JP4834394B2 - Imaging apparatus and control method thereof - Google Patents

Description

The present invention relates to an imaging apparatus having a focus adjustment control function and a control method thereof .

  In an autofocus (AF) control system mounted on a single-lens reflex camera, a focus state of a photographing lens with respect to a subject is detected from a positional relationship between a pair of images formed on a pair of light receiving element arrays, and the detection result is determined according to the detection result. A phase difference detection method for adjusting the focus of the photographing lens is used.

  In such an AF control system, the aberration generated in the photographing lens differs depending on the type of light source that illuminates the subject (for example, a natural light source or an artificial light source), and as a result, a difference occurs in the image position on the light receiving element array. . Due to this difference, even if the subject is at the same distance, the focus detection results may vary, and just focus may not be obtained.

For such a problem, focus detection and focus are performed by measuring infrared light and visible light, determining the type of light source based on the relationship between these photometric values, and performing correction according to the determination result. Techniques for improving adjustment accuracy are disclosed (for example, see Patent Documents 1 and 2).
Japanese Patent Publication No. 1-45883 (page 3, lower left column, line 11 to page 4, lower left column, line 10, line 12, etc.) JP 2000-292682 (paragraphs 0055 to 0086, FIGS. 5 to 9 and the like)

  However, the conventional light source discriminating technique represented by Patent Documents 1 and 2 uses an infrared sensor for measuring infrared light separately from the light receiving sensor for measuring visible light. That is, a technique for discriminating a light source without using an infrared sensor has not been proposed.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an imaging apparatus in which the type of light source is specified without using an infrared sensor when performing focus adjustment control, and high-precision focus adjustment can be performed regardless of the type of light source. I am trying.

To achieve the above object, an imaging apparatus of the present invention includes a light receiving element, which is movable in a second position retracted from the first position and the optical path is a light path to the light receiving element, a mirror that transmits part of the incident light, a second detection operation for detecting a first detection operation for detecting the light transmitted through the mirror by the light receiving element, and light not passing through the mirror by the light receiving element a detection unit for performing, based on an output from the light receiving element in the first and second detection operation, and determining means for determining the light of the light source incident on the light receiving element, the determination result of said determining means and having a control unit for performing focusing control based.

According to the present invention, the light source can be specified by utilizing the difference in output from the light receiving element in the first and second detection operations. Therefore, appropriate focus adjustment control according to the type of light source can be performed without using an infrared sensor as in the prior art .

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

  1 to 7 show the configuration of a camera system as an imaging system that is Embodiment 1 of the present invention.

  First, FIG. 6 shows a schematic configuration of the camera system of the present embodiment. The camera system of this embodiment is a single-plate digital color camera using an image sensor such as a CCD sensor or a CMOS sensor. A moving image or a still image can be acquired by driving the image sensor continuously or once. The imaging element is a so-called area sensor, converts received light into an electrical signal for each pixel arranged in a two-dimensional direction, and accumulates electric charges according to the amount of received light.

  In FIG. 6, reference numeral 101 denotes a camera body as an image pickup apparatus, and members described below are arranged therein.

  Reference numeral 102 denotes an interchangeable lens as a lens device, and an imaging optical system 103 as a photographing optical system is disposed therein. The interchangeable lens 102 is detachable from the camera body 101, and is electrically and mechanically connected to the camera body 101 via a mount mechanism.

  A plurality of interchangeable lenses having different focal lengths can be attached to and detached from the camera body 101, and images with various angles of view can be acquired by exchanging the interchangeable lenses.

  The interchangeable lens 102 has a drive mechanism (not shown). This drive mechanism moves the focusing lens that forms part of the imaging optical system 103 in the direction of the optical axis L1 to perform focus adjustment. Note that the focusing lens can also be adjusted by changing the refractive power by changing the interface shape by configuring the focusing lens with a flexible transparent elastic member or a liquid lens.

  In the interchangeable lens 102, a diaphragm (not shown) that adjusts the amount of light of the photographing light flux by changing the opening area of the light passage opening and a drive mechanism (not shown) that drives the diaphragm are arranged. .

  Reference numeral 106 denotes an imaging device housed in the imaging package 124. An optical low-pass that limits the cutoff frequency of the imaging optical system 103 so that a spatial frequency component higher than necessary in the subject image is not transmitted on the imaging element 106 in the optical path from the imaging optical system 103 to the imaging element 106. A filter 156 is provided. The imaging optical system 103 is also provided with an infrared cut filter (not shown).

  A subject image captured by the image sensor 106 is displayed on a display unit (image display unit) 107. The display unit 107 is attached to the back surface of the camera body 101 so that the user can directly observe the image displayed on the display unit 107. Here, if the display unit 107 is composed of an organic EL spatial modulation element, a liquid crystal spatial modulation element, a spatial modulation element using fine particle electrophoresis, etc., the power consumption can be reduced and made thin.

  In this embodiment, a CMOS process compatible sensor (CMOS sensor), which is one of amplification type solid-state image sensors, is used as the image sensor 106 in particular. One of the features of the CMOS sensor is that the MOS transistor of the area sensor unit and peripheral circuits such as an image sensor driving circuit, an AD conversion circuit, and an image processing circuit can be formed in the same process. As a result, the number of masks and process steps can be greatly reduced as compared with the CCD sensor. In addition, it has a feature that random access to an arbitrary pixel is possible, and readout that is thinned for display is easy, and real-time display can be performed at a high display rate.

    The image sensor 106 performs an output operation of a display image and an output operation of a high-definition image by using the above feature.

  Reference numeral 111 denotes a half mirror as a first optical member. The half mirror 111 reflects a part of the light beam from the imaging optical system 103 and guides it to an optical finder described later, and transmits the other light beam. Thereby, the light beam from the imaging optical system 103 is divided.

  The half mirror 111 is a movable mirror that is positioned obliquely in the photographic optical path (on the optical axis L1) or withdraws from the photographic optical path.

  Reference numeral 105 denotes a focusing screen arranged on the planned image formation plane of the subject image. The pentaprism 112 reflects the light beam from the half mirror 111 a plurality of times, converts the inverted image into an erect image, and guides it to the eyepiece lens 109.

  The eyepiece lens 109 is a lens for observing a subject image formed on the focusing screen 105, and actually includes three lenses (109a, 109b, and 109c in FIG. 1) as will be described later. The focusing screen 105, the pentaprism 112, and the eyepiece lens 109 constitute an optical viewfinder.

  The half mirror 111 has a refractive index of approximately 1.5 and a thickness of 0.5 mm. A sub-mirror 122 as a movable second optical member is disposed behind the half mirror 111 (on the image sensor 106 side). Of the light flux that has passed through the half mirror 111, the light flux on or near the optical axis L <b> 1 is reflected toward the focus detection unit 121.

