JPH0943506A - Camera - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a camera which has both photographic function of silver bromide photographic and video photographic, and is capable of highly precise range finding without having an AF mirror retracting mechanism. SOLUTION: This camera is provided with a photographic lens 1 which forms the image of the subject to be photographed, a main mirror M1 which divides the luminous flux that passes the lens M1 into first and second luminous fluxes L1 and L2, respectively, a silver bromide photographic system G provided with a shutter 6 at the front thereof so that a film 8 is placed at the position where the flux L1 forms an image, a semitransparent surface HM which divides the flux L2 into third and fourth luminous fluxes L3 and L4, respectively, a video photographic system V which has an imaging device 18 at the position where an image is formed by the flux L3 and a range finding element SE which measures the range using the flux L4 and a phase difference detecting system.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a camera, for example, a single-lens reflex camera or a camera capable of silver halide photography and video photography (including electronic photography still photography and movie photography). It is a thing.

[0002]

2. Description of the Related Art In a general single-lens reflex camera, distance measurement is performed by a distance measuring element arranged at the bottom of a mirror box of a camera body. Then, in order to guide the distance measuring light flux to this distance measuring element, AF (aut
ofocus) Mirror is placed. As the main mirror, a total reflection mirror that jumps up during film exposure is generally used, but a fixed half mirror (for example, pellicle mirror)
A camera used as a main mirror is also known. In either case, it is necessary to retract the AF mirror from the optical path during film exposure. Also, with a typical video camera, shooting is performed with an electronic photography method,
The image pickup element is also used as a distance measuring element, and the distance is measured by a contrast detection method.

[0003]

The single-lens reflex camera described above requires a mechanical mechanism for retracting the AF mirror from the optical path, which causes a problem that the configuration becomes complicated and large. On the other hand, in the above video camera,
Since the distance measurement is performed by the contrast detection method, there is a problem that the distance measurement accuracy is low. In addition, since the required performance cannot be satisfied in shooting that requires a high distance measurement such as silver salt photography, the camera cannot have both silver salt photography and video shooting functions. There is also. If the phase difference detection method is adopted, the distance measurement accuracy will be high and silver salt photography will be possible, but for that purpose, the AF mirror and its retracting mechanism for guiding the light flux for distance measurement to the distance measuring element are used. You will need it. Therefore, the same problem as in the single-lens reflex camera occurs.

The present invention has been made in view of the above points, and an object thereof is to provide a camera capable of performing distance measurement without providing a retracting mechanism for an AF mirror. Another object of the present invention is to provide a camera having both a silver salt photography function and a video shooting function and capable of performing distance measurement with high accuracy.

[0005]

In order to achieve the above object, a camera according to a first aspect of the present invention divides a photographing lens that forms a subject image and a luminous flux that has passed through the photographing lens so that a finder is formed from the luminous flux. First light splitting means for extracting a light beam for use in the distance measurement, second light splitting means for extracting a light flux for distance measurement from the light flux for splitting the light flux for the finder, and distance measuring light extracted by the second light splitting means And a distance measuring element for performing distance measurement using a light flux.

According to the structure of the first invention, the distance measuring light beam is obtained by splitting the finder light beam by the second light splitting means, so that the AF mirror and the retracting mechanism for the AF mirror are used for distance measuring. Is not necessary either. In addition, since the finder light beam is always generated by the first light dividing means and the distance measuring light beam is generated by the second light dividing means, the distance measuring element always receives the distance measuring light beam.

A second invention is characterized in that, in the structure of the first invention, the second light splitting means is located in the vicinity of the image plane of the image formed by the finder light beam. According to the configuration of the second invention, the size of the second light splitting means can be smaller than that of the case where the second light splitting means is located away from the vicinity of the image plane.

According to a third aspect of the present invention, a photographic lens for focusing light from a subject, a first light splitting means for splitting a light flux after passing through the photographic lens into a first light flux and a second light flux, and the first invention. A silver salt photography system provided with a shutter in front of the photosensitive member so that the photosensitive member can be positioned at the position of the image formed by the luminous flux, and the second luminous flux is divided into a third luminous flux and a fourth luminous flux. A second light splitting means, a video shooting system having an image pickup device at the position of the image formed by the third light flux, and a distance measuring element for performing distance measurement by the phase difference detection method using the fourth light flux. , Are provided.

