JP2005352137A - Exchange lens, camera body, and camera system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an exchange lens for improving detection precision of brightness information of an object, and to provide a camera body and a camera system. <P>SOLUTION: In the camera system allowing the exchange camera 1 having a photographing system 11 to attach and detach to and from the camera body 2, the exchange lens includes stereoscopic angle information concerning the axial outside of the photographing system, and a lens information storing means for storing spectral transmittance information of the photographing system. The camera body includes a light receiving means 19 for receiving a light flux passing the photographing system, and a correcting means for correcting shift between brightness distribution of an object by using information from a lens information means and brightness distribution of an object image on the basis of a signal obtained in the light receiving means. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an interchangeable lens, a camera body, and a camera system, and in particular, a photometric light receiving device provided with a light beam (hereinafter referred to as “subject light”) based on a subject image that has passed through a photographing system (photographing optical system). The luminance information of the subject is detected with high accuracy by using an output signal obtained from the light receiving element.

  Conventionally, various devices have been proposed as camera photometry devices. For example, in a single-lens reflex camera using an interchangeable interchangeable lens, a TTL photometry method that uses a light beam that has passed through a photographing system in order to output luminance information of a subject is generally used.

  That is, in a single-lens reflex camera using a silver salt film, a light-receiving element for photometry in which subject light that has passed through a photographing system to form an image on a planned focal plane is disposed at a position that is optically substantially equivalent to the planned focal plane. An image is formed on the surface, and the luminance information of the subject is calculated using the output signal obtained from the light receiving element, and the calculated luminance information of the subject is used for determining the exposure amount of the camera. It was general.

  FIG. 10 is a schematic diagram of a main part of a conventional general single-lens reflex camera. In the figure, reference numeral 111 denotes an interchangeable lens, and 112 denotes a camera body.

  As shown in the figure, in the single-lens reflex camera, the subject light transmitted through the photographing system 101 is reflected upward by the quick return mirror 102 and is focused at a position equivalent to the planned focal plane 103 on which the silver salt film is disposed. An image is formed on a focusing screen 104 having a surface.

  The focusing screen 104 in the figure is a diffusing surface arranged so that one surface thereof is optically transmissive with the intended focusing surface 103, and the light beam transmitted through the focusing screen 104 is used on this surface. The imaging state of the subject image at can be observed. Further, the other surface of the focusing screen 104 is a surface having a light condensing function (light condensing surface), and has a function of condensing the light beam emitted from the exit pupil of the photographing system 101 to the observer's pupil.

  The subject image formed on the focal plane of the focusing screen 104 is enlarged and viewed from the observer's pupil position 107 by a finder optical system composed of a pentaprism 105 and an eyepiece 106. It is configured to be.

  Also, in the same figure, behind the exit surface of the pentaprism 105, in order to avoid mechanical and optical interference with the eyepiece 106 arranged on the optical axis of the finder optical system, it is at a position away from the finder optical axis. A photometric optical system (photometric means) composed of a photometric lens 108 for photometry and a light receiving element 109 is arranged.

  In the figure, a part of the subject light formed on the focal plane of the focusing screen 104 and transmitted through the focusing screen 104 is re-imaged on the surface of the light receiving element 109 by the photometric lens 108 and obtained from the light receiving element 109. The output signal is used to measure the luminance distribution of the subject.

  As described above, on the focusing screen 104, it is possible to observe the condensing surface having an effect of converging the light beam emitted from the exit pupil of the photographing system 101 to the observer's pupil position 107 and the imaging state of the subject image. Therefore, the subject light incident on the photometric lens 108 varies greatly depending on the position and diameter of the exit pupil of the photographing system 101.

  Since a general single-lens reflex camera photometry device having the characteristics described above has the optical arrangement as described above, the output of the light-receiving element 109 for photometry is used to calculate the luminance information of the subject. However, it is necessary to apply various corrections according to the characteristics of the photographing system 101. In particular, in a divided photometry device that divides an object scene into a plurality of regions and outputs luminance information for each region, this correction technique is essential for accurate luminance information output.

