.
It can be moved up and down along 3,404.

Behind the shafts 403 and 404, in parallel with the shafts 403 and 404, a vertically long parent plate 402 is provided.
Is provided. Further, a transfer screw 405 is provided further behind the parent plate 402 so as to extend parallel to the shafts 403 and 404. The transfer screw 405 is used for the support member 4 provided at the upper end of the main plate 402.
08 and the first support plate 4 fixed to the substantially central portion of the main plate 402
It is supported by 11 so as to be rotatable around its axis. On the other hand, in the main plate 402, a vertically long slit 402 a parallel to the transfer screw 405 is formed so as to face the transfer screw 405. Then, on the back surface of the image pickup element holding member 401, an engaging member 413 which is penetrated through the slit 402a and screwed into the transfer screw 405 is fixed. Therefore, the ascending / descending position of the image sensor holding member 401 is regulated by the screwing of the transfer screw 405 and the engaging member 413.

A second support plate 412 is fixed below the first support plate 411 on the back surface of the master plate 402 in parallel with the first support plate 411. A DC motor 351 whose rotation is controlled by the element moving circuit 353 is attached to the lower surface of the second support plate 412. The drive shaft of the DC motor 351 is the second support plate 412.
And a pinion gear 422 is coaxially fixed to the tip thereof. On the other hand, a transfer gear 421 meshing with the pinion gear 422 is coaxially fixed to a portion of the transfer screw 405 that penetrates and protrudes through the first support plate 411. Therefore, when the DC motor 351 rotates, the image sensor holding member 401 moves up and down along the shafts 403 and 404 via the engaging member 413. as a result,
The image pickup device 200 moves up and down in the camera body 100 in the vertical direction. That is, at the time of shooting, the image sensor 200
Is controlled by the element moving circuit 353 so that the centers of the respective recording areas 201, 202, 203 are sequentially positioned on the photographing optical axis l ₁ (that is, behind the shutter 321) (at this time, the exposure control circuit). 332 is each recording area 201,
The shutter 321 is opened and closed every time 202 and 203 are arranged on the photographing optical axis l ₁ . ). Further, at the time of reading, the image pickup device 200 is configured so that the first mirror 3 described later is used.
It is controlled by the element moving circuit 353 so as to pass between the second mirror 42 and the third mirror 344.

On the other hand, the color filter 310 has a planar shape of substantially the same size as the image pickup device 200, and has the same structure as the lifting mechanism (FIGS. 4 and 5) for the image pickup device 200 (not shown). The elevating mechanism allows movement in parallel with the image sensor 200. Specifically, the color filter 310 can overlap the image pickup device 200 without displacement and move integrally with the image pickup device 200, or can move independently of the movement of the image pickup device 200. The color filter 310 covers the first storage area 201 when overlapping with the image pickup device 200 without deviation (R).
G covering the filter element 311 and the second storage area 202
From the (green) filter element 312 and the B (blue) filter element 313 covering the third storage area 203,
Composed. The movement of the color filter 310 is controlled by the filter movement circuit 350. That is, at the time of shooting, the color filters 310 are
It overlaps with and is transferred integrally. Therefore, as long as the subject is immovable, the first recording area 201 of the image sensor 200
In the second recording area 202, an image of a red light component in the light from the subject is recorded, in the second recording area 202, an image of a green light component in the light from the subject is recorded, and in the third recording area 203,
An image is recorded by the blue light component in the light from the subject.
When reading, the color filter 310 is
The B filter element 313 remains retracted at a position overlapping the back of the shutter 321. Therefore, the first mirror 34
Only the image pickup device 200 passes between the second mirror 344 and the second mirror 344.

The image pickup element drive circuit 333 described above is shown in FIG.
The control power supply 212 is connected between the electrode layer 214 and the liquid crystal electrode layer 220 of the image pickup device 200 at the time of shooting, and the control power supply 212 is connected to the image pickup device at the time of shooting. Remove from 200. The image sensor drive circuit 333 operates according to a command signal output from the system control circuit 300.

