JP6508267B2 - interchangeable lens - Google Patents

Description

  The present invention relates to an interchangeable lens.

  2. Description of the Related Art Conventionally, there has been known an automatic focus detection device which takes into consideration fluctuations of the image plane best position of a lens due to spherical aberration. For example, Patent Document 1 describes an automatic focus detection device that acquires a correction value of spherical aberration based on lens design from use aperture value data and object distance data.

JP-A-59-208514

The automatic focus detection device described in Patent Document 1 has a problem that correction of variations due to manufacturing errors can not be performed.
An object of the present invention is to provide an interchangeable lens having suitable optical characteristics.

According to a first aspect of the present invention, interchangeable lens, an optical system having a diaphragm and a focus lens, and the camera detachable detachable unit having an imaging unit, the imaging unit images by the optical system detection of the amount of deviation between the focus position to focus the position of the focus lens, and the correction amount of the available for any image plane position of the detection of the focusing position based on the contrast of an image by the optical system, A storage unit is provided which stores based on a combination of the aperture value of the aperture and the photographing distance or the image magnification .

  According to the present invention, it is possible to provide an interchangeable lens having suitable optical characteristics.

FIG. 1 is a block diagram showing a configuration of a camera system according to a first embodiment of the present invention. FIG. 2 is a cross-sectional view schematically showing the configuration of a camera body 100 and an interchangeable lens 200. FIG. 7 is a cross-sectional view schematically showing a configuration of the inspection apparatus 300. It is a figure which showed the change of the optimal focus position typically. It is a figure which shows an example of a correction table. 5 is a flowchart of an AF process performed by a body control unit 101. It is a flowchart of correction table creation processing which inspection control part 301 performs. It is a flowchart of the process called from the correction table preparation process shown in FIG.

First Embodiment
FIG. 1 is a block diagram showing a configuration of a camera system according to a first embodiment of the present invention. The camera system 1 includes a camera body 100 and an interchangeable lens 200. The interchangeable lens 200 can be attached to the camera body 100 by a known lens mounting mechanism. Although only one camera body 100 and one interchangeable lens 200 are shown in FIG. 1, in actuality, there are a plurality of types of camera bodies and a plurality of types of interchangeable lenses, and any camera body and interchangeable lens And can be used in combination.

  The interchangeable lens 200 can be attached not only to the camera body 100 but also to the inspection apparatus 300. At the time of manufacturing the interchangeable lens 200, the manufacturer of the interchangeable lens 200 attaches the interchangeable lens 200 to the inspection apparatus 300, and causes the inspection apparatus 300 to execute correction table creation processing described later.

  FIG. 2 is a cross-sectional view schematically showing the configuration of the camera body 100 and the interchangeable lens 200. As shown in FIG. The camera shown in FIG. 2 is a so-called single-lens reflex digital camera. The interchangeable lens 200 is provided with a photographing optical system including a plurality of lenses 202, 203 and 204, and a diaphragm 205 having an opening. Although FIG. 1 illustrates the photographing optical system as if it is composed of three lenses, it may be composed of any number of lenses. In addition, although the diaphragm 205 is provided between the lens 203 and the lens 204 in FIG. 1, the diaphragm 205 may be located in front of or behind the photographing optical system, as is well known. It is also good.

  A lens 203 included in the imaging optical system is a focus lens that adjusts the focus position of the imaging optical system, and can be driven in the direction X along the optical axis L of the imaging optical system by an actuator (not shown). The diaphragm 205 can change the aperture diameter (diaphragm diameter) R by an actuator (not shown).

  In the following description, for convenience, it is assumed that the open F-number of the imaging optical system of the interchangeable lens 200 is F2.0, the shortest imaging distance is 1 meter, and the focal distance is 50 mm. The following description is also applicable to the interchangeable lens 200 having a parameter different from the above-described parameters, in which case each of the above-described parameters may be read as appropriate.

  The interchangeable lens 200 includes a lens control unit 201 including a microprocessor and its peripheral circuit, and a ROM 206 that stores a predetermined control program and a correction table to be described later. The lens control unit 201 controls each unit of the interchangeable lens 200 by reading and executing a predetermined control program stored in advance in the ROM 206.