  The sub mirror 122 is rotatable around a rotation shaft 125 described later. The sub mirror 122 is housed in a lower portion of a mirror box (not shown) that holds the half mirror 111 and the sub mirror 122 in a second optical path state and a third optical path state described below.

  Reference numeral 104 denotes a pop-up illumination unit that irradiates a subject with illumination light. The pop-up illumination unit projects upward from the camera body 101 when used, and is stored in the camera body 101 when not used.

  Reference numeral 113 denotes a focal plane shutter (hereinafter referred to as a shutter), which has a front curtain and a rear curtain each composed of a plurality of light shielding blades. In the shutter 113, the photographing light flux is shielded by covering the aperture with the front curtain or the rear curtain except when acquiring an image. Further, at the time of image acquisition, the front curtain and the rear curtain travel while forming slits, thereby causing the photographing light flux to reach the image sensor 106.

  Reference numeral 119 denotes a main switch (power switch) for starting the camera. Reference numeral 120 denotes a release button that can be pressed in two stages. When the release button 120 is half-pressed, a shooting preparation operation (focus adjustment operation, photometry operation, etc.) of the camera is started, and when the release button 120 is fully pressed, the shooting operation is started.

  The focus detection unit 121 detects the focus state of the imaging optical system 103 by a phase difference detection method.

  Reference numeral 123 denotes a finder mode changeover switch. By operating the switch 123, an optical finder mode (OVF mode) and an electronic finder mode (EVF mode) described later can be selectively set. In the OVF mode, the subject image can be observed through the optical viewfinder. In the EVF mode, the subject image can be observed through the display unit 107.

  Reference numeral 180 denotes an information display unit in the optical viewfinder, which displays predetermined information (for example, information on photographing conditions such as shutter speed and aperture value) on the focusing screen 105. The photographer can observe predetermined information together with the subject image by looking into the eyepiece lens 109.

  In the configuration described above, the optical path switching unit including the half mirror 111 and the sub mirror 122 can take the first, second, third, and fourth optical path states.

  The first optical path state is a state in which the light beam from the imaging optical system 103 is guided to the optical finder and the focus detection unit 121. The second optical path state is a state in which the light beam from the imaging optical system 103 is guided to the image sensor 106 and the focus detection unit 121. The third optical path state is a state for causing the image sensor 106 to directly receive the light beam from the imaging optical system 103. Further, the fourth optical path state is a state in which the light beam from the imaging optical system 103 is guided to the focus detection unit 121.

  In the first optical path state, the half mirror 111 and the sub mirror 122 are disposed obliquely on the photographing optical path. A part of the light beam from the imaging optical system 103 is reflected by the half mirror 111 to be guided to the optical finder, and the light beam transmitted through the half mirror 111 is reflected by the sub mirror 122 and guided to the focus detection unit 121. As a result, in the first optical path state, the subject image can be observed through the eyepiece lens 109 and the focus detection unit 121 can perform focus detection. The finder mode corresponding to this optical path state is the OVF mode.

  In the second optical path state, the half mirror 111 is disposed obliquely on the photographing optical path. A part of the light beam from the imaging optical system 103 is reflected by the half mirror 111 and guided to the focus detection unit 121, and the light beam transmitted through the half mirror 111 is directed toward the image sensor 106. Note that the sub mirror 122 is in a state of being retracted from the photographing optical path. When the shutter 113 is opened in this second optical path state, a so-called through image generated based on the output of the image sensor 106 can be displayed on the display unit 107. The focus detection unit 121 can also perform focus detection. The viewfinder mode corresponding to this optical path state is the EVF mode. In this optical path state, it is also possible to perform imaging (continuous imaging or moving image imaging), which is a recording image acquisition operation.

  In the third optical path state, the half mirror 111 and the sub mirror 122 are retracted from the photographing optical path. In this optical path state, the light flux from the imaging optical system 103 reaches the image sensor 106 directly by opening the shutter 113. Thereby, imaging can be performed based on the output of the imaging element 106. This imaging in the optical path state can acquire a high-definition still image, and therefore is suitable for performing a large print by enlarging the still image.

  In the fourth optical path state, the sub mirror 122 is disposed obliquely on the photographing optical path. The light beam from the imaging optical system 103 is reflected by the sub mirror 122 and guided to the focus detection unit 121. In this optical path state, the focus detection unit 121 can perform focus detection. In this optical path state, the half mirror 111 is retracted from the photographing optical path.

  In order to switch the first to third optical path states described above at high speed, the large half mirror 111 is made of a transparent resin as compared with the sub mirror 122, and the weight is reduced. In addition, a polymer thin film having birefringence is attached to the back surface of the half mirror 111. For this reason, when the image is monitored by the display unit 107 in the second optical path state or when high-speed continuous shooting is performed, a stronger low-pass effect corresponding to not imaging using all the pixels of the image sensor 106. Is granted.

  Note that a fine pyramid-shaped periodic structure having a pitch smaller than the wavelength of visible light can be formed on the surface of the half mirror 111 with a resin so as to act as a so-called photonic crystal. Thereby, it is possible to reduce the surface reflection of light due to the difference in refractive index between air and resin, and to increase the light utilization efficiency. With this configuration, it is possible to prevent a ghost from occurring due to multiple reflection of light on the front and back surfaces of the half mirror 111 in the second optical path state.

  The mirror drive mechanism (see 145 in FIG. 7) composed of an electromagnetic motor and a gear train changes the positions of the half mirror 111 and the sub mirror 122 to change the optical path switching unit from the first optical path state to the fourth optical path state. Switch between.

  In imaging in the second optical path state, as will be described later, the half mirror 111 and the sub mirror 122 remain held at predetermined positions, and there is no need to operate the mirror drive mechanism. For this reason, it is possible to perform ultra-high-speed continuous shooting by increasing the speed of image processing on the signal from the image sensor 106. Further, the focus adjustment can be performed even when an image is displayed on the display unit 107.

  FIG. 7 shows an electrical configuration of the camera system of the present embodiment. This camera system has an imaging system, an image processing system, a recording / reproducing system, and a control system. First, a description will be given regarding capturing and recording of a subject image. In the figure, the same members as those described in FIG.

  The imaging system includes an imaging optical system 103 and an imaging element 106, and the image processing system includes an A / D converter 130, an RGB image processing circuit 131, and a YC processing circuit 132. The recording / reproducing system includes a recording processing circuit 133 and a reproducing processing circuit 134, and the control system includes a camera system control circuit (control circuit) 135, an operation detection circuit 136, and an image sensor driving circuit 137.

  Reference numeral 138 denotes a standardized connection terminal for connecting to an external computer or the like to transmit and receive data. The above electric circuit is driven by a small fuel cell (not shown).

The imaging system is an optical processing system that forms an image of a light beam from a subject on the imaging surface of the imaging element 106 via the imaging optical system 103. Imaging system, by adjusting aperture of the interchangeable lens 102 (light amount adjustment unit) of the travel of the front curtain and rear curtain of the shutter 113 exposes the image sensor 106 at an appropriate amount.