Below the quick return mirror 320, a first mirror 342 is fixed in parallel with the quick return mirror 320 in the lowered position. Below the first mirror 342, a light source 3 including a collimator lens 341 and a light emitting element (LED) is arranged in this order from above.
40 are arranged. Since the optical axis of the collimator lens 341 is oriented in the vertical direction, the first mirror 342 is
The optical axis after being reflected by is orthogonal to the surface direction of the image sensor 200. A third mirror 344 for bending the optical axis downward is fixed at a position where the optical axis after the reflection crosses the moving path of the image sensor 200. This third mirror 34
The scanner optical system 345 and the line sensor 346 are fixed in order on the optical axis folded back by 4. The line sensor 346 is, for example, a 2000-pixel CCD one-dimensional sensor. The second mirror 343 is provided above the first mirror 342 and on the near side in FIG.
However, it is fixed in a state in which the first mirror 342 is further erected. Therefore, the light emitted from the light source 340 is
The light passes through the collimator lens 341, laterally of the first mirror 342, and is guided to the second mirror 343, where it is reflected and guided to the image sensor 200. The light emitted from the light source 340 is reflected by the first mirror 342 and the third mirror 344, respectively, and guided to the line sensor 346 through the scanner optical system 345.

Therefore, at the time of photographing, by the light reflected by the second mirror 343, in the vicinity of each recording area 201, 202, 203 of the image pickup device 200, between the images recorded in each recording area 201, 202, 203. An alignment index that indicates the relative positional relationship of is optically formed. In addition, at the time of reading, the illumination light emitted from the light source 340 is reflected by the first mirror 342, transmitted through the image pickup device 200 located between the first mirror 342 and the third mirror 344, and then the third mirror. After being reflected by 344, it is guided to the line sensor 346. At this time, the image pickup device 200 is moved by the horizontal scanning line by the stepping motor 352 at low speed. Therefore, the image sensor 20
The recording areas 201, 202, and 203 of 0 move between the first mirror 342 and the third mirror 344 in the direction orthogonal to the optical path of the illumination light. Therefore, the image sensor 200
The components on each horizontal scan line that make up the image recorded in
It is illuminated by the light source 340, and an image is formed on the light receiving surface of the line sensor 346.

The on / off control of the light source 340 is performed by the system control circuit 300, and the line sensor 3
The read operation of the pixel signal generated at 46 is performed by the element reading circuit 3
Controlled by 54. Further, the element moving circuit 353 is
The DC motor 351 is controlled while receiving the synchronization signal from the element reading circuit 354. The element moving circuit 353 and the element reading circuit 354 are controlled by the system control circuit 300.

The pixel signal read from the line sensor 346 is amplified by the amplifier 355, and the A / D converter 3
It is converted by 56 into a digital pixel signal. Under the control of the system control circuit 300, this digital pixel signal is subjected to processing such as shade correction and gamma correction in the image processing circuit 357. And
The pixel signal after this processing is the interface circuit 358.
Has undergone certain processing such as format conversion,
It is output to an external computer (not shown) or the like via the communication connector 106 (see FIG. 2). The interface circuit 358 and the image processing device 357 operate according to a command signal from the system control circuit 300.

An operation section 360 including switches such as a release button 105 provided on the camera body 100 is connected to the system control circuit 300. The system control circuit 300 performs a shooting operation, an image signal reading operation, and the like according to the operation of the operation unit 360. A liquid crystal display unit 116 (see FIG. 2) for displaying various setting states of the camera body 100 is connected to the system control circuit 300.

Next, the configuration of the finder optical system in the camera body 100 will be described in detail with reference to FIGS. 6 and 7 which are optical configuration diagrams in which only the optical system is extracted from FIGS. 4 and 5.

When the quick return mirror 320 is in the lowered position, the surface of the quick mirror 320 intersects the photographing optical axis l _{1 at} an angle of 45 degrees. Therefore, the photographing optical axis l ₁ is turned up by 90 degrees by the surface of the quick return mirror 320.
The optical axis after being folded back in this way is hereinafter referred to as a finder optical axis l ₂ .

