JP2005208300A - Camera and focus detecting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the cost of an interchangeable lense, camera or the like by simplifying a correction method thereby downsizing a memory and a processing circuit, and to provide the camera and a focus detecting device which can correct the out of focusing highly precisely. <P>SOLUTION: When a light source illuminating a subject is detected by a light source detection part 4 in a camera body 1, a signal corresponding to the light source is outputted from the light source detection part 4. In addition, a correction value for correcting defocus according to the type of the light source, which is stored in a memory 3, is read as correction data. Based upon the signal from the light source detection part 4 and the correction data read from the memory 3, an AF control part 5 performs the focus detection. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a camera and a focus detection device. It is about.

  2. Description of the Related Art Conventionally, a technique has been developed that detects the luminance and background light of a subject at the time of shooting and corrects the distance during distance measurement. For example, a so-called phase difference AF (autofocus) system that detects a focus state of a measurement target from a positional relationship between a pair of images formed on a pair of light receiving element arrays and adjusts the focus of the photographing lens according to the detection result. Is known (for example, see Patent Document 1).

  In a camera or the like that employs the AF method described in Patent Document 1, a subject image is generally formed by a light beam that has passed through a photographing lens or the like. However, it is well known that at this time, a phenomenon in which the position of the focal point of the subject image varies depending on the wavelength of the light source incident on the photographing lens or the like.

For example, when taking a picture in a room, the subject may be illuminated using an artificial light source such as a tungsten lamp or a flood lamp. In this case, there may be a shift in the in-focus position of the subject image due to the optical characteristics of the photographing lens or the like, that is, the influence of chromatic aberration or the like. As an improvement of the above problem, chromatic aberration correction data of a specific wavelength with respect to the reference wavelength is stored in the interchangeable lens, and correction data is based on the main color of the subject light measured by the colorimetric means for measuring the color of the subject light. There is known a focus detection device that calculates the focus and corrects the focus (see, for example, Patent Document 2).
Japanese Patent Laid-Open No. 9-211306 JP 2003-2451064 A

  However, the apparatus described in Patent Document 2 performs correction by performing complex calculation based on chromatic aberration correction data of a specific wavelength with respect to a reference wavelength and main colors of subject light measured by a colorimetric means for measuring the color of subject light. The value is calculated. For this reason, there is a problem that the memory capacity in the interchangeable lens is increased, the processing circuit in the camera is enlarged, and the cost is increased.

  Accordingly, the present invention has been made in view of the above-described points. The object of the present invention is to simplify the correction method and reduce the size of the memory and processing circuit, thereby reducing the cost of an interchangeable lens, a camera, and the like. An object of the present invention is to provide a camera and a focus detection device that can be down and can perform high-precision focus shift correction.

  That is, the invention described in claim 1 is a lens-exchangeable camera having a lens barrel including a photographic lens and a camera body, and is a light source that is disposed inside the lens barrel and illuminates a subject. Correction value storage means for storing correction values for correcting defocus according to the type, light source detection means for detecting a light source that illuminates the subject, and outputting a signal corresponding to the light source, and the photographing lens A focus detection unit that detects the focus of the light source, and the focus detection unit is based on the output of the signal detected by the light source detection unit and the correction value stored in the correction value storage unit. Focus detection is performed.

  According to a second aspect of the present invention, there is provided an interchangeable lens camera having a lens barrel including a photographic lens and a camera body. The camera is disposed inside the lens barrel and is a type of light source that illuminates a subject. Accordingly, correction value storage means for storing correction values for correcting defocusing, light source detection means for detecting a light source that illuminates the subject, and outputting a signal corresponding to the light source, and focus of the photographing lens A correction amount for calculating a correction amount for correcting the output of the focus detection unit based on the focus detection unit that performs detection, the output of the light source detection unit, and the correction value stored in the correction value storage unit Computation means, and correction means for correcting the output of the focus detection means based on the correction amount calculated by the correction amount calculation means.

  According to a third aspect of the present invention, in the second aspect of the present invention, the correction unit performs correction based on a correction amount that continuously changes in accordance with a result detected by the light source detection unit. It is characterized by that.

  According to a fourth aspect of the present invention, in the first aspect of the invention, the light source detection unit further includes a light amount detection unit that detects at least one of the infrared light and near infrared light of the subject. It is characterized by comprising.

  According to a fifth aspect of the present invention, in the second aspect of the present invention, the light source detection means further includes a light quantity detection means for detecting a light quantity of at least one of infrared light and near infrared light of the subject. It is characterized by comprising.

  According to a sixth aspect of the present invention, in the third aspect of the present invention, the light source detection means further includes a light quantity detection means for detecting at least one of the infrared light and near infrared light of the subject. It is characterized by comprising.

  According to a seventh aspect of the invention, in the first aspect of the invention, the light source detection means is constituted by an external light type light detection means that does not use subject light that has passed through the photographing lens. It is characterized by.

  The invention described in claim 8 is the invention described in claim 2, wherein the light source detection means is constituted by an external light type light detection means that does not use subject light that has passed through the photographing lens. It is characterized by.

  The invention according to claim 9 is the invention according to claim 3, wherein the light source detection means is constituted by an external light type light detection means that does not use subject light that has passed through the photographing lens. It is characterized by.

  According to a tenth aspect of the present invention, in the invention according to the fourth aspect, the light source detection means is constituted by an external light type light detection means that does not use subject light that has passed through the photographing lens. It is characterized by.

  According to an eleventh aspect of the present invention, in the invention according to the fifth aspect, the light source detection means is constituted by external light type light detection means that does not use subject light that has passed through the photographing lens. It is characterized by.

  According to a twelfth aspect of the present invention, in the invention of the sixth aspect, the light source detection means is constituted by an external light type light detection means that does not use subject light that has passed through the photographing lens. It is characterized by.

  According to a thirteenth aspect of the present invention, in the invention according to any one of the seventh to twelfth aspects, the correction value stored in the correction value storage means is a change in at least one of a focal length and a subject distance. It has the form which changes corresponding to.

  According to the fourteenth aspect of the present invention, there is provided a photographing lens, a light source detection unit that detects a light source that illuminates a subject, and outputs a signal corresponding to the light source, and for correcting defocus according to the type of the light source. Based on the correction value storage means for storing the correction value, the output of the signal detected by the light source detection means, and the correction value stored in the correction value storage means, the focus of the photographing lens is adjusted. And a control means for controlling.

  According to a fifteenth aspect of the present invention, in the invention according to the fourteenth aspect, the control unit is configured to perform the operation based on an output of the light source detection unit and a correction value stored in the correction value storage unit. A correction amount for correcting the output of the focus detection means is calculated, and the defocus of the photographing lens is corrected based on the calculated correction amount.

  The invention according to claim 16 is the invention according to claim 14, wherein the light source detection means further includes a light quantity detection means for detecting at least one of the infrared light and near infrared light of the subject. It is characterized by comprising.

  According to a seventeenth aspect of the present invention, in the invention according to the fourteenth aspect, the light source detection means includes an external light type light detection means that uses light other than subject light that has passed through the photographing lens. It is characterized by.

  According to an eighteenth aspect of the present invention, in the invention according to the fourteenth aspect, the correction value stored in the correction value storage means changes in response to at least one change in focal length and subject distance. It has the form.

  According to a nineteenth aspect of the present invention, in the invention according to any one of the fourteenth to eighteenth aspects, the correction value storage means is disposed inside a lens barrel including the photographing lens. And

  According to the present invention, since the focus correction data in the interchangeable lens is provided according to the light source type, the correction method is greatly simplified, and the memory and processing circuit can be miniaturized. It is possible to provide a camera and a focus detection device that can reduce the cost and perform highly accurate focus deviation correction.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a block diagram showing a schematic configuration of a digital camera to which a focus detection apparatus of the present invention is applied.

  In FIG. 1, the digital camera includes a camera body 1 and an interchangeable lens 2. The interchangeable lens 2 has a memory 3 for storing a correction value for correcting a defocus according to the type of light source. On the other hand, the camera body 1 includes a light source detection unit 4 that outputs a signal corresponding to the light source and an AF control unit 5 that performs focus detection of the interchangeable lens 2.

  In such a configuration, when the light source that illuminates the subject is detected by the light source detection unit 4 in the camera body 1, a signal corresponding to the light source is output from the light source detection unit 4. Further, a correction value for correcting the defocus according to the type of light source stored in the memory 3 is read as correction data. The AF control unit 5 performs focus detection based on the signal from the light source detection unit 4 and the correction data read from the memory 3.

(First embodiment)
FIG. 2 is a perspective view schematically showing an internal configuration of a part of the digital camera according to the first embodiment of the present invention.

  In FIG. 2, the digital camera 10 of the present embodiment includes a camera body 11 and a lens barrel 12 that are configured separately, and the camera body 11 and the lens barrel 12 are attached to and detached from each other. It is configured freely.