  As a conventional example of the most common single-lens reflex camera, the built-in photometry device averages luminance information near the center of the object field in a camera that is supposed to measure subject luminance in an observation state where the viewfinder is observed. In such a conventional single-lens reflex camera, information on the open F value of the photographing system is transmitted from the photographing system side to the camera body side, and based on the information on the open F value. Thus, a technique for simply correcting the output of a light-receiving element for photometry (hereinafter also referred to as “photometry output”) has been generally implemented.

  In particular, in a divided photometry device that divides the object scene into a plurality of regions and outputs luminance information for each region, the photometric output can be corrected by using various information according to the characteristics of the imaging system. Necessary. Various photometric devices for cameras that correct such photometric output have been proposed (see Patent Documents 1 and 2).

  In Patent Document 1, information on the focal length, exit pupil position, aperture efficiency, and open F value for each imaging system is stored in the imaging system, and this information is stored in a CPU (camera microcomputer) in the camera body. A photometric device that corrects the output of a light receiving element by appropriately combining the above is disclosed.

  In Patent Document 2, a photometric device for a camera that corrects the photometric output based on the position of the exit pupil for each photographing system and each information of the open F value, and further calculates the photometric error due to the manufacturing error of the camera. A photometric device for a camera having a configuration as an expression is disclosed.

  As disclosed in the above Patent Documents 1 and 2, in a general single-lens reflex camera configured to be interchangeable with an interchangeable lens, information for each photographing system is represented by an open F value, an exit pupil position, and the like. It is an important technique to use the information regarding the incident angle and the distribution of the light flux reaching the planned focal plane from the imaging system to correct the photometric output.

  By the way, in a camera using an interchangeable lens that can be exchanged, there is also disclosed information that is unique to a photographing system and uses information other than the above for calculation processing of the camera (see Patent Document 3).

In Patent Document 3, information on the total spectral characteristics based on the spectral characteristics of each photographing system and the spectral characteristics of the image sensor is stored in an interchangeable lens, and the information is transmitted to the camera body side to thereby store the camera. A configuration for appropriately changing the white balance control of the image sensor on the main body side is disclosed.
Japanese Patent Publication No. 5-49206 JP 2001-318399 A Japanese Patent Publication No.7-83481

  In the photometric devices of the above-mentioned patent documents 1 and 2, a configuration is disclosed in which information such as information on the open F value of the imaging system and the position of the exit pupil is transmitted from the interchangeable lens side to the camera body side to correct the photometric output. ing.

  Such information waits for the meaning of information regarding the incident angle of the light beam incident on the planned focal plane from the imaging system, or information serving as a substitute for it. For example, the information on the open F value of the photographing system is information regarding the incident angle of the light beam incident on the center of the photographing screen, and can be replaced with the maximum angle of the light beam incident on the center of the photographing screen. Further, the information related to the position of the exit pupil has the meaning of information related to the incident angle of the principal ray of the imaging system that changes according to the distance from the center on the imaging screen. A light beam incident on a point at a position away from the center on the photographing screen generally exists around this principal ray within a range of the maximum angle corresponding to the open F value.

  It should be noted that at the point where the distance from the center is sufficiently distant from the center on the shooting screen, the problem of the amount of peripheral light loss in the shooting system cannot be ignored, and the range where the luminous flux incident on this point exists is reduced. come.

  The information on the focal length and the information on the aperture efficiency disclosed in the above-mentioned Patent Document 1 are the peripheral light amount drop based on the cosine fourth law and the peripheral light amount drop based on the fact that the aperture efficiency of the light beam reaching the peripheral part is not 100%. In any case, it is used as information indicating the existence range of the light beam incident on the point at a position sufficiently away from the center.

  As described above, Patent Documents 1 and 2 disclose a technique for correcting the output of a light-receiving element for photometry of a camera using various types of information resulting from optical characteristics of various types of imaging systems. Is based on the technical idea of correcting the output with respect to the information on the distribution of the incident angle of the light beam incident on the planned focal plane.

