JP5545278B2 - Lens adapter and camera body - Google Patents

Description

  The present invention relates to a lens adapter and a camera body.

  2. Description of the Related Art Conventionally, there has been known an image pickup apparatus that detects a focus state of an optical system by detecting a shift amount of an image plane of the optical system based on an output of a focus detection pixel provided in the image pickup element. As such an imaging device, for example, in order to prevent vignetting when performing focus detection, the aperture value of the optical system is set to a value (open side value) smaller than a predetermined aperture value, A method of performing focus detection is known (for example, Patent Document 1).

JP 2010-217618 A

  However, in the prior art, when the aperture value of the optical system is changed from the aperture value at the time of focus detection to the imaging aperture value in order to actually capture an image, the image plane of the optical system is changed along with the change of the aperture value. Moved, and as a result, there was a case where an image focused on the subject could not be taken.

  The problem to be solved by the present invention is to provide a lens adapter that can capture an image satisfactorily.

  The present invention solves the above problems by the following means. In the following description, reference numerals corresponding to the drawings showing the embodiment of the present invention are given and described. However, the reference numerals are only for facilitating the understanding of the invention and are not intended to limit the invention. .

[1] The lens barrel according to the present invention is mounted on the first communication unit (51) that acquires lens information from the mounted lens barrel (3 ), and is set when the focus adjustment state is detected. The aperture value of the aperture (34) of the lens barrel and a storage unit (52) for storing an open-side limit value set according to the type of the lens barrel, and the first communication unit acquired by the storage unit (52) An acquisition unit (51) that acquires the open side limit value corresponding to the attached lens barrel using lens information and the open side limit value stored in the storage unit; and A second communication unit (51) that transmits the acquired opening side limit value corresponding to the acquired lens barrel to the mounted camera body , and the acquisition unit is mounted from the lens information. If the lens barrel type can be identified, the label The open side limit value based on the type of the lens barrel is acquired, and when the type of the mounted lens barrel cannot be identified from the lens information, the predetermined open side limit value set in advance is acquired. Even when the aperture value of the aperture changes from the open side limit value to the imaging aperture value when performing actual imaging, the amount of movement of the image plane due to the change of the aperture value of the aperture is the optical system when performing actual imaging. It is within the range of the depth of field .

  According to the present invention, an image can be taken satisfactorily.

FIG. 1 is a block diagram showing a camera according to the present embodiment. FIG. 2 is a front view showing a focus detection position on the imaging surface of the imaging device shown in FIG. FIG. 3 is a front view schematically showing the arrangement of the focus detection pixels 222a and 222b by enlarging the III part of FIG. FIG. 4 is an enlarged front view showing one of the imaging pixels 221. FIG. 5A is an enlarged front view showing one of the focus detection pixels 222a, and FIG. 5B is an enlarged front view showing one of the focus detection pixels 222b. FIG. 6 is an enlarged cross-sectional view showing one of the imaging pixels 221. FIG. 7A is an enlarged cross-sectional view showing one of the focus detection pixels 222a, and FIG. 7B is an enlarged cross-sectional view showing one of the focus detection pixels 222b. 8 is a cross-sectional view taken along line VIII-VIII in FIG. FIG. 9 is a flowchart showing the operation of the camera according to the present embodiment. FIG. 10 is a diagram illustrating an example of the relationship between the aperture value at the time of focus detection set in the present embodiment and the photographing aperture value. FIG. 11 is a flowchart showing the scan operation execution process in step S119.

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

  FIG. 1 is a main part configuration diagram showing a digital camera 1 according to an embodiment of the present invention. A digital camera 1 (hereinafter simply referred to as a camera 1) according to the present embodiment includes a camera body 2, a lens barrel 3, and a lens adapter 5. The camera body 2 and the lens barrel 3 connect the lens adapter 5 to each other. It is couple | bonded so that attachment or detachment is possible.

  The lens barrel 3 is an interchangeable lens that can be attached to and detached from the camera body 2 via a lens adapter 5. As shown in FIG. 1, the lens barrel 3 includes a photographic optical system including lenses 31, 32, 33 and a diaphragm 34.

  The lens 32 is a focus lens, and can adjust the focal length of the photographing optical system by moving in the direction of the optical axis L1. The focus lens 32 is provided so as to be movable along the optical axis L1 of the lens barrel 3, and its position is adjusted by the focus lens drive motor 36 while its position is detected by the encoder 35.

  The specific configuration of the moving mechanism along the optical axis L1 of the focus lens 32 is not particularly limited. For example, a rotating cylinder is rotatably inserted into a fixed cylinder fixed to the lens barrel 3, a helicoid groove (spiral groove) is formed on the inner peripheral surface of the rotating cylinder, and the focus lens 32 is fixed. The end of the lens frame is fitted into the helicoid groove. Then, by rotating the rotating cylinder by the focus lens drive motor 36, the focus lens 32 fixed to the lens frame moves straight along the optical axis L1.

  As described above, the focus lens 32 fixed to the lens frame by rotating the rotary cylinder with respect to the lens barrel 3 moves straight in the direction of the optical axis L1, but the focus lens drive motor 36 as the drive source is the lens. The lens barrel 3 is provided. The focus lens drive motor 36 and the rotary cylinder are connected by a transmission composed of a plurality of gears, for example, and when the drive shaft of the focus lens drive motor 36 is driven to rotate in any one direction, it is transmitted to the rotary cylinder at a predetermined gear ratio. Then, when the rotating cylinder rotates in any one direction, the focus lens 32 fixed to the lens frame moves linearly in any direction of the optical axis L1. When the drive shaft of the focus lens drive motor 36 is rotated in the reverse direction, the plurality of gears constituting the transmission also rotate in the reverse direction, and the focus lens 32 moves straight in the reverse direction of the optical axis L1. .

  The position of the focus lens 32 is detected by the encoder 35. As described above, the position of the focus lens 32 in the optical axis L1 direction correlates with the rotation angle of the rotating cylinder, and can be obtained by detecting the relative rotation angle of the rotating cylinder with respect to the lens barrel 3, for example.