[0055] On the surface optically equivalent position of the imaging device 200 in the finder optical axis 1 on _2, (upper surface in FIG. 6, the same below) the upper surface of the focusing screen 326 which serves as a focal plane is arranged There is. Therefore, when the quick return mirror 320 is in the lowered position, an object image is formed by the imaging optical system 301 on the upper surface of the focusing plate 326. As shown in FIG. 5, the planar shape of the focusing plate 326 is a substantially rectangular shape corresponding to the shape of the image captured by the image sensor 200 (the shape of the aperture of the shutter 321).

From the top of the focusing plate 326, the viewfinder optical axis l
A plano-convex lens-shaped condenser lens 327 having a lower surface (lower surface in FIG. 6, hereinafter the same) as a plane is arranged at a position separated by 1.60 mm along the line ₂ . The condenser lens 327 is made of a glass material having a refractive index of 1.80518. And this condenser lens 327
Has a radius of curvature of 78.0 mm and a thickness on the finder optical axis l ₂ of 3.50 mm.

At a position 0.10 mm away from the upper surface of the condenser lens 327 along the finder optical axis l ₂ , a Porro prism 322 which is an erecting optical system has an incident surface 322.
It is arranged such that a is orthogonal to the finder optical axis l ₂ . FIG. 8 is a perspective view of the Porro prism 322. This Porro prism 322 has a refractive index of 1.77250.
6 to 8, the first reflecting surface 322b for vertically reversing the image together with the quick return mirror 320, and the second reflecting surface 322b for horizontally reversing the image are formed.
It has a reflective surface 322c and a third reflective surface 322d.

To describe the shape of the Porro prism 322 in more detail, the center of the first reflecting surface 322b is formed so that the finder optical axis l ₂ is folded back 90 degrees toward the object side and parallel to the photographing optical axis l ₁ . At a tilt angle of 45 degrees with respect to the finder optical axis l ₂ . The distance from the incident surface 322a to the first reflecting surface 322b on the finder optical axis l ₂ is 22.0 mm, which is longer than the half value of the vertical width of the optical path after being reflected by the first reflecting surface 322b. That is, the incident surface 322a is the lower surface (the third reflecting surface 322d of the Porro prism 322) in the other portion of the Porro prism 322.
Lower edge surface 322 of a portion sandwiched between the output surface 322e and the output surface 322e.
g), protruding by 10.5 mm (L3).

The second reflecting surface 322c has a finder optical axis l.
_{2 so as} to be folded back 90 degrees to the left when viewed from the side of the image pickup device 200, and at the center thereof, 45 with respect to the finder optical axis l ₂ .
They are intersecting at an angle. The distance from the first reflecting surface 322b to the second reflecting surface 322c on the finder optical axis l ₂ is 23.5 mm.

The third reflecting surface 322d has a finder optical axis l.
₂ is folded back to the side of the image sensor 200 by 90 degrees so as to be parallel to the photographing optical axis l ₁ and intersects the viewfinder optical axis l _{2 at} an angle of 45 degrees. The distance from the second reflecting surface 322c to the third reflecting surface 322d on the finder optical axis l ₂ is 27.5 mm.

The exit surface 322e intersects the finder optical axis l _{2 at} a right angle. Third reflective surface 322d
To the exit surface 332e is 27.0 mm. Therefore, the difference from the distance (23.5 mm) from the first reflecting surface 322b to the second reflecting surface 322c, that is, the photographing optical axis l between the finder optical axis l ₂ incident on the entrance surface 322a and the exit surface 322e. The distance (L1) in the direction of ₁ is
It is 3.5 mm. Further, the distance from the surface of the quick return mirror 320 to the surface of the image pickup device 200 on the photographing optical axis l ₁ is 22.0 mm, and therefore the exit surface 322e.
To the surface (extension surface) of the image sensor 200 (L
2) is 18.4 mm. Furthermore, the exit surface 322e
Is displaced from the edge of the incident surface 322a on the image pickup device 200 side by 8.5 mm in parallel with the image pickup optical axis l ₁ . The distance from the entrance surface 322a of the Porro prism 322 along the finder optical axis l ₂ to the exit surface 322e is 1
It will be 00 mm.