  Note that Patent Document 2 discloses a configuration for correcting variation in the appropriate correction amount of the photometric output caused by a manufacturing error for each camera using an arithmetic expression. However, in this document as well, the open F value and emission of the imaging system are disclosed. The position of the pupil is used as a parameter on the imaging system side, and as described above, the technical idea of correcting the output for the information related to the distribution of the incident angle of the light beam incident on the planned focal plane from the imaging system is the same. .

  Here, the parameter of the transmittance of the imaging system is taken up as one of the factors that hinder the proportional relationship between the open F value of the imaging system and the output of the light receiving element for photometry in the above-mentioned Patent Document 1. However, in Patent Document 1, since the parameter called transmittance is measured at a specific position in the camera body after passing through the lens in TTL photometry, it is judged that this difference is not a problem.

  Assuming that there are two types of imaging systems that have the same open F value, optical characteristics regarding the incident angle of the light flux such as the position of the exit pupil, focal length, and aperture efficiency are completely the same, and the transmittance is greatly different. Although the relative value of the illuminance distribution on the light receiving element surface for photometry is expected to be equal, the absolute value of the illuminance is expected to be greatly different. That is, it is expected that the camera will determine that the brightness of the subject is different.

  In the above-mentioned Patent Document 2, in such a case, it is estimated that the brightness of the subject is different. As a camera, the exposure amount is set appropriately, so that both films have a predetermined exposure amount. It is judged that it can be given.

  The difference in transmittance for each photographing system is a major obstacle to the purpose of accurately outputting the luminance information of the subject. In correcting the output of the light-receiving element for photometry, a procedure is usually taken in which a light source having a predetermined luminance is observed and the output signal of the light-receiving element for photometry at this time is corrected.

  Even if camera side factors such as manufacturing variations of the photometric optical system are ignored, the output signal of the light receiving element for photometry depends on factors on the interchangeable lens side such as the open F value of the photographing system, the position of the exit pupil, and the drop in peripheral light amount. It shows a tendency to vary. When the deviation from the proportional relationship between the open F value of the photographing system and the output of the light receiving element for photometry is to be implemented by appropriately performing various corrections, it is natural that the absolute value of the output signal of the light receiving element for photometry It is a simple method to correct the image so as to correspond to the luminance information of the subject.

  In addition, the luminance information of the subject is output when the exposure amount of the division photometry device that determines the appropriate exposure amount by dividing the object scene into a plurality of regions and outputting the luminance distribution information of the subject field. This is also due to the necessity of effectively using the absolute value of the luminance of the object field in inferring the state of the object field.

  In addition, in color photometry devices that output luminance information for each color by combining a color filter having a predetermined spectral transmittance characteristic with a light receiving element for photometry, not only the average transmittance information of the photographing system but also color information Needless to say, it is desirable to configure such that various signals are corrected and output based on the spectral transmittance information accompanied with the above.

  In the above Patent Document 3, information corresponding to the total spectral characteristic obtained by multiplying the spectral characteristic of the imaging system and the spectral sensitivity of the image sensor is stored in the interchangeable lens, and the white balance of the image sensor is appropriately controlled. However, this is of a technical idea that is significantly different from the technique of correcting the output signal of the photometric optical system for a single-lens reflex camera when an interchangeable lens is mounted.

  The present invention provides lens information means for recording solid angle information relating to the off-axis of the photographing system and spectral transmittance information of the photographing system, and information obtained from the lens information means using the luminance distribution of the subject and the light receiving means. It is an object of the present invention to provide an interchangeable lens, a camera body, and a camera system that can improve the accuracy of detecting luminance information of a subject by providing correction means that corrects a deviation from the illuminance distribution of the subject image based on the received signal.

The camera system of the present invention is a camera system in which an interchangeable lens having a photographing system is detachable from the camera body.
The interchangeable lens has lens information storage means that stores solid angle information about the off-axis of the imaging system and spectral transmittance information of the imaging system.
The camera body includes a light receiving unit that receives a light beam that has passed through the photographing system, a luminance distribution of a subject using information from the lens information storage unit, and an illuminance distribution of a subject image based on a signal obtained by the light receiving unit. And correction means for correcting the deviation.