  As the encoder 35 of this embodiment, an encoder that detects the rotation of a rotating disk coupled to the rotational drive of the rotating cylinder with an optical sensor such as a photo interrupter and outputs a pulse signal corresponding to the number of rotations, or a fixed cylinder And the contact point of the brush on the surface of the flexible printed wiring board provided on either one of the rotating cylinders, and the brush contact provided on the other, the amount of movement of the rotating cylinder (in either the rotational direction or the optical axis direction) A device that detects a change in the contact position according to the detection circuit using a detection circuit can be used.

  The focus lens 32 can move in the direction of the optical axis L1 from the end on the camera body side (also referred to as the closest end) to the end on the subject side (also referred to as the infinite end) by the rotation of the rotating cylinder described above. it can. Incidentally, the current position information of the focus lens 32 detected by the encoder 35 is sent to the camera control unit 21 to be described later via the lens control unit 37, and the focus lens drive motor 36 calculates the focus calculated based on this information. The driving position of the lens 32 is driven by being sent from the camera control unit 21 via the lens control unit 37.

  The diaphragm 34 is configured such that the aperture diameter around the optical axis L1 can be adjusted in order to limit the amount of light flux that passes through the photographing optical system and reaches the image sensor 22 and to adjust the blur amount. The adjustment of the aperture diameter by the diaphragm 34 is performed, for example, by sending an aperture diameter corresponding to the aperture value calculated in the automatic exposure mode from the camera control unit 21 via the lens control unit 37. Further, the aperture diameter corresponding to the set photographing aperture value is input from the camera control unit 21 to the lens control unit 37 by manual operation by the operation unit 28 provided in the camera body 2. The aperture diameter of the aperture 34 is detected by an aperture sensor (not shown), and the lens controller 37 recognizes the current aperture diameter.

  On the other hand, the camera body 2 is provided with an imaging element 22 that receives the light beam L1 from the photographing optical system on a planned focal plane of the photographing optical system, and a shutter 23 is provided on the front surface thereof. The image sensor 22 is composed of a device such as a CCD or CMOS, converts the received optical signal into an electrical signal, and sends it to the camera control unit 21. The captured image information sent to the camera control unit 21 is sequentially sent to the liquid crystal drive circuit 25 and displayed on the electronic viewfinder (EVF) 26 of the observation optical system, and a release button ( When (not shown) is fully pressed, the photographed image information is recorded in the memory 24 that is a recording medium. As the memory 24, any of a removable card type memory and a built-in type memory can be used. An infrared cut filter for cutting infrared light and an optical low-pass filter for preventing image aliasing noise are disposed in front of the imaging surface of the image sensor 22. Details of the structure of the image sensor 22 will be described later.

  A camera control unit 21 is provided in the camera body 2. The camera control unit 21 is electrically connected to the lens control unit 37 via the lens adapter 5, receives lens information from the lens control unit 37, and defocus amount and diaphragm aperture diameter to the lens control unit 37. Send information such as. The camera control unit 21 reads out the pixel output from the image sensor 22 as described above, generates image information by performing predetermined information processing on the read out pixel output as necessary, and generates the generated image information. Is output to the liquid crystal driving circuit 25 and the memory 24 of the electronic viewfinder 26. The camera control unit 21 controls the entire camera 1 such as correction of image information from the image sensor 22 and detection of a focus adjustment state and an aperture adjustment state of the lens barrel 3.

  In addition to the above, the camera control unit 21 detects the focus state of the photographing optical system by the phase detection method and the focus state of the optical system by the contrast detection method based on the pixel data read from the image sensor 22. Do. A method for detecting the focus state will be described later.

  In addition, the camera control unit 21 stores in advance in the memory 29 the limit value on the aperture side of the aperture value of the optical system when performing focus detection as the limit value on the aperture side. This narrowing limit value is the most narrow value among the narrowing values that can effectively prevent the occurrence of vignetting and obtain good focus detection accuracy when performing focus detection. be able to. Then, the camera control unit 21 controls the exposure when performing focus detection based on the open side limit value received from the adapter control unit 51 described later and the narrowing side limit value stored in the memory 29. Details of exposure control at the time of focus detection will be described later.

  The operation unit 28 is a shutter release button and an input switch for the photographer to set various operation modes of the camera 1, and can switch between an auto focus mode and a manual focus mode. Various modes set by the operation unit 28 are sent to the camera control unit 21, and the operation of the entire camera 1 is controlled by the camera control unit 21. The shutter release button includes a first switch SW1 that is turned on when the button is half-pressed and a second switch SW2 that is turned on when the button is fully pressed.

  A lens adapter 5 for mounting the lens barrel 3 on the camera body 2 is interposed between the lens barrel 3 and the camera body 2. The adapter control unit 51 receives the lens information from the lens control unit 37 via the electrical signal contact unit 61 provided in the mount unit 6, and sends the data received from the camera control unit 21 to the lens control unit 37. Information such as the focus amount and aperture diameter is transmitted. The adapter control unit 51 receives information such as the defocus amount and the aperture diameter from the camera control unit 21 via the electrical signal contact unit 41 provided on the mount unit 4, and On the other hand, the lens information received from the lens control unit 37 is transmitted. Thus, in the present embodiment, lens information and the like are transmitted and received between the camera control unit 21 and the lens control unit 37 via the lens adapter 5.

  In the memory 52 of the lens adapter 5, the limit value on the open side of the aperture value of the optical system when detecting the focus state of the optical system is stored in advance as the open side limit value. Here, for example, when the aperture value at the time of detecting the focus state of the optical system is F1.4 and the imaging aperture value at the time of actual imaging of the image is F2.8, the main imaging is performed after the focus detection. In addition, when the aperture value of the optical system is changed from F1.4, which is the aperture value at the time of focus detection, to F2.8, which is the photographing aperture value, the focal point is changed due to the movement of the image plane accompanying the change of the aperture value. The in-focus position detected at the time of detection deviates from the depth of field of the optical system at the time of actual shooting of the image, and a focused image cannot be taken with respect to the subject that was in focus at the time of focus detection There is a case. In particular, this tendency increases as the aperture value of the optical system becomes a value on the open side. Therefore, in such a case, for example, by restricting the aperture value on the open side when detecting the focus state of the optical system to F2 instead of F1.4, the amount of image plane movement accompanying the change of the aperture value can be reduced. Even when the aperture value of the optical system is suppressed and the aperture value at the time of detecting the focus state is changed to the imaging aperture value, an image in focus on the subject can be captured. In this way, the open side limit value is an open aperture value of the optical system that can capture a good image even when the aperture value of the optical system is changed from the aperture value at the time of focus detection to the shooting aperture value. This is a limit value on the side, and is a value unique to the lens barrel 3 corresponding to the lens barrel 3.