  The lens barrel 12 is configured by holding therein a photographic optical system 12a including a plurality of photographic lenses and their driving mechanisms. The photographing optical system 12a transmits a light beam from a subject so that an image of the subject formed by the subject light beam is formed at a predetermined position (on a photoelectric conversion surface of an image sensor 40 described later). For example, it is composed of a plurality of optical lenses. The lens barrel 12 is disposed so as to protrude toward the front surface of the camera body 11.

  The lens barrel 12 is the same as that generally used in conventional cameras and the like. Therefore, the detailed description of the configuration is omitted.

  The camera body 11 includes various constituent members and the like, and is a photographic optical system that is a connecting member for detachably mounting the lens barrel 12 that holds the photographic optical system 12a. This is a so-called single-lens reflex camera having a mounting portion (also referred to as a photographing lens mounting portion) provided on the front surface thereof.

  That is, an exposure opening having a predetermined aperture capable of guiding the subject light flux into the camera body 11 is formed in a substantially central portion on the front side of the camera body 11. A photographing optical system mounting portion (not shown) is formed at the peripheral edge of the exposure opening.

  On the outer surface side of the camera body 11, the above-described photographing optical system mounting portion is disposed on the front surface thereof, and various operation members for operating the camera body 11 at predetermined positions such as an upper surface portion and a rear surface portion. For example, a release button 13 for generating an instruction signal or the like for starting a photographing operation, and a diffuser plate in which a light source sensor 55 described later is disposed between the grip portion of the camera body 11 and the lens barrel 12. 14 etc. are arranged. The diffusion plate 14 is provided on the camera body 11 on the side of the photographing optical system connection part, and is configured to receive a subject to be photographed and light around it.

  Since the above-described operation members are not directly related to the present invention, the illustration and description of the operation members other than the release button 13 are omitted in order to avoid complication of the drawing.

  In the camera body 11, as shown in FIG. 2, various components such as a finder device 16, a shutter unit 17, an imaging unit 18, and a plurality of circuit boards including a main circuit board 19 are provided. (Only the main circuit board 19 is shown in FIG. 2), respectively, are arranged at predetermined positions.

  The finder device 16 is provided to form a desired subject image formed by the photographing optical system 12a at a predetermined position different from the photoelectric conversion surface of the image sensor 40 (see FIG. 2). An observation optical system is configured.

  The viewfinder device 16 includes a quick return mirror 16a, a pentaprism 16b, and an eyepiece 16c.

  The quick return mirror 16a can be guided to the observation optical system side by bending the optical axis of the subject luminous flux transmitted through the photographing optical system 12a. The pentaprism 16b receives the light beam emitted from the quick return mirror 16a and forms an erect image. The eyepiece 16c is used to form an image in an optimal form for magnifying and observing the image formed by the pentaprism 16b.

  The quick return mirror 16a is configured to be movable between an exposure retracting position retracted from the optical axis of the photographing optical system 12a and a predetermined position on the optical axis. In a normal state, the quick return mirror 16a is configured to be movable. The optical axis is arranged at a predetermined angle with respect to the optical axis, for example, an angle of 45 degrees. As a result, the subject luminous flux transmitted through the photographing optical system 12a is arranged above the quick return mirror 16a with the optical axis thereof being bent by the quick return mirror 16a when the digital camera 10 is in a normal state. Reflected toward the pentaprism 16b. That is, this is the finder observation position of the quick return mirror (movable mirror) 16a.

  On the other hand, while the digital camera 10 is performing the photographing operation, during the actual exposure operation, the quick return mirror 16a is moved to a predetermined position retracted from the optical axis of the photographing optical system 12a. It has become. As a result, the subject luminous flux is guided to the image sensor 40 side and irradiates the photoelectric conversion surface.

  The shutter unit 17 controls the irradiation time of the subject light beam onto the photoelectric conversion surface of the image sensor 40, and includes a shutter mechanism.

  The imaging unit 18 includes an assembly including the shutter unit 17 and an imaging element 40 that obtains an image signal corresponding to a subject image formed based on a subject light beam that includes the shutter unit 17 and passes through the photographing optical system 12a. Is done.

  The main circuit board 19 is mounted with various electric members constituting an electric circuit of an image signal processing circuit (not shown) that performs various signal processing on the image signal acquired by the image sensor 40. Yes. Further, a strobe contact (not shown) is provided on the upper portion of the camera body 11 so that an external strobe can be attached and the strobe can be emitted at a predetermined light amount and timing by communicating with the external strobe. Yes.

  As the shutter unit 17, for example, a focal plane type shutter mechanism, a drive circuit for controlling the operation of the shutter mechanism, and the like that are generally used in conventional cameras and the like are applied. . Therefore, the detailed description of the configuration is omitted.

  FIG. 3 is a block diagram schematically showing mainly the electrical configuration of the digital camera.

  In FIG. 3, as described above, this digital camera is mainly composed of a camera body 11 and a lens barrel 12 as an interchangeable lens, and a desired lens with respect to the front surface of the camera body 11. The lens barrel 12 is set to be detachable.

  The lens barrel 12 is controlled by a lens control microcomputer (hereinafter referred to as Lμcom) 25. On the other hand, control of the camera body 11 is performed by a body control microcomputer (hereinafter referred to as “Bμcom”) 50.

  The Lμcom 25 and Bμcom 50 are electrically connected via the communication connector 63 so that they can communicate with each other when they are combined. As a camera system, the Lμcom 25 is operated in cooperation with the Bμcom 50 in a dependent manner.

  In the lens barrel 12, a photographing lens 21 and a diaphragm 22 are provided. The taking lens 21 is driven by a DC motor (not shown) existing in the lens driving mechanism 23. The diaphragm 22 is driven by a stepping motor (not shown) existing in the diaphragm drive mechanism 24. Lμcom 25 controls each of these motors in accordance with the command of Bμcom50.

  The lens barrel 12 is provided with a correction value memory 27 that stores correction data for correcting a focus shift amount described later. The correction data stored in the correction value memory 27 is read out by the Lμcom 25. Then, it transmits to Bmicrocom50 by communication.

  On the other hand, the following components are arranged in the camera body 11 as shown.

  For example, a single-lens reflex type structural member (quick return mirror 16a, pentaprism 16b, eyepiece 16c, focusing screen 31, submirror 35) as an optical system, a focal plane type shutter unit 17 on the optical axis, and the submirror An AF sensor unit 36 for receiving a reflected light beam from 35 and automatically measuring the distance is provided.

  Further, in the camera body, a photometric circuit 33 for performing photometric processing based on a light beam from the pentaprism 16b via a photometric sensor (light detecting means) 32, and an AF sensor drive for driving and controlling the AF sensor unit 36. A circuit 37; a mirror drive mechanism 38 for controlling the drive of the quick return mirror 16a; a shutter charge mechanism 47 for charging a spring for driving the front curtain and the rear curtain of the shutter unit 17; And a shutter control circuit 48 for controlling the above.

  On the optical axis, a CCD unit (imaging device) 40 that is an imaging means for photoelectrically converting the subject image that has passed through the optical system is provided as a photoelectric conversion device.

  The digital camera also includes image processing for image processing using a CCD interface circuit 41 connected to the CCD unit 40, a liquid crystal monitor 43, an SDRAM 44 provided as a storage area, a flash ROM 45, a recording medium 46, and the like. A controller (image forming means) 42 is provided so that an electronic recording display function can be provided together with an electronic imaging function.

  The other storage area stores predetermined control parameters necessary for camera control. As a correction amount storage means, for example, a non-volatile memory 49 made of an EEPROM is provided so as to be accessible from the Bμcom 50.

  In addition, the photometric sensor 32 is disposed at a position on the upper portion of the eyepiece lens 16c so as to stare at the focusing screen 31. This photometric sensor 32 collects subject light obtained via the photographing optical system 21, the quick return mirror 16a, the focusing screen 31, and the pentaprism 16b on the sensor with a photometric lens and measures the brightness. It is.

  The photometric sensor 32 is composed of a silicon photodiode, and an infrared cut filter is inserted between the sensor and a photometric lens (not shown). The spectral sensitivity of the photometric sensor 32 combined with these optical systems is substantially equal to the visual sensitivity.

  Further, a strobe for measuring the amount of light reflected on the white or gray shutter curtain at a position where the shutter section 17 is blurred (position where the shutter curtain is blurred from the side of the camera with the quick return mirror 16a retracted from the optical path). A photometric sensor 51 is provided. In the case of shooting conditions such that the strobe light is emitted, the brightness when the external strobe device 64 is pre-flashed before shooting after the diaphragm 22 finishes the aperture operation and the quick return mirror 16a is retracted from the optical path. The strobe photometry sensor 51 detects the output, and the output is supplied to the Bμcom 50 via the strobe light detection circuit 52.

  The Bμcom 50 obtains the strobe emission amount according to this output and transmits it to the external strobe device 64 via the strobe communication circuit 61 to control the strobe emission amount and timing at the time of actual photographing. The strobe photometry sensor 51 is also composed of a silicon photodiode, and an infrared cut filter (not shown) is inserted between the strobe photometry sensor 51 and a photometry lens (not shown). The spectral sensitivity of the strobe photometry sensor 51 combined with these optical systems is substantially equal to the visual sensitivity.

