JP6194642B2 - interchangeable lens - Google Patents

Description

  The present invention relates to an interchangeable lens.

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

JP 59-208514 A

The automatic focus detection device described in Patent Document 1 has a problem that variation due to manufacturing errors cannot be corrected.
The subject of this invention is providing the interchangeable lens which has a suitable optical characteristic.

The interchangeable lens according to claim 1 is an interchangeable lens that can be attached to and detached from a camera having an imaging unit, and an in-focus position at which an image by a photographing optical system having a focus lens is focused on the imaging unit and the focus lens. For each of a plurality of combinations of the photographing F value and the photographing distance in the phase difference type focus adjustment control based on the defocus amount with respect to the position and the contrast type focus adjustment control based on the contrast of the image by the photographing optical system. And a storage unit for storing a correction amount of the image plane position that can be used for both the phase difference focus adjustment control and the contrast focus adjustment control .

  ADVANTAGE OF THE INVENTION According to this invention, the interchangeable lens which has a suitable optical characteristic can be provided.

It is a block diagram which shows the structure of the camera system which concerns on the 1st Embodiment of this invention. 2 is a cross-sectional view schematically showing the configuration of a camera body 100 and an interchangeable lens 200. FIG. 2 is a cross-sectional view schematically showing a configuration of an inspection apparatus 300. FIG. It is the figure which showed the fluctuation | variation of the optimal focus position typically. It is a figure which shows an example of a correction table. 5 is a flowchart of AF processing executed by the body control unit 101. It is a flowchart of the correction table creation process which the test | inspection control part 301 performs. It is a flowchart of the process called from the correction table creation process shown in FIG.

(First embodiment)
FIG. 1 is a block diagram showing a configuration of a camera system according to the 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 mount mechanism. Although only one camera body 100 and one interchangeable lens 200 are shown in FIG. 1, there are actually a plurality of types of camera bodies and a plurality of types of interchangeable lenses. 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. When the interchangeable lens 200 is manufactured, 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 a correction table creation process described later.

  FIG. 2 is a cross-sectional view schematically showing the configuration of the camera body 100 and the interchangeable lens 200. 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 composed of a plurality of lenses 202, 203, and 204, and a stop 205 having an opening. In FIG. 1, the photographic optical system is illustrated as if it is composed of three lenses, but it may be composed of any number of lenses. In FIG. 1, the diaphragm 205 is provided between the lens 203 and the lens 204, but as is well known, the diaphragm 205 may be in front of or behind the photographing optical system, or between other lenses. Also good.

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

  In the following description, for the sake of convenience, it is assumed that the open F value of the photographing optical system of the interchangeable lens 200 is F2.0, the shortest photographing distance is 1 meter, and the focal length is 50 millimeters. The following description can be applied to the interchangeable lens 200 having parameters different from the above parameters. In this case, the above parameters may be appropriately read.

  The interchangeable lens 200 includes a lens control unit 201 including a microprocessor and its peripheral circuits, and a ROM 206 that stores a predetermined control program and a correction table 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 CMOS that captures a subject image formed by a photographing optical system. The image sensor 102 is arranged so that the imaging surface 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 element 102 in the camera body 100. When not photographing, the quick return mirror 103 exists on the optical path of the photographing optical system, and reflects the subject light toward the focusing screen 104 and the pentaprism 105. The photographer can view the subject image from the viewfinder unit 107 through the eyepiece 106.

  A sub mirror 108 is installed on the back surface of the quick return mirror 103. The surface (reflecting surface) of the quick return mirror 103 is half-mirror processed, and subject light incident thereon passes through the quick return mirror 103 and enters the sub mirror 108. The sub mirror 108 reflects this light beam below the camera body 100. Below the camera body 100, a focus detection device 109 that performs focus detection by 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, performs focus detection by a well-known method for detecting a phase difference between the pair of light beams, and performs a defocus amount. Is detected.