  The camera body 100 includes an imaging element 102 such as a CCD or a CMOS that captures an object image formed by the imaging optical system. The imaging element 102 is disposed such that the imaging plane coincides with the planned focal plane of the imaging optical system. A quick return mirror 103 is installed between the imaging optical system and the imaging surface of the imaging device 102 in the camera body 100. At the time of non-shooting, the quick return mirror 103 exists on the light path of the shooting optical system, and reflects subject light in the direction of the focusing screen 104 and the pentaprism 105. A photographer can visually recognize a subject image from the finder unit 107 via the eyepiece lens 106.

  A sub mirror 108 is installed on the back of the quick return mirror 103. The surface (reflecting surface) of the quick return mirror 103 is half-mirror processed, and the subject light incident thereon is transmitted through the quick return mirror 103 and incident on the sub mirror 108. The sub mirror 108 reflects this light flux below the camera body 100. Below the camera body 100, a focus detection device 109 for performing focus detection of a so-called pupil division phase difference detection method is provided. The focus detection device 109 divides the reflected light from the sub mirror 108 into a pair of light beams by a pair of re-imaging lenses and performs focus detection by a known method of detecting the phase difference between the pair of light beams, To detect

  The camera body 100 includes a body control unit 101 including a microprocessor and its peripheral circuits. The body control unit 101 controls each unit of the camera body 100 by reading and executing a predetermined control program stored in advance in a memory (not shown). The body control unit 101 and the lens control unit 201 may be configured by an electronic circuit that performs an operation equivalent to the above control program.

  The body control unit 101 and the lens control unit 201 are configured to be able to communicate with each other via electrical contacts (not shown) provided around the lens mount. The body control unit 101 transmits, for example, a drive command of the focus lens 203 and a drive command of the diaphragm 205 to the lens control unit 201 by data communication via the electric contact. Further, the lens control unit 201 transmits part or all of the correction table stored in the ROM 206 to the body control unit 101 by this data communication. Note that this data communication may be performed by a method (for example, wireless communication, optical communication, etc.) other than the transmission and reception of the electric signal through the electrical contact.

  When a predetermined automatic focusing operation (for example, a half depression operation of a release switch (not shown)) is performed, the body control unit 101 executes an automatic focusing (AF) process described later. The focus lens 203 is driven by this AF process. The subject is in focus.

  When a predetermined still image shooting operation (for example, full-press operation of a release switch (not shown)) is performed, the body control unit 101 performs shooting control. At this time, the body control unit 101 moves the quick return mirror 103 and the sub mirror 108 to the retracted position that does not block the subject light, and then drives the lens for driving the diaphragm 205 to the aperture diameter corresponding to the imaging F value. It is transmitted to the control unit 201. The lens control unit 201 drives the diaphragm 205 according to the drive command. Thereafter, the body control unit 101 controls a shutter or the like (not shown) to cause the imaging device 102 to capture a subject image. Then, various image processing is added to the imaging signal output from the imaging element 102 to generate still image data and store it in a storage medium (for example, a memory card or the like, not shown).

  On the back of the camera body 100, a monitor 110 configured of a display element such as liquid crystal is provided. The body control unit 101 uses the monitor 110 to, for example, reproduce captured still image data and moving image data, display a setting menu for shooting parameters (F value, shutter speed, etc.), display through images during moving image shooting, etc. I do.

  FIG. 3 is a cross-sectional view schematically showing the configuration of the inspection apparatus 300. As shown in FIG. The inspection apparatus 300 has a mounting mechanism similar to that of the camera body 100, and can mount the interchangeable lens 200 in the same manner as the camera body 100. In the inspection apparatus 300, an imaging element 302, a quick return mirror 303, a sub mirror 308, and a focus detection device 309 are installed in the same arrangement as each part having the same name of the camera body 100. The inspection control unit 301 can mutually communicate with the lens control unit 201 via an electrical contact (not shown) as in the case of the body control unit 101 described above.