  The light source sensor 55 described above is a light source detection unit configured by an external light sensor in the present embodiment, and detects subject light that has not passed through the lens barrel 12 via the diffusion plate 14. The light source sensor 55 includes a visible light sensor 69 and an infrared light sensor 68. Since the subject light is incident through the diffusion plate 14, the field of view of the sensor is the same, and a wide angle of view is obtained. Have.

  The visible light sensor 69 correctly has visible and near infrared spectral sensitivities, but an infrared cut filter (not shown) is inserted between the visible light sensor 69 and the diffuser plate 14. Finally, only visible light is received. The light source sensor 55 compresses the photocurrent corresponding to each spectral sensitivity sensor, converts the current to voltage, and outputs the result. The output of the light source detection sensor is A / D converted by the light source detection circuit 54 so that the brightness of the entire subject according to the spectral sensitivity of each sensor can be detected.

  Further, the Bμcom 50 is provided with an operation display LCD 57 for notifying the user of the operation state of the camera by display output, a camera operation switch (SW) 58, and a strobe communication circuit 61. The camera operation switch 58 includes a group of switches including operation buttons necessary for operating the camera, such as a release switch, a mode change switch, a photometric mode change switch, and a power switch.

  The strobe communication circuit 61 receives a signal based on the light emission amount of the strobe obtained by the strobe photometric sensor 51 and calculated by Bμcom50. Then, a signal is output to the strobe device 64 via the communication connector 62, and the strobe device 64 emits light with a predetermined amount of light.

  Further, the camera body 11 is provided with a battery 60 as a power source and a power circuit 59 for converting the voltage of the power source into a voltage required by each circuit unit constituting the digital camera and supplying the same. ing.

  In the digital camera configured as described above, each unit operates as follows.

  The image processing controller 42 controls the CCD interface circuit 41 in accordance with a command from the Bμcom 50 and takes in image data from the CCD unit 40. This image data is converted into a video signal by the image processing controller 42 and output and displayed on the liquid crystal monitor 43. The user can confirm the captured image from the display image on the liquid crystal monitor 43.

  The SDRAM 44 is a memory for temporarily storing image data, and is used as a work area when image data is converted. The image data is set to be stored in the recording medium 50 after being converted into JPEG data.

  The mirror drive mechanism 38 is a mechanism for driving the quick return mirror 16a to the UP (up) position and the DOWN (down) position. When the quick return mirror 16a is in the DOWN position, the light beam from the photographing lens 21 is divided and guided to the AF sensor unit 36 side and the pentaprism 16b side.

  The output from the AF sensor in the AF sensor unit 36 is transmitted to the Bμcom 50 via the AF sensor driving circuit 37 and a known distance measurement process is performed.

  Here, how the distance measurement result by the AF sensor unit 36 is affected by the type of the light source that illuminates the subject will be described.

  First, the wavelength characteristics of the light source will be described.

  FIG. 4 is a schematic diagram illustrating spectral characteristics of various illumination light sources that illuminate a subject. Illustrative examples of illumination light sources include A: fluorescent lamp, B: incandescent lamp, C: blue flood lamp, D: daylight.

  As shown in FIG. 4, the spectral characteristics of the fluorescent lamp are in the range from about 300 nm to about 800 nm with the peak at about 500 nm. Further, the spectral characteristics of the incandescent lamp are in a region closer to a longer wavelength than the vicinity of about 300 nm with the vicinity of about 1000 nm as the apex. The spectral characteristics of the blue flood lamp have a steep sensitivity in the vicinity of about 800 nm and are in a region from about 300 nm to about 850 nm. And the spectral characteristic of general natural light (daylight) has a spectral characteristic over a relatively entire range from a region closer to a longer wavelength than about 300 nm.

  FIG. 5 is a diagram illustrating a state in which a gap between two images formed on the light receiving unit of the AF sensor unit 36 is shifted depending on the type of the light source that illuminates the subject.

  For example, assuming that the interval between two images is focused in daylight, and the same subject is illuminated with a blue flood lamp and photographed, the following occurs. That is, as shown in FIG. 5, it can be seen that a deviation of about +0.2 pixels occurs on the light receiving surface of the distance measuring sensor 28 as compared with the focused state in daylight. This is because the optical components of the photographic lens and the AF optical system are different when the wavelength component of the AF detection light beam is different. Since this is disclosed in Japanese Patent No. 2666274, description thereof is omitted here.

  The above approximately +0.2 pixel corresponds to, for example, +0.1 mm in terms of the focus position. The distance measuring sensor has a line sensor and means the pixel.

  In this way, when the in-focus position is shifted by the illumination light source, a so-called out-of-focus photograph is generated, which becomes a problem. For this reason, in the present invention, the type of the light source is discriminated by the light source sensor 55, and the above-mentioned problem is corrected by using the correction value in the correction value memory 27 in the lens barrel 12 and correcting the deviation. Has solved.

  FIG. 6 schematically shows a detection area of the AF sensor unit 36 and a detection area of the light source sensor 55 that constitute a part of the focus detection device in the camera of the present embodiment, and a photographing screen of these detection areas. The relationship with respect to (shooting angle of view) 57a is shown.

  In FIG. 6, a region 56 (a region indicated by hatching in FIG. 6) indicates a detection area of the AF sensor unit 36. Similarly, a region 57b indicates a detection area of the light source sensor 55.

  In addition, the user can view the subject from the eyepiece 16c adjacent to the pentaprism 16b. On the other hand, a part of the light beam that has passed through the pentaprism 16b is guided to the photometric sensor 32, and a well-known photometric process is performed based on the amount of light detected here.

  The photometric sensor 32 converts the photocurrent corresponding to each photometric pattern into a compressed current and outputs it. The output of the photometric sensor 32 is A / D converted by the photometric circuit 33, and the subject luminance corresponding to each pattern can be detected.

  Further, the exposure value (shutter speed, aperture, ISO sensitivity) is determined based on the photometric result obtained by the finder photometry.

  This digital camera has a plurality of shooting modes (P: program mode, A: aperture priority mode, S: shutter speed priority mode, M: manual mode), depending on the shooting mode selected by the photographer. The exposure value is calculated and determined. Based on the determined exposure value, shutter speed control, aperture control, and sensitivity control are performed.

  If the subject brightness is low and light can be emitted while the external strobe device 64 is connected, the Bμcom 50 determines that strobe light emission is necessary, and performs strobe light emission control.

  The shutter speed is generated by the focal plane shutter of the shutter unit 17. The synchronization time of flash emission of the strobe device 64 is 1/180 seconds.

  The aperture 22 is in the lens barrel 12 and is realized by instructing the lens to drive the aperture by communication between Bμcom 50 and Lμcom 25.

  The sensitivity control is realized by applying an analog gain to the output data of the CCD unit 40 and is performed by the interface circuit 41.

  The amount of light emitted from the strobe device 64 is measured by the strobe photometric sensor 51.

  As described above, the strobe photometric sensor 51 is disposed at a position where the shutter unit 17 is obscured so as to measure the reflected light of the white or gray shutter curtain. The strobe photometry sensor 51 measures the light reflected by the shutter curtain obtained by the pre-emission of the strobe device 64 after the quick return mirror 16a is raised. The Bμcom 50 calculates the light emission amount from the measured light amount, and communicates with the strobe device 62 via the strobe communication circuit 61. As a result, the amount of main light emission of the flash device 64 at the time of shooting is reflected.

  Next, the principle of detecting the type of light source will be described.

  FIG. 7 shows the spectral sensitivity characteristic of a visible light sensor 69 described later and the spectral sensitivity characteristic of an infrared light sensor 68 described later, which measure illumination light for illuminating a subject in the camera of this embodiment. It is a figure.

  The spectral sensitivity characteristic of the visible light sensor 69 in the camera according to the present embodiment is as shown by the symbol E in FIG. 7. The spectral sensitivity characteristic near the short wavelength region with the apex (peak: maximum value) near about 500 nm. And has sensitivity in the visible light region. Further, the spectral sensitivity characteristic of the infrared light sensor 68 in the same camera has a spectral sensitivity characteristic up to a long wavelength region of about 1000 nm with a vertex of about 600 nm as the apex, as indicated by reference numeral F in FIG. Yes.

  In the following description, photometry by the visible light sensor 69 is referred to as visible photometry, and photometry by the infrared light sensor 69 is referred to as infrared photometry.

  FIG. 8 is a diagram showing the difference (ΔBV) between infrared photometry and visible photometry by the above-mentioned light source, normalized using a tungsten lamp as a reference, and is a diagram showing a light source determination method in this embodiment. is there.

  In FIG. 8, since the reference light source is a tungsten lamp, the luminance difference ΔBV is 0.0 for a tungsten lamp, −1.1 for sunlight, −7.1 for a white fluorescent lamp, and 3 daylight. -7.5 for white fluorescent lamps, -6.2 for daylight white fluorescent lamps, -7.5 for 3-wave daylight fluorescent lamps, and +1.3 for blue flood lamps. Here, “standardized with a tungsten lamp” is a value obtained by subtracting the luminance difference when the camera is irradiated with the tungsten lamp from the luminance difference when the camera is irradiated with each light source light.