The air-equivalent distance s from the upper surface (focus surface) of the focusing plate 326 to the exit surface 322e of the professional prism 322 is calculated based on the above-described data, and is represented by the following equation (1).

S = 1.6 + 3.5 / 1.80518 + 0.1 + 100 / 1.77250 = 60.06 [mm] (1) At a position 0.10 mm away from the exit surface 322e of the Porro prism 322 along the viewfinder optical axis l _2. A first fine-dalupe system 323 composed of a positive lens system is arranged coaxially with the finder optical axis l ₂ . The thickness of the entire first fine-daloop system 323 along the finder optical axis l ₂ is 6.5 mm. Therefore, the exit surface of the _first fine-dalupe system 323 exists closer to the object side than the edge of the entrance surface 322a on the imaging element 200 side in the direction parallel to the photographing optical axis l ₁ . Therefore, the image sensor 200, the image sensor holding member 401, and the shaft 403 do not interfere with the first fine loupe system 323.

The focal length (fe) of the first fine loupe system 323 is 63.11 mm. Each distance L mentioned above
The ratios of 1 to L3 to fe are as follows, respectively. L1 / fe = 0.06 L2 / fe = 0.29 L3 / fe = 0.17 first finder magnifier system along the exit surface 323 to the finder optical axis l ₂ 21.91mm (L4) to a position separated , A relay optical system 3 of the same size for displacing the eye point in a direction away from the first fine loupe system 323.
25 are arranged. Therefore, this relay optical system 32
5, in the direction of the finder optical axis l _2, the image pickup element 2
00, the image pickup device holding member 401, and the shaft 403. The ratio of the distance L4 to fe is as follows. L4 / fe = 0.35 Further, the finder optical axis l ₂ passes through the side of the image sensor 200 between the first fine-dalupe system 329 and the relay optical system 325.

At a position 1.00 mm away from the exit surface of the relay optical system 325 along the finder optical axis l ₂ , the image formed by the first fine-dalupe system 323 and the relay optical system 325 is horizontally and vertically inverted. An erecting prism 328 is arranged to cause the erecting.

A second fine-dalupe system 329 for magnifying and observing the real image inverted by the erecting prism 328 at a position 1.02 mm away from the exit surface of the erecting prism 328 along the finder optical axis l ₂ . Are arranged.

