JP4931225B2 - Imaging device - Google Patents

Description

  The present invention relates to an imaging apparatus that performs focus detection and focus control in a phase difference detection system, and more particularly to an imaging apparatus that uses a contrast detection system (also referred to as a TV-AF system) and performs focus correction according to a light source.

  In focus control in an imaging apparatus such as a single-lens reflex digital camera, focus detection is often performed by a so-called phase difference detection method. In focus control by the phase difference detection method (hereinafter referred to as phase difference AF), the light from the imaging lens is reflected by a mirror and then divided into two, and the phase difference between the two images formed by the divided luminous flux is detected as a line sensor. It is detected by a light receiving element such as. Then, by calculating the driving direction and driving amount of the focus lens from the defocus information obtained based on the phase difference, a focused state can be obtained at high speed.

Further, recently, in order to accuracy of Ri by the phase difference A F, sometimes used in combination with TV-AF. In TV-AF, a focus evaluation value signal indicating a contrast state of a video is generated from a video signal obtained by using an imaging device that photoelectrically converts a subject image formed by an imaging lens. Then, the focus lens is moved to a position where the focus evaluation value signal is maximized. In the phase difference AF, the light from the imaging lens is guided to the light receiving element via the focus detection optical system, so that the focus accuracy is affected by the influence of the manufacturing error, the placement error, and the like of the focus detection optical system. On the other hand, in the TV-AF, since an image sensor for obtaining a recording image is used, high-precision focus control is possible.

  In the imaging apparatus disclosed in Patent Document 1, the difference between the in-focus position obtained by phase difference AF and the in-focus position obtained by TV-AF for the same subject is stored as a correction amount. Then, the accuracy of the phase difference AF is improved by moving the focus lens to a position where the correction amount is added (or subtracted) to the in-focus position obtained by the phase difference AF.

  However, the amount of chromatic aberration of the imaging lens and the focus detection optical system differs depending on the light source that illuminates the subject, that is, the wavelength of light from the subject. For this reason, a difference arises in the focus position obtained by phase difference AF with a light source. Therefore, in the imaging apparatus disclosed in Patent Document 1 in which the influence of such a light source is not taken into consideration, an error due to the light source is included in the focus position difference itself between the phase difference AF and the TV-AF. There is a limit to the improvement.

On the other hand, in the camera disclosed in Patent Document 2, the type of the light source is determined using a remote control receiver having sensitivity to infrared light and a photometry circuit having sensitivity to visible light, and a phase difference is determined according to the light source. Defocus information obtained by AF is corrected. Thereby, the fluctuation | variation of the focus precision by the difference in a light source is reduced.
JP 2003-279843 A JP 2000-292682 A

  However, in the imaging device disclosed in Patent Document 2, a remote control receiving unit that the photographer may unconsciously cover with a hand such as a grip unit for the photographer to hold the imaging device is used as the light source. Used for detection. If the remote control receiver is covered with hands, correct light source detection cannot be performed.

  Further, since the remote control receiver generally has a wide light receiving field angle, there is a possibility that the photographer detects infrared light from an object different from the subject that the photographer really wants to focus within the imaging range. In this case, if the object receives light from a light source that is different from the light source that illuminates the subject, it is detected as a light source that is different from the light source that illuminates the subject to be focused, and correction of defocus information corresponding to the light source is performed. Is not done correctly.

  The present invention provides an imaging apparatus capable of performing highly accurate phase difference AF regardless of the type of light source.

Imaging apparatus according to one aspect of the present invention is formed, I detachable capable imaging apparatus der the imaging lens, and an imaging device for photoelectrically converting an object image formed by the imaging lens, the light from the imaging lens A focus detection unit that generates defocus information according to the shift amounts of the plurality of images, a first focus process for obtaining a focus position of the imaging lens based on the defocus information, and the imaging element. Control means for performing a second focus process for obtaining the in-focus position of the imaging lens based on focus evaluation value information corresponding to the contrast of the obtained image, and the focus detection means includes light capable of receiving light. A member for limiting the wavelength range of the first wavelength range to a second wavelength range narrower than the first wavelength range is detachable in the optical path, and the light in the first wavelength range not limited by the member The second defocus information based on the shift amount of the plurality of images formed by the first defocus information based on the shift amount of the plurality of images formed by the light and the light of the second wavelength range limited by the member. The defocus information is generated, and the control means generates a first focus corresponding to a difference between the focus position obtained based on the second defocus information and the focus position obtained in the second focus process. And the second correction information regarding the focus shift caused by the chromatic aberration corresponding to the second wavelength range acquired from the imaging lens are stored in the storage unit in association with the identification information for identifying the imaging lens. When the first lens whose identification information is stored in the storage means is attached, the control means includes the first correction information and the first correction information corresponding to the identification information stored in the storage means. Supplement of 2 Information, on the basis of said first defocus information, and performs focus control of the first imaging lens.

