JP2009282551A - Imaging device and imaging system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that it is difficult to capture high-quality image with an optimum light quantity according to performances of various interchangeable lenses. <P>SOLUTION: The imaging device with an interchangeable photographic lens device configured to record an image captured by an imaging element 221 as electronic data comprises: a control means 409 which receives, from a photographic lens device installed thereto, MTF (modulation transfer function) characteristic data according to at least one of focal distance and F value of the lens device, and sets, based on the received MTF characteristic data and pixel pitch information of the imaging element, a use limit F value which causes small-aperture diffraction by the photographic lens device, the value being adjustable by a light quantity adjustment means provided in the photographic lens device. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

The present invention relates to an imaging apparatus such as a video camera, and more particularly to an imaging apparatus in which a photographic lens apparatus is replaceable.

  1. First, a zoom lens conventionally used in a video camera will be described.

  As a zoom lens for a video camera, for example, there is a zoom lens composed of four lens groups of a fixed convex, a movable concave, a fixed convex, and a movable convex in order from the subject side.

  8A and 8B show a lens barrel structure of a zoom lens having a general four-group lens configuration. In addition, (B) has shown the AA sectional view in (A).

  The four lens groups 201a to 201d constituting this zoom lens are as follows. Reference numeral 201a denotes a fixed front lens, and 201b denotes a variator lens group that performs a zooming operation by moving along the optical axis. Reference numeral 201c denotes a fixed afocal lens 201c, and reference numeral 201d denotes a focusing lens group that moves along the optical axis to maintain a focal plane at the time of zooming and perform focusing.

  Guide bars 203, 204a, and 204b are arranged in parallel with the optical axis 205, and guide and prevent rotation of the moving lens group. The DC motor 206 serves as a drive source for moving the variator lens group 201b.

  The front lens 201 a is held by the front lens barrel 202, and the variator lens group 201 b is held by the V moving ring 211. The afocal lens 201c is held by the intermediate frame 215, and the focusing lens group 201d is held by the RR moving ring 214.

  The front lens barrel 202 is positioned and fixed to the rear lens barrel 216. The guide bar 203 is positioned and supported by both the lens barrels 202 and 216, and the guide screw shaft 208 is rotatably supported. The guide screw shaft 208 is driven to rotate by transmitting the rotation of the output shaft 206 a of the DC motor 206 through the gear train 207.

  The V moving ring 211 that holds the variator lens group 201b includes a pressing spring 209 and a ball 210 that engages with a screw groove 208a formed in the guide screw shaft 208 by the force of the pressing spring 209. Then, when the guide screw shaft 208 is rotationally driven by the DC motor 206, the guide bar 203 moves forward and backward in the optical axis direction while being guided and restricted by the guide bar 203.

  Guide bars 204 a and 204 b are fitted and supported on the rear barrel 216 and the intermediate frame 215 positioned on the rear barrel 216. The RR movable ring 214 can advance and retreat in the optical axis direction while being guided and restricted by the guide bars 204a and 204b.

  An aperture unit 235 (aperture drive source 224) is fixed to the intermediate frame 215.

  The RR moving ring 214 that holds the focusing lens group 201d is formed with a sleeve portion that is slidably fitted to the guide bars 204a and 204b, and the rack 213 is integrated with the RR moving ring 214 in the optical axis direction. It is assembled to become.

  The stepping motor 212 rotationally drives a lead screw 212a formed integrally with its output shaft. A rack 213 assembled to the RR moving ring 214 is engaged with the lead screw 212a. When the lead screw 212a rotates, the RR moving ring 214 moves in the optical axis direction while being guided by the guide bars 204a and 204b. To do.

  Note that a stepping motor may be used as a driving source for the variator lens group, similarly to the driving source for the focusing lens group.

  The front lens barrel 202, the intermediate frame 215, and the rear lens barrel 216 form a lens barrel main body that accommodates a lens or the like in a substantially sealed manner.

  Further, when moving the lens group holding frame using such a stepping motor, after detecting that the holding frame is positioned at one reference position in the optical axis direction using a photo interrupter or the like, the stepping motor The number of applied driving pulses is continuously counted. Thereby, the absolute position of the holding frame is detected.

  2. Next, the electrical configuration of the conventional imaging apparatus will be described with reference to FIG. In this figure, the same reference numerals as those in FIG. 8 are used for the components of the lens barrel described in FIG.

  Reference numeral 221 denotes a solid-state image sensor such as a CCD, and 222 denotes a drive source for the variator lens group 201b, which includes a motor 206 (or a stepping motor), a gear train 207, a guide screw shaft 208, and the like.

  A driving source 223 for the focusing lens group 201d includes a stepping motor 212, a lead screw shaft 212a, a rack 213, and the like.

  Reference numeral 224 denotes a drive source for a diaphragm unit 235 disposed between the variator lens group 201b and the afocal lens 201c.

  225 is a zoom encoder and 227 is a focus encoder. Each of these encoders detects the absolute position of the variator lens group 201b and the focusing lens group 201d in the optical axis direction. As shown in FIG. 8, when a DC motor is used as a variator drive source, an absolute position encoder such as a volume or a magnetic type is used.

  When a stepping motor is used as a drive source, it is common to use a method in which the holding frame is arranged at the reference position as described above and then the number of operation pulses input to the stepping motor is continuously counted. is there.

  Reference numeral 226 denotes a diaphragm encoder, which employs a system in which a Hall element is disposed inside a diaphragm drive source 224 such as a motor and detects the rotational positional relationship between the rotor and the stator.