  The image sensor 106 has 3700 square pixels arranged in the long side direction and 2800 in the short side direction, and has a total of about 10 million pixels. Each pixel is provided with one of R (red), G (green), and B (blue) color filters, so that two G and four R and B pixels each form one set. It is a Bayer array pixel.

  In the Bayer array, the overall image performance is improved by arranging more G pixels that are easily felt when the photographer looks at the image than the R and B pixels. In general, in image processing using this type of image sensor 106, a luminance signal is generated mainly from G, and a color signal is generated from R, G, and B.

  The signal read from the image sensor 106 is supplied to the image processing system via the A / D converter 130. The A / D converter 130 is a signal conversion circuit that converts a signal from each pixel into, for example, a 10-bit digital signal according to the amplitude thereof, and outputs the signal. Subsequent image signal processing is executed by digital processing. The

  The image processing system is a signal processing system that generates an image signal of a desired format from R, G, and B digital signals. The R, G, and B color signals are converted into a luminance signal Y and a color difference signal (RY), It is converted into a YC signal represented by (BY).

  The RGB image processing circuit 131 is a signal processing circuit that processes a signal from 3700 × 2800 pixels received from the image sensor 106 via the A / D converter 130, and is a high-performance by white balance circuit, gamma correction circuit, and interpolation calculation. It has an interpolation operation circuit that performs resolution.

  The YC processing circuit 132 is a signal processing circuit that generates a luminance signal Y and color difference signals RY and BY. The processing circuit 132 includes a high-frequency luminance signal generation circuit that generates a high-frequency luminance signal YH, a low-frequency luminance signal generation circuit that generates a low-frequency luminance signal YL, and a color difference that generates color difference signals RY and BY. It consists of a signal generation circuit. The luminance signal Y is formed by combining the high frequency luminance signal YH and the low frequency luminance signal YL.

  The recording / reproducing system is a processing system that outputs an image signal to a recording medium (not shown) (such as a semiconductor memory or an optical disk) and outputs an image signal to the display unit 107. The recording processing circuit 133 performs image signal writing processing and reading processing on the recording medium. The reproduction processing circuit 134 reproduces the image signal read from the recording medium and outputs it to the display unit 107.

  The recording processing circuit 133 also includes a compression / decompression circuit that compresses YC signals representing still images and moving images in a predetermined compression format (for example, JPEG format) and decompresses the compressed data when the compressed data is read out. Have. The compression / decompression circuit includes a frame memory for signal processing. The YC signal from the image processing system is stored in this frame memory for each frame, and is read and compressed for each of a plurality of blocks. The compression encoding is performed, for example, by subjecting the image signal for each block to two-dimensional orthogonal transformation, normalization, and Huffman encoding.

  The reproduction processing circuit 134 is a circuit that performs matrix conversion on the luminance signal Y and the color difference signals RY and BY, for example, into RGB signals. The signal converted by the reproduction processing circuit 134 is output to the display unit 107, and a visible image is displayed (reproduced).

  The reproduction processing circuit 134 and the display unit 107 can be connected via a wireless communication line such as Bluetooth. If comprised in this way, the image imaged with the camera can be monitored from the distant place.

  On the other hand, the operation detection circuit 136 which is a part of the control system detects operations of the release button 120, the finder mode changeover switch 123, and the like. The camera system control circuit 135 controls driving of each member in the camera including the half mirror 111 and the sub mirror 122 according to the detection signal of the operation detection circuit 136, and generates and outputs a timing signal at the time of imaging. To do.

  The image sensor drive circuit 137 generates a drive signal for driving the image sensor 106 under the control of the camera system control circuit 135. The information display circuit 142 controls driving of the information display unit 180 in the optical viewfinder.

The control system controls driving of each circuit in the imaging system, the image processing system, and the recording / reproducing system in accordance with an external operation. For example, the control system detects that the release button 120 has been pressed, and controls the driving of the image sensor 106, the operation of the RGB image processing circuit 131, the compression processing of the recording processing circuit 133, and the like. The control system controls the state of each segment in the information displayed in the optical viewfinder by the information display circuit 142.

  Next, focus adjustment will be described. An AF control circuit 140 and a lens system control circuit 141 are connected to the camera system control circuit 135. These control circuits communicate with each other data necessary for each process with the camera system control circuit 135 as a center.

  The AF control circuit 140 is included in a focus detection light receiving element (hereinafter referred to as a focus detection sensor) 167 included in the focus detection unit 121 and provided corresponding to a focus detection area provided at a predetermined position on the photographing screen. In response to the output signal, a focus detection signal is generated. Then, the focus state (defocus amount) of the imaging optical system 103 is detected.

  When the defocus amount is detected, the AF control circuit 140 converts the defocus amount into a driving amount of a focusing lens that is a part of the imaging optical system 103. Then, this focusing lens drive amount information (focus adjustment information) is transmitted to the lens system control circuit 141 via the camera system control circuit 135.

  For the moving subject, the AF control circuit 140 takes into account the time lag from when the release button 120 is pressed until the actual imaging operation is started, and based on the prediction result of an appropriate lens stop position. Instructs the driving amount of the focusing lens. The camera system control circuit 135 causes the illumination unit 104 to emit light when it is determined that the subject brightness is low and sufficient focus detection accuracy cannot be obtained based on the result of metering the subject brightness by a photometry circuit (not shown). Illuminate the subject. At this time, the subject may be illuminated by a white LED (not shown) or a fluorescent tube provided in the camera body 101.

  When the lens system control circuit 141 receives the focusing lens drive amount information sent from the camera system control circuit 135, the lens system control circuit 141 moves the focusing lens to the optical axis via a drive mechanism (not shown) in the lens device 102 based on the drive amount information. Move in the direction of L1.

  When the AF control circuit 140 detects that the subject is in focus, this detection information is transmitted to the camera system control circuit 135. At this time, if the release button 120 is pressed, the imaging control is performed by the imaging system, the image processing system, and the recording / reproducing system as described above.

Aperture adjusts the light quantity of the light flux from the object toward the image side in response to a command from the lens system control circuit 141. The camera system control 135 and the lens system control circuit 141 are configured to be able to communicate with each other via the mount part electrical contact (communication unit) 102a on the interchangeable lens 102 side and the mount part electrical contact 101a on the camera body 101 side. Yes. Reference numeral 145 denotes a mirror driving mechanism for driving the half mirror 111 and the sub mirror 122 that constitute the optical path switching unit.

  1 to 5 show a more specific configuration of the camera system of the present embodiment. Note that only part of the interchangeable lens 102 is shown. In these drawings, operations of the half mirror 111 and the sub mirror 122 are mainly shown in time series. 1 to 5, the same members as those described in FIGS. 6 and 7 are denoted by the same reference numerals.