An imaging apparatus control method according to another aspect of the present invention is an imaging apparatus control method in which an imaging lens can be attached and detached, and the amount of deviation of a plurality of images formed by light from the imaging lens is reduced. A detection step of generating corresponding defocus information, a first focus process for obtaining a focus position of the imaging lens based on the defocus information, and a focus according to a contrast of an image obtained using the imaging element And a control step for performing a second focus process for obtaining a focus position of the imaging lens based on the evaluation value information. In the detection step, the wavelength range of light that can be received is narrower than the first wavelength range. By retracting the member for limiting to the wavelength range of 2 from the optical path, the first deformation based on the shift amounts of the plurality of images formed by the light in the first wavelength range And generating the second defocus information based on the shift amounts of the plurality of images formed by the light in the second wavelength range by inserting the member into the optical path and generating the control information. In the step, the first correction information corresponding to the difference between the in-focus position obtained based on the second defocus information and the in-focus position obtained in the second focus process is acquired from the imaging lens. Second correction information related to defocus due to chromatic aberration corresponding to the second wavelength range is stored in a storage unit in association with identification information for identifying the imaging lens, and the identification information is stored in the storage unit. When the first lens is attached, in the control step, the first correction information and the second correction information corresponding to the identification information stored in the storage means, and the first data Based on the Okasu information, and performs focus control of the first imaging lens.

  According to the present invention, information on the in-focus position is obtained by phase difference AF that is not easily affected by the light source using light in the narrow second wavelength range, and the in-focus position and the TV-AF are obtained. Focus control is performed using the difference from the in-focus position. For this reason, highly accurate phase difference AF can be performed irrespective of the kind of light source.

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

  FIG. 1 shows a single-lens reflex digital camera as an image pickup apparatus that is Embodiment 1 of the present invention. Various imaging lenses 2 are detachably attached to the camera body 1.

  In the camera body 1, an auxiliary light unit 3 for assisting focus detection by irradiating auxiliary light to a dark subject is provided so as to be built-in or detachable.

  The light from the subject that has passed through the imaging optical system 21 provided in the imaging lens 2 is a main that is configured by a half mirror disposed on the optical path (imaging optical path) from the imaging optical system 21 in the camera body 1. The light passes through the mirror 5 and is reflected by the sub-mirror 6. A state in which the main mirror 5 and the sub mirror 6 are arranged in the imaging optical path is also referred to as a mirror-down state.

  The reflected light is guided to the AF image sensor 16 through the AF reflecting mirror 12, the field lens 13, the IR cut filter 14, and the eyeglass lens (secondary imaging optical system) 15.

The IR cut filter 14 has spectral characteristics (transmittance characteristics) indicated by a curve a in FIG. That is, the IR cut filter 14 has a high transmittance with respect to light in the wavelength range from about 400 nm to about 730 nm, and hardly transmits light in the infrared wavelength range (first wavelength range) higher than about 730 nm. (Cut).

  The field lens 13, the IR cut filter 14, and the eyeglass lens 15 constitute a focus detection optical system, and the focus detection optical system and the AF image sensor 16 constitute a focus detection unit.

  The reflected light is divided into a plurality of light beams by the focus detection optical system, and the plurality of divided light beams form a plurality of images on the AF image sensor 16. The plurality of images include a plurality of pairs of images that are paired with each other (hereinafter referred to as two images).

  The AF image sensor 16 includes a plurality of pairs of light receiving element arrays (light receiving sensors) that photoelectrically convert the plurality of pairs of two images, and receives a clock signal and a control signal from the camera microcomputer 11 that is a control unit. Charge accumulation control is performed by photoelectric conversion at the light receiving sensor. FIG. 7 shows an arrangement example of a plurality of pairs of light receiving sensors L1 to L8 within the imaging range. The region where each pair of light receiving sensors is provided is also referred to as a focus detection region. The camera microcomputer 11 performs at least one area for performing a focus detection operation (defocus information and in-focus position information generation operation) from among the plurality of focus detection areas automatically or in accordance with a selection operation of the photographer. Select. The selected focus detection area is referred to as a selected focus detection area in the following description.