  Here, for example, in the case where threshold values are provided at positions where the luminance difference is −3 and +0.5, when the value of the luminance difference ΔBV exceeds −3, it is determined that the lamp is a fluorescent lamp. It can be determined as a lamp.

  FIG. 9 is a diagram showing the arrangement of the light source sensor 55, and FIG. 10 is a plan view showing the configuration of the light source sensor 55.

  The light source sensor 55 is disposed behind the diffusion plate 14 inside the camera exterior 65 of the camera body 11. The light source sensor 55 has a configuration in which an infrared sensor 68 and a visible infrared sensor (SPD) 69 and a control IC 72 for controlling these sensors are mounted on a clear mold 66. Further, an infrared cut filter 70 is disposed on the front surface of the visible infrared light sensor 68, that is, on the side facing the diffusion plate 14. Since infrared light is cut by the infrared cut filter 70, the visible infrared light sensor 69 is a visible light sensor having spectral sensitivity close to visible light.

  In this embodiment, in order to perform visible photometry, a sensor having spectral sensitivity in the infrared visible region and an infrared cut filter are combined. In the case of such a configuration, light that is incident on the sensor without being cut by infrared rays is generated depending on the position of the infrared cut filter. Since this amount varies depending on the assembly error of the camera and the like, the absolute amount of the luminance difference between visible light and infrared light when the light from each light source is irradiated on the camera is different.

  However, the value obtained by standardizing the luminance difference based on the reference light source (in this embodiment, tungsten light) is constant regardless of the individual camera difference. Therefore, the light source can be determined stably based on the principle shown in FIG.

  Next, the operation of the camera configured as described above will be described. The various operations described below are controlled by the Bμcom 50.

  First, with reference to the flowchart of FIG. 11, the operation when the camera body is loaded with a battery, the A / D adapter or the like is turned on, or the power switch is turned on will be described.

  First, in step S <b> 1, the entire circuit is initialized by the Bμcom 50 in the camera body 11. Next, in step S2, the state of the power switch (SW) is determined. Here, when the power switch is off, the operation of the camera ends. On the other hand, when the power switch is turned on, the process proceeds to step S3, where communication is performed between Bμcom 50 and Lμcom 25, the initialization operation in the lens barrel 12, and the lens barrel 12 Various data such as focus correction data in the correction value memory 27 and focal length information of the lens are exchanged.

  In step S4, the state of the release switch (SW) is determined. If the release switch is off, the process proceeds to step S2, and the state of the power switch is determined again. On the other hand, if the release switch is on, the process proceeds to step S5, and the subroutine “release” is executed. Thereafter, the process proceeds to step S2.

  FIG. 12 is a flowchart for explaining the operation of the subroutine “Release” performed when taking a picture out of the actions of the camera of the present embodiment.

  When the power of the camera is on and the camera is in a shooting preparation state in which a shooting operation can be performed, the user operates an operation member that is linked to the first release switch among the camera operation switches 58. Then, when a predetermined command signal (first release signal) corresponding to this operation is generated, the release operation subroutine of FIG. 12 is called and the same sequence is started.

  First, in step S11, the first release signal is received by the Bμcom 50, the photometric sensor 32 is driven and controlled via the photometric circuit 33, and photometry is performed. Thereby, photometric data which is the photometric result is acquired. Next, in step S12, the light source detection by the light source detection circuit 54 is similarly performed by the Bμcom 50, and the light source detection data as a result is acquired. The light source detection data acquired in this way is stored in predetermined areas (BVA, BVB) of a RAM (not shown) built in the Bμcom 50.

  Subsequently, in step S13, the state of the charging voltage of the strobe capacitor (not shown) included in the strobe device 64 is confirmed by the Bμcom 50, and whether or not the charging is performed at a level at which the strobe light emission operation can be performed. Is determined (charging check process). In the charging check process, if the subject has low brightness when the ranging operation sequence in step S14 is performed, a flash light emitting device including the strobe device 64 is used to direct auxiliary light toward the subject. Since it is necessary to irradiate, the voltage of the strobe capacitor is checked in advance at this stage.

  Note that it is determined whether or not the subject has low brightness during the distance measuring operation, and whether or not the auxiliary light needs to be irradiated during the distance measuring operation is determined based on the photometric result in step S12 described above. Based on.

  In step S14, the focus detection device is driven and controlled by Bμcom 50, and the subroutine “ranging operation” sequence is executed. The details of this subroutine “ranging operation” will be described later. Subsequently, in step S15, the distance measurement result of the distance measurement operation in step S14 described above is referred to and it is determined whether or not the focus position cannot be detected.

  If the focal position cannot be detected, the process proceeds to step S22. In step S22, a non-focus display process is performed in which a display indicating that the in-focus position cannot be detected is performed using a predetermined information display device (not shown) or the like. Thereafter, the sequence of the release process ends.

  On the other hand, if it is confirmed in step S15 that the focal position has been detected as a result of the distance measuring operation in step S14, the process proceeds to step S16. In step S16, it is confirmed whether or not the auxiliary light used by the flash light emitting device is emitted during the distance measuring operation in step S14 (see FIG. 13). If it is determined that the auxiliary light is emitted during the distance measuring operation, the process proceeds to step S17. If it is determined that the auxiliary light is not emitted, the process proceeds to step S18.

  In step S17, it is determined whether or not an excessive amount of light (over) or an insufficient amount of light (under) has occurred as a result of the auxiliary light being emitted during the distance measuring operation, compared to the appropriate exposure amount. Here, when it is determined that the light amount is over or under, it is considered that the distance measurement result obtained by the distance measurement operation performed under such circumstances is not reliable. Therefore, in such a case, the process proceeds to step S14, and the amount of auxiliary light is changed in the subsequent processing, and the same distance measuring operation is executed again.

  The predetermined operation such as the adjustment of the amount of auxiliary light during the distance measuring operation is described in detail in Japanese Patent Application Laid-Open No. Hei 6-289281 by the present applicant. Also in the camera of the present embodiment, it is assumed that auxiliary light irradiation is performed during the distance measuring operation in accordance with these conventionally used means. Therefore, detailed description thereof is omitted in the present embodiment.

  Next, in step S18, it is determined whether or not the subject image formed by the photographic lens moved based on the distance measurement result of the distance measurement operation is in focus. If it is determined that the subject is in focus, the process proceeds to step S19. If it is determined that the subject is not in focus, the process proceeds to step S20.

  In step S19, since it is in the in-focus state, the Bμcom 50 uses a display / warning device (not shown) such as a finder LED display or a buzzer sounding to inform the user that the in-focus state has been achieved. Notification is made (focus display processing). Thereafter, this routine ends (return).

  On the other hand, since it is a case where it is an out-of-focus state in step S20, a predetermined lens driving process is executed. In this case, the distance measurement result in step S14 is transmitted to Lμcom 25 in the lens barrel 12. With this Lμcom 25, drive control is performed so that the photographic lens is moved to a predetermined position based on the distance measurement result.

  In step S21, it is determined by Bμcom50 whether or not the lens has been in focus as a result of the lens driving process in step S20. Here, when it is determined that the in-focus state is obtained, the process proceeds to step S19. Then, after the focus display process is executed in step S19, a series of operations is completed (return). If it is determined in step S21 that the lens is still out of focus, the process proceeds to step S14 and the same distance measuring operation is repeated again.

  Next, the operation of the subroutine “ranging” in step S14 of the flowchart of FIG. 12 described above will be described with reference to the flowchart of FIG.

  As described above, when the subroutine “ranging” is executed in step S14 of the flowchart of FIG. 12, integration is first executed in step S31. Incidentally, the integration operation during the distance measuring operation has been conventionally disclosed by the above-mentioned JP-A-6-289281. Therefore, detailed description thereof is omitted here.

  Next, in step S32, distance measurement data as a distance measurement result is read out from the AF sensor unit 36 by Bμcom 50. Subsequently, in step S33, photometric data is calculated by a predetermined calculation process based on the sensor data read from the AF sensor unit 36 by the process of step S32. This photometric data is stored in a predetermined area (BVAF) of a RAM (not shown) in Bμcom.

  It should be noted that the predetermined photometric calculation executed here is in accordance with the means disclosed in the above-mentioned JP-A-6-289281.

  Next, in step S34, if the amount of light is insufficient due to a low-luminance environment or the like during the integration operation of the AF sensor unit 36 in the processing of step S31, the flash light emitting device is used. Predetermined processing such as determining whether or not it is necessary to irradiate the subject with auxiliary light and setting the light emission amount of the auxiliary light in that case is performed.

  In step S35, it is determined whether or not the distance measurement result cannot be detected by the distance measurement operation. As a result, when it is determined that the detection is impossible, the process proceeds to step S50. In step S50, after the out-of-focus flag is set (set), the series of the distance measuring operation sequence is terminated, and the process returns to the predetermined process in the flowchart of FIG. 12 described above (return).