  In this embodiment, the open side limit value is stored in the memory 52 of the lens adapter 5 for each type of the lens barrel 3, and the adapter control unit 51 is based on the lens information received from the lens barrel 3. By identifying the type of the lens barrel 3, an open side limit value corresponding to the type of the lens barrel 3 is acquired. Then, the adapter control unit 51 transmits the open side limit value acquired according to the type of the lens barrel 3 from the adapter control unit 51 to the camera control unit 21. When the type of the lens barrel 3 cannot be identified, the adapter control unit 51 acquires a predetermined opening side limit value stored in the memory 52, and uses the acquired predetermined opening side limit value as the camera control unit. To 21.

  The open side limit value is stored in the memory 52 as the number of aperture stages from the open aperture value. For example, when the open side limit value is F2 as the aperture value (F value), the open aperture value is F1.2, and the aperture value of the optical system is changed from the open aperture value F1.2 to the open side limit value. When the number of aperture stages of the aperture 34 for changing to a certain F2 is 2, the adapter control unit 51 stores the open side limit value as 2 stages. Thus, by storing the open side limit value as the number of aperture stages from the open aperture value, for example, even when the lens position of the zoom lens is changed, the open aperture value according to the lens position of the zoom lens Based on the above, it is possible to obtain the open side limit value according to the lens position of the zoom lens, and it is not necessary to store the open aperture value for each lens position of the zoom lens. The above-described open aperture value, open side limit value, and number of aperture stages are examples, and are not limited to these values.

  Next, the image sensor 22 according to the present embodiment will be described.

  FIG. 2 is a front view showing the imaging surface of the image sensor 22, and FIG. 3 is a front view schematically showing the arrangement of the focus detection pixels 222a and 222b by enlarging the III part of FIG.

  As shown in FIG. 3, the imaging element 22 of the present embodiment includes a green pixel G having a color filter in which a plurality of imaging pixels 221 are two-dimensionally arranged on the plane of the imaging surface and transmit a green wavelength region. A red pixel R having a color filter that transmits a red wavelength region and a blue pixel B having a color filter that transmits a blue wavelength region are arranged in a so-called Bayer Arrangement. That is, in four adjacent pixel groups 223 (dense square lattice arrangement), two green pixels are arranged on one diagonal line, and one red pixel and one blue pixel are arranged on the other diagonal line. The image sensor 22 is configured by repeatedly arranging the pixel group 223 on the imaging surface of the image sensor 22 in a two-dimensional manner with the Bayer array pixel group 223 as a unit.

  The unit pixel group 223 may be arranged in a dense hexagonal lattice arrangement other than the dense square lattice shown in the figure. Further, the configuration and arrangement of the color filters are not limited to this, and an arrangement of complementary color filters (green: G, yellow: Ye, magenta: Mg, cyan: Cy) can also be adopted.

  FIG. 4 is an enlarged front view showing one of the imaging pixels 221, and FIG. 6 is a cross-sectional view. One imaging pixel 221 includes a micro lens 2211, a photoelectric conversion unit 2212, and a color filter (not shown), and a photoelectric conversion unit is formed on the surface of the semiconductor circuit substrate 2213 of the image sensor 22 as shown in the cross-sectional view of FIG. 2212 is built in and a microlens 2211 is formed on the surface. The photoelectric conversion unit 2212 is configured to receive an imaging light beam that passes through an exit pupil (for example, F1.0) of the photographing optical system by the micro lens 2211, and receives the imaging light beam.

  In addition, focus detection pixel rows 22a, 22b, and 22c in which focus detection pixels 222a and 222b are arranged in place of the above-described imaging pixels 221 at the center of the image pickup surface of the image pickup element 22 and three positions that are symmetrical from the center. Is provided. As shown in FIG. 3, one focus detection pixel column includes a plurality of focus detection pixels 222 a and 222 b that are alternately arranged adjacent to each other in a horizontal row (22 a, 22 c, 22 c). Yes. In the present embodiment, the focus detection pixels 222a and 222b are densely arranged without providing a gap at the position of the green pixel G and the blue pixel B of the image pickup pixel 221 arranged in the Bayer array.

  Note that the positions of the focus detection pixel rows 22a to 22c shown in FIG. 2 are not limited to the illustrated positions, and may be any one or two, or may be arranged at four or more positions. it can. In actual focus detection, the photographer manually operates the operation unit 28 from among a plurality of focus detection pixel rows 22a to 22c, and selects a desired focus detection pixel row as a focus detection position. You can also

  FIG. 5A is an enlarged front view showing one of the focus detection pixels 222a, and FIG. 7A is a cross-sectional view of the focus detection pixel 222a. FIG. 5B is an enlarged front view showing one of the focus detection pixels 222b, and FIG. 7B is a cross-sectional view of the focus detection pixel 222b. As shown in FIG. 5A, the focus detection pixel 222a includes a micro lens 2221a and a semicircular photoelectric conversion unit 2222a. As shown in the cross-sectional view of FIG. A photoelectric conversion portion 2222a is formed on the surface of the semiconductor circuit substrate 2213, and a micro lens 2221a is formed on the surface. The focus detection pixel 222b includes a micro lens 2221b and a photoelectric conversion unit 2222b as shown in FIG. 5B, and a semiconductor of the image sensor 22 as shown in a cross-sectional view of FIG. 7B. A photoelectric conversion unit 2222b is formed on the surface of the circuit board 2213, and a microlens 2221b is formed on the surface. Then, as shown in FIG. 3, these focus detection pixels 222a and 222b are alternately arranged adjacent to each other in a horizontal row, thereby forming focus detection pixel rows 22a to 22c shown in FIG.