  The camera microcomputer 11 takes in phase difference data that is an output signal from the light receiving sensor pair corresponding to the selected focus detection region. Then, the phase difference data is processed by a focus detection algorithm based on a phase difference detection method to calculate (generate) defocus information of the imaging optical system 21. Thereby, defocus information corresponding to the phase difference between the two images of the subject included in the selected focus detection area is obtained. The defocus information includes a defocus amount and a defocus direction called a front pin and a rear pin.

  The focus detection unit is configured by the focus detection unit and the function (defocus calculation unit) up to the generation of defocus information of the camera microcomputer 11.

  The camera microcomputer (focus control unit) 11 obtains the in-focus position of the imaging lens 2 (imaging optical system 21) based on the calculated defocus information and correction information described later. The in-focus position here is actually information including the drive amount and drive direction of a focus lens (not shown) included in the imaging optical system 21. Then, the focus position information is transmitted to the lens microcomputer 22 provided in the imaging lens 2.

  The lens microcomputer 22 moves the focus lens via a lens drive mechanism (not shown) based on the received focus position information. Thereby, the in-focus state of the imaging lens 2 (imaging optical system 21) with respect to the subject included in the selected focus detection area is obtained.

  The process up to the calculation of the focus position information based on the defocus information or the like in the camera microcomputer 11 corresponds to the first focus process, and the process up to the transmission of the focus position information to the imaging lens 2 is the focus control on the camera side. Equivalent to.

  On the other hand, the lens microcomputer 22 transmits identification information (hereinafter referred to as a lens ID) for individual identification of the imaging lens 2 to the camera microcomputer 11. The lens microcomputer 22 also transmits information (including direction: hereinafter referred to as color focus shift information) regarding the amount of focus shift caused by chromatic aberration at a plurality of wavelengths of the imaging optical system 21 to the camera microcomputer 11. To do. The color focus shift information of each imaging lens 2 corresponds to the second correction information. The color focus shift information is stored in a memory (for example, EEPROM) 19 in association with the lens ID.

  The auxiliary light unit 3 described above includes a light projecting optical system 31, a light source 32 such as an IRED (near infrared light emitting diode), and an auxiliary light driving circuit 33 that drives the light source 32. The auxiliary light drive circuit 33 receives a command from the camera microcomputer 11, causes the light source 32 to emit light, and irradiates the subject with auxiliary light via the light projecting optical system 31. As a result, a specific pattern is projected onto a dark subject, and assists generation of phase difference data by the AF image sensor 16.

  The auxiliary light unit 3 operates automatically or in response to a manual operation when the luminance of the subject detected by the photometry unit described later is low.

  Between the field lens 13 and the IR cut filter 14 in the focus detection unit, an optical filter 17 having a spectral characteristic (transmittance characteristic) indicated by a curve b in FIG. 6 is arranged.

The optical filter 17 has a high transmittance with respect to light in a wavelength range from about 520 nm to about 570 nm, and hardly transmits (cuts) light in other (other) wavelength ranges. That is, light in a narrow wavelength range (second wavelength range) is transmitted as compared with the IR cut filter 14. The transmission wavelength range of the optical filter 17 overlaps a part of the transmission wavelength range of the IR cut filter 14.

  The optical filter 17 is inserted into the optical path in the focus detection unit, that is, the focus detection optical path by the filter driving mechanism 18 or moved (retracted) out of the focus detection optical path.

  A finder optical system including a pentaprism 103 and an eyepiece optical system 104 is disposed in the camera body 1. Light that is incident from the imaging optical system 21 and reflected by the main mirror 5 is guided to the finder optical system.

  A photometric sensor 105 receives a part of light incident on the pentaprism 103 via the photometric lens 106. The photometric sensor 105 can perform photometry in a plurality of areas corresponding to the areas (focus detection areas) of a plurality of pairs of light receiving sensors L1 to L8 within the imaging range shown in FIG. Actually, photometry is performed in the selected focus detection area.