  On the other hand, if a distance measurement result is detected in step S35, the process proceeds to step S36. Then, in step S36, it is determined whether or not the result of the integration by the application of the auxiliary light from the flash light emitting device (strobe device 64) is excessive. Here, when it is determined that the light amount is over, a series of distance measuring operation sequence ends, and the process returns to the predetermined processing of the flowchart of FIG. 12 described above (return). Then, the distance measuring operation is performed again according to a predetermined procedure.

  If it is determined in step S36 that the light amount is not over, the process proceeds to step S37, and the illuminance distribution correction process is executed. This illuminance distribution correction process is a process for correcting the sensitivity deviation of the sensor data. Subsequently, in step S38, a correlation calculation process is executed. Thereby, a so-called two-image interval is detected.

  Since the details of this correlation calculation process are disclosed in the above-mentioned Japanese Patent Laid-Open No. 6-289281, etc., the correlation calculation process is executed according to the conventional means also in this embodiment. And

  In step S39, the result of the correlation calculation process in step S38 is determined. If it is determined that there is a correlation, the process proceeds to step S40. If it is determined that there is no correlation, the process proceeds to step S47.

  In step S40, an image shift amount calculation process is executed. Next, in step S41, a calculation process is performed to calculate a shift amount of the imaging position with respect to the image sensor surface on the optical axis, that is, a defocus amount, from the image shift amount calculated in the process of step S40. The

  Next, in step S42, based on the detection result by the light source sensor 55 (by the light source detection in step S12 in the flowchart of FIG. 12), the subroutine “light source determination” processing (see FIG. 15) is executed. The detailed operation of this subroutine “light source determination” will be described later.

  In step S43, the subroutine “defocus correction” (see FIG. 14) is executed based on the result of the subroutine “light source determination” in the process of step S42. After the subroutine “defocus correction”, the process proceeds to step S44.

  In step S44, it is determined whether or not the calculated defocus amount is within the depth of focus range, that is, whether or not it is within the focus tolerance range. Here, if it is determined that it is within the focus allowable range, the process proceeds to step S46, and if it is determined that it is not within the focus allowable range, the process proceeds to step S45.

  In step S45, the corrected defocus amount is transmitted to Lμcom 25 by Bμcom50. Thereafter, a series of distance measuring operation sequence ends, and the process returns to the predetermined process of the flowchart of FIG. 12 described above (return). Then, the distance measuring operation is performed again according to a predetermined procedure.

  On the other hand, in step S46, after the focusing flag setting (setting) process is executed, a series of distance measuring operation sequence ends. As a result, the process returns to the predetermined process of the flowchart of FIG. Then, the distance measuring operation is performed again according to a predetermined procedure.

  If it is determined in step S39 that there is no correlation as a result of the correlation calculation process, the process proceeds to step S47 to determine whether illumination with auxiliary light has been performed during the sensor integration operation. Made. If it is determined that the auxiliary light is illuminated, the process proceeds to step S48. If it is determined that the auxiliary light is not illuminated, the process proceeds to step S50.

  In step S48, processing for increasing the amount of auxiliary light and performing illumination is executed. In step S49, it is determined whether or not the distance measurement result cannot be detected. If it is determined that there is no improvement in the distance measurement result despite the increase in the amount of auxiliary light, the process proceeds to step S50 described above, and the out-of-focus flag is set (set). Is done. Thereafter, the series of the distance measuring operation sequence is terminated, and the process returns to the predetermined process of the flowchart of FIG. 12 described above (return).

  On the other hand, if it is determined in step S49 that the distance measurement result has been improved by increasing the amount of auxiliary light, that is, if the distance measurement result is detected, a series of distance measurement operations are performed. The sequence is terminated, and the process returns to the predetermined process in the flowchart of FIG. 12 described above (return).

  In step S34, when the auxiliary light is used and the distance measuring operation is performed, the auxiliary light flag (F_HOJO) is set, and when the auxiliary light is not used, the auxiliary light flag is cleared.

  FIG. 14 is a flowchart showing the sequence of the subroutine “defocus correction” in step S43 of the flowchart of FIG.

  When this routine is entered, first, in step S61, it is determined by referring to the flag [F_HOJO] whether or not the distance is measured using the auxiliary light from the strobe device 64. Here, when the flag [F_HOJO] is set, the process proceeds to step S62, and the memory g [D_SYUSA] storing the aberration correction amount is determined by a function g that is different for each focal length described later. The values of the spherical aberration amount [f] of the photographing lens and the chromatic aberration amount [hojo] generated by the auxiliary light are stored. Thereafter, the process proceeds to step S70.

  Here, the function g is determined by the characteristics of the photographing lens, and is stored in the correction value memory 27 in the lens barrel 12.

Table 1 below shows focus correction data stored in advance in the correction value memory 27.

Corresponding to the focal length of the taking lens 21, the function g _n, the spherical aberration correction amount f _n, as chromatic aberration correction amount, the fluorescent lamp fluo _n, sun _n for daylight, incandescent lamp infr _n, bruf for blue flood lamps _n, Hojo _n is an auxiliary light, are stored, respectively. These data are stored in a memory in the camera body 11 such as the SDRAM 44 by communication between the Bμcom 50 and the Lμcom 25.

The focal length of the photographic lens 21 is also determined by Bμcom 50 by the above communication, and the function g _n and the spherical aberration amount f _n are selected. Further, the chromatic aberration amount is selected according to the light source determination result, and an aberration correction amount D_SYUSA is created.

  If the flag [F_HOJO] is not set in step S61, the process proceeds to step S63.

  In step S63, the result of the light source determination process described above (step S42 in the flowchart of FIG. 12 or FIG. 13) is referred to, and it is confirmed whether or not the light source illuminating the subject is a blue flood lamp. That is, it is confirmed whether or not the flag [F_BRUF] is set.

  If the flag [F_BRUF] is set and it is confirmed that the flag is a blue flood lamp, the process proceeds to step S64. In step S64, the spherical aberration amount [f] of the photographing lens determined by the function g that differs for each focal length with respect to the memory [D_SYUSA] that stores the aberration correction amount and the chromatic aberration amount [bruf] generated by the blue flood lamp. The value of is stored. Here, the function g is determined by the characteristics of the taking lens. Thereafter, the process proceeds to step S70 described later.

  On the other hand, if it is determined in step S63 that the lamp is not a blue flood lamp, the process proceeds to step S65. In step S65, the result of the light source determination process is referred to, and it is confirmed whether or not the light source illuminating the subject is an incandescent bulb, that is, whether or not the flag [F_INFR] is set.

  If the flag [F_INFR] is set and it is confirmed that the light bulb is an incandescent lamp, the process proceeds to step S66. In step S66, the spherical aberration amount [f] of the photographing lens determined by the function g that differs for each focal length in the memory [D_SYUSA] that stores the aberration correction amount and the chromatic aberration amount [infr] generated by the incandescent bulb. ] Is stored. Thereafter, the process proceeds to step S70 described later.

  If it is determined in step S65 that the light bulb is not an incandescent lamp, the process proceeds to step S67. In step S67, the result of the light source determination process is referred to, and it is confirmed whether or not the light source illuminating the subject is a fluorescent lamp, that is, whether or not the flag [F_FLUO] is set.

  If the flag [F_FLUO] is set and it is confirmed that the lamp is a fluorescent lamp, the process proceeds to step S68. In this step S68, the spherical aberration amount [f] of the taking lens determined by the function g that differs for each focal length in the memory [D_SYUSA] that stores the aberration correction amount and the chromatic aberration amount [fluo generated by the fluorescent lamp] ] Is stored. Thereafter, the process proceeds to step S70.

  On the other hand, if it is determined in step S67 that the light source is not a fluorescent lamp, the light source on which the subject is illuminated is neither an incandescent lamp, a fluorescent lamp, nor a blue flood lamp. It is. Accordingly, the spherical aberration amount [f] of the photographing lens determined by the function g that differs for each focal length and the chromatic aberration amount [sun] generated by daylight are stored in the memory [D_SYUSA] that stores the aberration correction amount. . Thereafter, the process proceeds to step S70 described later.

  In step S70, the data stored in the memory [D_SYUSA] is added to the memory [D_DF]. Thereafter, a series of defocus correction processing ends (return).

  In this way, the Bμcom 50 also has a function of correcting various information related to the calculated in-focus position as a result of a predetermined calculation process. Then, the corrected information is output to Lμcom 25, whereby the photographing lens 21 is moved by a predetermined lens driving amount.

  Next, the detailed operation of the subroutine “light source detection” in step S42 in the flowchart of FIG. 13 will be described with reference to the flowchart of FIG.

  When this routine is entered, first in step S81, flags F_FLUO, F_SUN, F_INFR, and F_BRUF indicating the type of light source are cleared, and the output of the light source sensor 55 is read. Next, the luminance of the light source is calculated from the output of the light source sensor 55 in step S82. Further, in step S83, luminance values of visible light and infrared light are respectively calculated.