  In the figure, reference numeral 103 a denotes a lens located closest to the image plane among a plurality of lenses constituting the imaging optical system 103. Reference numeral 102b denotes a mount mechanism on the interchangeable lens 102 side, and 101b denotes a mount mechanism on the camera body 101 side.

  Reference numeral 164 denotes a condenser lens that serves as a light beam capturing window in the focus detection unit 121. Reference numeral 165 denotes a reflecting mirror, 166 denotes a re-imaging lens, and 167 denotes the above-described focus detection sensor (light receiving element).

  The light beam emitted from the imaging optical system 103 and reflected by the half mirror 111 (second optical path state) or the sub mirror 122 (first optical path state) enters the condenser lens 164. Thereafter, the light beam is deflected by the reflection mirror 165, and a secondary image of the subject is formed on the focus detection sensor 167 by the action of the re-imaging lens 166.

  The focus detection sensor 167 is provided with at least two pixel columns. Between the output signal waveforms of the two pixel columns, a relatively laterally shifted state is observed according to the imaging state of the subject image formed by the imaging optical system 103 on the focus detection region. The shift direction of the output signal waveform is reversed at the front and rear pins, and the principle of the phase difference detection method is to detect this phase difference (shift amount) including the shift direction using a method such as correlation calculation. is there.

  Reference numerals 109-1 to 109-3 denote lenses constituting the eyepiece 109 shown in FIG. Reference numeral 163 denotes an eyepiece shutter which is a light shielding member capable of moving back and forth with respect to the optical path of the optical viewfinder. The eyepiece shutter 163 is a member for avoiding an influence on imaging due to the light that has entered backward from the eyepiece lens 109 reaching the imaging element 106.

  The configuration of the mirror drive mechanism 145 will be described with reference to FIG. FIG. 3 shows a diagram when the camera is in the first optical path state described above.

  The half mirror 111 is held by a half mirror receiving plate (not shown). The half mirror receiving plate is provided with pins 173 and 174, and the half mirror 111 and the pins 173 and 174 are integrally movable through the half mirror receiving plate.

  Reference numeral 170 denotes a half mirror drive lever, and 171 denotes a half mirror support arm. The half mirror drive lever 170 is supported to be rotatable with respect to the rotation shaft 170a, and the half mirror support arm 171 is supported to be rotatable with respect to the rotation shaft 171a.

  The half mirror drive lever 170 is connected to a drive source via a power transmission mechanism (not shown), and can rotate around a rotation shaft 170a by receiving a drive force from the drive source. Further, the half mirror support arm 171 is connected to a structure having substantially the same shape on the opposite wall surface side of the mirror box via the connection portion 171b.

  A pin 173 provided on a half mirror receiving plate (not shown) is slidably engaged with a through hole 171c provided at the tip of the half mirror support arm 171. Thereby, the half mirror 111 can be rotated centering on the through-hole 171c via the half mirror receiving plate. Further, an urging force in the direction of arrow A is applied to an intermediate position between the pin 173 and the pin 174 in the half mirror receiving plate by a torsion spring (not shown).

  In the first optical path state shown in FIG. 3, the mirror stoppers 160 and 161 are in the state of entering the movement locus of the half mirror 111 outside the imaging optical path. In this state, the half mirror 111 is positioned in contact with the mirror stoppers 160 and 161 by receiving a biasing force in the direction of arrow A by the torsion spring. As a result, the half mirror 111 is placed obliquely on the photographing optical path.

  Here, the pin 173 does not contact the first cam surface 170b of the half mirror drive lever 170, and the pin 174 does not contact the second cam surface 170c of the half mirror drive lever 170.

  Further, the sub mirror 122 is located behind the half mirror 111 in a state where the rotation around the rotation shaft 125 is suppressed.

  In the above-described first optical path state, the light beam reflected by the half mirror 111 out of the light beam emitted from the imaging optical system 103 is guided to the optical viewfinder. Further, the light beam transmitted through the half mirror 111 is reflected by the sub-mirror 122 behind the half mirror 111 and guided to the focus detection unit 121.

  When the mirror stoppers 160 and 161 are retracted from the movement trajectory of the half mirror 111, the pin 173 comes into contact with the first cam surface 170b of the half mirror drive lever 170 by the biasing force in the direction of arrow A by a torsion spring (not shown). The pin 174 contacts the second cam surface 170c of the half mirror drive lever 170. This is the same when the half mirror drive lever 170 is rotated in the clockwise direction in FIG.

  Then, the pins 173 and 174 move along the first cam surface 170b and the second cam surface 170c, respectively, according to the rotation amount of the half mirror drive lever 170. Thereby, the attitude | position of the half mirror 111 changes.

  That is, the half mirror support arm 171 rotates in conjunction with the rotation of the half mirror drive lever 170. Then, the half mirror receiving plate connected to the half mirror drive lever 170 and the half mirror support arm 171 via the pins 173 and 174 rotates, and the half mirror 111 rotates together with the half mirror receiving plate.

  1 to 5 show the operations of the half mirror 111 and the sub mirror 122. FIG. FIG. 1 shows a second optical path state, and FIG. 2 shows a transition process from the first optical path state to the second optical path state. FIG. 4 shows a transition process from the first optical path state to the third optical path state, and FIG. 5 shows the third optical path state.

  When in the first optical path state (FIG. 3), the half mirror 111 and the sub mirror 122 guide the light beam emitted from the subject emitted from the imaging optical system 103 to the optical viewfinder and the focus detection unit 121 as described above. Act on.

  In the second optical path state (FIG. 1), the half mirror 111 acts to guide the light beam emitted from the imaging optical system 103 to the image sensor 106 and the focus detection unit 121. Further, when in the third optical path state (FIG. 5), the half mirror 111 and the sub mirror 122 are retracted from the photographing optical path.

  Next, a method and operation for detecting a light source in a shooting environment will be described with reference to FIGS. FIG. 8 shows typical spectral characteristics of light from a natural light source that is the sun and light from an artificial light source such as a fluorescent lamp.

  FIG. 9 shows the spectral reflectance and spectral transmittance of the half mirror 111. FIG. 10 shows the spectral sensitivity characteristics of the focus detection sensor 167.

  FIG. 11A schematically shows the second optical path state of the optical path switching unit. In this optical path state, the focus detection operation for obtaining the defocus amount by receiving the light reflected by the half mirror 111 by the focus detection sensor 167. It can be performed. At this time, the second sensor output detection operation for detecting the output value of the focus detection sensor 167 (the sum of spectral output distributions described later) can be performed.

  FIG. 11B schematically shows a first optical path state of the optical path switching unit, and in this optical path state, a focus detection operation using light transmitted through the half mirror 111 and reflected by the sub-mirror 122 can be performed. . At this time, the first sensor output detection operation for detecting the output value from the focus detection sensor 167 can be performed.