  The photoelectric conversion units 2222a and 2222b of the focus detection pixels 222a and 222b have such a shape that the microlenses 2221a and 2221b receive a light beam that passes through a predetermined region (eg, F2.8) of the exit pupil of the photographing optical system. Is done. Further, the focus detection pixels 222a and 222b are not provided with color filters, and their spectral characteristics are the total of the spectral characteristics of a photodiode that performs photoelectric conversion and the spectral characteristics of an infrared cut filter (not shown). ing. However, it may be configured to include one of the same color filters as the imaging pixel 221, for example, a green filter.

  In addition, although the photoelectric conversion units 2222a and 2222b of the focus detection pixels 222a and 222b illustrated in FIGS. 5A and 5B have a semicircular shape, the shapes of the photoelectric conversion units 2222a and 2222b are not limited thereto. Other shapes such as an elliptical shape, a rectangular shape, and a polygonal shape can also be used.

  Here, a so-called phase difference detection method for detecting the focus state of the photographing optical system based on the pixel outputs of the focus detection pixels 222a and 222b described above will be described.

  FIG. 8 is a cross-sectional view taken along the line VIII-VIII in FIG. 3. The focus detection pixels 222 a-1, 222 b-1, 222 a-2, and 222 b-2 that are arranged in the vicinity of the photographing optical axis L 1 and adjacent to each other are It shows that light beams AB1-1, AB2-1, AB1-2, and AB2-2 irradiated from the distance measuring pupils 351 and 352 of the exit pupil 350 are received. 8 illustrates only the focus detection pixels 222a and 222b that are located in the vicinity of the photographing optical axis L1, but other focus detection pixels other than the focus detection pixels illustrated in FIG. 8 are illustrated. In the same manner, the light beams emitted from the pair of distance measuring pupils 351 and 352 are respectively received.

  Here, the exit pupil 350 is an image set at a distance D in front of the microlenses 2221a and 2221b of the focus detection pixels 222a and 222b arranged on the planned focal plane of the photographing optical system. The distance D is a value uniquely determined according to the curvature and refractive index of the microlens, the distance between the microlens and the photoelectric conversion unit, and the distance D is referred to as a distance measurement pupil distance. The distance measurement pupils 351 and 352 are images of the photoelectric conversion units 2222a and 2222b respectively projected by the micro lenses 2221a and 2221b of the focus detection pixels 222a and 222b.

  In FIG. 8, the arrangement direction of the focus detection pixels 222a-1, 222b-1, 222a-2, 222b-2 coincides with the arrangement direction of the pair of distance measuring pupils 351, 352.

  As shown in FIG. 8, the microlenses 2221a-1, 2221b-1, 2221a-2, and 2221b-2 of the focus detection pixels 222a-1, 222b-1, 222a-2, and 222b-2 are photographic optical systems. Near the planned focal plane. The shapes of the photoelectric conversion units 2222a-1, 2222b-1, 2222a-2, 2222b-2 arranged behind the micro lenses 2221a-1, 2221b-1, 2221a-2, 2221b-2 are the same as the micro lenses 2221a-1, 2221b-1, 2221a-2, 2221b-2. Projected onto the exit pupil 350 that is separated from the lenses 2221 a-1, 2221 b-1, 2221 a-2, and 2221 b-2 by a distance measurement distance D, and the projection shape forms distance measurement pupils 351 and 352.

  That is, the microlens and the photoelectric conversion unit in each focus detection pixel so that the projection shapes (distance measurement pupils 351 and 352) of the focus detection pixels coincide on the exit pupil 350 at the distance D. Is determined, and the projection direction of the photoelectric conversion unit in each focus detection pixel is thereby determined.

  As shown in FIG. 8, the photoelectric conversion unit 2222a-1 of the focus detection pixel 222a-1 is formed on the microlens 2221a-1 by the light beam AB1-1 that passes through the distance measuring pupil 351 and goes to the microlens 2221a-1. A signal corresponding to the intensity of the image to be output is output. Similarly, the photoelectric conversion unit 2222a-2 of the focus detection pixel 222a-2 passes through the distance measuring pupil 351, and the intensity of the image formed on the microlens 2221a-2 by the light beam AB1-2 toward the microlens 2221a-2. The signal corresponding to is output.

  Further, the photoelectric conversion unit 2222b-1 of the focus detection pixel 222b-1 passes through the distance measuring pupil 352, and the intensity of the image formed on the microlens 2221b-1 by the light beam AB2-1 directed to the microlens 2221b-1. Output the corresponding signal. Similarly, the photoelectric conversion unit 2222b-2 of the focus detection pixel 222b-2 passes through the distance measuring pupil 352, and the intensity of the image formed on the microlens 2221b-2 by the light beam AB2-2 toward the microlens 2221b-2. The signal corresponding to is output.

  Then, a plurality of the above-described two types of focus detection pixels 222a and 222b are arranged in a straight line as shown in FIG. 3, and the outputs of the photoelectric conversion units 2222a and 2222b of the focus detection pixels 222a and 222b are used as the distance measurement pupil 351. Of the pair of images formed on the focus detection pixel array by the focus detection light fluxes passing through each of the distance measurement pupil 351 and the distance measurement pupil 352. Data on the distribution is obtained. Then, by applying an image shift detection calculation process such as a correlation calculation process or a phase difference detection process to the intensity distribution data, an image shift amount by a so-called phase difference detection method can be detected.

  Then, a conversion calculation is performed on the obtained image shift amount according to the center-of-gravity interval of the pair of distance measuring pupils, thereby obtaining a focal plane corresponding to the current focal plane (the position corresponding to the position of the microlens array on the planned focal plane). The deviation of the focal plane in the detection area), that is, the defocus amount can be obtained.

  The calculation of the image shift amount by the phase difference detection method and the calculation of the defocus amount based thereon are executed by the camera control unit 21.

  Further, the camera control unit 21 reads the output of the imaging pixel 221 of the imaging element 22 and calculates a focus evaluation value based on the read pixel output. This focus evaluation value can be obtained by, for example, extracting a high frequency component of an image output from the imaging pixel 221 of the imaging element 22 using a high frequency transmission filter and integrating the extracted high frequency component. It can also be obtained by extracting high-frequency components using two high-frequency transmission filters having different cutoff frequencies and integrating them.