In step S84, the difference between visible light (BV_eye) and infrared light (BV_ir) is calculated according to the following equation.
D_BV ← BV_ir-BV_eye
D_BV ← D_BV-DBV_REF
Here, DBV_REF is a luminance difference between visible light and infrared light at the time of reference tungsten light (incandescent lamp) irradiation, and is stored as an adjustment value in Bμcom 50 as a different value depending on the individual camera.

  In this way, the calculated difference is normalized based on tungsten light (incandescent lamp).

  Next, in step S85, it is determined whether or not the above-described luminance value of visible light is a usable value. This is because when the luminance is too bright or too dark, the light source detection accuracy of the light source sensor deteriorates, and the output of the light source detection is not very reliable. In this case, in step S85, it is determined whether the luminance value of visible light is less than −2 or greater than 8.

  Here, if the luminance value of the visible light is smaller than −2 or larger than 8, the process proceeds to step S84 and the light source is unknown. On the other hand, if the luminance value is −2 or more and 8 or less, the process proceeds to step S86.

  In step S86, the luminance difference D_BV calculated in step S84 is compared with the fluorescent lamp threshold value BV_TH_kei. If the brightness difference D_BV is smaller than the fluorescent lamp threshold BV_TH_kei, the process proceeds to step S90, and if greater, the process proceeds to step S87.

  In step S87, it is determined whether or not the brightness difference D_BV calculated in step S84 is between the fluorescent lamp threshold BV_TH_kei and the sunlight threshold BV_TH_sun. Here, if the luminance difference D_BV is within the range of both thresholds, the process proceeds to step S91, and if it is outside the range of both thresholds, the process proceeds to step S88.

  In step S88, it is determined whether or not the luminance difference D_BV calculated in step S84 is between the sunlight threshold value BV_TH_sun and the tungsten light threshold value BV_TH_fl. Here, if the luminance difference D_BV is within the range of both thresholds, the process proceeds to step S92, and if it is outside the range of both thresholds, the process proceeds to step S89.

  In step S89, the brightness difference D_BV calculated in step S84 is compared with the tungsten light threshold value BV_TH_fl. If the luminance difference D_BV is larger than the tungsten light threshold BV_TH_fl, the process proceeds to step S93, and if smaller, the process proceeds to step S94.

As shown in Table 2 below, for example, the threshold value of each light source described above is set such that the fluorescent light threshold value BV_TH_kei is −3, the sunlight threshold value BV_TH_sun is −0.5, and the tungsten light threshold value BV_TH_fl is +0.5. Is done.

  In step S90, the light source is regarded as a fluorescent lamp (1 is set in the flag [F_FLUO]). Similarly, in step S91, the light source is regarded as sunlight, and in step S92, the light source is regarded as tungsten light. Further, in step S93, the light source is regarded as a blue flood lamp. In step S94, the light source is unknown as described above. When the light source is unknown, the flag [F_FLUO] is set because the correction value of the fluorescent lamp that is the reference light source when adjusting the in-lens defocus correction value is used.

  When the light source is thus detected, the routine is exited.

  As described above, according to the first embodiment, it is possible to contribute to the improvement of the focus adjustment accuracy of the camera.

(Second Embodiment)
Next, a second embodiment of the present invention will be described.

  In the first embodiment described above, the case where one of the types of light sources is selected is taken as an example. However, in reality, there are a plurality of light sources for shooting at a window in a fluorescent lamp room. There are not a few situations of shooting. The second embodiment described below is configured so that an appropriate exposure amount is obtained even when the light source is a mixture of a plurality of types.

  The second embodiment is different from the first embodiment only in the control operation, and the configuration and basic operation of the camera are basically shown in FIGS. The same reference numerals are assigned to the same parts, and illustration and description thereof are omitted.

  First, calculation of the correction amount, which is a feature of the second embodiment, will be described with reference to FIG.

  In the second embodiment, when calculating the correction amount, an amount (hereinafter referred to as the mix level) corresponding to the light source mixing ratio obtained in the subroutine “light source detection” in step S42 in the flowchart of FIG. It is a feature that correction is performed in accordance with the mixing ratio of the light sources.

  In the case of a certain light source, for example, sunlight, even if the same sunlight is a light source, a side close to a fluorescent lamp and a side close to tungsten light are conceivable. For this reason, in the present embodiment, it is assumed that the other light source is closer to the light source as a mix level of the light sources.

  In FIG. 16, the horizontal axis represents D_BV, which is a value obtained by standardizing the luminance difference between infrared light and visible light, which will be described later, with reference light, and the vertical axis represents the aberration correction amount. Numerical values such as 0, 100, and 200 indicate the value of the mix level amount in each light source.

For example, the formula for calculating the mix level for sunlight is:
Mix level = ((D_BV−BV_kei)
/ (BV_TH_sun-BV_TH_kei))
× 200
It is.

  In this mix level, the luminance that is 1/2 of the determination threshold with other light sources is set to 100. For example, when sunlight is the main light source and close to tungsten light, the value is larger than 100, and when close to a fluorescent lamp, the value is smaller than 100.

  That is, assuming that BV_sun_REF, which is the reference value of sunlight, is 100, the mix level is 200 in the case of BV_TH_sun, which is the threshold value of tungsten and sunlight, and the mix level of BV_TH_kei, which is the threshold value of sunlight and fluorescent lamp, is 0. Between these values, the value changes linearly. In other words, if the mix level is 50, the main light source is sunlight, but the light from the fluorescent lamp is mixed a little.

  Based on the mix level thus obtained, the aberration correction amount g of each light source is obtained.

  For example, when the mix level of sunlight is 100, the value of g (f, sun) is the aberration correction amount. When the fluorescent lamp mix level is 100, the value of g (f, fluo) is the aberration correction amount.

  When the sunlight mix level is 0, that is, BV_TH_kei, the value of (g (f, fluo) + g (f, sun)) / 2 is the aberration correction amount. Furthermore, as described above, when the sunlight mix level is 50, the aberration correction amount is a value obtained by linearly interpolating the correction value of BV_TH_kei and the correction value when the sunlight mix level is 100.

  Thus, in calculating the correction amount for each light source, the correction amount is calculated from the mix level of the light sources using linear interpolation.

  Next, the detailed operation according to the second embodiment of the subroutine “light source detection” in step S42 in the flowchart of FIG. 13 will be described with reference to the flowchart of FIG.

  When this routine is entered, first, in step S101, the output of the light source sensor 55 is read. Next, the luminance of the light source is calculated from the output of the light source sensor 55 in step S102. Further, in step S103, the luminance values of visible light and infrared light are respectively calculated.

  In step S104, a difference between visible light (BV_eye) and infrared light (BV_ir) is calculated, and the calculated difference is normalized with reference to tungsten light.

  Next, in step S105, it is determined whether or not the above-described luminance value of visible light is a usable value. This is because when the luminance is too bright or too dark, the accuracy of the light source sensor deteriorates and the output value is not very reliable. In this case, in step S105, it is determined whether the luminance value of visible light is less than −2 or greater than 8.

  Here, if the luminance value of the visible light is less than −2 or greater than 8, the process proceeds to step S104 and the light source is determined to be unknown. On the other hand, if the luminance value is not less than −2 and not more than 8 in step S105, the process proceeds to step S106.

  In step S106, the luminance difference D_BV calculated in step S104 is compared with a fluorescent lamp threshold value BV_TH_kei. If the brightness difference D_BV is smaller than the fluorescent lamp threshold BV_TH_kei, the process proceeds to step S110, and if greater, the process proceeds to step S107.

  In step S107, it is determined whether or not the luminance difference D_BV calculated in step S104 is between the fluorescent lamp threshold BV_TH_kei and the sunlight threshold BV_TH_sun. Here, if the luminance difference D_BV is within the range of both threshold values, the process proceeds to step S111, and if it is outside the range of both threshold values, the process proceeds to step S108.

  In step S108, it is determined whether the luminance difference D_BV calculated in step S104 is between the sunlight threshold BV_TH_sun and the tungsten light threshold BV_TH_fl. Here, if the luminance difference D_BV is within the range of both thresholds, the process proceeds to step S112, and if it is outside the range of both thresholds, the process proceeds to step S109.

  In step S109, the brightness difference D_BV calculated in step S104 is compared with the tungsten light threshold value BV_TH_fl. If the luminance difference D_BV is larger than the tungsten light threshold BV_TH_fl, the process proceeds to step S113, and if smaller, the process proceeds to step S114.

  In addition, the threshold value of each light source is the same as that of the example mentioned above.

  In step S110, an amount indicating a mixing ratio of light sources when the light source includes a fluorescent lamp, that is, a mix level is calculated. Then, an aberration correction amount g corresponding to the mix level is calculated (see FIG. 16). The calculation formula and concept of the mix level are as described above. Similarly, in step S111, a mix level when the light source includes sunlight is calculated, and in step S112, a mix level when the light source includes tungsten light is calculated. In step S113, the mix level when the light source includes a blue flood lamp is calculated, and the aberration correction amount g is calculated in the same manner.