  The main mirror 5 and the sub mirror 6 move (retract) out of the optical path from the imaging optical system 21 at the time of TV-AF and at the time of imaging for acquiring a recording image. This state is also called a mirror up state. Thereby, the light from the imaging optical system 21 goes to the shutter 101. During TV-AF, the shutter 101 is kept open, whereby the subject image formed by the imaging optical system 21 is projected onto the imaging element 102. The image sensor 102 photoelectrically converts the subject image and outputs an analog image signal. The analog image pickup signal is digitized by the image processing circuit 43, and further subjected to various kinds of image processing to be converted into image data (here, a video signal). The image data is subjected to a predetermined format conversion and temporarily stored in the image display memory 45, and then transferred to the liquid crystal driver 41 to be converted into an analog video signal. The image display memory 45 is controlled by a memory control circuit 44 that operates according to a command from the camera microcomputer 11. The analog video signal is displayed on the liquid crystal display 42 as an electronic viewfinder video.

  The camera microcomputer 11 performs TV-AF using image area data corresponding to the selected focus detection area among the image data as the video signal. Specifically, a high frequency component is extracted from the image data of the image region to generate an AF evaluation value signal (focus evaluation value information), and a position where the AF evaluation value signal is maximum, that is, a focus position is searched. Move the focus lens as follows. The search operation for the in-focus position by the TV-AF corresponds to the second focus process.

  On the other hand, during imaging, the exposure amount of the imaging element 102 is controlled by opening and closing the shutter 101. The image sensor 102 photoelectrically converts a subject image received while the shutter 101 is open, and outputs an analog image signal. The imaging element 102 is a photoelectric conversion element such as a CCD sensor or a CMOS sensor. The analog image pickup signal is digitized by the image processing circuit 43 and further subjected to various types of image processing to be converted into image data (here, a still image signal). The image data is subjected to a predetermined format conversion and temporarily stored in the image display memory 45, and then transferred to the liquid crystal driver 41 to be converted into an analog still image signal. The analog still image signal is displayed as a captured image on the liquid crystal display 42. The digital still image data output from the image processing circuit 43 is recorded on a recording medium (not shown) (semiconductor memory, optical disk, etc.) that is detachably attached to the camera body 1.

  FIG. 2 shows a flowchart of the phase difference AF calibration operation in the camera of this embodiment. This calibration operation is executed by the camera microcomputer 11 in accordance with a computer program stored in its internal memory. The same applies to a focus control operation by phase difference AF described later. “S” means a step.

  In the calibration operation, the camera microcomputer 11 first determines whether the calibration mode is selected by a switch (not shown) provided in the camera body 1 (S101). If the calibration mode has not been selected, this flow ends. If the calibration mode is selected, the camera microcomputer 11 communicates with the lens microcomputer 22 and receives the lens ID (S102).

  Next, the camera microcomputer 11 inserts the optical filter 17 into the focus detection optical path via the filter drive mechanism 18 (S103). Then, phase difference AF is performed (S104). Thereby, defocus information by phase difference AF with the optical filter 17 inserted is obtained, and a focus position (hereinafter referred to as filter phase difference focus position) is obtained based on the defocus information.

  When the phase difference AF is completed (S105), the focus lens is moved to the filter phase difference in-focus position (S106).

  Here, the reason why the phase difference AF is performed with the optical filter 17 inserted in S103 to S106 will be described.

  As shown in FIG. 3, the focus shift amount included in the focus position information obtained by the phase difference AF is the wavelength of light from the subject, even for the same subject (subject having the same contrast located at the same distance), That is, it varies depending on the type of light source that illuminates the subject. This is because the chromatic aberration of the imaging optical system 21 and the focus detection optical system changes depending on the wavelength of light from the subject.

  FIG. 4 shows representative examples of spectral characteristics of various light sources. A2 indicates the spectral characteristics of the A light source (tungsten bulb), B2 indicates the spectral characteristics of sunlight, and C2 indicates the spectral characteristics of the fluorescent lamp.

  For example, when the light from the light source is single wavelength light of 600 nm, the amount of focus shift due to chromatic aberration is zero as shown in FIG. On the other hand, when the light from the light source is a single wavelength light of 500 nm, the amount of defocus is -0.1 mm, and when the light is a single wavelength light of 750 nm, the amount of defocus is 0.15 mm.

  Then, the sum of the result of multiplying the spectral intensity for each wavelength in the spectral characteristics of each light source shown in FIG. 4 by the amount of focus deviation for each wavelength shown in FIG. 3 is the amount of focus deviation caused by the difference in the light source.