The interchangeable lens of the present invention is an interchangeable lens that can be attached to and detached from a camera body that includes light receiving means for receiving light that has passed through the photographing system and obtaining the illuminance distribution of the subject,
The interchangeable lens includes lens information storage means that stores spectral transmittance information relating to spectral transmittance and solid angle information relating to a solid angle off-axis of the imaging system.

The camera body of the present invention is a camera body having light receiving means for receiving light that has passed through a photographing system and obtaining an illuminance distribution of a subject, and a mechanism to which an interchangeable lens including the photographing system can be attached and detached.
The camera body uses the spectral transmittance information related to the spectral transmittance stored in the lens information storage means of the interchangeable lens and the solid angle information related to the off-axis solid angle of the photographing system,
The present invention is characterized in that a correction means for obtaining a deviation between the luminance distribution of the subject and the illuminance distribution of the subject image based on the signal obtained by the light receiving means and correcting the deviation is provided.

  According to the present invention, it is possible to output information corresponding to the luminance of the subject with higher accuracy, and to perform appropriate exposure processing and captured image processing based on the information obtained here, and to output a good image. It is possible to achieve an interchangeable lens and a camera body and a camera system that can

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a schematic diagram of a main part of a camera system (image pickup apparatus) according to a first embodiment of the present invention. The camera system of the present embodiment is effective for a single-lens digital camera.

  In the figure, reference numeral 2 denotes a camera body, and 1 denotes an interchangeable lens (lens body) that can be attached to and exchanged with the camera body 2. Reference numeral 11 denotes an imaging system (imaging optical system) that constitutes the interchangeable lens 1 and optically forms a subject image on the surface of the imaging element 13. Reference numeral 12 denotes a quick return mirror (QR mirror), and reference numeral 13 denotes an image pickup device arranged on a planned focal plane of the photographing system 11, which is composed of, for example, a CCD. Reference numeral 14 denotes a focusing screen, 15 denotes a pentaprism as an image inverting means, 16 denotes an eyepiece, 17 denotes an observer's pupil position, 18 denotes a photometric lens, and 19 denotes a photometric light receiving element (light receiving means).

  Reference numeral 3 denotes a lens microcomputer, which drives and controls each function of the interchangeable lens 1. The lens microcomputer 21 also has information on the solid angle of each image height of the light beam emitted from the photographing system 11 (for example, solid angle information at a plurality of points on and off the axis) and information on the spectral transmittance of the photographing system 11 (light Lens information storage means (for example, ROM or the like) for storing the on-axis and / or off-axis spectral transmittance information).

  Reference numeral 4 denotes a camera microcomputer that controls driving of each member of the camera body 2. The camera microcomputer 4 has correction means for correcting a deviation between the luminance distribution of the subject and the illuminance distribution of the subject image by using information from the lens information means in the lens microcomputer 3 in response to the signal from the light receiving means 19. Yes.

  In this embodiment, by using each information from the lens information means, the correction means appropriately corrects the output signal of the light-receiving element 19 for photometry so that the luminance information of the subject can be obtained with high accuracy.

  In the single-lens reflex camera shown in the figure, the subject light transmitted through the photographing system 11 is on the surface of the image sensor 13 in which the image pickup surface is disposed on the planned focal plane in a state where the quick return mirror 12 is retracted from the photographing optical path. An image is formed.

  On the other hand, in the state where the quick return mirror 12 is arranged in the photographing optical path as shown in the figure, the subject light is imaged on the focusing screen 14 arranged so as to be optically equivalent to the planned focal plane. It is the composition which becomes.