  When the light source detection and aberration correction amount g are obtained in this way, the process proceeds to step S42 in the flowchart of FIG. 13, and the subroutine “defocus correction” in the second embodiment shown in FIG. 18 is executed. .

  FIG. 18 is a flowchart for explaining the operation of the subroutine “defocus correction” in the second embodiment.

  When this subroutine is entered, in step S121, the aberration correction amount g calculated according to the light source mix level is input to the flag [D_SYUSA]. Next, in step S122, the detected defocus amount D_DF plus D_SYUSA that is the aberration correction amount g is input to D_DF. Thereby, the aberration-corrected defocus amount is calculated. Thereafter, the routine is exited.

  As described above, according to the second embodiment, the correction amount is changed even for the same light source in accordance with the output luminance difference of the light source sensor 55. Even if it is a case that is very close to the light source determination threshold, such as a mixed light of a fluorescent lamp and sunlight, correction according to the mixing ratio of the light sources is possible. Further, since the correction amount is continuously changed according to the output of the light source sensor 55, even when continuous shooting is performed, a stable exposure can be obtained without abruptly changing the correction amount according to the light source determination result. can get.

  As described above, appropriate AF can be performed according to the light source, and photographing can be performed.

  In the first and second embodiments described above, an example applied to a single-lens reflex digital camera has been described. However, the present invention is not limited to this, and a lens-integrated camera may be used.

(Third embodiment)
Next, a third embodiment of the present invention will be described.

  The third embodiment is an example in which correction by subject distance is added.

  It is known that the amount of focus deviation generated by the light source varies depending on the position of the focus lens. It is also known that this is caused by the change of spherical aberration depending on the focus lens position, that is, the amount of extension of the focus lens (see FIG. 19).

  Since the focus lens position corresponds to the subject distance, the following description will be given with the same meaning. The focus lens position is detected by a focus encoder (not shown) in the lens driving mechanism 23.

Table 3 below shows focus shift correction data corresponding to the light source stored in the correction value memory 27 in the lens barrel 12.

  This focus lens has, for example, a closest shooting distance of 0.5 m, and has a focus deviation correction data obtained by dividing a subject distance of 0.5 m to infinity into four areas.

  FIG. 19 shows the characteristics of only one type of light source, and the average defocus amount in each area is used as the correction data g.

  FIGS. 20 and 21 are flowcharts for explaining the operation of the subroutine “defocus correction” for correcting the focus shift using the focus shift correction data shown in Table 3 in the third embodiment.

  Hereinafter, this operation will be described.

When the subroutine “defocus correction” in step S43 in the flowchart of FIG. 13 is entered, the flag [F_HOJO] is first determined in step S131 of the flowcharts of FIGS. Here, when the flag [F_HOJO] is set, the process proceeds to step S132 to determine whether or not the subject distance L is 5 m or more. As a result, if the subject distance L is 5 m or more, the process proceeds to step S133, and the aberration correction amount g _1h is input to the flag [D_SYUSA] according to the correction data in Table 3 above. Thereafter, the process proceeds to step S170.

On the other hand, if the subject distance L is less than 5 m in step S132, the process proceeds to step S134 to determine whether or not the subject distance L is between 2 m and 5 m. If the subject distance L is between 2 m and 5 m, the process proceeds to step S135, and the aberration correction amount g _2h is input to the flag [D_SYUSA] according to the correction data in Table 3 above. Thereafter, the process proceeds to step S170.

Furthermore, if the subject distance L is less than 2 m in step S134, the process proceeds to step S136, and it is determined whether or not the subject distance L is between 1 m and 2 m. If the subject distance L is between 1 m and 2 m, the process proceeds to step S137, and the aberration correction amount g _3h is input to the flag [D_SYUSA] according to the correction data in Table 3 above. Thereafter, the process proceeds to step S170.

If the subject distance L is less than 1 m in step S136, the process proceeds to step S138, and the aberration correction amount g _4h is input to the flag [D_SYUSA] according to the correction data in Table 3 above. Thereafter, the process proceeds to step S170.

  On the other hand, if the flag [F_HOJO] is not set in step S131, the process proceeds to step S139 and it is determined whether or not the flag [F_BRUF] is set. If the flag [F_BRUF] is set, the process proceeds to step S140.

In step S140, it is determined whether or not the subject distance L is 5 m or more. As a result, if the subject distance L is 5 m or more, the process proceeds to step S141, and the aberration correction amount g _1b is input to the flag [D_SYUSA] according to the correction data in Table 3 above. Thereafter, the process proceeds to step S170.

On the other hand, if the subject distance L is less than 5 m in step S140, the process proceeds to step S142 to determine whether or not the subject distance L is between 2 m and 5 m. If the subject distance L is between 2 m and 5 m, the process proceeds to step S143, and the aberration correction amount g _2b is input to the flag [D_SYUSA] according to the correction data in Table 3 above. Thereafter, the process proceeds to step S170.

Furthermore, if the subject distance L is less than 2 m in step S142, the process proceeds to step S144, and it is determined whether or not the subject distance L is between 1 m and 2 m. Here, if the subject distance L is between 1 m and 2 m, the process proceeds to step S145, and the aberration correction amount g _3b is input to the flag [D_SYUSA] according to the correction data in Table 3 above. Thereafter, the process proceeds to step S170.

If the subject distance L is less than 1 m in step S144, the process proceeds to step S146, and the aberration correction amount g _4b is input to the flag [D_SYUSA] according to the correction data in Table 3 above. Thereafter, the process proceeds to step S170.

  If the flag [F_BRUF] is not set in step S139, the process proceeds to step S147 to determine whether or not the flag [F_INFR] is set. If the flag [F_INFR] is set, the process proceeds to step S149.

In step S149, it is determined whether or not the subject distance L is 5 m or more. As a result, if the subject distance L is 5 m or more, the process proceeds to step S150, and the aberration correction amount g _1i is input to the flag [D_SYUSA] according to the correction data in Table 3 above. Thereafter, the process proceeds to step S170.

On the other hand, if the subject distance L is less than 5 m in step S149, the process proceeds to step S151 and it is determined whether or not the subject distance L is between 2 m and 5 m. If the subject distance L is between 2 m and 5 m, the process proceeds to step S152, and the aberration correction amount g _2i is input to the flag [D_SYUSA] according to the correction data in Table 3 above. Thereafter, the process proceeds to step S170.

Furthermore, if the subject distance L is less than 2 m in step S151, the process proceeds to step S153 to determine whether or not the subject distance L is between 1 m and 2 m. If the subject distance L is between 1 m and 2 m, the process proceeds to step S154, and the aberration correction amount g _3i is input to the flag [D_SYUSA] according to the correction data in Table 3 above. Thereafter, the process proceeds to step S170.

If the subject distance L is less than 1 m in step S153, the process proceeds to step S155, and the aberration correction amount g _4i is input to the flag [D_SYUSA] according to the correction data in Table 3 above. Thereafter, the process proceeds to step S170.

  If the flag [F_INFR] is not set in step S147, the process proceeds to step S148 to determine whether or not the flag [F_FLUO] is set. If the flag [F_FLUO] is set, the process proceeds to step S156.

In step S156, it is determined whether or not the subject distance L is 5 m or more. As a result, if the subject distance L is 5 m or more, the process proceeds to step S157, and the aberration correction amount g _1f is input to the flag [D_SYUSA] according to the correction data in Table 3 above. Thereafter, the process proceeds to step S170.

On the other hand, if the subject distance L is less than 5 m in step S156, the process proceeds to step S158 to determine whether or not the subject distance L is between 2 m and 5 m. If the subject distance L is between 2 m and 5 m, the process proceeds to step S159, and the aberration correction amount g _2f is input to the flag [D_SYUSA] according to the correction data in Table 3 above. Thereafter, the process proceeds to step S170.

Further, if the subject distance L is less than 2 m in step S158, the process proceeds to step S160, and it is determined whether or not the subject distance L is between 1 m and 2 m. If the subject distance L is between 1 m and 2 m, the process proceeds to step S161, and the aberration correction amount g _3f is input to the flag [D_SYUSA] according to the correction data in Table 3 above. Thereafter, the process proceeds to step S170.

If the subject distance L is less than 1 m in step S160, the process proceeds to step S162, and the aberration correction amount g _4f is input to the flag [D_SYUSA] according to the correction data in Table 3 above. Thereafter, the process proceeds to step S170.

  If the flag [F_FLUO] is not set in step S148, the process proceeds to step S163. In this case, since the auxiliary light, the blue flood lamp, the incandescent lamp, and the fluorescent lamp are not included, the light source is determined to be sunlight.

In step S163, it is determined whether or not the subject distance L is 5 m or more. As a result, if the subject distance L is 5 m or more, the process proceeds to step S164, and the aberration correction amount g _1s is input to the flag [D_SYUSA] according to the correction data in Table 3 above. Thereafter, the process proceeds to step S170.

On the other hand, if the subject distance L is less than 5 m in step S164, the process proceeds to step S165 to determine whether the subject distance L is between 2 m and 5 m. If the subject distance L is between 2 m and 5 m, the process proceeds to step S166, and the aberration correction amount g _2s is input to the flag [D_SYUSA] according to the correction data in Table 3 above. Thereafter, the process proceeds to step S170.