According to the structure of the third invention, the fourth light flux used for the distance measurement of the phase difference detection method is obtained by dividing the second light flux by the second light splitting means, so that the fourth light flux is used for distance measurement. Neither the AF mirror nor the retracting mechanism for the AF mirror is necessary. Further, the second light flux is always generated by the first light splitting means and the fourth light flux
Since the light flux is generated by the second light splitting means, the distance measuring element receives the fourth light flux even during the silver halide photography.

In a fourth aspect based on the configuration of the third aspect, the second light splitting means is located near the image plane of the primary image formed by the second light flux before reaching the image pickup device. It is characterized by doing. According to the structure of the fourth invention, the second light splitting means can be made smaller than when it is located away from the vicinity of the image plane.

According to a fifth aspect of the present invention, in the configuration of the third aspect of the invention, the curtain surface of the shutter has a reflectance substantially equal to that of the photosensitive member, and the reflected light on the curtain surface of the shutter is formed. An image forming lens for forming an image is provided, and the photometric element is arranged so that the image formed by the image forming lens is positioned on the light receiving surface. According to the configuration of the fifth invention, an image is formed on the light receiving surface of the photometric element by the reflected light on the curtain surface of the shutter.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A camera embodying the present invention will be described below with reference to the drawings. FIG. 1 shows a vertical sectional structure of the first embodiment, and FIGS. 2 to 4 show a condenser lens 11 constituting the present embodiment.

The camera of this embodiment comprises a lens barrel OP and a camera body BO. In the lens barrel OP, a taking lens 1 and a taking lens 1 for forming a subject image
A diaphragm 2 that regulates a light beam that has entered the diaphragm 2 and a diaphragm controller 3 that controls the diaphragm 2 are provided. On the other hand, in the camera body BO, there are provided a main mirror M1, a silver salt photography system G, a video photography system V, a photometry element SE, a distance measurement element SF and the like.

The main mirror M1 is a fixed half mirror (for example, a fixed half mirror that splits the light flux after passing through the taking lens 1 into a first light flux L1 for silver salt photography and a second light flux L2 for finder and video photography. Pellicle mirror). In the figure, each light flux is represented by a paraxial ray.

The video shooting system V is a part of the second light flux L2.
An image sensor 18 including an area CCD (Charge Coupled Device) at the position of the secondary image I2 formed by (third light flux L3)
And condenser lenses 11 and 12, a total reflection mirror M2, an ND filter 13, an ND filter control unit 14, a relay lens 15, a relay diaphragm 16, and a relay diaphragm control unit 17.

The second light beam L2 extracted by the light beam splitting by the main mirror M1 is first of all the condenser lens 1
It is incident on 1 and 12. Condenser lens 11, 12
Is a condenser lens for guiding a part of the second light flux L2 (third light flux L3) to the relay lens 15, and a primary image I1 is formed as an aerial image in the vicinity of the incident surface thereof. In a normal single-lens reflex camera, a focusing plate (diffusing plate) is provided near the image plane of the primary image I1.
However, in the present embodiment, the focusing screen is not provided in order to prevent the quality of the video shot image from deteriorating.

As shown in FIG. 4, the condenser lens 11 is composed of three lens pieces, and a semi-transmissive film is formed on one plane of one lens piece so that the semi-transmissive film is positioned inside the lens. It is a combination of two lens pieces. As shown in FIG. 1, the condenser lens 11 has a semi-transmissive surface HM formed of the semi-transmissive film at a position near the image plane of the primary image I1 formed by the second light flux L2 before reaching the image sensor 18. It is positioned so that it is positioned.

In this way, the semi-transmissive surface HM passes through the second light flux L2.
If it is located near the image plane of the image formed by
Since the size of the semi-transmissive surface HM is smaller than that when M is located away from the vicinity of the image plane, the size of the semi-transmissive surface HM can be reduced. This makes it possible to avoid the structures of the semi-transmissive surface HM and the condenser lens 11 from becoming complicated and large. Further, since the light beam splitting is performed in the optical path of the light beam after passing through the taking lens 1, an interchangeable lens for a conventional single-lens reflex camera can be used as the taking lens 1. On the other hand, if the photographic lens 1 is constructed so that the light flux for distance measurement is taken out from the middle of the photographic lens 1, the photographic lens 1 must be provided with a light splitting means, a distance measuring element, etc. The lens cannot be used. Instead of the condenser lens 11 having the semi-transmissive surface HM, a half mirror corresponding to the semi-transmissive surface HM may be used in combination with the condenser lens.