  The focusing screen 14 is formed in a substantially flat plate shape as shown in the figure, and one surface thereof is a diffusing surface disposed so as to be optically equivalent to the planned focal plane of the imaging system 11, Using the light beam that has passed through the focusing screen 14, the imaging state of the subject image on this surface can be observed. Further, the other surface of the focusing screen 14 is a surface having a light condensing function (light condensing surface), and has a function of condensing the light beam emitted from the exit pupil of the photographing system 11 at the pupil position 17 of the observer. Yes.

  The subject image formed on the focal plane of the focusing screen 14 is magnified by a finder optical system composed of a pentaprism 15 and an eyepiece 16 and then enlarged and observed from the pupil position 17 of the observer. It is configured to be.

  Also, in the same figure, behind the exit surface of the pentaprism 15, in order to avoid mechanical and optical interference with the eyepiece 16 disposed on the optical axis of the finder optical system, a position away from the finder optical axis is provided. A photometric optical system (photometric means) composed of a photometric lens 18 for photometry and a light receiving element 19 is disposed.

  In the drawing, a part of the subject light formed on the focal plane of the focusing screen 14 and transmitted through the focusing screen 14 is re-imaged on the light receiving element 19 surface by the photometric lens 18 and obtained from the light receiving element 19. The output signal is used to measure the luminance distribution of the subject.

  As described above, on the focusing screen 14, it is possible to observe the condensing surface having the function of condensing the light beam emitted from the exit pupil of the photographing system 11 at the pupil position 17 of the observer and the imaging state of the subject image. Accordingly, the subject light incident on the photometric lens 18 varies greatly depending on the position and diameter of the exit pupil of the imaging system 11.

  FIG. 2 is a detailed view of a main part of the light-receiving element 19 for photometry shown in FIG. In the figure, 21 is an infrared cut filter for blocking infrared light having a wavelength longer than a predetermined wavelength, 22 is a color filter array in which a plurality of color filters (R, G, B) are laid out in a two-dimensional mosaic pattern, and 23 is It is a light receiving element array.

  In this embodiment, an infrared cut filter 21, a color filter array 22, and a light receiving element array 23 are used to output a luminance signal of a subject as a two-dimensional color signal.

  FIG. 3 is an explanatory diagram (plan view) of the color filter array 22 shown in FIG. In the figure, 3R is a filter part that selectively transmits light of a wavelength that humans feel red, 3G is a filter part that selectively transmits light of a wavelength that humans primarily feel green, and 3B is mainly blue by humans. It is a filter part that selectively transmits light of a sensed wavelength, and is configured to be able to output luminance signals corresponding to three colors from the light receiving element array 23 corresponding to each of these color filter arrays 22.

  The three types of color signals of the present embodiment are configured to have spectral characteristics substantially equivalent to the three types of color signals of the image signal output from the image sensor 13 shown in FIG. The luminance signal can be output with high accuracy for each color.

  FIG. 4 shows a photometric light-receiving element obtained by multiplying the three types of filter parts constituting the color filter array 22 of the first embodiment of the present invention, the infrared cut filter 21 and the spectral sensitivity of the light-receiving element array 23 itself. It is the graph which showed the spectral sensitivity characteristic.

  In the figure, 4R, 4G, and 4B correspond to the filter portions 3R, 3G, and 3B of the three types of color filter array 22 shown in FIG. It is comprised so that it may have a spectral sensitivity characteristic substantially equivalent to.

  The luminance signal for each color of the subject formed on the light-receiving element for photometry shown in FIG. 3 is added for each area of the object scene by performing addition processing or the like by the calculation means in the camera body (in the camera microcomputer 4). Are output as color signals.

  FIG. 5 is an explanatory diagram showing an example of a scene classification pattern according to the first embodiment of the present invention. In this embodiment, as shown in the figure, the object scene is classified into a grid-like small area and a color signal for each small area is output, and the situation classification of the object scene is performed from these output signals. A photometric device that determines an appropriate exposure amount.

  The light-receiving element 19 for photometry is not limited to the configuration shown in FIG.

  Next, consider mounting interchangeable lenses having various specifications on a single-lens reflex camera equipped with the photometric optical system of the present embodiment. FIG. 6 is a cross-sectional view of the main part of the photometric optical system of the camera body 2 when the most standard interchangeable lens is attached to the camera body of Example 1 shown in FIG. In FIG. 6, the same elements as those shown in FIG.