(Description of auto focus adjustment)
Next, an automatic focusing (AF) process performed by the body control unit 101 will be described. The body control unit 101 performs AF processing (hereinafter referred to as contrast AF processing) that performs focus detection in the so-called contrast detection method and AF processing (hereinafter referred to as phase difference AF processing) that performs the focus detection in the so-called pupil division phase difference detection method. It is configured to be able to execute two types of AF processing. The body control unit 101 may use these two types of AF processing properly according to the shooting conditions, the characteristics of the subject, etc., or perform either AF processing based on an explicit instruction from the user. May be

  The AF processing of the contrast detection method by the body control unit 101 will be described. The body control unit 101 performs well-known contrast detection calculation using the imaging signal output from the imaging element 102. The body control unit 101 performs this contrast detection calculation while driving the focus lens 203 in a predetermined range (for example, between the drive limit position on the near side and the drive limit position on the infinity side) to obtain a focus evaluation value (contrast value). Automatic focus adjustment is performed by detecting the position of the focus lens 203 at which the light intensity peaks. The body control unit 101 retracts the quick return mirror 103 from the light path at least while performing the contrast detection AF process.

  When performing contrast AF, it is desirable that the aperture diameter R be as large as possible so that more light is taken into the image sensor 102. For example, the body control unit 101 performs contrast AF with the open stop (F2.0), and at the time of shooting, drives the aperture diameter R to the shooting stop to perform shooting. That is, the body control unit 101 makes the aperture diameter R different between when performing contrast AF processing and when photographing. In other words, the body control unit 101 makes the shape of the pupil region when performing contrast AF processing different from the shape of the pupil region at the time of shooting. As described above, when the aperture diameter R (the shape of the pupil region) is changed, the best image plane position (best focus position), which is the optimum imaging position of the object image, fluctuates.

  FIG. 4 is a view schematically showing the fluctuation of the best image plane position, and FIG. 4A shows the situation when the diaphragm diameter R of the diaphragm 205 is R1, and FIG. The drawing shows that the aperture diameter R is R2 (<R1). In FIG. 4, for convenience, the photographing optical system 31 including the plurality of lenses 202, 203 and 204 is illustrated as one thin lens.

  Now, let us consider subject light emitted from one point 30 of the subject 40 located at the shooting distance D. As shown in FIG. 4A, of the subject light from one point 30, the focal position of a light flux (a light flux from a region with a low image height) that has passed through the pupils 33 and 34 near the optical axis L of the photographing optical system 31. At a focal position 36 of a light flux (a light flux from a region having a high image height) 37 and a pupil 32, 35 near the end of the photographing optical system 31, a positional deviation 38 occurs due to spherical aberration or the like. At the time of optical design, the best image plane position (image forming position optimum for imaging) 39 is determined in consideration of this deviation, and the state where the imaging plane is at this best image plane position 39 is treated as the in-focus state.

  When the stop 205 is narrowed as shown in FIG. 4B, the subject light directed to the pupils 32 and 35 near the end of the photographing optical system 31 is blocked by the stop 205 and is not used for imaging. At this time, the range of the positional deviation 44 changes, and the best image plane position 45 also changes. Therefore, for example, even if AF is performed in the state of FIG. 4A and the best image plane position 39 is determined, the best image plane position 39 is different from the best image plane position 45 in the state of FIG. 4B. The fluctuation amount 46 of the best image plane position 45 due to the aperture diameter R changes according to the change of the position of the object, that is, the photographing distance D. In addition, the fluctuation amount 46 is affected by manufacturing variations, that is, individual differences among individual lenses.

  Next, AF processing of the pupil division phase difference detection method by the body control unit 101 will be described. The focus detection device 109 separately receives subject light from a pair of different pupils of the imaging optical system 31, and detects a phase difference between the light reception outputs. In the following description, it is assumed that the pupils 32 and 35 shown in FIG. 4A are used for detection of the phase difference. The focus detection device 109 calculates the defocus amount based on the detected phase difference, and outputs the defocus amount to the body control unit 101. The body control unit 101 performs automatic focusing by driving the focus lens 203 by a distance corresponding to the defocus amount.

  The pupils 32, 35 used by the focus detection device 109 for focus detection are predetermined. At the time of focus detection, the aperture diameter R is at least of such a size that the light flux from the pupils 32, 35 can not be kicked. For example, in the case of an open stop, the light flux from the pupils 32, 35 can not be kicked. The body control unit 101 causes the focus detection device 109 to perform focus detection after driving the stop 205 to the open stop (F2.0), and focuses the target subject based on the result. Thereafter, the body control unit 101 narrows the stop 205 to the shooting stop and performs shooting.