  In the EVF imaging mode (second detection mode) in which imaging is performed by switching the optical path switching unit from the EVF mode to the third optical path state, the focus detection operation and the first sensor output are performed in the second optical path state shown in FIG. 11A. A detection operation (second sensor output detection operation) is performed. Then, a second sensor output detection operation (first sensor output detection operation) is performed in the first optical path state shown in FIG. 11B. Thereafter, the state shifts to the third optical path state for imaging. In the first and second optical path states, whether the light reaching the focus detection sensor 167 is transmitted through the half mirror 111 is different from whether it is reflected by the half mirror 111 or the sub mirror 122.

  FIG. 12 shows the spectral output distribution of the focus detection sensor 167 during the first and second sensor output detection operations when the light source is a natural light source in the EVF imaging mode. FIG. 13 shows the spectral output distribution of the focus detection sensor 167 during the first and second sensor output detection operations when the light source is an artificial light source in the EVF imaging mode.

  Here, the spectral transmittance characteristics of the lenses constituting the interchangeable lens 102 (imaging optical system 103) and the spectral reflectance characteristics of the sub-mirror 122, which is a mirror having only a reflecting action, have a wide spectral range centering on visible light. It is almost constant. Further, the influence on the spectral output distribution of the focus detection sensor 167 is small. For this reason, the spectral output distribution of the focus detection sensor 167 shown in FIGS. 12 and 13 includes the spectral characteristics of the light source shown in FIGS. 8 to 10 and the spectral reflectance / transmission of the half mirror 111 on which the deposited film is formed. It can be considered that the rate characteristics and the sensitivity distribution of the focus detection sensor 167 are affected. The output value from the focus detection sensor 167 is the integral sum (area) of the spectral output distributions shown in FIGS.

  In FIG. 12, the output value (hereinafter referred to as sensor output) of the focus detection sensor 167 by the reflected light from the half mirror 111 (hereinafter referred to as half mirror reflected light) during the second sensor output detection operation under a natural light source. 100. At this time, the sensor output by light transmitted through the half mirror 111 (hereinafter referred to as half mirror transmitted light) during the first sensor output detection operation under a natural light source is 260.

  On the other hand, in FIG. 13, when the sensor output by the half mirror reflected light in the second sensor output detection operation under the artificial light source is 100, the half mirror in the first sensor output detection operation under the artificial light source. The sensor output by the transmitted light is 64.

  Therefore, in the EVF imaging mode, when the relative value of the sensor output during the first sensor output detection operation and the second sensor output detection operation changes from 100 to 260, the light source of the shooting environment is a natural light source. It can be determined that there is. When the relative value of the sensor output changes from 100 to 64, it can be determined that the light source of the shooting environment is an artificial light source. That is, the light source can be determined by calculating the change (change amount and change direction [increase / decrease]) between the sensor outputs obtained by the two sensor output detection operations.

  FIG. 14A schematically shows the first optical path state of the optical path switching unit, similarly to FIG. 11B, and in this optical path state, focus detection using light transmitted through the half mirror 111 and reflected by the sub mirror 122 is performed. The action can be performed. At this time, the first sensor output detection operation for detecting the output value from the focus detection sensor 167 can be performed.

  FIG. 14B schematically shows a fourth optical path state of the optical path switching unit. In this optical path state, an output value from the focus detection sensor 167 that receives light reflected by the sub mirror 122 without passing through the half mirror 111. The second sensor output detection operation for detecting the signal can be performed.

  In the OVF imaging mode (first detection mode) in which imaging is performed by switching the optical path switching unit from the OVF mode to the third optical path state, the focus detection operation and the first sensor output are performed in the first optical path state shown in FIG. 14A. A detection operation (first sensor output detection operation) is performed. Next, a second sensor output detection operation (second sensor output detection operation) is performed in the fourth optical path state shown in FIG. 14B. Thereafter, the state shifts to the third optical path state for imaging. The first and fourth optical path states differ in whether light reaching the focus detection sensor 167 passes through the half mirror 111.

  FIG. 15 shows the spectral output distribution of the focus detection sensor 167 during the first and second sensor output detection operations when the light source is a natural light source in the OVF imaging mode. FIG. 16 shows the spectral output distribution of the focus detection sensor 167 during the first and second sensor output detection operations when the light source is an artificial light source in the OVF imaging mode. The spectral output distributions shown in FIGS. 15 and 16 are obtained in the same manner as the spectral output distributions shown in FIGS. 12 and 13.

  In FIG. 15, the sensor output by the half mirror transmitted light in the first sensor output detection operation under a natural light source is 100. At this time, the sensor output by light that does not pass through the half mirror 111 (hereinafter referred to as half-mirror non-transmitted light) during the second sensor output detection operation under a natural light source is 140.

  On the other hand, in FIG. 16, assuming that the sensor output by the half mirror transmitted light in the second sensor output detection operation under the artificial light source is 100, the half mirror in the first sensor output detection operation under the artificial light source. The sensor output by non-transmitted light is 250.

  Therefore, in the OVF imaging mode, when the relative value of the sensor output during the first sensor output detection operation and the second sensor output detection operation changes from 100 to 140, the light source of the shooting environment is a natural light source. It can be determined that there is. When the relative value of the sensor output changes from 100 to 250, it can be determined that the light source of the shooting environment is an artificial light source. That is, the light source can be determined by calculating the change between the sensor outputs obtained by the two sensor output detection operations.

  If the light source in the shooting environment can be specified, the correction value of the focusing lens driving amount information corresponding to the light source can be generated.

  For example, when the light source is a natural light source, the correction value is set to 0. On the other hand, when the light source is an artificial light source, a correction value stored in a memory (not shown) is read in advance according to chromatic aberration generated in the imaging optical system 103 by light from the artificial light source. In this case, the correction value corresponding to the chromatic aberration generated for each of the various interchangeable lenses that can be attached to the camera body 101 is stored in the memory, and the correction value corresponding to the identification information of the attached interchangeable lens is read out. It may be. Further, the correction value may be calculated based on the sensor output, the amount of change, and the like.

  It should be noted that different correction values (non-zero correction values) depending on whether the light source is a natural light source or an artificial light source are stored in advance in a memory (not shown) or calculated based on the sensor output, the amount of change thereof, or the like. Or you may.

  Thereby, it is possible to eliminate variation in the calculation result of the focusing lens driving amount caused by the difference in chromatic aberration generated in the imaging optical system 103 depending on the type of light source, and to obtain high focusing accuracy regardless of the type of light source. be able to. In addition, the focusing lens can be adjusted to a focus position with respect to light of a desired wavelength regardless of the spectral characteristics of the incident light beam from the light source.

  Next, an imaging sequence in the camera system of the present embodiment will be described with reference to FIG. The sequence of FIG. 17 is mainly executed by the camera system control circuit 135 and the AF control circuit 140 in accordance with a computer program stored therein.