Here, a concrete example of the condenser lens 11 is shown in FIGS. FIG. 2 shows a condenser lens 11 used when distance measurement is performed only in the center of the shooting range. On the other hand, FIG. 3 shows a condenser lens 11 used when performing wide-focus distance measurement (multipoint distance measurement), and therefore the semi-transmissive surface HM is larger than that provided in the condenser lens 11 of FIG. Has become.

The second light flux L2 extracted by the main mirror M1 is split by the semi-transmissive surface HM into a third light flux L3 for video shooting and a fourth light flux L4 for distance measurement. Then, the third light flux L3 transmitted through the semi-transmissive surface HM is ND filter 13
The secondary image I2 is formed on the image sensor 18 by moving to the side. On the other hand, on the side of the condenser lens 11, an imaging lens 5 for forming an image of the fourth light flux L4 reflected by the semi-transmissive surface HM and a distance measuring element SF composed of a line CCD are arranged. An image of L4 is formed on the distance measuring element SF by the image forming lens 5. Then, based on the AF information obtained by the distance measuring element SF, the phase difference detection type AF is performed. Since the phase difference detection method and the contrast detection method have advantages and disadvantages, respectively, AF in the phase difference detection method using the distance measuring element SF and AF in the contrast detection method using the image sensor 18 are different. A switchable configuration is preferable.

A total reflection mirror M2 is arranged behind the condenser lens 12. The third light flux L3 reflected by the total reflection mirror M2 enters the disc-shaped ND filter 13. The ND filter 13 is a light amount limiting unit that limits the light amount of the third light flux L3 toward the image sensor 18.
Since the ND filter 13 is formed with a region having a different transmittance for each predetermined rotation angle range, it is desired to rotate the ND filter 13 to position an appropriate region in the optical path of the third light flux L3. It can be dimmed by the transmittance. The control of the rotational angle position of the ND filter 13 is performed by the ND filter control unit 14 based on the photometric value obtained by the photometric element SE described later.

The third light flux L passing through the ND filter 13
3 enters the relay lens 15. Relay lens 15
So that a secondary image I2 is formed on the image sensor 18,
The third light flux L3 is guided to the image sensor 18. Further, in the relay lens 15, a relay diaphragm (iris diaphragm) 16 that restricts the light quantity of the third light flux L3 toward the image sensor 18 is provided as a light quantity limiting means. The aperture control of the relay aperture 16 is performed by the relay aperture control unit 17 based on the photometric value obtained by the photometric element SE described later.

As described above, since the ND filter 13 is used together with the relay diaphragm 16 as a means for limiting the amount of light to the image pickup device 18, even if the absolute value of the relay diaphragm 16 is unknown, a small aperture blur occurs. It is possible to prevent the deterioration of the image quality due to the small aperture blur.

Secondary image I2 formed on the image pickup device 18
Will be recorded in a recording medium (not shown) by a signal from the image sensor 18 in the electrophotographic system. Video recording is completed by recording the image on the recording medium, but the signal from the image pickup device 18 is also used for displaying the image on the liquid crystal finder (not shown). While looking at the LCD finder, the user turns on a release button (not shown) to take a silver salt photograph (a half-press of the release button starts photometry, and a full-press starts film exposure). By turning on a recording button (not shown), a movie or still video is shot.

Although the exposure control of the silver salt photography system G is always performed based on the photometric value obtained by the photometric element SE, the light amount control of the video photography system V in movie shooting is performed only at the beginning of shooting. It is performed based on the photometric value obtained by the element SE, and thereafter, like the conventional video camera,
This is performed by feedback control using the image sensor 18 as a photometric element.

The silver salt photography system G is provided with a shutter 6 and a film rail 7 in front of the film 8 so that the film 8 can be positioned at the position of the image I formed by the first light flux L1. A film pressure plate 9 is provided at the rear of 8. Then, the image I formed on the surface of the film 8 is recorded by a silver salt photographic method, as in a normal single-lens reflex camera.
(That is, film exposure is performed). In addition,
Instead of the film 8, another photosensitive member that can be used for recording in the silver salt photographic system may be used.

The curtain surface of the shutter 6 has a reflectance almost equal to that of the film 8. And mirror box MB
An image forming lens 4 for forming an image of the reflected light (shown by a chain double-dashed line) on the curtain surface of the shutter 6 is provided at the bottom of the image receiving surface S. A photometric element SE composed of an SPC (silicone photo cell) is arranged so as to be located above. The photometric value obtained by the photometric element SE is used for control by the aperture control unit 3 and the shutter speed control unit (not shown) for the silver salt photography system G, and the ND filter control unit 14 for the video photography system V. It is also used for control by the relay diaphragm control unit 17.