  The focus detection device 109 performs focus detection using the light beams from the pupils 32 and 35 shown in FIG. On the other hand, the light flux used for imaging is not the light flux from the pupils 32 and 35. For example, a wider range of light flux including the pupils 32 and 35 may be used, or a light flux narrower than the pupils 32 and 35 may be used. In any case, the shape of the pupil region used for phase difference detection AF is different from the shape of the pupil region at the time of shooting (substantially circular shape centered on the optical axis). Therefore, as described in the description of the contrast AF, the best image plane position at the time of AF may be different from the best image plane position at the time of photographing.

  The inspection apparatus 300 measures the fluctuation of the best image plane position according to the change of the shape of the pupil area (diaphragm diameter R) and the photographing distance D described above, and creates a correction table to be described later. Since the measurement by the inspection apparatus 300 is performed for each individual of the interchangeable lens 200, the correction table has different contents even for the same model. The inspection apparatus 300 creates a correction table based on the measured results, and stores the correction table in the ROM 206 of the interchangeable lens 200. The camera body 100 performs AF processing in consideration of the variation of the best image plane position by referring to the correction table stored in the ROM 206 of the interchangeable lens 200.

(Description of correction table)
FIG. 5 is a diagram showing an example of the correction table. The correction table is composed of a first correction table 60 for phase difference AF shown in FIG. 5A and a second correction table 70 for contrast AF shown in FIG. 5B.

  In the first correction table 60 for phase difference AF shown in FIG. 5A, the shift amount of the focus lens 203 is stored for each combination of the image magnification (approximately equal to the reciprocal of the photographing distance D) and the F value. There is. Hereinafter, the meaning of the “displacement amount of the focus lens 203” will be described by taking a specific example.

  For example, in FIG. 5A, the value of "D11" is stored in the column of the image magnification "0" and the F value "F 4.0". This is from the lens position where the defocus amount detected by the focus detection device 109 is 0 when the image magnification is 0 (that is, the photographing distance D is infinity) and the F-number of the diaphragm 205 is F 4.0. This means that the position at which the focus lens 203 has been moved by D11 is a true in-focus position. In other words, “when the shooting distance D is infinity and the shooting F value is F4.0, the focus lens 203 is driven so that the defocus amount detected by the focus detection device 109 is“ 0 ”. Also, moving the focus lens 203 to a position deviated from that by “D11” means that better imaging results can be obtained. The positive shift amount indicates the close direction, and the negative shift amount indicates the infinite distance.

  The camera body 100 moves the focus lens 203 to a position where the defocus amount output from the focus detection device 109 is 0 when the shooting distance is infinity and the shooting F value is F4.0, and then the focus lens for only D11 Drive 203. By doing this, the defocus amount output from the focus detection device 109 will not be 0, but in practice this is the optimum focus position for shooting.

  In the second correction table 70 for contrast AF shown in FIG. 5B, the shift amount of the focus lens 203 is stored for each combination of the image magnification and the F value.

  In the case of contrast AF, unlike phase difference AF, the F value at the time of AF is not always the same. For example, after contrast AF is performed at F2.0, shooting may be performed at F5.6, and after contrast AF is performed at F2.8, shooting may be performed at F2.0. Although “the shift amount of the focus lens 203” is stored in the second correction table 70 on the basis of F 2.0 (open F value), the shift amount is appropriately selected from the second correction table 70 and calculation is performed By doing this, it is possible to acquire the optimal AF amount for performing contrast AF and imaging using an arbitrary f-number.

  For example, in FIG. 5B, the value of "D51" is stored in the column of the image magnification "0" and the F value "F 4.0". “When the image magnification is 0 (that is, the photographing distance D is infinity) and the F value is F4.0, the contrast value (focus evaluation value) when the image magnification is 0 and the F value is F2.0 This means that the position at which the focus lens 203 is moved by D51 from the lens position at which is the peak is the true in-focus position. In other words, “If the image magnification is 0, contrast AF is performed at F2.0, and then the aperture stop 205 is narrowed to F4.0. It means that it is "shifted by D51".