  In the vertical axis direction of FIG. 3, + indicates a focus shift in the front pin direction, and-indicates a focus shift in the rear pin direction.

  The A light source (A2) has a high light intensity near 700 nm, whereas the sunlight (B2) has a maximum light intensity near 550 nm and a slightly lower light intensity near 700 nm. For this reason, it is in the tendency for the focus shift | offset | difference of a back pin direction to generate | occur | produce under sunlight rather than the case of A light source.

  Further, the fluorescent lamp (C2) has almost zero light intensity of 650 nm or more, and has high light intensity in a wavelength range in which a focus shift occurs on the minus side shown in FIG. Therefore, in the case of under a fluorescent lamp, there is a tendency that a larger focus shift in the rear pin direction occurs than in the case of under sunlight.

  On the other hand, when phase difference AF is performed by inserting an optical filter 17 having a transmittance characteristic as shown by a curve b in FIG. 6, that is, a transmittance peak at 550 nm into the focus detection optical path, The difference in the amount of defocus under each fluorescent lamp is as small as about ± 5 μm.

  That is, by inserting the optical filter 17 and performing the phase difference AF, it is possible to obtain a filter phase difference in-focus position with little difference under various light sources such as sunlight and fluorescent lamps.

  Next, the camera microcomputer 11 enters the mirror-up state (S107) and opens the shutter 101 (S108). Then, TV-AF is started from the filter phase difference in-focus position in S106 (S109). During this TV-AF, the amount of movement of the focus lens from the filter phase difference in-focus position is counted (S110). In this embodiment, since the focus lens is driven by an actuator that operates by applying a pulse signal, such as a stepping motor or a vibration type motor, the amount of movement can be obtained by counting the number of pulses of the pulse signal applied to the actuator. .

  When the focus lens is moved to the in-focus position (hereinafter referred to as the TV-AF in-focus position) by TV-AF and TV-AF is completed (S111), the camera microcomputer 11 performs the following processing. That is, the difference between the filter phase difference in-focus position and the TV-AF in-focus position, that is, the focus lens movement amount (number of pulses) counted in S110 is used as calibration data in association with the lens ID acquired in S102. 19 (S112). This calibration data corresponds to the first correction information. Further, the camera microcomputer 11 retracts the optical filter 17 out of the focus detection optical path. Thus, the calibration sequence is completed.

  Next, a focus control sequence by phase difference AF using the calibration data will be described with reference to FIG. Here, the calibration mode described above is not selected, and the normal imaging mode is selected.

  First, the camera microcomputer 11 performs phase difference AF in a state where the optical filter 17 is retracted out of the focus detection optical path, and obtains pre-correction defocus information which is first defocus information (S201). When the phase difference AF is completed (S202), communication with the imaging lens 2 is performed to obtain a lens ID (S204). Here, in the phase difference AF, when the phase difference AF does not end within a predetermined time because the subject is a low contrast subject or the like, this sequence is ended as it is (S203).

  The camera microcomputer 11 communicates with the memory 19 (S205), and determines whether or not the lens ID acquired from the imaging lens 2 in S204 is in the lens ID stored in the memory 19 (S206). That is, it is determined whether or not the above-described calibration has already been performed on the imaging lens 2 attached to the camera body 1. If there is no corresponding lens ID in the memory 19, that is, if the imaging lens 2 has not yet been calibrated, the process proceeds directly to S208. In S208, the focus position (the driving amount and direction of the focus lens) is calculated based on the pre-correction defocus information, and the focus lens is moved to the focus position.

  On the other hand, if there is a corresponding lens ID in the memory 19 in S206, that is, if the imaging lens 2 has already been calibrated, the process proceeds to S207.

In S207, calibration data (first correction information) corresponding to the lens ID is read from the memory 19. Next, the read calibration data is added to the pre-correction defocus information obtained by the phase difference AF performed in S201. Further, the camera microcomputer 11 reads out the color focus shift information (second correction information) corresponding to the lens ID from the memory 19 and adds it to the pre-correction defocus information. In this embodiment, the optical filter 17 is color focus shift information in a wavelength range from about 520 nm to about 570 nm. Thus,
Defocus information after correction (second defocus information)
= Defocus information before correction + Calibration data (first correction information)
+ Color focus shift information (second correction information)
To calculate defocus information after correction.