Specific lens data of the finder optical system described above (an optical system from the focus surface to the exit surface of the second finder dupe system 329 along the finder optical axis l ₂ ) is shown below. In the following, the surface No. is the number of each surface counted from the focus surface as the starting point. Specifically, No. 1 is the focusing surface, and Nos. 2 and 3 are condenser lenses 3.
The entrance and exit surfaces of No. 27, Nos. 4 to 5 are Porro prism 3
22 entrance and exit surfaces (each reflecting surface is omitted), No. 6-
8 is each surface of the first fine loupe system 323, No. 9 to 1
5 is each surface of the relay optical system 325, No. 16 to 19 are each surface of the erecting prism 328 (including each reflecting surface), No. 20 to
Reference numeral 26 indicates each surface of the second fine loupe system 329. Further, r is the radius of curvature of each surface. Further, d is the distance on the optical axis to the next surface. Further, n is the refractive index of the material up to the next surface with respect to the d-line (air is omitted). Also, ν is the Abbe number. Surface No. r d n ν 1 ∞ 1.60 2 ∞ 3.50 1.80518 24.5 3 -78.00 0.10 4 ∞ 100.00 1.77250 49.6 5 ∞ 0.10 6 38.13 5.70 1.74400 44.8 7 -43.00 0.80 1.80518 25.4 8 320.00 21.91 9 -7.60 1.20 1.80518 24.5 10 21.27 7.10 1.55963 61.2 11 -14.79 0.58 12 -39.01 3.02 1.78590 44.2 13 -18.00 0.24 14 59.20 2.80 1.71700 47.9 15 -30.39 1.00 16 ∞ 49.71 1.51633 64.1 17 ∞ 0.90 18 ∞ 29.72 1.56883 56.3 19 ∞ 1.02 20 94.43 3.20 1.80610 40.9 21 -52.20 22 27.00 3.65 1.74400 44.8 23 1430.84 0.24 24 21.95 3.89 1.62280 57.0 25 54.40 1.20 1.80518 25.4 26 20.14 On the other hand, as shown in FIG. 5, on the side of the first fine loupe system 323 on the exit surface 322e of the Porro prism 322, a focus is formed. A condenser lens 330 for condensing the light diffused from the plate 326 is arranged. This condenser lens 3
Behind 30 is provided a photometric sensor 324 for receiving the light converged by the condenser lens 330 and detecting the brightness of the focusing plate 326. This photometric sensor 3
The output of 24 is input to the exposure control circuit 332 as described above, and is displayed on the information display member in the camera body surface or in the viewfinder as a photometric value for the image sensor of the subject, and the photographer determines the exposure condition at the time of shooting. It is used when doing. (Operation of Embodiment) Next, an operation of the still video camera according to the present embodiment configured as described above will be described.

The image pickup device 200 includes an image pickup device holding member 40.
When 1 is at the lowermost position of the shafts 403, 404,
It can be mounted on the image sensor holding member 401 by the mounting mechanism 600. That is, the image sensor 200 is in the slot 1
When it is inserted from 20 and the dial 121 is rotated,
A rubber roller (not shown) in the mounting mechanism 600 rotates to mount the image sensor 200 at a predetermined position of the image sensor holding member 401.

When the image pickup device 200 is mounted on the image pickup device holding member 401 in this way, the system control circuit 300 controls the device movement circuit 353 and the filter movement circuit 350, and the first recording area 2 of the image pickup device 200 is controlled.
01 and the R filter element 311 of the color filter 310 are positioned in the photographing optical axis l ₁ (behind the shutter 321). At this time, the shutter 321 remains closed and the quick return mirror 320 is in the lowered position. Therefore,
The light beam that has passed through the photographing optical system 301 is reflected by the quick return mirror 320 and guided to the focusing plate 326. As a result, a subject image is formed on the focusing plate 326 in a focused state according to the focus adjustment state of the imaging optical system 301. The light diffused by the focusing plate 326 is incident on the incident surface 322 a of the Porro prism 322 via the condenser lens 327. And this Porro prism 32
2 is reflected toward the object side by the first reflecting surface 322b along the finder optical axis l ₂ , and the second reflecting surface 32
2c is reflected to the left side when viewed from the photographer side, is reflected to the photographer side by the third reflection surface 322d, and is emitted from the exit surface 32.
It is emitted from 2e. Then, the emitted light enters the first fine-daloop system 323. Since the focal length of the first fine-dalupe system 323 is longer than the air-equivalent distance of the optical path from the focusing plate 326, the first fine-dalupe system 323 changes the virtual image of the real image of the subject image on the focusing plate 326 to the object side. To form. This virtual image is relayed by the relay optical system 325, subjected to left-right and up-down reversal by the erecting prism 328, magnified by the second fine-dalupe system 329, and observed by the photographer.