  On the other hand, in the fields where the image magnification is "0" and the F value is "F8.0", the value "D52" is stored. The camera body 100 drives the focus lens 203 by (D52−D51) after AF is performed when the shooting distance D is infinity and the F value for AF is F4.0 and the shooting F value is F8.0. This makes it possible to obtain an optimal focus position for the F-number at the time of shooting.

  FIG. 6A is a flowchart of phase difference AF processing performed by the body control unit 101. In step S400, the body control unit 101 sets an aperture F value (F2.0) in the diaphragm 205. In step S410, the body control unit 101 causes the focus detection device 109 to execute focus detection of the phase difference detection method, and acquires the defocus amount Df from the focus detection device 109.

  In step S420, the body control unit 101 determines whether the defocus amount Df is zero. If the defocus amount Df is not 0, the body control unit 101 advances the process to step S430. In step S430, the body control unit 101 converts the defocus amount Df into a lens drive amount, and drives the focus lens 203 by the lens drive amount. Thereafter, the body control unit 101 advances the process to step S410, and repeats the processes of steps S410 to S430 until the defocus amount Df becomes zero.

  If the defocus amount Df is 0 in step S420, the body control unit 101 advances the process to step S440. In step S440, the body control unit 101 determines the corresponding shift amount based on the current shooting distance of the shooting optical system 31 obtained from the lens control unit 201 and the shooting F value set in advance by the user as shown in FIG. Acquired from the first correction table 60 shown in FIG. The imaging F-number may be determined as appropriate by the body control unit 101 according to the imaging environment. In step S450, the body control unit 101 drives the focus lens 203 by the shift amount acquired in step S440.

  FIG. 6B is a flowchart of the contrast AF process performed by the body control unit 101. In step S500, the body control unit 101 sets a predetermined AF f-number for the diaphragm 205. The AF F value is set to an F value that is as open as possible and the light amount is not saturated by, for example, a known exposure calculation or the like.

  In step S510, the body control unit 101 causes the image sensor 102 to capture an image. In step S520, the body control unit 101 detects the amount of contrast from the imaging result. In step S530, the body control unit 101 determines whether or not the peak of the contrast amount is detected in step S520.

  If no peak is detected, the body control unit 101 advances the process to step S540, and drives the focus lens 203 to detect the peak of the contrast amount. Thereafter, the body control unit 101 advances the process to step S510, and repeats the processes of steps S510 to S540 until the peak of the contrast amount is detected.

  If the peak of the contrast amount is detected in step S530, the body control unit 101 advances the process to step S550. In step S550, the body control unit 101 generates a corresponding shift amount based on the current shooting distance D of the shooting optical system 31 acquired from the lens control unit 201 and the AF f-number set in step S500 (see FIG. Acquired from the second correction table 70 shown in b). Hereinafter, the shift amount acquired here is referred to as shift amount 1.

  In step S560, the body control unit 101 determines the corresponding shift amount based on the current shooting distance D of the shooting optical system 31 acquired from the lens control unit 201 and the shooting F value preset by the user (see FIG. Acquired from the second correction table 70 shown in b). Hereinafter, the shift amount acquired here is referred to as shift amount 2.

  In step S570, the body control unit 101 drives the focus lens 203 by (displacement amount 2-displacement amount 1). As a result, an optimal focus position (best image position) at the shooting F-number can be obtained.

(Description of measurement procedure by inspection device 300)
FIG. 7 is a flowchart of the correction table creation process performed by the inspection control unit 301. The inspection control unit 301 executes this correction table creating process at the time of manufacturing the interchangeable lens 200, and creates a correction table of the interchangeable lens 200.

  First, in step S100, the inspection control unit 301 waits for the installation of the measurement chart at a point at a shooting distance of 1 meter. The measurement chart is, for example, white paper printed with vertical stripes and horizontal stripes at predetermined intervals. When the inspection staff installs the measurement chart, the inspection control unit 301 advances the process to step S110. In step S110, the inspection control unit 301 executes a first measurement process described later. By this first measurement process, measurement results regarding a shooting distance of 1 meter can be obtained.

  Next, in step S120, the inspection control unit 301 waits for the installation of the measurement chart at a point 30 times the focal length (1.5 meters). When the inspection staff installs the measurement chart, the inspection control unit 301 advances the process to step S130. In step S130, the inspection control unit 301 executes a first measurement process described later. By this first measurement process, a measurement result on a shooting distance of 1.5 meters is obtained.