  Then, the camera control unit 21 sends a control signal to the lens control unit 37 to drive the focus lens 32 at a predetermined sampling interval (distance) to obtain a focus evaluation value at each position, and the focus evaluation value is maximum. The focus detection by the contrast detection method is performed in which the position of the focus lens 32 is obtained as the focus position. Note that this in-focus position is obtained when, for example, when the focus evaluation value is calculated while driving the focus lens 32, the focus evaluation value rises twice and then moves down twice. Can be obtained by performing an operation such as interpolation using the focus evaluation value.

  Next, an operation example of the camera 1 according to the present embodiment will be described. FIG. 9 is a flowchart showing an operation example of the camera 1 according to the present embodiment. The following operation is started when the camera 1 is turned on.

  First, in steps S101 to S103, the adapter controller 51 of the mount adapter 5 performs processing for transmitting the open side limit value stored in the memory 52 to the camera body 2.

  Specifically, first, in step S101, the adapter control unit 51 identifies the type of the lens barrel 3, and determines whether the type of the lens barrel 3 has been identified. The method for identifying the type of the lens barrel 3 is not particularly limited. For example, the memory 52 of the lens adapter 5 stores identification information for identifying the type of the lens barrel 3, and the adapter. The control unit 51 receives lens information including identification information for identifying the type of the lens barrel 3 from the lens control unit 37. The adapter control unit 51 collates the identification information of the lens barrel 3 received from the lens control unit 37 with the identification information of the lens barrel 3 stored in the memory 52 of the lens adapter 5, thereby The type of the cylinder 3 can be identified. If the type of the lens barrel 3 can be identified, the process proceeds to step S102. If the type of the lens barrel 3 cannot be identified, the process proceeds to step S103.

  In step S102, since the type of the lens barrel 3 is identified, the open limit value corresponding to the type of the lens barrel 3 is acquired from the memory 52 of the lens adapter 5 by the adapter control unit 51 and acquired. The open side limit value is transmitted to the camera control unit 21.

  On the other hand, if it is determined in step S101 that the type of the lens barrel 3 cannot be identified, the process proceeds to step S103. In step S103, since the type of the lens barrel 3 could not be identified, the adapter control unit 51 obtains a predetermined opening-side limit value set in advance from the memory 52 of the lens adapter 5 and transmits it to the camera control unit 21. Is done.

  In step S104, the camera control unit 21 performs processing for setting the aperture value (F value) of the optical system to an aperture value for performing focus detection. Specifically, the camera control unit 21 first receives, from the adapter control unit 51, the open side limit value of the aperture value of the optical system when detecting the focus state of the optical system as the open side limit value. At the same time, the limit value on the aperture side of the aperture value of the optical system when detecting the focus state of the optical system is acquired from the memory 29 as the limit value on the aperture side. In the present embodiment, since the open side limit value is stored in the memory 52 of the lens adapter 5 as the number of apertures from the open aperture value, the camera control unit 21 determines from the open aperture value and the open aperture value. Based on the number of aperture stages, the limit value (F value) on the open side of the aperture value of the optical system when performing focus detection is obtained as the open side limit value.

  Then, the camera control unit 21 sets the aperture value of the optical system for performing focus detection based on the acquired open side limit value and aperture side limit value. Specifically, the camera control unit 21 reduces the aperture value of the optical system when the imaging aperture value set for actual imaging of the image is closer to the aperture side than the aperture side limit value. Set to the side limit value. Here, FIG. 10 is a diagram illustrating an example of the relationship between the aperture value set for performing focus detection and the imaging aperture value. In the example shown in FIG. 10, in the lens barrel 3 having an open aperture value of F1.2 and a maximum aperture value (maximum F value) of F16, the open side limit value is acquired as F2.8, and the aperture side The scene where the limit value is acquired as F5.6 is shown. For example, in FIG. 10A, the photographing aperture value is set to F16, and the photographing aperture value F16 is a value on the narrowing side with respect to the narrowing side limit value F5.6. The unit 21 sets the aperture value of the optical system to F5.6, which is the aperture limit value. In FIG. 10B, since the photographing aperture value is F8, similarly to FIG. 10A, the camera control unit 21 changes the aperture value of the optical system to F5. Set to 6.

  In addition, when the photographing aperture value set for the actual photographing of the image is the same value as the aperture-side limit value or a value closer to the open side than the aperture-side limit value, the camera control unit 21 Set the aperture value to the shooting aperture value. For example, in FIG. 10C, since the photographing aperture value is F5.6 which is the same as the narrowing limit value, the camera control unit 21 sets the aperture value of the optical system to F5.6 which is the photographing aperture value. To do. In FIG. 10D, the photographing aperture value is set to F4, and the photographing aperture value F4 is a value closer to the open side than the narrowing-side limit value F5.6. The unit 21 sets the aperture value of the optical system to F4 that is the photographing aperture value. Similarly, in (E) to (G) of FIG. 10, as with (D) of FIG. 10, since the shooting aperture value is a value closer to the open side than the aperture-side limit value, the camera control unit 21 Set the aperture value of the optical system to the shooting aperture value.

  In step S105, the camera control unit 21 divides the shooting screen into a plurality of areas, and performs multi-division photometry (multi-pattern metering) in which photometry is performed for each of the divided areas, and the luminance value Bv of the entire shooting screen is calculated. Is done. Then, at least one of the light receiving sensitivity Sv and the exposure time Tv is changed by the camera control unit 21 based on the calculated luminance value Bv of the entire shooting screen so that proper exposure is obtained on the entire shooting screen. In step S105, at least one of the light receiving sensitivity Sv and the exposure time Tv is changed while the aperture Av set in step S104 is fixed. Then, based on the changed light reception sensitivity Sv and exposure time Tv, for example, the exposure to the image sensor 22 is controlled by setting the shutter speed of the shutter 23 and the light reception sensitivity of the image sensor 22.

  In step S106, the camera control unit 21 determines whether or not an appropriate exposure has been obtained on the entire shooting screen by the exposure control in step S105. If only the change of the light receiving sensitivity Sv and the exposure time Tv does not provide proper exposure of the entire photographing screen, the process proceeds to step S107. On the other hand, the photographing screen is changed by changing at least one of the light receiving sensitivity Sv and the exposure time Tv. If proper exposure is obtained as a whole, the process proceeds to step S109.