Here, when the photographer presses the release button 105 of the operation unit 360, the photographing operation by the system control circuit 300 is started. That is, under the control of the exposure control circuit 332, the quick return mirror 320 moves to the retracted position, the shutter 321 opens and closes according to the appropriate shutter speed, and the image of the red light component is recorded in the first recording area 201. It After the shutter 321 is closed, under the control of the element moving circuit 353 and the filter moving circuit 350, the image pickup device 200 and the color filter 310 rise, and the second recording area 202 and the G filter element 312 are in the photographing optical axis l ₁ . It is located behind the shutter 321. Then, the shutter 321 is opened and closed again, and an image based on the green light component is recorded in the second recording area 202. Similarly, after the shirt 321 is closed, the third recording area 2
03 and the B filter element 313 are positioned in the photographing optical axis l ₁ (behind the shutter 321), the shutter 321 is opened and closed again, and an image based on the blue light component is displayed in the third recording area 20.
It is recorded in 3.

When the shutter 321 is closed and the recording of the image by the blue light component is completed, the image pickup element holding member 4 is controlled under the control of the element moving circuit 353 and the filter moving circuit 350.
01 and the image sensor 200 are lowered to the initial position, and the quick return mirror 320 is returned to the lowered position under the control of the exposure control circuit 332. This allows the photographer to view the subject image again through the viewfinder optical system.

As described above, in this embodiment,
Second reflecting surface 322c and third reflecting surface 322
finder light emitted from the emission surface 322e by d
Axis l ₂Is in a plane parallel to the surface of the image sensor 200.
At the finder optical axis l which is incident from the incident surface 322a.
₁It is shifted laterally from the position. Therefore, the first
Finder optical axis l from the fine loupe system 323₂
Is the movement path RS of the image sensor 200 and the shaft 403.
Pass between Therefore, it is incident from the viewfinder window 110.
Then the second fine-dalupe system 329, erecting prism 32
8 and external light transmitted through the relay lens 325
Do not expose the image element 200 from the back side.
Yes. Also, the finder optical axis l₂Shoot optical path l₁Must be separated from
Since there is no need to change the size of the entire camera body 100 in the vertical direction
It does not become large. Also, the finder optical axis l₂of
The shift amount in the lateral direction is determined by the movement path RS of the image sensor 200.
Has been kept to a minimum to avoid interference with
To increase the overall size of the camera body 100 in the horizontal direction.
Never.

The exit surface 322 of the Porro prism 322
e is displaced toward the object side with respect to the edge of the incident surface 322a on the image pickup device 200 side, and the first fine-daloop system 323 is arranged in the space formed by the displacement. Therefore, the exit surface of the first fine-daloop system 323 is located closer to the object side in the direction of the photographing optical axis l ₁ than the surface of the image sensor 200. Therefore, at the time of shooting, the first fine loupe system 323 causes the color filter 3 to
The interference with the image pickup device 200, the image pickup device 200, and the image pickup device holding member 401 is prevented.

Further, the entrance surface 322 of the Porro prism 322
Since a projects from the lower surface of the other portion of the Porro prism 322 (the lower edge surface 322g of the portion of the Porro prism 322 which is sandwiched between the third reflection surface 322d and the emission surface 322e), Two
The portion sandwiched by the reflecting surface 322c and the third reflecting surface 322d, that is, the portion protruding toward the object side is separated above the focusing plate 326 and the condenser lens 327. Therefore, the lens mount 10 positioned closer to the image sensor 200 than the ridgeline between the second reflecting surface 322c and the third reflecting surface 322d.
Even if the interchangeable lens 130 is attached to the lens 1, the outer periphery of the interchangeable lens 130 does not interfere with the Porro prism housing portion 100a of the casing of the camera body 100. Further, when the interchangeable lens 130 is attached, the aperture ring and the distance ring (not shown) of the image pickup lens are operated and the image pickup lens 130 is
A space is secured for attaching and detaching.

A space through which the color filter 310, the image pickup device 200, and the image pickup device holding member 401 can pass is formed between the output face of the first fine-dalupe system 323 and the input face of the relay lens 325. There is. Therefore,
Despite adopting the configuration in which the eye point of the finder is moved rearward by the relay lens 325, the erecting prism 327, and the second fine loupe system 328, these optical systems 325, 327, 3 are used at the time of shooting.
28 is prevented from interfering with the color filter 310, the image sensor 200, and the image sensor holding member 401.