  Next, in step S140, the inspection control unit 301 waits for the installation of the measurement chart at a point at which the imaging distance (3 meters) is 60 times the focal length. When the inspection staff installs the measurement chart, the inspection control unit 301 advances the process to step S150. In step S150, the inspection control unit 301 executes a first measurement process described later. By this first measurement process, a measurement result on a shooting distance of 3 meters is obtained.

  Finally, in step S160, the inspection control unit 301 creates and outputs the correction table shown in FIG. 5 based on the results of the first measurement process performed in steps S110, S130, and S150. This output is written to the ROM 206 in the interchangeable lens 200 to be measured. The method of creating the correction table from the measurement results will be described in detail later.

  FIG. 8A is a flowchart of a first measurement process called from the correction table creation process shown in FIG. 7. First, in step S200, the inspection control unit 301 sets the aperture 205 to F2.0 (open aperture). In step S210, the inspection control unit 301 calls a second measurement process described later.

  In step S220, the inspection control unit 301 sets the aperture 205 to F4.0, and calls a second measurement process described later in step S230. In step S240, the inspection control unit 301 sets the aperture 205 to F8.0, and calls a second measurement process described later in step S250.

  FIG. 8B is a flowchart of a second measurement process called from the first measurement process shown in FIG. First, in step S300, the inspection control unit 301 causes the imaging device 302 to capture an object image. In step S310, the inspection control unit 301 detects the contrast amount (focus evaluation value) of the imaging signal. In step S320, the inspection control unit 301 determines whether the current contrast amount (focus evaluation value) is a peak (maximum). If the contrast amount (focus evaluation value) is not peak (maximum), the process proceeds to step S330. In step S330, the inspection control unit 301 drives the focus lens 203 in a predetermined direction, and the process proceeds to step S310. The inspection control unit 301 repeatedly executes steps S310 to S330 to repeat the drive of the focus lens 203 and the detection of the contrast amount (focus evaluation value), and the contrast amount (focus evaluation value) is peaked (maximum) by a so-called hill climbing method. The lens position of the focus lens 203 which becomes

  In step S320, if the contrast amount (focus evaluation value) is a peak (maximum), the inspection control unit 301 advances the process to step S340. The inspection control unit 301 stores the current position of the focus lens 203 in step S340. In step S350, the inspection control unit 301 causes the focus detection device 309 to perform focus detection of the phase difference detection method, and acquires the defocus amount. That is, the inspection control unit 301 obtains the defocus amount output of the focus detection device 309 in the in-focus state after obtaining the in-focus state by the contrast AF in the second measurement process shown in FIG. .

Next, the correction table creation method of the inspection control unit 301 in step S160 of FIG. 7 will be described in detail. By executing the processing described in FIGS. 7 to 8, the inspection control unit 301 obtains the following lens positions LP1 to LP9 and defocus amounts Df1 to Df9.
LP1: The position of the focus lens 203 at which the contrast is maximum when the photographing distance = 3 meters (focal length × 60), F value = F2.0 Df1: Defocus amount LP2 output by the focus detection device 309 when storing the above LP1. : The position of the focus lens 203 where the contrast is maximum when the shooting distance = 3 meters, F value = F 4.0 Df2: The defocus amount output by the focus detection device 309 when storing the above LP2 LP3: shooting distance = 3 meters, The position of the focus lens 203 where the contrast is maximized when F number = F8.0 Df3: Defocus amount output by the focus detection device 309 at the time of storing the above LP3 LP4: Shooting distance = 1.5 meters (focal length x 30) , F value = F2.0, the position D of the focus lens 203 at which the contrast becomes maximum 4: The defocus amount output by the focus detection device 309 at the time of storing the LP4 LP5: The position of the focusing lens 203 at which the contrast is maximal when the photographing distance = 1.5 meters and the F value = F4.0 Df5: The above LP5 storage When the focus detection device 309 outputs defocus amount LP6: shooting distance = 1.5 m, F value = F 8.0, the position of the focus lens 203 where the contrast becomes maximum Df6: the focus detection device 309 at the time of storing the above LP6 The amount of defocus LP7: the shooting distance = 1 meter (closest position), F value = F2.0, the position of the focus lens 203 where the contrast is maximum Df7: the focus detection device 309 outputs when storing the above LP7 Defocus amount LP8: Shooting distance = 1 meter, F value = F4.0, Contrast Position of the focus lens 203 at which the focus is maximized Df8: defocus amount output by the focus detection device 309 when storing the LP8 LP9: focus lens at which the contrast is maximized when the photographing distance = 1 meter and F value = F8.0. 203 position Df9: defocus amount output by the focus detection device 309 when storing the LP9