  The focusing screen 14 shown in FIG. 1 has a condensing surface and a diffusing surface as described above, and when an interchangeable lens having a medium distance from the planned focal plane to the exit pupil is attached, The exit pupil and the observer's pupil position 17 are configured to have a substantially imaging relationship (conjugate relationship).

  On the other hand, as shown in FIG. 6, the photometric optical system is arranged in a direction inclined by an angle θc from the focal plane when viewed at a point O at the center of the screen (on the optical axis). A part of the light beam diffused by the diffusing surface is used to form a photometric output. At this time, a part of the diffused light in the direction inclined by the angle θt at the point (image height H) + H at the upper part of the screen, and the direction inclined by the angle θb at the point (image height −H) -H at the lower part of the screen. A part of the diffused light is used for forming a photometric output.

  FIG. 7 shows the diffusion characteristics of the diffusing surface formed on the focusing screen 14 of this embodiment and the luminous flux used for photometry. The point O at the center of the screen is 7c, the point + H at the top of the screen is 7t, and the point at the bottom of the screen. -H corresponds to diffused light from the region of 7b, and when these diffused lights are integrated, photometric outputs corresponding to these points are obtained.

  7c, 7t, and 7b in the figure are figures corresponding to solid angles of light beams that reach the three points O, + H, and -H on the focusing screen 14 from the imaging system 11, respectively. As the F value decreases, these regions become narrower.

  Now, consider the case where the distance from the exit pupil position of the imaging system 11 to the planned focal plane changes, and if this distance is short, medium, or long, the imaging optical system and photometric optical system Cross-sectional views of the main part are shown in FIGS. 8 (A), (B), and (C).

  8A shows the case where the distance from the exit pupil position to the planned focal plane is short, FIG. 8B shows the case where the distance from the exit pupil position to the planned focal plane is medium, and FIG. 8C shows the exit pupil. This represents a case where the distance from the position to the planned focal plane is long.

  When the exit pupil distance of the imaging system changes as shown in FIGS. 8A, 8B, and 8C, the light is diffused from three points O, + H, and -H on the focusing screen, and the photometric optical system Since the diffusion angle of the light beam used to form the photometric output changes after passing through the lens, information on the solid angle of the light beam emitted from the imaging system, such as the exit pupil position of the imaging system, is required to obtain a highly accurate luminance signal. (Solid angle information) is held according to the position on the focusing screen, and it is necessary to appropriately correct the photometric output from the light receiving element 19 based on the information.

  Thus, by using information mainly related to the solid angle of the light beam emitted from the photographing system 11, the luminance of the subject generated by the layout of the photometric optical system as described above and the diffusion characteristics of the diffusion plate formed on the focusing screen. Deviations in the proportional relationship between the photometric output and the photometric output are mostly corrected by existing correction techniques. However, when these corrections are made, the difference in the spectral transmittance characteristics of the imaging system directly affects the photometric output. become.

  Considering the case where interchangeable lenses with various specifications are mounted on the camera body, it is assumed that the photometric output will vary depending on the layout of the photometric optical system and the diffusion characteristics of the diffuser plate formed on the focusing screen. However, in consideration of outputting a photometric output in a narrow area only in the center of the screen, it is necessary to correct the camera system so that the same photometric output is output when an interchangeable lens having the same open F value is attached. It becomes. This is not necessary if the device is sufficient if the output signal of the photometric optical system and the amount of light exposed on the imaging surface are always in a proportional relationship regardless of their absolute values. Since an appropriate exposure amount is determined using not only the information but also the absolute value of the subject brightness, the subject brightness value itself is required.

  Further, as shown in the present embodiment, when configuring a color photometric device that outputs three types of color signals as the luminance signal of the subject, in particular, by using the intensity ratio of the three types of color signals, a substantial subject can be detected. Although the color signal is formed, if the intensity ratio changes due to the difference in the spectral transmittance characteristics of the photographing system, the determination of the color of the subject is erroneous.