  In step S1, the process waits until the main switch 119 is operated (ON), and the operation proceeds to step S2. In step S <b> 2, current is supplied (activated) to various electric circuits in the camera body 101.

In step S3, to determine the finder mode has been set, the process proceeds to step S4 A if it is set to the OVF mode, the process proceeds to step S 4B when it is set to the EVF mode.

  In step S4A, the information display unit 180 in the optical viewfinder is driven to display predetermined information on the display unit provided in the optical viewfinder. In this OVF mode, a subject image can be observed through the eyepiece lens 109 together with the predetermined information.

  In step S4B, an image or predetermined information is displayed on the display unit 107. In the EVF mode, the subject image can be observed together with the predetermined information via the display unit 107.

  Here, when the operation detection circuit 136 detects that the finder mode changeover switch 123 has been operated, the finder mode is switched. For example, when the OVF mode is switched to the EVF mode, the subject image is displayed on the display unit 107 by driving the imaging system and the image processing system.

  In step S5, the process waits until it is detected that the release button 120 has been half-pressed based on the output of the operation detection circuit 136, that is, until SW1 is turned on, and SW1 is turned on. Proceed to

  In step S <b> 6, subject brightness is measured (photometry), and the focus detection unit 121 performs a focus detection operation. Here, in the EVF imaging mode, the focus detection operation is performed in the second optical path state illustrated in FIG. 11A, and in the OVF imaging mode, the focus detection operation is performed in the first optical path state illustrated in FIG. 14A. At this time, the first sensor output detection operation is also performed, and the sensor output is stored in a memory (not shown).

  The camera system control circuit 135 calculates an exposure value (shutter speed and aperture value) based on the photometric result. Further, the AF control circuit 140 detects a phase difference between signals corresponding to the two images from the focus detection sensor 167, and calculates a defocus amount from the phase difference. Further, a focusing lens drive amount is calculated based on the defocus amount.

Then, the focusing lens of the imaging optical system 103 is driven by focus adjustment control by the AF control circuit 140 and the lens system control circuit 141. The lens system control circuit 141 drives the iris based on the calculated aperture value, to adjust the amount of light. Thereafter, the focus detection operation may be performed again for in-focus confirmation. If it is determined that the in-focus state is not achieved, the calculation of the focusing lens drive amount and the driving of the focusing lens may be performed again.

  In step S7, based on the output of the operation detection circuit 136, it is determined whether or not the release button 120 is fully pressed, that is, whether or not the SW2 is in an ON state. If SW2 is in the ON state, the process proceeds to step S8. If SW2 is in the OFF state, the process returns to step S5.

  In step S8, the half mirror 111 and the sub mirror 122 are brought into a state in which a second sensor output detection operation can be performed via the mirror driving mechanism. In other words, the optical path switching unit is switched to the first optical path state shown in FIG. 11B in the EVF imaging mode, and to the fourth optical path state shown in FIG. 14B in the OVF imaging mode.

  In step S9, the second sensor output detection operation is performed, and the result is compared with the detection result in the first sensor output detection operation to determine the light source. When the identified light source is a light source that requires correction of the driving amount of the focusing lens (for example, an artificial light source), a correction value is generated (read from the memory or calculated).

  In step S10, the focusing lens is driven by an amount corresponding to the correction value.

  In step S11, the half mirror 111 and the sub mirror 122 are switched to the third optical path state (FIG. 5).

  In step S12, the shutter 113 is operated based on the previously calculated shutter speed to expose the image sensor 106.

  In step S13, a high-definition image is captured by the image processing system based on the signal read from the image sensor 106.

   Note that the above-described imaging sequence is a sequence in the case of performing imaging with priority on the focusing accuracy, but in this embodiment, the sequence for performing imaging with priority on shortening the release time lag can be selected by the focus adjustment mode selection switch 126. In this case, as indicated by a dotted line in the figure, in the above-described imaging sequence, a sequence from Step S8 to Step 11 skipping Steps S9 and S10 is executed. Further, when continuous shooting is performed, the latter sequence may be automatically selected.

   Note that the camera of this embodiment performs focus detection by the phase difference detection method in the focus detection unit 121 even when an image acquired using the image sensor 106 is monitored on the display unit 107 (EVF mode). Can do. Thereby, in the EVF mode, it is possible to perform a high-speed focus adjustment operation as compared with the case where focus detection is performed by the contrast detection method (TV-AF method).

  Next, the finder mode switching operation will be described. While the electric circuit in the camera is operating, the state of each operation switch is detected via the operation detection circuit 136. When it is detected that the finder mode changeover switch 123 has been operated, the finder mode (OVF mode and EVF mode) switching operation is started (step S3 in FIG. 17).

  FIG. 18 is a flowchart for explaining the finder mode switching operation. The sequence in FIG. 18 is executed mainly by the camera system control circuit 135 in accordance with a computer program stored therein.

  In step S100, the current finder mode is detected. When the finder mode changeover switch 123 is operated from the OVF mode to the EVF mode, the process proceeds to step S101. On the other hand, when the finder mode changeover switch 123 is switched from the EVF mode to the OVF mode, the process proceeds to step S111.

  First, switching from the OVF mode to the EVF mode will be described. In the OVF mode, the optical path switching unit including the half mirror 111 and the sub mirror 122 is in the first optical path state (FIG. 3). In the EVF mode, since the subject light is not guided to the optical viewfinder, the eyepiece shutter 163 is first closed by the eyepiece driving circuit 143 and the actuator 144 in step S101. That is, the eyepiece shutter 163 is caused to enter the finder optical path between the lens 109-2 and the lens 109-3 constituting the eyepiece lens 109.

  This is to prevent the photographer from misunderstanding that the subject image cannot be seen through the eyepiece lens 109 when the EVF mode is set. Another reason for this is to prevent the occurrence of a ghost due to the back incident light from the optical viewfinder entering the image sensor 106.

  In step S102, the information display unit 180 in the finder is driven to turn off the information display in the optical finder. This is because, since the eyepiece shutter 163 is already closed in step S101, the photographer cannot see this display even if information is displayed in the optical viewfinder. Thereby, power consumption can be reduced and consumption of the battery can be suppressed.

  In step S103, by operating the mirror driving mechanism 145, the sub mirror 122 is retracted to the lower part of the mirror box in preparation for shifting the half mirror 111 to the second optical path state (FIG. 1) (FIG. 1).

  In step S104, the mirror stoppers 160 and 161 are retracted from the movement locus of the half mirror 111.

  After the mirror stoppers 160 and 161 are retracted, in step S105, the mirror driving mechanism 145 rotates the half mirror driving lever 170 in the counterclockwise direction in FIG. As a result, the half mirror 111 enters the second optical path state (FIG. 1) through the state shown in FIG. 2 by receiving a biasing force in the direction of arrow A by a torsion spring (not shown).