Further, if the subject distance L is less than 2 m in step S165, the process proceeds to step S167, and it is determined whether or not the subject distance L is between 1 m and 2 m. If the subject distance L is between 1 m and 2 m, the process proceeds to step S168, and the aberration correction amount g _3s is input to the flag [D_SYUSA] according to the correction data in Table 3 above. Thereafter, the process proceeds to step S170.

If the subject distance L is less than 1 m in step S167, the process proceeds to step S169, and the aberration correction amount g _4s is input to the flag [D_SYUSA] according to the correction data in Table 3 above. Thereafter, the process proceeds to step S170.

  In step S170, a value obtained by adding D_SYUSA to the defocus amount D_DF detected according to the type of the light source and the subject distance L is input to D_DF. Thereby, the aberration-corrected defocus amount is calculated. Thereafter, the routine is exited.

  In the first to third embodiments described above, four types of light sources such as sunlight, fluorescent lamp, tungsten light (incandescent lamp), and blue flood lamp are detected, but not only these four types. It is also possible to detect a finer light source and perform accurate correction.

  The embodiment of the present invention has been described above, but it goes without saying that the present invention can be modified without departing from the gist of the present invention.

It is a block diagram which shows schematic structure of the digital camera to which the focus detection apparatus of this invention was applied. 1 is a perspective view schematically showing an internal configuration of a part of a digital camera according to a first embodiment of the present invention. 1 is a block configuration diagram schematically illustrating mainly an electrical configuration of a digital camera according to a first embodiment. It is the schematic which shows the spectral characteristic of the various illumination light sources which illuminate a to-be-photographed object. FIG. 5 is a diagram showing a state in which a gap between two images formed on the light receiving portion of the AF sensor unit 36 is shifted depending on the type of light source that illuminates the subject. The detection area of the AF sensor unit 36 and the detection area of the light source sensor 55 that constitute a part of the focus detection device in the camera of the present embodiment are schematically shown, and the shooting screens (shooting angle of view) of these detection areas FIG. In the camera of the first embodiment, the illumination light for illuminating the subject is measured, and is a diagram showing the spectral sensitivity characteristic of a visible light sensor 69 and the spectral sensitivity characteristic of an infrared light sensor 68 described later. . It is the figure which expressed and standardized the difference ((DELTA) BV) of the infrared photometry by a light source and a visible photometry on the basis of a tungsten lamp, and is the figure which showed the light source determination method in this embodiment. It is the figure shown about arrangement | positioning of the light source sensor. 5 is a plan view showing a configuration of a light source sensor 55. FIG. It is a flowchart explaining operation | movement at the time of turning on power supply of a battery loading, an A / D adapter etc. to a camera main body, or a power switch being turned on. It is a flowchart explaining operation | movement of the subroutine "release" performed when taking a photograph among the effects | actions of the camera of 1st Embodiment. 13 is a flowchart for explaining the operation of a subroutine “ranging” in step S14 of the flowchart of FIG. It is a flowchart which shows the sequence of the subroutine "defocus correction | amendment" in step S43 of the flowchart of FIG. It is a flowchart explaining the detailed operation | movement of the subroutine "light source detection" of step S42 in the flowchart of FIG. It is a 2nd embodiment of the present invention, and is a figure explaining correction amount calculation according to the mixture ratio of a light source. It is a flowchart explaining the detailed operation | movement by 2nd Embodiment of the subroutine "light source detection" of step S42 in the flowchart of FIG. 12 is a flowchart for explaining the operation of a subroutine “defocus correction” in the second embodiment. It is the 3rd Embodiment of this invention, and is the figure which showed the characteristic about only one type of light source. 14 is a flowchart for explaining the operation of a subroutine “defocus correction” for correcting a focus shift using the focus shift correction data of Table 3 in the third embodiment. 14 is a flowchart for explaining the operation of a subroutine “defocus correction” for correcting a focus shift using the focus shift correction data of Table 3 in the third embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1,11 ... Camera body, 2 ... Interchangeable lens, 3 ... Memory, 4 ... Light source detection part, 5 ... Auto-focus (AF) control part, 10 ... Digital camera, 12 ... Lens barrel, 12a ... Shooting optical system, 13 ... release button, 14 ... diffuser plate, 16 ... finder device, 16a ... quick return mirror, 16b ... pentaprism, 16c ... eyepiece lens, 17 ... shutter part, 18 ... imaging unit, 21 ... taking lens, 22 ... aperture, 25 Lens microcomputer (Lμcom), 27 Correction value memory, 32 Photometric sensor, 33 photometric circuit, 35 Sub-mirror, 36 AF sensor unit, 40 CCD unit (imaging device), 41 CCD interface circuit 42 ... Image processing controller, 43 ... Liquid crystal monitor, 49 ... Non-volatile memory (EEPROM), 5 DESCRIPTION OF SYMBOLS ... Body control microcomputer (Bmicrocom), 51 ... Strobe photometry sensor, 52 ... Strobe light detection circuit, 53 ... Strobe light control circuit, 54 ... Light source detection circuit, 55 ... Light source sensor, 61 ... Strobe communication circuit, 62, 63 ... Communication connector, 64 ... Strobe device.

Claims (19)

A lens interchangeable camera having a lens barrel including a taking lens and a camera body,
A correction value storage means that is disposed inside the lens barrel and stores a correction value for correcting the defocus according to the type of light source that illuminates the subject;
Light source detection means for detecting a light source that illuminates a subject and outputting a signal corresponding to the light source;
Focus detection means for detecting the focus of the photographing lens;
Comprising
The camera according to claim 1, wherein the focus detection means performs focus detection based on the output of the signal detected by the light source detection means and a correction value stored in the correction value storage means. A lens interchangeable camera having a lens barrel including a taking lens and a camera body,
A correction value storage means that is disposed inside the lens barrel and stores a correction value for correcting the defocus according to the type of light source that illuminates the subject;
Light source detection means for detecting a light source that illuminates a subject and outputting a signal corresponding to the light source;
Focus detection means for detecting the focus of the photographing lens;
Correction amount calculation means for calculating a correction amount for correcting the output of the focus detection means based on the output of the light source detection means and the correction value stored in the correction value storage means;
Correction means for correcting the output of the focus detection means based on the correction amount calculated by the correction amount calculation means;
A camera comprising:   The camera according to claim 2, wherein the correction unit performs correction based on a correction amount that continuously changes in accordance with a result detected by the light source detection unit.   2. The camera according to claim 1, wherein the light source detection means further comprises a light quantity detection means for detecting at least one of the infrared light and near infrared light of the subject.   The camera according to claim 2, wherein the light source detection unit further includes a light amount detection unit that detects at least one of the infrared light and near infrared light of the subject.   4. The camera according to claim 3, wherein the light source detection means further comprises a light quantity detection means for detecting at least one of the infrared light and near infrared light of the subject.   2. The camera according to claim 1, wherein the light source detection means is constituted by an external light type light detection means that does not use subject light that has passed through the photographing lens.   3. The camera according to claim 2, wherein the light source detection means is constituted by an external light type light detection means that does not use subject light that has passed through the photographing lens.   4. The camera according to claim 3, wherein the light source detection means is constituted by external light type light detection means that does not use subject light that has passed through the photographing lens.   5. The camera according to claim 4, wherein the light source detection means is constituted by external light type light detection means that does not use subject light that has passed through the photographing lens.   6. The camera according to claim 5, wherein the light source detection means is constituted by outside light type light detection means that does not use subject light that has passed through the photographing lens.   The camera according to claim 6, wherein the light source detection unit includes an external light type light detection unit that does not use subject light that has passed through the photographing lens.   13. The correction value stored in the correction value storage means has a format that changes in response to at least one change in focal length and subject distance. Camera described in. A taking lens,
Light source detection means for detecting a light source that illuminates a subject and outputting a signal corresponding to the light source;
Correction value storage means for storing a correction value for correcting defocus according to the type of the light source;
Control means for controlling the focus of the photographing lens based on the output of the signal detected by the light source detection means and the correction value stored in the correction value storage means;
A focus detection apparatus comprising:   The control means calculates a correction amount for correcting the output of the focus detection means based on the output of the light source detection means and the correction value stored in the correction value storage means. The focus detection apparatus according to claim 14, wherein a defocus of the photographing lens is corrected based on a correction amount.   15. The focus detection apparatus according to claim 14, wherein the light source detection means further comprises a light quantity detection means for detecting at least one of the infrared light and near infrared light of the subject.   15. The focus detection apparatus according to claim 14, wherein the light source detection means is constituted by external light type light detection means that uses light other than subject light that has passed through the photographing lens.   15. The focus detection apparatus according to claim 14, wherein the correction value stored in the correction value storage means has a format that changes in response to at least one change in focal length and subject distance. .   The focus detection apparatus according to claim 14, wherein the correction value storage unit is disposed inside a lens barrel including the photographing lens.

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