  In step S107, it is determined that a proper exposure cannot be obtained on the entire photographing screen only by changing the light receiving sensitivity Sv and the exposure time Tv, so the camera control unit 21 changes the aperture Av. Specifically, when the photographing aperture value is a value closer to the aperture side than the aperture side limit value, the camera control unit 21 sets the aperture value of the optical system between the open side limit value and the aperture side limit value. The aperture Av is changed based on the luminance value Bv of the entire shooting screen so that it is within the range. For example, in FIG. 10A, since the photographing aperture value F16 is a value closer to the aperture than the aperture limit value F5.6, the camera control unit 21 determines that the aperture value of the optical system is The aperture Av is changed so as to be within the range from F2.8 which is the open side limit value to F5.6 which is the aperture side limit value, and exposure control is performed so that proper exposure is obtained on the entire photographing screen. The same applies to (B) of FIG.

  Further, when the photographing aperture value is the same value as the aperture-side limit value or a value closer to the open side than the aperture-side limit value, the camera control unit 21 sets the aperture value of the optical system to the aperture-side limit value and the imaging. The aperture Av is changed based on the brightness value Bv of the entire shooting screen so that it is within the range of the aperture value. For example, in FIG. 10C, since the photographing aperture value F5.6 is the same value as the aperture limit value F5.6, the camera controller 21 determines that the aperture value of the optical system is open. The aperture Av is changed so as to be within the range from F2.8 which is the side limit value to F5.6 which is the photographing aperture value. In FIG. 10D, since the photographing aperture value F4 is a value closer to the open side than the aperture-side limit value F5.6, the camera control unit 21 determines that the aperture value of the optical system is The aperture Av is changed so as to be within the range from F2.8 which is the open side limit value to F4 which is the photographing aperture value.

  The camera control unit 21 keeps the aperture value of the optical system as the shooting aperture value when the shooting aperture value is the same value as the open limit value or a value closer to the open side than the open limit value. To do. For example, in (E) of FIG. 10, F2.8, which is the photographing aperture value, is the same value as F2.8, which is the open limit value, and therefore the camera control unit 21 captures the aperture value of the optical system. The aperture value is F2.8. The same applies to (F) to (G) in FIG. In the present embodiment, for example, as shown in FIGS. 10A to 10D, the camera control unit 21 can change the aperture Av within a predetermined aperture value range. Even when the brightness value Bv of the entire shooting screen changes again, the aperture Av is changed to the open side with a slight margin so that the aperture Av does not have to be changed again.

  In step S108, the camera control unit 21 re-determines the light receiving sensitivity Sv and the exposure time Tv so that a proper exposure can be obtained on the entire photographing screen at the aperture Av changed in step S107. Specifically, as in step S105, the camera control unit 21 performs multi-pattern photometry over the entire shooting screen, and calculates the luminance value Bv of the entire shooting screen. Then, the camera control unit 21 determines and determines the light receiving sensitivity Sv and the exposure time Tv with which appropriate exposure can be obtained over the entire photographing screen based on the calculated luminance value Bv and the aperture Av set in step S107. Based on the light receiving sensitivity Sv and the exposure time Tv, and the aperture Av set in step S107, the exposure to the image sensor 22 is controlled.

  In step S109, the camera control unit 21 performs a defocus amount calculation process using a phase difference detection method. Specifically, first, a light beam from the optical system is received by the image sensor 22, and each focus detection pixel 222 a configuring the three focus detection pixel rows 22 a to 22 c of the image sensor 22 by the camera control unit 21. , 222b, a pair of image data corresponding to the pair of images is read out. In this case, when a specific focus detection position is selected by a manual operation of the photographer, only data from focus detection pixels corresponding to the focus detection position may be read. Then, the camera control unit 21 performs image shift detection calculation processing (correlation calculation processing) based on the read pair of image data, and images at the focus detection positions corresponding to the three focus detection pixel rows 22a to 22c. The shift amount is calculated, and the image shift amount is converted into a defocus amount. Further, the camera control unit 21 evaluates the reliability of the calculated defocus amount. For example, the camera control unit 21 can determine the reliability of the defocus amount based on the matching degree and contrast of the pair of image data.

  In step S110, the camera control unit 21 determines whether or not the shutter release button provided in the operation unit 28 is half-pressed (the first switch SW1 is turned on). If the shutter release button is pressed halfway, the process proceeds to step S111. On the other hand, if the shutter release button has not been pressed halfway, the process returns to step S105, and display of a through image, exposure control, and calculation of the defocus amount are repeatedly executed until the shutter release button is pressed halfway. .

  In step S111, the camera control unit 21 determines whether or not the defocus amount can be calculated by the phase difference detection format. If the defocus amount can be calculated, it is determined that distance measurement is possible and the process proceeds to step S112. On the other hand, if the defocus amount cannot be calculated, it is determined that distance measurement is not possible and the process proceeds to step S116. . In the present embodiment, even if the defocus amount can be calculated, if the reliability of the calculated defocus amount is low, it is treated that the defocus amount cannot be calculated, and the process proceeds to step S116. I will do it. In the present embodiment, for example, when the subject has a low contrast, the subject is an ultra-low brightness subject, or the subject is an ultra-high brightness subject, it is determined that the reliability of the defocus amount is low. .

  In step S112, the camera control unit 21 calculates and calculates the lens driving amount necessary to drive the focus lens 32 to the in-focus position based on the defocus amount calculated in step S109. The lens driving amount is sent to the focus lens driving motor 36 via the lens control unit 37. As a result, the focus lens driving motor 36 drives the focus lens 32 based on the calculated lens driving amount.

  In step S113, the camera control unit 21 determines whether or not the shutter release button is fully pressed (the second switch SW2 is turned on). If the second switch SW2 is on, the process proceeds to step S114. On the other hand, if the second switch SW2 is not on, the process returns to step S105.

  In step S <b> 114, processing for setting the aperture value of the optical system to the imaging aperture value is performed by the camera control unit 21 in order to perform actual imaging of the image. For example, in FIG. 10A, the camera control unit 21 changes the aperture value of the optical system from the aperture value at the time of focus detection (from the open limit value F2.8 to the aperture side) in order to actually capture an image. The range is changed from F5.6 which is the limit value) to F16 which is the photographing aperture value. In subsequent step S115, the image pickup device 22 performs actual shooting of the image with the aperture value set in step S114, and the image data of the shot image is stored in the memory 24.