  When the half mirror 111 is in the second optical path state, a part of the light beam from the imaging optical system 103 is reflected by the half mirror 111 and guided to the focus detection unit 121. Further, the remaining light flux passes through the half mirror 111 and travels toward the image sensor 106 side.

  In the second optical path state, the half mirror 111 is positioned in contact with the mirror stoppers 175 and 176 disposed outside the imaging optical path by receiving a biasing force in the direction of arrow A by the torsion spring. At this time, the pin 173 does not contact the first cam surface 170b of the half mirror drive lever 170, and the pin 174 does not contact the second cam surface 170c of the half mirror drive lever 170.

  The position of the reflecting surface of the half mirror 111 is substantially the same as the position where the reflecting surface of the sub mirror 122 is located in the first optical path state. Thereby, the deviation between the reflected light guided to the focus detection unit 121 by the sub mirror 122 in the first optical path state and the reflected light guided to the focus detection unit 121 by the half mirror 111 in the second optical path state is minimized. Therefore, the position of the focus detection area can be hardly changed.

  Here, the focus position of the subject image formed by the light transmitted through the half mirror 111 being imaged on the image sensor 106 is slightly shifted from the focus position when the subject light does not pass through the half mirror 111. . For this reason, in step S106, the focus correction mode is activated to correct the shift of the focus position.

  In the first optical path state, the camera system control circuit 135 sharply forms the subject image on the image sensor 106 when the half mirror 111 and the sub mirror 122 are retracted from the photographing optical path (third optical path state). The focusing lens driving amount is calculated as follows.

  On the other hand, when the focus correction mode is on in the second optical path state, the focusing lens is driven so that the subject image that is transmitted through the half mirror 111 and projected onto the image sensor 106 is sharply formed. Correct the amount. As a result, when the focus correction mode is set in the second optical path state, the focusing lens drive position in the second optical path state is in focus in the third optical path state by an amount corresponding to the correction of the focusing lens drive amount. Deviation from position.

  Accordingly, when the EVF mode is set, the release button 120 is fully pressed to start the imaging operation, and when the second optical path state is switched to the third optical path state, the shutter 113 is synchronized with this. Charge the front curtain drive mechanism. That is, the shutter 113 is closed. Further, the focusing lens is driven to the in-focus position in the third optical path state by the amount that the focus position of the subject image is corrected by the focus correction mode. Thereafter, the image sensor 106 is exposed by operating the shutter 113 at the calculated shutter speed.

  With this configuration, the focus state is accurately confirmed based on the image displayed on the display unit 107 in the second optical path state, and then an image in focus in the third optical path state is captured. be able to.

  In step S107, the front curtain of the shutter 113 is opened and the image sensor 116 is continuously exposed, and a through image for display on the display unit 107 can be acquired.

  In step S108, the display unit 107 is powered on.

  In step S109, display of the through image on the display unit 107 is started, and the process returns to step S100.

  Next, a case will be described in which the process proceeds to step S111 in order to switch from the EVF mode to the OVF mode by determining the finder mode in step S100.

  In the EVF mode in the initial state, the optical path splitting system composed of the half mirror 111 and the sub mirror 122 is in the second optical path state (FIG. 1), and through image display is performed on the display unit 107 as described above.

  In step S111, the power of the display unit 107 is turned off, and the through image acquisition by the image sensor 106 is stopped.

  In step S112, the rear curtain of the shutter 113 is moved to close the shutter 113, and the front curtain / rear curtain drive mechanism is charged in preparation for imaging.

  In step S <b> 113, the mirror stoppers 160 and 161 are retracted from the movement locus of the half mirror 111 in order to enable the movement of the half mirror 111.

  In step S114, the half mirror drive lever 170 is rotated in the clockwise direction in FIG. 1, and the half mirror 111 and the sub mirror 122 are in the state of FIG. 2, the state of FIG. 3, the state of FIG. 4, and the state of FIG. (Third optical path state).

  When the half mirror drive lever 170 is rotated in the clockwise direction, the pin 174 is pushed and moved into the second cam surface 170c, and the pin 173 is pushed and moved into the first cam surface 170b. As a result, the half mirror support arm 171 rotates clockwise about the rotation shaft 171a, and the half mirror 111 rotates clockwise about the pin 173.

  In step S115, the mirror stoppers 160 and 161 are inserted into the movement locus of the half mirror 111.

  Since the mirror stoppers 160 and 161 are inserted after the half mirror 111 is moved to the third optical path state, there is no collision with the half mirror 111 when the mirror stoppers 160 and 161 are inserted. For this reason, it is possible to increase the mechanical reliability when switching the position of the half mirror 111 (when switching between the OVF mode and the EVF mode).

  In this embodiment, the half mirror 111 is moved to the third optical path state. However, since the mirror stoppers 160 and 161 do not have to collide with the half mirror 111, the half mirror 111 corresponds to the third optical path state. You may move to the vicinity of the position to do.

  In step S116, the half mirror drive lever 170 is rotated counterclockwise in FIG. As a result, the half mirror 111 is moved from the third optical path state (FIG. 5) to the first optical path state (FIG. 3) through the state of FIG. At this time, the half mirror 111 is brought into contact with the mirror stoppers 160 and 161 by receiving a biasing force of a spring (not shown) provided in the mirror driving mechanism 145.

  In step S117, the eyepiece shutter 163 is opened.

  In step S118, based on the output from the operation detection circuit 136, it is determined whether or not the manual (M) focus mode is set. If the manual focus mode is selected, the process proceeds to step S107. If the manual focus mode is selected instead of the manual focus mode, the process proceeds to step 120.

  In the manual focus mode, it is not necessary to operate the focus detection unit 121, and the background blur can be grasped more accurately by using an electronic image (through image) than by an optical viewfinder. For this reason, the process proceeds to step S107 in which a through image display is performed on the display unit 107.

  In step S120, the sub mirror 122 is set at a predetermined position so as to guide subject light to the focus detection unit 121. That is, as shown in FIG. 5, the sub-mirror 122 housed in the lower part of the mirror box is moved behind the half mirror 111 by rotating about the rotation shaft 125 (FIG. 3).

  In step S121, the information display unit 180 in the optical viewfinder is driven to display predetermined information in the viewfinder. Then, the process returns to step S100.

  As described above, according to the camera of the present embodiment, it is possible to determine the light source of the shooting environment from only the output value from the focus detection sensor 167 without using an infrared sensor. Then, by performing correction of the focusing lens drive amount according to the specified light source, high-precision focus adjustment control can be performed regardless of the type of light source.

  In addition, in this embodiment, since the light source is determined using the focus detection sensor 167, the half mirror 111, and the sub mirror 122, which are existing components in the single-lens reflex camera, the cost can be reduced without requiring a new dedicated component. You can suppress the up.