  The camera body 100 includes a body control unit 101 that includes a microprocessor and its peripheral circuits. The body controller 101 controls each part 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 corresponding to the control program.

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

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

  When a predetermined still image shooting operation (for example, a full pressing 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 a retracted position that does not block the subject light, and then issues a drive command for driving the diaphragm 205 to the aperture diameter corresponding to the photographing F value. Transmit to the control unit 201. The lens control unit 201 drives the diaphragm 205 in response to this drive command. Thereafter, the body control unit 101 controls a shutter or the like (not shown) to cause the image sensor 102 to capture a subject image. Then, various image processing is applied to the image pickup signal output from the image pickup element 102 to generate still image data and store it in a storage medium (not shown) (for example, a memory card).

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

  FIG. 3 is a cross-sectional view schematically showing the configuration of the inspection apparatus 300. The inspection apparatus 300 includes a mount mechanism similar to that of the camera body 100, and the interchangeable lens 200 can be mounted 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 apparatus 309 are installed in the same arrangement as each part of the camera body 100 having the same name. Similar to the body control unit 101 described above, the inspection control unit 301 can communicate with the lens control unit 201 via an electrical contact (not shown).

(Explanation of automatic focus adjustment)
Next, automatic focus adjustment (AF) processing executed 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 using a so-called contrast detection method, and AF processing (hereinafter referred to as phase difference AF processing) that performs focus detection using a so-called pupil division phase difference detection method. The two types of AF processing can be executed. The body control unit 101 may selectively use these two types of AF processing according to shooting conditions, subject characteristics, and the like, or may execute either AF processing based on an explicit instruction from the user. May be.

  The contrast detection AF process performed by the body control unit 101 will be described. The body control unit 101 performs a 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 within a predetermined range (for example, between the drive limit position on the near side and the drive limit position on the infinity side), and the focus evaluation value (contrast value). Automatic focus adjustment is performed by detecting the position of the focus lens 203 at a peak. The body control unit 101 retracts the quick return mirror 103 from the optical path at least during execution of the contrast detection AF process.

  When performing contrast AF, it is desirable to make the aperture diameter R 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 wide aperture (F2.0), and performs shooting by driving the aperture diameter R to the shooting aperture during shooting. That is, the body control unit 101 changes the aperture diameter R between when the contrast AF process is performed and when the image is captured. In other words, the body control unit 101 makes the shape of the pupil region when executing the contrast AF process 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) that is the optimum image formation position of the subject image changes.

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

  Now, consider the subject light emitted from a certain point 30 of the subject 40 located at the photographing distance D. As shown in FIG. 4A, the focal position of a light beam (light beam from a region having a low image height) that has passed through pupils 33 and 34 in the vicinity of the optical axis L of the photographing optical system 31 out of the subject light from one point 30. 37 and a focal position 36 of a light beam (light beam from a region having a high image height) that has passed through the pupils 32 and 35 in the vicinity of the end of the photographic optical system 31 has a displacement 38 caused by spherical aberration or the like. At the time of optical design, the best image plane position (imaging position optimal for imaging) 39 is determined in consideration of this shift, and the state where the imaging plane is the best image plane position 39 is handled as the in-focus state.

  When the diaphragm 205 is narrowed as shown in FIG. 4B, the subject light toward the pupils 32 and 35 near the end of the photographing optical system 31 is blocked by the diaphragm 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 the best image plane position 39 is determined by performing AF in the state of FIG. 4A, the best image plane position 39 is different from the best image plane position 45 in the state of FIG. The fluctuation amount 46 of the best image plane position 45 due to the aperture diameter R changes according to the change in the position of the subject, that is, the shooting distance D. In addition, the fluctuation amount 46 is affected by manufacturing variations, that is, individual differences among individual lenses.

  Next, the pupil division phase difference detection method AF processing 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 photographing 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 phase difference detection. The focus detection device 109 calculates a defocus amount based on the detected phase difference, and outputs it to the body control unit 101. The body control unit 101 performs automatic focus adjustment by driving the focus lens 203 by a distance corresponding to the defocus amount.