[0076]

Second Embodiment FIG. 10 is an optical configuration diagram showing an optical system according to a second embodiment of the present invention. As shown in FIG.
The second embodiment is characterized in that the relay lens 325, the erecting prism 327, and the second fine-daloop system 328 are omitted as compared with the first embodiment.
Such a configuration is possible when the space occupied by the mechanism arranged behind the image sensor 200 is small in the direction of the finder optical axis l ₂ . In the case of such a configuration, the photographer directly observes the subject image on the focusing plate 326 by focusing on the eye point of the first fine-dalupe system 328. The eye point of the first fine loupe system 328 is set outside the finder window 110.
Then, on the finder optical axis l ₂ , a space through which the color filter 310, the image sensor 200, and the image sensor holding member 401 can pass is formed between the exit surface of the first finder dupe system 323 and the finder window 110. Has been done. Therefore, it is possible to prevent the viewfinder window 110 and the eyes of the photographer from interfering with the color filter 310, the image pickup device 200, and the image pickup device holding member 401 during photographing. Other configurations in the second embodiment, such as the distances L1, L2, L3 and the focal length fe, are the same as those in the first embodiment, and therefore the description and illustration thereof are omitted.

[0077]

According to the finder optical system of the camera of the present invention configured as described above, it is possible to prevent the finder optical axis from interfering with the moving space of the image sensor without increasing the size of the entire camera. You can

[Brief description of drawings]

FIG. 1 is a perspective view of a still video camera according to a first embodiment of the present invention as viewed from the front upper side.

FIG. 2 is a perspective view of the still video camera and the image sensor of FIG. 1 as viewed from the lower rear side.

FIG. 3 is a block diagram showing an internal configuration of the still video camera shown in FIG.

FIG. 4 is a side view of a mechanism for raising and lowering an image sensor in the camera body and its vicinity.

FIG. 5 is a top view of a mechanism for raising and lowering an image sensor in the camera body and its vicinity.

FIG. 6 is an optical configuration diagram in which only the optical system is extracted from FIG.

FIG. 7 is an optical configuration diagram in which only the optical system is extracted from FIG.

FIG. 8 is a perspective view of a professional prism.

FIG. 9 is a vertical cross-sectional view showing the configuration of an image sensor.

FIG. 10 is an optical configuration diagram showing a configuration of a finder according to a second embodiment of the present invention.

[Explanation of symbols]

200 image sensor 320 quick return mirror 322 Porro prism 322a entrance surface 322b First reflection surface 322c Second reflective surface 322d Third reflective surface 322e exit surface 323 1st fine loupe system 325 Relay optical system 326 focus plate 401 image sensor holding member RS moving passage

─────────────────────────────────────────────────── ─── Continuation of the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) G03B 13/06 H04N 5/225

Claims (15)