The inspection control unit 301 determines values D20, D30, D40, D21, D41, D22, D32, D42, D60, D70, D80, D61 of the correction tables shown in FIGS. , D71, D81, D62, D72, and D82 are calculated. In the following equation, a predetermined coefficient for converting the defocus amount to the movement amount of the focus lens 203 is K.
D20 = Df1 × K
D30 = Df4 × K
D40 = Df7 × K
D21 = (Df2-Df1) × K
D31 = (Df5-Df4) × K
D41 = (Df8-Df7) x K
D22 = (Df3-Df1) × K
D32 = (Df6-Df4) × K
D42 = (Df9-Df7) x K
D60 = 0
D70 = 0
D80 = 0
D61 = LP2-LP1
D71 = LP5-LP4
D81 = LP8-LP7
D62 = LP3-LP1
D72 = LP6-LP4
D82 = LP8-LP7

  Note that the value of D10 corresponding to the shooting distance = infinity and F value = F2.0 is determined by extrapolation based on D20, D30, and D40. This is because the measurement chart can not be placed at infinity. The same applies to D11, D12, D50, D51, and D52, which are calculated by extrapolation. Further, the inspection control unit 301 calculates and stores an interpolation value by extrapolation based on the values obtained by the above-described formulas in the column described as “*” in the correction table illustrated in FIG. 5.

According to the camera system according to the first embodiment described above, the following effects can be obtained.
(1) The interchangeable lens 200 includes automatic focusing (AF) control of a pupil division phase difference detection method based on a pair of light fluxes passing through each of the pair of pupil regions 32 and 35 of the photographing optical system 31 and contrast of the object image. Store the amount of correction of the best image plane position corresponding to each of a plurality of combinations of the imaging F number and the imaging distance D which can be used in each of the amount-based contrast detection type automatic focusing (AF) control The ROM 206 is provided. Since this is done, it is possible to correct variations due to lens manufacturing errors. Further, both automatic focusing control of the pupil division phase difference detection method and automatic focusing control of the contrast detection method can be coped with.

(2) The ROM 206 stores two correction amounts corresponding to each of a plurality of combinations of the imaging F value and the imaging distance for each combination, and one of the two correction amounts is the pupil division phase difference detection method The correction amount that can be used in the automatic focusing control of the present invention is stored in the first correction table 60, and the other is the correction amount that can be used in the automatic focusing control of the contrast detection method, and is stored in the second correction table 70. As a result, both automatic focusing control of the pupil division phase difference detection method and automatic focusing control of the contrast detection method can be supported.

Second Embodiment
In the first embodiment described above, the correction table includes the first correction table 60 for phase difference AF and the second correction table 70 for contrast AF. The correction table can also be a single correction table, which can be used for phase difference AF or contrast AF. In this embodiment, a method of using this single correction table in a camera system having the same configuration as that of the first embodiment will be described. In the following description, the same parts as those of the first embodiment are denoted by the same reference numerals as those of the first embodiment, and the description thereof is omitted.

  The ROM 206 in the interchangeable lens 200 of the present embodiment has only the first correction table 60 shown in FIG. 5A as a correction table. The phase difference AF process may be performed as in the first embodiment. On the other hand, the contrast AF process is performed using the values of the first correction table 60. In the contrast AF process of the first embodiment, the second correction table includes the shift amount 1 corresponding to the combination of the shooting distance D and the F value at the time of AF, and the shift amount 2 corresponding to the combination of the shooting distance D and the shooting F value. 70. The focus lens 203 is moved by (shift amount 2- shift amount 1). In the present embodiment, the same process is performed using the first correction table 60 instead of the second correction table 70. The first correction table 60 already includes the aberration correction amounts of the pupil and the free pupil used for the phase difference AF by the processing shown in FIGS. 7 and 8. Therefore, even with only the first correction table 60, it is possible to correspond to the phase difference AF and the contrast AF.