  The pupils 32 and 35 used for focus detection by the focus detection device 109 are determined in advance. At the time of focus detection, the aperture diameter R is at least large enough to prevent the luminous flux from the pupils 32 and 35 from being kicked. For example, with an open aperture, the light flux from the pupils 32 and 35 is not kicked. The body control unit 101 drives the aperture 205 to the full aperture (F2.0) and then causes the focus detection device 109 to perform focus detection, and focuses on the target subject based on the result. After that, the body control unit 101 narrows down the aperture 205 to the shooting aperture 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 beam used for imaging is not the light beam from the pupils 32 and 35. For example, a light beam in a wider range including the pupils 32 and 35 may be used, or a light beam in a narrower range 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 photographing (substantially circular shape with the optical axis as the center). Accordingly, as described in the description of contrast AF, the best image plane position during AF may differ from the best image plane position during shooting.

  The inspection apparatus 300 measures fluctuations in the best image plane position according to changes in the shape of the pupil region (aperture diameter R) and the photographing distance D described above, and creates a correction table described later. Since the measurement by the inspection apparatus 300 is performed for each individual 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 actually measured result and stores it in the ROM 206 of the interchangeable lens 200. The camera body 100 refers to a correction table stored in the ROM 206 of the interchangeable lens 200, and performs AF processing in consideration of a change in the best image plane position.

(Explanation of correction table)
FIG. 5 is a diagram illustrating an example of the correction table. The correction table includes 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 image magnification (generally equal to the reciprocal of the shooting distance D) and F value. Yes. The meaning of the “shift amount of the focus lens 203” will be described below with a specific example.

  For example, in FIG. 5A, the value “D11” is stored in the column of the image magnification “0” and the F value “F4.0”. This is because “when the image magnification is 0 (that is, the shooting distance D is infinity) and the F value of the diaphragm 205 is F4.0, the lens position from which the defocus amount detected by the focus detection device 109 becomes 0 is obtained. , The position where the focus lens 203 is moved by D11 is the true in-focus position ”. In other words, “when the shooting distance D is infinity and the shooting F value is F4.0, from the position where the focus lens 203 is driven so that the defocus amount detected by the focus detection device 109 becomes“ 0 ”. Also, it is possible to obtain a better photographing result by moving the focus lens 203 to a position shifted by “D11” therefrom. Note that a positive shift amount represents the closest direction, and a negative shift amount represents the infinity direction.

  When the shooting distance is infinity and the shooting F value is F4.0, the camera body 100 moves the focus lens 203 to a position where the defocus amount output from the focus detection device 109 becomes 0, and then the focus lens is set to D11. 203 is driven. By doing so, the defocus amount output from the focus detection device 109 is not zero, but actually, this is the optimum focus position for photographing.

  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 image magnification and F value.

  In contrast AF, unlike the phase difference AF, the F value during AF is not always the same. For example, after performing contrast AF at F2.0, shooting may be performed at F5.6, or after performing contrast AF at F2.8, shooting may be performed at F2.0. The second correction table 70 stores “the shift amount of the focus lens 203” based on F2.0 (open F value). The calculation is performed by appropriately selecting the shift amount from the second correction table 70. By doing so, it is possible to obtain an optimum shift amount when performing contrast AF and photographing with an arbitrary F value.

  For example, in FIG. 5B, the value “D51” is stored in the column of the image magnification “0” and the F value “F4.0”. This is because, when the image magnification is 0 (that is, the shooting distance D is infinity) and the F value is F4.0, the contrast value (focus evaluation value) is obtained when the image magnification is 0 and the F value is F2.0. It means that the position where the focus lens 203 is moved by D51 from the lens position where the peak is “is the true in-focus position”. In other words, “Contrast AF is performed at F2.0 while the image magnification is 0, and then the diaphragm 205 is narrowed down to F4.0, from the time when the optimum focus position is F2.0 (in terms of the position of the focus lens 203). ) Is shifted by D51 ”.