  Therefore, in this embodiment, the correction means appropriately corrects the output signal of the light receiving element 19 for photometry using information (spectral transmittance information) related to the spectral transmittance characteristics of the light beam emitted from the photographing system 11, A deviation between the luminance distribution of the subject and the illuminance distribution of the subject image can be obtained, and the deviation can be corrected, whereby the luminance information of the subject and particularly the color information of the subject can be output with high accuracy.

  FIG. 9 is a graph showing the spectral transmittance characteristics of the imaging system of Example 1 of the present invention. Table 1 shows an example of spectral characteristic data (spectral transmittance information) of the photographing system stored in a ROM (storage memory) as lens information storage means.

  Spectral characteristic data is stored in a ROM (storage means) provided in the lens CPU 3 in the interchangeable lens 1 corresponding to the center of the screen and the point of the image height L on the screen, and is appropriate according to the light receiving area. Data is used for correcting the photometric output from the light receiving means 19 of the camera body 2. In the present embodiment, the spectral transmittance itself for each wavelength of 10 nm in the visible wavelength range is stored in advance in the ROM of the interchangeable lens 1.

  As described above, in the present embodiment, the above-described photometric optical system is used by mainly using information related to the solid angle of a predetermined image height (predetermined field angle) of the light beam emitted from the photographing system 11 as described above. Assuming that the deviation of the proportional relationship between the luminance distribution of the subject and the photometric output (illuminance distribution of the subject image) caused by the layout of the light and the diffusion characteristics of the diffusion plate formed on the focusing screen is corrected, the photographing system Thus, it is possible to satisfactorily correct the influence of the difference in spectral transmittance characteristics of 11 on the photometric output.

  In particular, in this embodiment, by appropriately correcting the photometric output using information related to the spectral transmittance characteristics of the light beam emitted from the imaging system 11, the luminance information of the subject and particularly the color information of the subject are output with higher accuracy. It is possible.

  As described above, in this embodiment, in the camera system including the interchangeable lens and the single-lens reflex camera body using the interchangeable lens as described above, a part of subject light transmitted through the photographing system is received for photometry in the camera body. When configuring a photometric device that forms an image on the element surface and outputs luminance information of the subject using an output signal from the light receiving element, by appropriately using information on the optical characteristics of each interchangeable lens, The detection accuracy of luminance information is improved.

  In the camera system of the present embodiment, in order to make it possible to output the luminance information of the subject with higher accuracy, the information from the lens information storage means includes a plurality of sets according to the state of the imaging system or the position on the imaging surface. It is good also as information.

  Further, the reason that the subject image is used in this embodiment is that the subject image is also partially effective when it means the subject image itself formed on the image sensor arranged on the planned imaging plane of the photographing system.

  Assuming the best embodiment, the subject image is optically substantially equivalent to the scheduled imaging plane of the imaging system, and is formed on the imaging element surface arranged to form pre-imaging information. This is because it is particularly effective when the subject image is selected.

  In the first embodiment, the present invention is applied to the configuration of the photometric optical system of the most common single-lens reflex camera, and an apparatus for determining the exposure amount in the photographing operation is assumed. As described in the above, it is possible to set or adjust the white balance before photographing by adopting a configuration that can output color signals with high accuracy.

  In the first embodiment, the optical system is arranged on the exit surface of the pentaprism assuming the configuration of the most common single-lens reflex camera system as the photometric optical system. The present invention can also be applied to a camera body that uses the element itself as a light-receiving element for photometry.

  In the first embodiment, the spectral transmittance itself in the visible wavelength region is stored in the ROM of the photographing system every 10 nm. However, for the sake of simplification, representative three wavelengths (R, G, B) are stored. For example, assuming a camera capable of photographing an infrared wavelength, the transmittance characteristic for a predetermined infrared wavelength is stored in a ROM of the photographing system. It is good also as a structure memorize | stored.