(57) [Claims] 1. A camera for recording a subject image on an image pickup device by projecting the subject image formed by an image pickup optical system on the surface of the image pickup device and moving the image pickup device in one direction along the surface. In the finder optical system, the reflective optical member is arranged between the image pickup optical system and the image pickup element, and is folded back in the moving direction of the image pickup element with the photographing optical axis of the image pickup optical system as the finder optical axis. A first reflecting surface that folds the finder optical axis that is folded back by the reflective optical member toward the object side, and the finder optical axis that is folded back by the first reflecting surface is moved in a plane parallel to the surface of the imaging element. A second reflecting surface that is folded back in a direction orthogonal to the direction, and a finder optical axis that is folded back by the second reflecting surface is parallel to the photographing optical axis. A Porro prism having a third reflecting surface that folds back to the image pickup device side, and a fine loupe that is arranged closer to the object side than the end of the first reflecting surface on the image pickup device side on the finder optical axis that is folded back by the third reflecting surface. A finder optical system for a camera, characterized by including. 2. The image pickup device has a rectangular shape whose major axis direction is the moving direction, and a plurality of recording areas for respectively recording the subject images are formed side by side in the long axis direction of the image pickup device. The finder optical system for a camera according to claim 1. 3. The second reflecting surface and the third reflecting surface of the Porro prism are arranged so that the finder optical axis folded back by the third reflecting surface passes through a moving area of the image pickup device. The viewfinder optical system for a camera according to claim 1, wherein the axis is folded back. 4. The reflection optical member is selectively arranged in the photographing optical axis, and when arranged in the photographing optical axis, reflects the light transmitted through the photographing lens toward the Porro prism. The finder optical system for a camera according to claim 1, wherein the light transmitted through the photographing lens is passed toward the image pickup device when the light is retracted from the photographing optical axis. 5. The Porro prism has an entrance surface and an exit surface, and a finder magnifier for enlarging a subject image formed on the finder optical axis is disposed outside the exit surface of the Porro prism. The finder optical system for a camera according to claim 1, wherein: 6. A finder optical system for a camera according to claim 5, wherein the exit surface of said Porro prism is located closer to the object side in the direction of said photographing optical axis than the edge of said entrance surface on the side of the image sensor. 7. The focal length of the fine loupe is fe,
When the deviation amount in the direction of the photographing optical axis between the finder optical axis bent by the reflective optical member and the exit surface of the Porro prism is L1, the expression 0 <L1 / fe <0.1 is satisfied. 7. The viewfinder optical system for a camera according to claim 6, wherein. 8. A finder optical system for a camera according to claim 5, wherein the exit surface of the fine loupe is closer to the object side in the photographing optical axis direction than the surface of the image pickup device. 9. The focal length of the fine loupe is fe,
When the amount of deviation in the direction of the photographing optical axis between the exit surface of the Porro prism and the surface of the image sensor is L2, the expression 0.17 <L2 / fe <0.34 is satisfied. The finder optical system of the camera according to claim 8. 10. An incident surface of the Porro prism projects toward the reflective optical member side more than a lower edge surface of a portion of the Porro prism sandwiched between the second reflective surface and the third reflective surface. The viewfinder optical system of the camera according to claim 5. 11. The focal length of the fine loupe is f
e, the second reflection surface and the third reflection surface of the Porro prism
When the distance in the direction of the finder optical axis that is incident on the incident surface between the lower edge surface of the portion sandwiched by the reflective surfaces and the incident surface of the Porro prism is L3, the formula 0.08 <L3 / The finder optical system for a camera according to claim 10, wherein fe <0.25 is satisfied. 12. A finder optical system for a camera according to claim 11, wherein said Porro prism is made of a glass material having a refractive index of 1.7 or more. 13. A relay optical system is disposed behind the fine loupe on the optical axis of the finder with a space between the image pickup element and the exit surface of the fine loupe. The viewfinder optical system of the camera according to claim 5. 14. The focal length of the fine loupe is f
The equation 0.25 <L4 / fe <0.43 is satisfied, where e is the distance L4 between the exit surface of the fine loupe and the entrance surface of the relay optical system. Viewfinder optics of the camera. 15. A viewfinder optical system of a camera for recording a subject image on a recording medium by projecting the subject image formed by the imaging optical system onto the surface of the recording medium, comprising: A reflective optical member that is arranged between the reflective optical member and the imaging optical axis of the imaging optical system and is folded back in a direction perpendicular to the optical axis of the imaging optical type with the optical axis of the imaging optical system as a viewfinder optical axis. The optical axis of the imaging optical system parallel to the optical axis of the imaging optical system
Reflection surface, second reflection in which the finder optical axis folded back by the first reflection surface is folded back in a direction orthogonal to a plane including the optical axis of the imaging optical system and the finder optical axis folded back by the reflection optical member. An erecting optical system having a surface and a third reflecting surface that folds the finder optical axis that is folded back by the second reflecting surface toward the recording medium side in parallel with the photographing optical axis, and is folded by the third reflecting surface. A finder optical system for a camera, further comprising: a finder magnifier arranged on the object side of an end of the first reflecting surface on the image sensor side on the finder optical axis.