  On the other hand, the value “D52” is stored in the column where the image magnification is “0” and the F value is “F8.0”. The camera body 100 drives the focus lens 203 only after the execution of AF (D52-D51) when the shooting distance D is infinity, the F value during AF is F4.0, and the shooting F value is F8.0. Thereby, it is possible to obtain an optimum focus position with respect to the F value at the time of photographing.

  FIG. 6A is a flowchart of phase difference AF processing executed by the body control unit 101. In step S400, the body control unit 101 sets an open F value (F2.0) for the diaphragm 205. In step S <b> 410, the body control unit 101 causes the focus detection device 109 to perform focus detection by 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 or not 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 sets the corresponding shift amount based on the current shooting distance of the shooting optical system 31 acquired from the lens control unit 201 and the shooting F value preset by the user in FIG. ) From the first correction table 60 shown in FIG. Note that the photographing F value may be appropriately determined by the body control unit 101 according to the photographing 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 executed by the body control unit 101. In step S <b> 500, the body control unit 101 sets a predetermined AF F value for the diaphragm 205. The F value for AF is set to an F value that is as close to the open as possible and does not saturate the light amount by, for example, a known exposure calculation.

  In step S <b> 510, the body control unit 101 captures an image with the image sensor 102. In step S520, the body control unit 101 detects the contrast amount from the imaging result. In step S530, the body control unit 101 determines whether or not a contrast amount peak has been 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 a contrast amount peak is detected.

  When the contrast amount peak is detected in step S530, the body control unit 101 advances the process to step S550. In step S550, the body control unit 101 sets 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 AF F value set in step S500 as shown in FIG. Obtained from the second correction table 70 shown in b). Hereinafter, the obtained shift amount is referred to as a shift amount 1.

  In step S560, the body control unit 101 sets 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 in FIG. Obtained from the second correction table 70 shown in b). Hereinafter, the obtained shift amount is referred to as a shift amount 2.

  In step S570, the body control unit 101 drives the focus lens 203 by (shift amount 2−shift amount 1). As a result, an optimum focus position (best image plane position) can be obtained in the photographing F value.

(Description of measurement procedure by inspection apparatus 300)
FIG. 7 is a flowchart of the correction table creation process executed by the inspection control unit 301. The inspection control unit 301 executes this correction table creation process when the interchangeable lens 200 is manufactured, and creates a correction table for the interchangeable lens 200.

  First, in step S100, the inspection control unit 301 waits for the installation of a measurement chart at a point at an imaging distance of 1 meter. The measurement chart is obtained, for example, by printing vertical stripes and horizontal stripes at predetermined intervals on a white paper. 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. With this first measurement process, a measurement result relating to an imaging distance of 1 meter is obtained.

  Next, in step S120, the inspection control unit 301 waits for installation of a measurement chart at a point with an imaging distance (1.5 meters) that is 30 times the focal length. 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 relating to an imaging distance of 1.5 meters is obtained.

  Next, in step S140, the inspection control unit 301 waits for installation of a measurement chart at a point with an imaging distance (3 meters) that 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 relating to an imaging 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 from the results of the first measurement processing executed in steps S110, S130, and S150. This output is written in the ROM 206 in the interchangeable lens 200 to be measured. A method for creating the correction table from the measurement result will be described in detail later.

  FIG. 8A is a flowchart of the first measurement process called from the correction table creation process shown in FIG. 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 diaphragm 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 diaphragm 205 to F8.0 and calls a second measurement process described later in step S250.