1 is a schematic view of the main part of a camera system according to a first embodiment of the present invention. Explanatory drawing of the light receiving element for photometry of Example 1 of this invention Explanatory drawing of the color filter of the light receiving element for photometry of Example 1 of this invention Explanatory drawing of the spectral sensitivity of the light receiving element for photometry of Example 1 of this invention Explanatory drawing at the time of carrying out the light receiving element for photometry of Example 1 of this invention Sectional drawing of the principal part of the photometry optical system of Example 1 of this invention Explanatory drawing of the light-diffusion characteristic of the focusing screen of Example 1 of this invention and the light beam utilized for photometry Explanatory drawing when the photographing system of various exit pupil distances is mounted on the first embodiment of the present invention. Explanatory drawing of the spectral transmittance characteristic data of the imaging system of Example 1 of the present invention Schematic diagram of the main parts of a conventional single-lens reflex camera

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Interchangeable lens 2 Camera body 3 Lens microcomputer 4 Camera microcomputer 11 Imaging system 12 QR mirror 13 Imaging element 14 Focus plate 15 Pentaprism 16 Eyepiece 17 Position of pupil of observer 18 Photometric lens 19 Light receiving element for photometry

Claims (12)

In a camera system in which an interchangeable lens having a photographing system can be attached to and detached from the camera body,
The interchangeable lens has lens information storage means that stores solid angle information about the off-axis of the imaging system and spectral transmittance information of the imaging system.
The camera body includes a light receiving unit that receives a light beam that has passed through the photographing system, a luminance distribution of a subject using information from the lens information storage unit, and an illuminance distribution of a subject image based on a signal obtained by the light receiving unit. And a correction means for correcting the deviation.   2. The camera system according to claim 1, wherein the information from the lens information storage unit is a plurality of sets of information corresponding to off-axis positions on an imaging surface on which an image by the imaging system is formed.   The camera system according to claim 1, wherein the subject image is a subject image formed on an image sensor arranged on a scheduled imaging plane of the photographing system.   The subject image is optically substantially equivalent to a scheduled imaging plane of the photographing system, and is a subject image formed on an image sensor arranged to form pre-shooting information. Item 2. The camera system according to Item 1. An interchangeable lens that can be attached to and detached from the camera body with light receiving means for receiving light that has passed through the imaging system and determining the illuminance distribution of the subject,
The interchangeable lens has lens information storage means for recording spectral transmittance information relating to spectral transmittance and solid angle information relating to a solid angle off-axis of the photographing system.   6. The interchangeable lens according to claim 5, wherein the information from the lens information storage means is a plurality of sets of information corresponding to off-axis positions on an imaging surface where an image by the imaging system is formed.   The interchangeable lens according to claim 5, wherein the subject image is a subject image formed on an image sensor arranged on a scheduled imaging plane of the photographing system.   The subject image is a subject image that is optically substantially equivalent to a planned imaging plane of the photographing system and is formed on an image sensor arranged to form pre-shooting information. Item 6. The interchangeable lens according to Item 5. A camera body having a light receiving means for receiving light passing through a photographing system to obtain an illuminance distribution of a subject, and a mechanism to which an interchangeable lens including the photographing system can be attached and detached,
The camera body uses the spectral transmittance information related to the spectral transmittance stored in the lens information storage means of the interchangeable lens and the solid angle information related to the off-axis solid angle of the photographing system,
A camera body comprising a correcting means for obtaining a deviation between a luminance distribution of a subject and an illuminance distribution of a subject image based on a signal obtained by the light receiving means and correcting the deviation.   The camera body according to claim 9, wherein the information from the lens information storage unit is a plurality of sets of information corresponding to off-axis positions on an imaging surface on which an image by the imaging system is formed.   The camera body according to claim 9, wherein the subject image is a subject image formed on an image sensor disposed on a scheduled imaging plane of the photographing system.   The subject image is a subject image that is optically substantially equivalent to a planned imaging plane of the photographing system and is formed on an image sensor arranged to form pre-shooting information. Item 10. The camera body according to Item 9.