  Next, in S208, an in-focus position is calculated based on the corrected defocus information, and the focus lens is moved to the in-focus position. Thus, the focus control sequence using the phase difference AF is completed.

  As described above, in the present embodiment, after obtaining information on a focus position (filter phase difference focus position) with less influence of the light source by phase difference AF using light in a narrow wavelength range, the filter phase difference focus is obtained. Focus control is performed using the difference (first correction information) between the focus position and the TV-AF focus position. For this reason, according to the present embodiment, highly accurate phase difference AF can be performed regardless of the type of light source.

  In this embodiment, the calibration data for the imaging lens actually mounted on the camera can be stored in the memory in advance in the calibration mode. When an imaging lens is attached, focus control is performed using calibration data corresponding to the imaging lens and color focus shift information (second correction information) stored in the imaging lens. . For this reason, highly accurate phase difference AF using the optimal correction information can be performed for each of the imaging lenses mounted on the camera.

  A single-lens reflex camera that is Embodiment 2 of the present invention will be described below. The basic configuration of the camera of the present embodiment is the same as the camera described in Embodiment 1 with reference to FIG. For this reason, in the present embodiment, the same reference numerals as those in the first embodiment are assigned to the components common to the first embodiment. However, the camera of the present embodiment does not have the optical filter 17 and the driving mechanism 18 described in the first embodiment.

  Instead, the AF image sensor 16 has a configuration as shown in FIG. A1 and B1, A2 and B2,... A8 and B8 are light receiving sensors (first light receiving sensors) that are paired with each other. These light receiving sensors are sensors for performing phase difference AF using the light from the imaging optical system 21 whose infrared component is cut by the IR cut filter 14.

  The AF image sensor 16 includes light receiving sensors (second light receiving sensors) A1 ′, B1 that are paired with each other in close proximity to and in parallel with the light receiving sensors A1, B1, A2, B2,. ', A2', B2 '... A8', B8 'are provided. These light receiving sensors A1 ', B1', A2 ', B2' ... A8 ', B8' are provided with an optical filter (not shown) having a transmittance characteristic indicated by a curve b in FIG. These light receiving sensors with filters A1 ′, B1 ′, A2 ′, B2 ′... A8 ′, B8 ′ perform phase difference AF using light components in a narrow wavelength range near 550 nm out of the light from the imaging optical system 21. It is a sensor for.

  FIG. 9 shows a flowchart of the calibration operation in the camera of this embodiment.

  In S301 and S302, the camera microcomputer 11 performs the same operation as S101 and S102 described in FIG.

  In S303, the camera microcomputer 11 selects the light receiving sensors A1 'to B8' with filters. Further, a light receiving sensor pair corresponding to the selected focus detection region is selected from the light receiving sensors A1 'to B8' with filters (S303). Then, phase difference AF is performed using the selected light receiving sensor with a filter (S304). Thereby, the obtained in-focus position corresponds to the filter phase difference in-focus position having a small difference regardless of the light source, as described in the first embodiment.

  When the phase difference AF is completed (S305), the camera microcomputer 11 sets the mirror up state (S306) and opens the shutter 101 (S307). In this state, TV-AF is started from the filter phase difference in-focus position (S308).

  During this TV-AF, the amount of movement of the focus lens from the filter phase difference in-focus position is counted (S310). Also in this embodiment, the number of pulses of the pulse signal applied to the actuator that drives the focus lens is counted.

  When the focus lens is thus moved to the TV-AF in-focus position by TV-AF and TV-AF is completed (S311), the camera microcomputer 11 performs the following processing. That is, the difference between the filter phase difference in-focus position and the TV-AF in-focus position, that is, the focus lens movement amount (number of pulses) counted in S310 is used as calibration data in association with the lens ID acquired in S302. 19 (S312). This calibration data corresponds to the first correction information. Thus, the calibration sequence is completed.

  Note that the focus control sequence based on phase difference AF using calibration data is the same as the sequence described with reference to FIG. 5 in the first embodiment.

  In the present embodiment, as in the first embodiment, highly accurate phase difference AF can be performed regardless of the type of light source. In addition, it is possible to perform highly accurate phase difference AF using optimal correction information for each imaging lens mounted on the camera.