  FIG. 8B is a flowchart of the second measurement process called from the first measurement process shown in FIG. First, in step S <b> 300, the inspection control unit 301 captures a subject image with the image sensor 302. 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 or not the current contrast amount (focus evaluation value) is a peak (maximum). If the contrast amount (focus evaluation value) is not a peak (maximum), the process proceeds to step S330. In step S330, the inspection control unit 301 drives the focus lens 203 in a certain direction, and the process proceeds to step S310. The inspection control unit 301 repeatedly executes steps S310 to S330 to repeatedly drive the focus lens 203 and detect the contrast amount (focus evaluation value), and the contrast amount (focus evaluation value) peaks (maximum) by a so-called hill-climbing method. The lens position of the focus lens 203 is specified.

  In step S320, when the contrast amount (focus evaluation value) is a peak (maximum), the inspection control unit 301 advances the process to step S340. In step S340, the inspection control unit 301 stores the current position of the focus lens 203. In step S350, the inspection control unit 301 causes the focus detection device 309 to perform focus detection by 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 in the second measurement process illustrated 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 with reference to 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 maximized when the shooting distance = 3 meters (focal length × 60) and the F value = F2.0. Df1: Defocus amount output by the focus detection device 309 when storing the LP1 LP2 : The position of the focus lens 203 at which the contrast becomes maximum when the shooting distance = 3 meters and the F value = F4.0 Df2: Defocus amount output by the focus detection device 309 when storing the LP2 LP3: Shooting distance = 3 meters The position of the focus lens 203 at which the contrast becomes maximum when F value = F8.0 Df3: Defocus amount output by the focus detection device 309 when storing the LP3 LP4: Shooting distance = 1.5 meters (focal length × 30) When the F value = F2.0, the position of the focus lens 203 at which the contrast becomes maximum D 4: Defocus amount output by the focus detection device 309 when storing the LP4 LP5: position of the focus lens 203 at which the contrast is maximized when the shooting distance = 1.5 meters and the F value = F4.0 Df5: the LP5 storage Defocus amount output by the focus detection device 309 at times LP6: The position of the focus lens 203 at which the contrast becomes maximum when the shooting distance = 1.5 meters and the F value = F8.0 Df6: The focus detection device 309 when storing the LP6 LP7: position of the focus lens 203 at which the contrast becomes maximum when the shooting distance = 1 meter (closest position) and F value = F2.0 Df7: output by the focus detection device 309 when storing the LP7 Defocus amount LP8: Contrast when shooting distance = 1 meter, F value = F4.0 Df8: Defocus amount output by the focus detection device 309 when storing the LP8 LP9: Focus lens with the maximum contrast when the shooting distance is 1 meter and the F value is F8.0 203 position Df9: Defocus amount output by the focus detection device 309 when storing the LP9

The inspection control unit 301 calculates the correction table values D20, D30, D40, D21, D31, D41, D22, D32, D42, D60, D70, D80, D61 shown in FIGS. , D71, D81, D62, D72, and D82. In the following equation, K is a predetermined coefficient for converting the defocus amount into the movement amount of the focus lens 203.
D20 = Df1 × K
D30 = Df4 × K
D40 = Df7 × K
D21 = (Df2-Df1) × K
D31 = (Df5-Df4) × K
D41 = (Df8−Df7) × K
D22 = (Df3-Df1) × K
D32 = (Df6-Df4) × K
D42 = (Df9−Df7) × 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 shooting distance = infinity and F value = F2.0 is determined by extrapolation based on D20, D30, and D40. This is because the measurement chart cannot be placed at a position at infinity. Similarly, D11, D12, D50, D51, and D52 are values calculated by extrapolation. In addition, the inspection control unit 301 calculates and stores an interpolated value by extrapolation based on the values obtained by the above formulas in the column marked “*” in the correction table shown in FIG.

According to the camera system according to the first embodiment described above, the following operational effects can be obtained.
(1) The interchangeable lens 200 includes an automatic focus adjustment (AF) control of a pupil division phase difference detection method based on a pair of light beams that have passed through each of the pair of pupil regions 32 and 35 of the photographing optical system 31, and the contrast of the subject image. The amount of correction of the best image plane position corresponding to each of a plurality of combinations of the photographing F value and the photographing distance D, which can be used in each of the automatic focus adjustment (AF) control of the contrast detection method based on the amount. ROM 206 is provided. Since it did in this way, the dispersion | variation by the manufacturing error of a lens can be correct | amended. Further, it is possible to cope with both the automatic focus adjustment control using the pupil division phase difference detection method and the automatic focus adjustment control using the contrast detection method.