  On the other hand, if it is determined in step S111 that the defocus amount cannot be calculated, the process proceeds to step S116 in order to obtain an exposure suitable for focus detection. In step S116, the camera control unit 21 performs exposure control for focus detection so that an exposure suitable for focus detection is obtained. Specifically, the camera control unit 21 performs spot photometry in predetermined areas including the focus detection areas (focus detection pixel rows 22a, 22b, and 22c shown in FIG. 2) based on the output of the image sensor 22, A luminance value SpotBv within a predetermined area including the focus detection area is calculated. Then, the camera control unit 21 receives the light sensitivity Sv, the exposure time Tv, and the exposure time Sv so as to obtain an exposure suitable for focus detection (for example, an exposure one step brighter than the appropriate exposure) based on the calculated luminance value SpotBv. The aperture Av is determined. In the exposure control for focus detection in step S116, as in steps S105 to S108, the camera control unit 21 preferentially changes the light reception sensitivity Sv and the exposure time Tv, and sets the light reception sensitivity Sv and the exposure time Tv. The aperture Av is changed based on the open-side limit value and the narrowing-side limit value acquired in step S101 only when the exposure suitable for focus detection cannot be obtained only by the change. For example, as shown in FIGS. 10A to 10B, the camera control unit 21 determines that the aperture value of the optical system is equal to the aperture value of the optical system when the imaging aperture value is a value closer to the aperture than the aperture limit value. The aperture Av is changed based on the luminance value SpotBv in a predetermined area including the focus detection area so that it is within the range between the open side limit value and the aperture side limit value. Also, as shown in FIGS. 10C to 10D, when the photographing aperture value is the same value as the aperture-side limit value or a value closer to the open side than the aperture-side limit value, the aperture of the optical system Based on the luminance value SpotBv in the predetermined area including the focus detection area, the aperture Av is changed so that the value falls within the range between the open side limit value and the photographing aperture value. Further, FIG. As shown in (G), when the photographing aperture value is the same value as the open side limit value or a value closer to the open side than the open side limit value, the aperture value of the optical system remains the shooting aperture value. And

  In step S117, the camera control unit 21 calculates the defocus amount based on the image data obtained with the exposure suitable for focus detection. In the subsequent step S118, the camera control unit 21 calculates the defocus amount. Based on the image data obtained by the exposure, it is determined whether or not the defocus amount has been calculated. If the defocus amount can be calculated, the process proceeds to step S112, and the driving process of the focus lens 32 is performed based on the calculated defocus amount. On the other hand, even if the exposure is suitable for focus detection, if the defocus amount cannot be calculated, the process proceeds to step S119, and scanning operation execution processing described later is performed. In step S118, as in step S111, even when the defocus amount can be calculated, if the reliability of the calculated defocus amount is low, the defocus amount cannot be calculated. .

  In step S119, the camera control unit 21 performs a scan operation execution process for executing the scan operation. Here, the scan operation is a predetermined calculation of the defocus amount and the focus evaluation value by the phase difference detection method by the camera control unit 21 while the focus lens 32 is scan-driven by the focus lens drive motor 36. Thus, the detection of the in-focus position by the phase difference detection method and the detection of the in-focus position by the contrast detection method are simultaneously performed at predetermined intervals. Hereinafter, the scan operation execution process according to the present embodiment will be described with reference to FIG. FIG. 11 is a flowchart showing a scan operation execution process according to the present embodiment.

  First, in step S201, the camera control unit 21 performs a scan operation start process. Specifically, the camera control unit 21 sends a scan drive start command to the lens control unit 37, and the lens control unit 37 drives the focus lens drive motor 36 based on the command from the camera control unit 21 to focus. The lens 32 is scan-driven along the optical axis L1. The direction in which the scan drive is performed is not particularly limited, and the scan drive of the focus lens 32 may be performed from the infinite end to the close end, or may be performed from the close end to the infinite end. Good.

  Then, while driving the focus lens 32, the camera control unit 21 reads out a pair of image data corresponding to the pair of images from the focus detection pixels 222a and 222b of the image sensor 22 at predetermined intervals. The phase difference detection method calculates the defocus amount, evaluates the reliability of the calculated defocus amount, and drives the focus lens 32 to drive the pixel output from the imaging pixel 221 of the imaging element 22 at a predetermined interval. Reading is performed, and based on this, a focus evaluation value is calculated, thereby acquiring a focus evaluation value at a different focus lens position, thereby detecting a focus position by a contrast detection method.

  In step S202, it is determined whether or not the defocus amount has been calculated by the phase difference detection method as a result of the scanning operation performed by the camera control unit 21. If the defocus amount can be calculated, it is determined that distance measurement is possible and the process proceeds to step S205. On the other hand, if the defocus amount cannot be calculated, it is determined that distance measurement is not possible and the process proceeds to step S203. .

  In step S203, it is determined whether the in-focus position has been detected by the contrast detection method as a result of the scanning operation performed by the camera control unit 21. If the in-focus position can be detected by the contrast detection method, the process proceeds to step S207. If the in-focus position cannot be detected, the process proceeds to step S204.

  In step S <b> 204, the camera control unit 21 determines whether the scan operation has been performed for the entire driveable range of the focus lens 32. If the scan operation is not performed for the entire driveable range of the focus lens 32, the process returns to step S202, and steps S202 to S204 are repeated to perform the scan operation, that is, while the focus lens 32 is scan-driven. The operation of simultaneously executing the calculation of the defocus amount by the phase difference detection method and the detection of the in-focus position by the contrast detection method at predetermined intervals is continuously performed. On the other hand, if the scan operation has been completed for the entire driveable range of the focus lens 32, the process proceeds to step S208.

  As a result of executing the scanning operation, if it is determined in step S202 that the defocus amount can be calculated by the phase difference detection method, the process proceeds to step S205. In step S205, the defocus amount is calculated by the phase difference detection method. A focusing operation based on the defocus amount is performed.