According to the camera system of the second embodiment described above, the following effects can be obtained.
(1) The ROM 206 stores one correction amount corresponding to each of a plurality of combinations of the imaging F value and the imaging distance D for each combination, and the one correction amount corresponds to that of the pupil division phase difference detection method. It can be used for both auto focusing control and auto focusing control of contrast detection method. Since this is done, the amount of data in the ROM 206 can be reduced compared to the first embodiment.

  The following modifications are also within the scope of the present invention, and one or more of the modifications can be combined with the above-described embodiment.

(Modification 1)
The content of the correction table shown in FIG. 5 is an example, and the configuration of the correction table can be different from that in FIG. For example, the image magnification and the F value may be divided more finely to store more “shift amounts”. Further, in FIG. 5, it can be arbitrarily determined in which column the interpolation value is stored and in which column the actually measured value is stored. For example, the measured shift amounts may be stored in more columns. Furthermore, the interpolation value may be stored in advance, or may be appropriately generated by the lens control unit 201 according to a request from the camera body 100 and transmitted to the camera body 100. Alternatively, the body control unit 101 may appropriately generate it.

(Modification 2)
The measuring method of the "shift amount" by the inspection apparatus 300 may be different from that described in each of the above-described embodiments. For example, instead of driving the focus lens 203, the image sensor 302 may be driven in the front-rear direction with respect to the optical axis L by a piezo element or the like to measure the change in the best image plane position. Further, the change of the best image plane position may be measured by moving the measurement chart in the front-rear direction with respect to the optical axis L. In the case of applying these modified examples, the focus lens 203 may be fixed along with the photographing distance D to perform measurement. When moving the measurement chart, it is necessary to convert the movement distance of the measurement chart for which the best image plane position has been obtained into the movement distance of the imaging surface by the photographing optical system 31.

(Modification 3)
The present invention can also be applied to a so-called zoom lens whose focal length is variable. In this case, a plurality of correction tables shown in FIG. 5 may be stored in the interchangeable lens 200 for each focal length. That is, a three-dimensional correction table may be prepared.

  The present invention is not limited to the above embodiment as long as the features of the present invention are not impaired, and other embodiments considered within the scope of the technical idea of the present invention are also included in the scope of the present invention. .

100: Camera body, 200: Interchangeable lens, 300: Inspection device

Claims (6)

An optical system having a focus lens and a stop;
A detachable unit attachable to and detachable from a camera having an imaging unit;
Use the detected deviation amount of the image by the optical system is in-focus position to focus on the imaging unit and the position of the focus lens, and either of the detection of the focusing position based on the contrast of an image by the optical system An interchangeable lens comprising: a storage unit configured to store a correction amount of a possible image plane position based on a combination of an aperture value of the aperture and a photographing distance or an image magnification . In the interchangeable lens according to claim 1,
The storage unit is an interchangeable lens that stores the correction amount for each of a plurality of combinations of an aperture value of the aperture and an imaging distance or an image magnification. In the interchangeable lens according to claim 2,
The storage unit is configured to detect the in-focus position based on an aperture value of the aperture for performing imaging with the imaging unit or an aperture value or contrast of the aperture for detecting the shift amount. An interchangeable lens that stores the correction amount for each combination of a value and the photographing distance or the image magnification. The interchangeable lens according to any one of claims 1 to 3.
An interchangeable lens comprising: a moving unit configured to move the focus lens based on the correction amount. In the interchangeable lens according to claim 3,
The amount of correction stored for each combination of the aperture value of the aperture for detecting the displacement amount and the photographing distance or the image magnification, and the aperture of the aperture for detecting the in-focus position based on contrast An interchangeable lens comprising: a moving unit configured to move the focus lens based on the correction amount stored for each combination of the value and the photographing distance or the image magnification. In the interchangeable lens according to any one of claims 1 to 5,
The storage unit is an interchangeable lens that stores a correction amount of an image plane position on which an image by the optical system is formed.

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