(2) The ROM 206 stores two correction amounts corresponding to each of a plurality of combinations of the shooting F value and the shooting distance, and one of the two correction amounts is a pupil division phase difference detection method. The correction amount that can be used in the automatic focus adjustment control is stored in the first correction table 60, and the other correction amount that can be used in the contrast detection type automatic focus adjustment control is stored in the second correction table 70. Since it did in this way, it can respond to both automatic focus adjustment control of a pupil division phase difference detection system, and automatic focus adjustment control of a contrast detection system.

(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 be a single correction table that can be used for both phase difference AF and 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 this embodiment has only the first correction table 60 shown in FIG. 5A as the 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 in the first correction table 60. In the contrast AF process of the first embodiment, the second correction table uses 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, and the focus lens 203 was moved by (shift amount 2−shift amount 1). In the present embodiment, the same processing is performed using the first correction table 60 instead of the second correction table 70. The first correction table 60 already includes aberration correction amounts for the pupil and the release pupil used for the phase difference AF by the processing shown in FIGS. Therefore, even with only the first correction table 60, it is possible to deal with phase difference AF and contrast AF.

According to the camera system according to the second embodiment described above, the following operational effects can be obtained.
(1) The ROM 206 stores one correction amount corresponding to each of a plurality of combinations of the photographing F value and the photographing distance D for each combination, and the one correction amount is based on the pupil division phase difference detection method. It can be used for both automatic focus control and contrast detection type auto focus control. Since it did in this way, the data amount of ROM206 can be reduced compared with 1st Embodiment.

  The following modifications are also within the scope of the present invention, and one or a plurality of 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 shown in FIG. For example, the image magnification and the F value may be divided more finely to store a larger number of “shift amounts”. 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 actually measured shift amount may be stored in a larger number of columns. Furthermore, the interpolation value may be stored in advance, or the lens control unit 201 may appropriately generate and transmit the interpolation value to the camera body 100 in response to a request from the camera body 100. Or you may make it the body control part 101 produce | generate suitably.

(Modification 2)
The “shift amount” measuring method 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 change in the best image plane position may be measured by driving the imaging element 302 in the front-rear direction with respect to the optical axis L by a piezo element or the like. Further, the change in 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. When applying these modified examples, the focus lens 203 may be fixed in accordance with the shooting distance D and measured. When the measurement chart is moved, it is necessary to convert the movement distance of the measurement chart from which the best image plane position is obtained into the movement distance of the imaging plane by the photographing optical system 31.

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

  As long as the characteristics of the present invention are not impaired, the present invention is not limited to the above-described embodiments, and other forms conceivable within the scope of the technical idea of the present invention are also included in the scope of the present invention. .

DESCRIPTION OF SYMBOLS 100 ... Camera body, 200 ... Interchangeable lens, 300 ... Inspection apparatus

Claims (2)

An interchangeable lens that can be attached to and detached from a camera having an imaging unit,
Focus adjustment control of a phase difference method based on a defocus amount between a focus position at which an image by a photographing optical system having a focus lens is focused on the imaging unit and a position of the focus lens, and contrast of an image by the photographing optical system in a focusing control of the contrast method based on the bets, for each combination of plural kinds of the photographic F number and the photographing distance, available for any image of the focusing control of focusing control and contrast method of phase difference method exchange lenses Ru comprising a storage unit for storing the correction amount of the surface position. The interchangeable lens according to claim 1,
Wherein the storage unit, a correction amount corresponding to each combination of the plurality of types of imaging F value and the photographing distance, one SL 憶 interchangeable lens you for each combination.

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