  That is, in step S205, the camera control unit 21 first performs a stop operation of the scanning operation, and then performs lens driving necessary to drive the focus lens 32 from the calculated defocus amount to the in-focus position. The amount is calculated, and the calculated lens driving amount is sent to the lens driving motor 36 via the lens control unit 37. Then, the lens driving motor 36 drives the focus lens 32 to the in-focus position based on the lens driving amount calculated by the camera control unit 21. When the driving of the focus lens 32 to the in-focus position is completed, the process proceeds to step S206. In step S206, the camera control unit 21 determines that the focus is achieved.

  As a result of executing the scanning operation, if it is determined in step S203 that the in-focus position has been detected by the contrast detection method, the process proceeds to step S207, and based on the in-focus position detected by the contrast detection method. The drive operation of the focus lens 32 is performed.

  That is, after the scanning operation is stopped by the camera control unit 21, a lens driving process for driving the focus lens 32 to the in-focus position is performed based on the in-focus position detected by the contrast detection method. . When the driving of the focus lens 32 to the in-focus position is completed, the process proceeds to step S206, and the camera control unit 21 determines that the focus is in-focus.

  On the other hand, if it is determined in step S204 that the scan operation has been completed for the entire driveable range of the focus lens 32, the process proceeds to step S208. In step S208, as a result of performing the scanning operation, focus detection could not be performed by any of the phase difference detection method and the contrast detection method, so that the scanning operation end processing is performed, and then in step S209 The camera control unit 21 determines that focusing cannot be performed.

  Then, after the scan operation execution process in step S119 is completed, the process proceeds to step S120, and the camera control unit 21 determines whether or not the camera is in focus based on the result of the focus determination in the scan operation execution process. Done. In the scanning operation execution process, when it is determined that the focus is achieved (step S206), the process proceeds to step S113. On the other hand, if it is determined that focusing cannot be performed (step S209), the process proceeds to step S121, and in-focus display is performed in step S121. The in-focus indication is performed by the electronic viewfinder 26, for example.

  As described above, in this embodiment, the limit value on the open side of the aperture value of the optical system when performing focus detection is stored in the memory 52 of the lens adapter 5 as the open side limit value, and adapter control is performed. The unit 51 recognizes the type of the lens barrel 3 based on the lens information received from the lens barrel 3, and transmits an open-side limit value corresponding to the lens barrel 3 to the camera control unit 21. Thereby, the aperture value of the optical system when performing focus detection is set by the camera control unit 21 based on the open side limit value received from the adapter control unit 51 and the aperture side limit value acquired from the memory 29. The Specifically, in the present embodiment, as shown in FIGS. 10A to 10D, when the photographing aperture value at the time of actual photographing of the image is closer to the narrowing side than the open side limit value, By restricting the aperture value of the optical system at the time of focus detection to be closer to the aperture side than the open side limit value, the image is actually captured from the aperture value at the time of focus detection. Even when the photographing aperture value is changed, the amount of movement of the image plane of the optical system accompanying the change of the aperture value of the optical system can be set to a predetermined value or less, and as a result, the in-focus position detected in the focus detection Can be set within the range of the depth of field of the optical system at the time of actual photographing of the image, so that an image in focus on the subject can be photographed.

  In the present embodiment, as shown in FIGS. 10A to 10B, when the photographing aperture value when the image is actually captured is a value closer to the narrowing side than the narrowing side limit value, By limiting the aperture value of the optical system when performing focus detection to a value closer to the open side than the limit value on the aperture side, it is possible to effectively prevent the occurrence of vignetting during focus detection. The state can be detected appropriately. Furthermore, in this embodiment, as shown in FIGS. 10A to 10G, the aperture value of the optical system when performing focus detection is limited so as not to be a value closer to the aperture than the imaging aperture value. As a result, when the image is actually captured, the depth of field when the image is captured is shallower than the depth of field when the focus is detected, and the focus is reduced when the image is captured. It is possible to effectively prevent the subject focused at the time of detection from deviating from the depth of field of the optical system, and as a result, an image focused on the subject can be taken well.

  The embodiment described above is described for facilitating the understanding of the present invention, and is not described for limiting the present invention. Therefore, each element disclosed in the above embodiment is intended to include all design changes and equivalents belonging to the technical scope of the present invention.

  For example, in the above-described embodiment, the focus adjustment of the focus lens 32 is started by half-pressing the shutter release button provided in the operation unit 28. However, the present invention is not limited to this configuration. The camera 1 may be configured to activate the focus adjustment of the focus lens 32 by connecting a personal computer and receiving a signal from the personal computer, or a signal from a remote controller corresponding to the camera 1 may be received by the camera 1. It is good also as a structure which starts the focus adjustment of the focus lens 32 by receiving. In this case, in step S111, it may be determined whether a signal for starting focus adjustment of the focus lens 32 is received from a personal computer or a remote controller.

  The camera 1 of the above-described embodiment is not particularly limited. For example, the present invention is applied to other optical devices such as a digital video camera, a single-lens reflex digital camera, a lens-integrated digital camera, and a camera for a mobile phone. May be.

DESCRIPTION OF SYMBOLS 1 ... Digital camera 2 ... Camera body 21 ... Camera control part 22 ... Imaging device 221 ... Imaging pixel 222a, 222b ... Focus detection pixel 28 ... Operation part 3 ... Lens barrel 32 ... Focus lens 36 ... Focus lens drive motor 37 ... Lens Control unit 5 ... Lens adapter

Claims (1)

A first communication unit for acquiring lens information from the attached lens barrel ;
A storage unit that stores the aperture value of the aperture of the mounted lens barrel that is set when detecting the focus adjustment state , and stores an open-side limit value that is set according to the type of the lens barrel ;
An acquisition unit that acquires the open side limit value corresponding to the attached lens barrel using the lens information acquired by the first communication unit and the open side limit value stored in the storage unit. When,
A second communication unit that transmits the open side limit value corresponding to the mounted lens barrel acquired by the acquiring unit to a mounted camera body ,
When the acquisition unit can identify the type of the mounted lens barrel from the lens information, the acquisition unit acquires the open side limit value based on the type of the lens barrel;
When the type of the mounted lens barrel cannot be identified from the lens information, the predetermined opening side limit value set in advance is acquired,
Even when the aperture value of the aperture changes from the open side limit value to the shooting aperture value for the actual shooting, the amount of movement of the image plane due to the change of the aperture value of the aperture stops in the optical system for the actual shooting. A lens adapter characterized by being within the depth of field .

Images