The photometric element SE is a conventionally known T
Similar to a TL (through the taking lens) direct photometric device, diffused light reflected by the shutter curtain surface near the film surface is observed, so that the ND filter 13 and the relay diaphragm 16 out of the light flux passing through the taking lens 1 are observed. Photometry is performed using the first light flux L1 that has not entered. Therefore, the photometric value is not affected by the ND filter 13 and the relay diaphragm 16, and therefore TTL photometry can be performed with high accuracy.

Further, if the distance measuring element is arranged at the bottom of the mirror box MB on the shutter side as in the prior art, the photometric element S is formed by the AF mirror located behind the main mirror.
A part of the reflected light flux toward E is vignetted, and the photometric element S
Part of the image is not formed on E. This causes a decrease in photometric accuracy, but since no AF mirror is provided in this embodiment, such a problem does not occur. That is, even if the photometric element SE is arranged at the position where the shutter curtain is seen from the bottom of the mirror box MB, there is no vignetting due to the AF mirror, so that the degree of freedom in the arrangement of the main mirror M1 and the photometric accuracy are increased.

Furthermore, since the image is formed on the light receiving surface S of the photometric element SE by the reflected light from the curtain surface of the shutter 6, the subject can be accurately measured, and the average photometry or the center-weighted photometry is performed. Not only that, multi-segment photometry (evaluation photometry) can also be performed. Further, the photometric element SE can be used both for normal silver salt open metering and silver salt aperture metering for flash light control (TTL direct light metering during flash photography).

If this photometric element SE is used, it is not necessary to use the image pickup element 18 for photometric purposes.
Video circuit (not shown) based on the photometric value obtained by
It is possible to operate the ND filter 13 and the relay diaphragm 16 before the operation of, and to reactivate the ND filter 13 and the relay diaphragm 16 after the operation of the video circuit. That is, it is possible to control the relay aperture 16 and set the ND filter 13 before the video circuit is activated, and it is possible to perform aperture control after the video circuit is activated and to set the ND filter 13 again. Therefore, it is possible to prevent overexposure of the image pickup device 18 at the initial stage of video shooting when the image pickup device 18 is used for photometry, and not only the light amount control in the video shooting but also in the silver salt photography system. The exposure control can be accurately performed.

As described above, according to the configuration of this embodiment, the fourth light flux L4 for distance measurement is secondly transmitted by the semi-transmissive surface HM.
Since the light flux L2 is obtained by being divided, neither the AF mirror nor the retracting mechanism for the AF mirror is necessary for distance measurement. Therefore, distance measurement can be performed without providing a retracting mechanism for the AF mirror. That is, if the AF mirror is arranged behind the main mirror as in the conventional case, the AF mirror has to be retracted when taking a silver halide photograph. However, if there is no AF mirror as described above, the retract mechanism of the AF mirror, etc. Since the mechanical mechanism of is unnecessary, the effect that the configuration can be simplified can be obtained.

Further, if the AF mirror disposed behind the main mirror is retracted during silver salt photography as in the conventional case, distance measurement cannot be performed during silver salt photography, but in the present embodiment. , The main mirror M1 which is always the first light splitting means
Causes the second light flux L2 to be generated, and the semi-transmissive surface HM which is the second light splitting means to generate the fourth light flux L4, so that the distance measuring element SF always receives the fourth light flux L4. Therefore, the distance measurement information can always be obtained by the distance measurement element SF. For example, it is possible to obtain distance measurement information for video shooting even during silver salt photography, and blackout does not occur even if silver salt photography is performed during movie shooting.
The effect that not only distance measurement but also photometry is not interrupted is obtained.

Since the distance measurement is performed by the phase difference detection method, the distance measurement can be performed with high accuracy, and the performance required for silver halide photography, which requires high speed for distance measurement, is satisfied. Therefore, both photographing functions of silver salt photography and video photographing are realized, and the present embodiment is provided with a fast distance measuring ability for any photographing. Further, since the taking lens 1 is shared by the silver salt photography system G and the video taking system V, and the TTL distance measurement / photometry is performed using the light that has passed through the photography lens 1, the photographing and distance measurement / photometry are performed. There is no parallax between the two, and it is possible to cope with changes in the angle of view of the taking lens 1 and the like.

Further, if the lens barrel OP can be shared with the interchangeable lens for the conventional single-lens reflex camera, the flange back is constant, so that the total reflection mirror is flipped up in the conventional mirror box MB. A space can be provided in front of the main mirror M1 which is a fixed half mirror by the space required. Therefore, if the main mirror M1 is arranged in front of the conventional total reflection main mirror, a space can be provided on the side of the shutter 6 of the mirror box MB. The body BO can be made compact.