1 is a schematic diagram illustrating a configuration of a camera that is Embodiment 1 of the present invention. FIG. 5 is a flowchart of a calibration operation in the camera of Embodiment 1. The figure which shows the amount of focus shift | offset | difference by the chromatic aberration of an imaging lens. The figure which shows the spectral characteristics of various light sources. 6 is a flowchart of an AF operation sequence in the cameras according to the first and second embodiments. The figure which shows the transmittance | permeability characteristic of IR cut filter of Example 1, 2 and an optical filter. FIG. 3 is a diagram illustrating an arrangement of light receiving sensors on an AF image sensor according to the first embodiment. FIG. 6 is a diagram illustrating an arrangement of light receiving sensors on an AF image sensor in a camera that is Embodiment 2 of the present invention. 10 is a flowchart of a calibration operation in the camera of Embodiment 2.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Camera body 2 Imaging lens 3 Auxiliary light unit 5 Main mirror 6 Sub mirror 11 Camera microcomputer 12 AF reflecting mirror 13 Field lens 14 IR cut filter 15 Glasses lens 16 AF image sensor 17 Optical filter 21 Imaging optical system 22 Lens microcomputer 101 Shutter 102 Image sensor 105 Photometric sensor

Claims (5)

An imaging device in which an imaging lens can be attached and detached,
An image sensor that photoelectrically converts a subject image formed by the imaging lens;
Focus detection means for generating defocus information in accordance with the shift amounts of a plurality of images formed by light from the imaging lens;
Based on the focus evaluation value information according to the first focus processing for obtaining the in-focus position of the imaging lens based on the defocus information and the contrast of the image obtained by using the imaging element, the imaging lens is adjusted. Control means for performing a second focus process for obtaining a focal position;
The focus detection means includes a member for limiting the wavelength range of light that can be received to a second wavelength range that is narrower than the first wavelength range so that it can be inserted into and removed from the optical path, and is not limited by the member. a first defocus information based on the shift amount of the plurality of images formed by the light of the first wavelength range, the moiety limited pre SL plurality of which are formed by the light of the second wavelength range by material Generating second defocus information based on the image shift amount;
It said control means includes first correction information corresponding to the difference between the focus position which has been determined by the second focusing process and the focus position determined based on the previous SL second defocus information, the image pickup lens Storing the second correction information relating to the defocus due to chromatic aberration corresponding to the second wavelength range acquired from the storage unit in association with the identification information for identifying the imaging lens,
When the first lens whose identification information is stored in the storage unit is attached, the control unit includes the first correction information and the second correction information corresponding to the identification information stored in the storage unit. An image pickup apparatus that performs focus control of the first image pickup lens based on correction information and the first defocus information . When a second lens whose identification information is not stored in the storage unit is attached, the control unit performs focus control of the second imaging lens based on the first defocus information. The imaging apparatus according to claim 1.   The imaging apparatus according to claim 1, wherein the second wavelength range overlaps a part of the first wavelength range. The focus detection unit includes an optical filter having a higher transmittance for light in the second wavelength range than the transmittance for light in other wavelength ranges as the member , and the optical filter is disposed outside the optical path, generating a first defocus information imaging apparatus according to any one of claims 1-3 which is inserted the optical filter into the optical path and generates the second defocus information . A control method for an image pickup apparatus in which an image pickup lens can be attached and detached,
A detection step of generating defocus information in accordance with a shift amount of a plurality of images formed by light from the imaging lens;
Focusing of the imaging lens based on first focus processing for obtaining a focusing position of the imaging lens based on the defocus information and focus evaluation value information corresponding to a contrast of an image obtained using the imaging element A control step for performing a second focus process for obtaining a position,
In the detection step, a member for limiting the wavelength range of light that can be received to the second wavelength range narrower than the first wavelength range is retracted from the optical path, thereby forming the light in the first wavelength range. said generating a first defocus information based on displacement amounts of the plurality of images, by inserting the member into the optical path, before Symbol deviation of the plurality of images formed by the light in the second wavelength range generating a second defocus information based on the amount,
Wherein in the control step, a pre-Symbol first correction information corresponding to the difference between the focus position which has been determined by the second focusing process and the focus position determined based on the second defocus information, the image pickup lens Storing the second correction information relating to the defocus due to chromatic aberration corresponding to the second wavelength range acquired from the storage unit in association with the identification information for identifying the imaging lens,
When the first lens whose identification information is stored in the storage means is attached, in the control step, the first correction information and the second correction information corresponding to the identification information stored in the storage means An imaging apparatus control method , comprising: performing focus control of the first imaging lens based on correction information and the first defocus information .