  In addition, since the output of the same focus detection sensor 167 is detected in two sensor output detection operations, the correction amount can be determined without being affected by variations in sensor sensitivity. Further, since the output from the focus detection sensor 167 to which the light beam from the photographing optical system is guided is used, a sufficient amount of light can be secured and the accuracy of light source determination can be improved.

  In the above-described embodiment, the case where the process for determining the light source in the shooting environment is performed during the transition from the finder observation state to the imaging state. However, the sensor output detection is performed twice before and after the finder mode switching. An operation may be performed to determine the light source. Since the optical path state before and after the finder mode switching operation is the state shown in FIGS. 11A and 11B, the light source can be determined in the same manner as in the transition from the finder observation state to the imaging state in the EVF imaging mode.

  In addition, when the light source is determined before and after the finder mode switching operation in this way, the above-described sequence can be performed in which priority is given to shortening the release time lag. In this case, in step S6 of FIG. 17, the focusing lens driving amount including the correction value is calculated, and the process proceeds from step S8 to step S11.

  Further, the camera may be configured to have a dedicated mode for determining the light source. For example, a light source discrimination switch is provided, and a correction value is calculated through first and second sensor output detection operations according to the switch operation. Also in this case, in step S6 in FIG. 17, the focusing lens driving amount including the correction value is calculated, and the process proceeds from step S8 to step S11.

  Further, in the above embodiment, the change between the sensor output due to the light transmitted through the half mirror and reflected by the sub mirror and the sensor output due to the light reflected by one of the half mirror and the sub mirror without passing through the half mirror. Focus adjustment control is performed based on the above. However, as described above, the spectral reflectance characteristics of the submirror have little influence on the spectral output distribution of the focus detection sensor. For this reason, the present invention essentially has a configuration in which the sensor output by the light transmitted through the half mirror is compared with the sensor output by one of the light reflected by the half mirror and the light not passing through the half mirror. It can be said that there is.

  The “optical member” referred to in the present invention is not limited to the one having the mirror shape shown in the above embodiment, but a so-called beam splitter in which an optical film is formed on the surface of a transparent body having an entrance surface and an exit surface. It may be a member.

It is sectional drawing which shows the structure of the camera system (2nd optical path state) which is Example 1 of this invention. It is sectional drawing which shows the structure of the camera system of Example 1 (during the transition to the 1st optical path state from 2nd). It is sectional drawing which shows the structure of the camera system (1st optical path state) of Example 1. FIG. It is sectional drawing which shows the structure of the camera system of Example 1 (during the transition to the 1st to 3rd optical path state). It is sectional drawing which shows the structure of the camera system (3rd optical path state) of Example 1. FIG. 1 is a diagram illustrating a schematic configuration of a camera system according to Embodiment 1. FIG. FIG. 2 is a block diagram illustrating an electrical configuration of the camera system according to the first embodiment. It is a figure which shows the spectral characteristic of a light source. It is a figure which shows the spectral reflectance / transmittance characteristic of a half mirror. It is a figure which shows the spectral sensitivity distribution of a focus detection sensor. 6 is a schematic diagram illustrating an optical path state (second optical path state) during a first sensor output detection operation in the EVF imaging mode in the camera system of Embodiment 1. FIG. 6 is a schematic diagram illustrating an optical path state (first optical path state) during a second sensor output detection operation in the EVF imaging mode in the camera system of Embodiment 1. FIG. It is a figure which shows the sensor output of the 1st and the 2nd under a natural light source in EVF imaging mode. It is a figure which shows the sensor output of the 1st and 2nd under artificial light source in EVF imaging mode. 6 is a schematic diagram illustrating an optical path state (first optical path state) during a first sensor output detection operation in an OVF imaging mode in the camera system of Embodiment 1. FIG. 6 is a schematic diagram illustrating an optical path state (fourth optical path state) during a second sensor output detection operation in the OVF imaging mode in the camera system of Embodiment 1. FIG. It is a figure which shows the sensor output of the 1st and 2nd time under natural light source in OVF imaging mode. It is a figure which shows the sensor output of the 1st and 2nd under artificial light source in OVF imaging mode. 3 is a flowchart illustrating an imaging sequence in the camera system according to the first exemplary embodiment. 6 is a flowchart illustrating a finder mode switching operation sequence in the camera system according to the first exemplary embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 103 Imaging optical system 106 Image pick-up element 107 Display unit 109 Eyepiece 111 Half mirror 121 Focus detection unit 122 Submirror 167 Focus detection sensor (light receiving element)

Claims (8)

A light receiving element;
A mirror that is movable to a first position that is on the optical path to the light receiving element and a second position that is retracted from the optical path and that transmits a part of the incident light;
Detection means for performing a first detection operation for detecting light transmitted through the mirror by the light receiving element, and a second detection operation for detecting light not passing through the mirror by the light receiving element;
Discrimination means for discriminating a light source of light incident on the light receiving element based on outputs from the light receiving element in the first and second detection operations;
An image pickup apparatus comprising: control means for performing focus adjustment control based on a determination result of the determination means. The discriminating unit discriminates a light source of the incident light based on a change between an output from the light receiving element in the first detection operation and an output of the light receiving element in the second detection operation. The imaging apparatus according to claim 1 . The control unit performs focus adjustment based on at least one of the outputs from the light receiving elements in the first and second detection operations, and then corrects the focus adjustment result based on the determination result of the determination unit. the imaging apparatus according to claim 1 or 2, characterized in that the focusing control so. The detection means performs the second detection operation after performing the first detection operation,
The control means performs focus adjustment control so as to correct the focus adjustment result based on the determination result of the determination means after performing focus adjustment based on the output from the light receiving element in the first detection operation. The imaging device according to claim 3 , wherein the imaging device is performed. First instruction means for instructing start of a shooting preparation operation;
Second instruction means for instructing the start of the photographing operation,
The detection means performs the first detection operation after an instruction to start the photographing preparation operation is given by the first instruction means, and the second instruction means after the instruction to start the photographing operation is given by the second instruction means. The imaging apparatus according to claim 4 , wherein a detection operation is performed. The control means performs focus adjustment control so as to correct the focus adjustment result based on the determination result of the determination means between the time when the second detection operation is performed and the start of shooting. The imaging apparatus according to claim 5 , characterized in that: The light receiving element, an imaging apparatus according to any one of claims 1 to 6, characterized in that it constitutes a sensor for performing focus adjustment by the phase difference detection method. An imaging device comprising: a light receiving element; and a mirror that is movable to a first position on the optical path to the light receiving element and a second position retracted from the optical path and transmits a part of the incident light. Control method,
A detection step of performing a first detection operation for detecting light transmitted through the mirror by the light receiving element, and a second detection operation for detecting light not passing through the mirror by the light receiving element;
A determination step of determining a light source of light incident on the light receiving element based on outputs from the light receiving element in the first and second detection operations;
A control step of performing focus adjustment control based on a determination result of the determination step.