[0036]

As described above, according to the first and second inventions, the distance measuring light beam is obtained by dividing the finder light beam by the second light splitting means, so that it is used for the AF mirror. It is possible to perform distance measurement without providing a retracting mechanism. Further, since the distance measuring light beam is always generated by the second light splitting means and is received by the distance measuring element, the distance measuring information can always be obtained.

According to the third to fifth inventions, the fourth light beam used for distance measurement in the phase difference detection method is obtained by dividing the second light beam by the second light splitting means, so that the AF mirror is used. It is possible to perform distance measurement without providing a retracting mechanism. Further, since the fourth light flux is always generated by the second light splitting means and is received by the distance measuring element, it is possible to obtain distance measuring information for video shooting even during silver salt photography.

Further, according to the third to fifth inventions, since the distance measurement is performed by the phase difference detection method, it is possible to perform the distance measurement with high accuracy and the distance measurement is required to be fast. The performance required for shooting is also satisfied. Therefore, both the photography function of silver salt photography and the photography function of video photography are realized, and fast distance measurement capability is imparted to both photography. Also,
The shooting lens is shared by both the silver salt photography system and the video shooting system, and TTL distance measurement is performed using the light that has passed through the shooting lens, so parallax does not occur between shooting and distance measurement, It is also possible to deal with changes in the angle of view of the taking lens.

Further, according to the second and fourth inventions, the second
Since the light splitting means can be downsized, it is possible to prevent the structure from becoming complicated and large. Further, according to the fifth invention, since an image is formed on the light receiving surface of the photometric element,
Accurate photometry of the subject is possible, and multi-segment photometry and direct photometry during flash photography are also possible.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view showing an embodiment of the present invention.

2 is a perspective view showing an arrangement of a condenser lens and a distance measuring element used when performing distance measurement only in a central portion of a shooting range in the embodiment of FIG. 1, and a distance measuring optical path.

FIG. 3 is a perspective view showing an arrangement of a condenser lens and a distance measuring element used when performing photometry corresponding to wide focus and an optical path for distance measurement in the embodiment of FIG.

FIG. 4 is a perspective view showing an assembly structure of the condenser lens shown in FIG.

[Explanation of symbols]

 OP ... Lens barrel BO ... Camera body G ... Silver salt photography system V ... Video photography system MB ... Mirror box SE ... Photometric element SF ... Distance measuring element M1 ... Main mirror (first light splitting means) M2 ... Total reflection mirror HM ... Semi-transmissive surface (second light splitting means) I ... Image I1 ... Primary image I2 ... Secondary image 1 ... Photographing lens 4 ... Imaging lens 5 ... Imaging lens 6 ... Shutter 8 ... Film (photosensitive member) 11 , 12 ... Condenser lens 13 ... ND filter 14 ... ND filter control unit 15 ... Relay lens 16 ... Relay diaphragm 17 ... Relay diaphragm control unit 18 ... Imaging device

Claims (5)

[Claims] 1. A photographic lens for forming a subject image, a first light splitting unit for splitting a light flux after passing through the photographic lens to extract a finder light flux from the light flux, and splitting the finder light flux. A second light splitting means for taking out the light flux for distance measurement from the light flux, and a distance measuring element for performing distance measurement using the light flux for distance measurement taken out by the second light splitting means. And the camera. 2. The camera according to claim 1, wherein the second light splitting means is located near an image plane of an image formed by the finder light beam. 3. A photographing lens for forming an image of light from an object, a first light splitting means for splitting a light flux after passing through the photographing lens into a first light flux and a second light flux, and the first light flux. A silver halide photography system provided with a shutter in front of the photosensitive member so that the photosensitive member can be positioned at the position of the image, and second light for dividing the second light flux into a third light flux and a fourth light flux. A dividing unit, a video shooting system having an image pickup device at the position of the image formed by the third light flux, and a distance measuring element for performing distance measurement by the phase difference detection method using the fourth light flux. A camera characterized by that. 4. The camera according to claim 3, wherein the second light splitting means is located in the vicinity of the image plane of the primary image formed by the second light flux before reaching the image pickup device. . 5. The curtain surface of the shutter has a reflectance substantially equal to that of the photosensitive member, and an image forming lens for forming an image of light reflected on the curtain surface of the shutter is provided. 4. The camera according to claim 3, wherein the photometric element is arranged so that the formed image is located on the light receiving surface.