  A CPU 232 controls the camera. Reference numeral 228 denotes a camera signal processing circuit which performs predetermined amplification, gamma correction, and the like on the output of the solid-state image sensor 221. The contrast signal of the video signal subjected to these predetermined processes passes through the AE gate 229 and the AF gate 230. That is, an optimum signal extraction range for exposure determination and focusing is set in this gate in the entire screen. The size of the gate may be variable or a plurality of gates may be provided.

  Reference numeral 231 denotes an AF signal processing circuit that processes an AF signal for AF (autofocus), and generates one or a plurality of outputs related to high-frequency components of the video signal. Reference numeral 233 denotes a zoom switch, and reference numeral 234 denotes a zoom tracking memory. The zoom tracking memory 234 stores information on the focusing lens position to be set according to the subject distance and the variator lens position at the time of zooming. Note that the memory in the CPU 232 may be used as the zoom tracking memory.

  For example, it is assumed that the zoom switch 233 is operated by the photographer. In this case, the CPU 232 drives and controls the zoom drive source 222 and the focussing drive source 223 so that a predetermined positional relationship between the variator lens and the focusing lens calculated based on information in the zoom tracking memory 234 is maintained. In this drive control, the absolute position of the current variator lens in the optical axis direction as a detection result of the zoom encoder 225, the calculated position of the variator lens to be set, and the current focus lens as a detection result of the focus encoder 227 are displayed. The absolute position in the optical axis direction and the calculated position where the focus lens should be set are made to coincide with each other.

  In the autofocus operation, the CPU 232 controls the focusing drive source 223 so that the output of the AF signal processing circuit 231 has a peak.

  Further, in order to obtain an appropriate exposure, the CPU 232 controls the driving of the aperture driving source 224 so that the average value of the output of the Y signal that has passed through the AE gate 229 is a predetermined value, and the output of the aperture encoder 226 becomes this predetermined value. Then, the opening diameter is controlled.

  3. Next, the TV signal AF will be described. Here, the above-described autofocus operation will be described in more detail. This method is advantageous in terms of cost because the number of components is reduced as compared with the case where other AF sensors are provided because the image pickup device itself of the image pickup apparatus is also used as a sensor for performing autofocusing. In addition, since the state of the image on the imaging plane is directly detected, even when the lens part expands or contracts due to a temperature change and the focus position changes, the correct focus position is detected according to the change. Is possible.

  FIG. 10 shows the principle. In the graph of FIG. 10, the horizontal axis represents the lens group position for focus adjustment, and the vertical axis represents the high-frequency component (focus voltage) of the imaging signal. In the drawing, the peak of the focus voltage is shown at a position A indicated by an arrow, and this position A is a lens position in focus.

  Here, an example of how to obtain the focal voltage F is given. FIG. 11A shows an actual imaging field of view, where 720 is an angle of view, 718 is a range in which a video signal for performing automatic focus adjustment is extracted, and 719 is a subject image.

  In FIG. 11B, (a) shows the state of the subject image within the range from which the video signal is extracted. Further, (b) is a video signal (Y signal) of the subject image shown in (a).

  When this signal is differentiated, it becomes a waveform as shown in (c), and further converted into an absolute value (d).

  A signal (e) obtained by sampling and holding this becomes a focus voltage. This uses the fact that the high-frequency component of the contrast signal of the subject image is maximized in a focused state, and various methods other than the above can be used as a method of creating the focus voltage. It has been known.

  In many cases, a high-pass filter for extracting only high-frequency components is used. However, this filter has several types of characteristics, and a focus voltage is created for a plurality of frequencies, and correct based on the plurality of information. It is also known to guarantee focus.

  FIG. 12 shows a configuration of a camera in which such an automatic focus adjustment device and an inner focus lens are combined.

  An imaging element such as a CCD is disposed at the image forming position 805. Then, a luminance signal Y is generated through this image sensor, and information in the predetermined frame 718 is taken into a focus detection circuit (AF circuit) 821.

  The AF circuit 821 obtains the focus voltage by the above-described method or the like, and based on this value, the driving direction of the focusing lens 804B, the sign of the change in the focus voltage accompanying the driving, etc. In the case of a focus, it is determined whether the blur is a so-called front pin or rear pin. Based on the determination result, the focus lens driving motor 822 is driven in a predetermined direction.

  In the method called the TV signal autofocus as described here, the imager of the imaging apparatus also serves as the autofocus sensor in this way, so that the imaging state of the imaging surface can be measured directly, and high You can grasp the focus on accuracy.

  4). Next, a zoom tracking method will be described. 2. As described above. However, as mentioned briefly, when focusing is performed with a lens group behind such a variator, the locus that the focusing lens during zooming follows depends on the subject distance.

  For this reason, the absolute positions in the optical axis direction of both the variator lens and the focusing lens at the start of zooming are measured, and from this information, the positional relationship between the two lenses when zooming is clarified, An operation is performed to protect the position. This makes it possible to maintain focus during zooming. This operation is referred to herein as zoom tracking.

Patent Document 1 (Japanese Patent Laid-Open No. 1-321416) discloses a method for calculating the following focusing lens position. First, the focusing lens positions for a plurality of variator lens positions between the wide end and the tele end are stored for a plurality of subject distances. Next, at the start of zooming, it is known where the variator lens position and the focusing lens position at that time are in the map information stored in the storage means in the microcomputer. Then, interpolation is performed from the data of that point, the data stored closest to the front pin side at the same focal length, and the data stored closest to the rear pin side, and at each focal length (variator position) FIG. 13 shows an explanatory diagram of a tracking curve (trajectory) near the telephoto end. In this figure, the horizontal axis is the variator lens position, and Vn is the tele end position. The vertical axis represents the focusing lens position.

  For example, P1, P4, P7, and P10 are stored for an infinite distance and P2, P5, P8, and P11 are stored for 10 m. At this time, when zooming in the wide direction from the state at the P point (a state where the object distance is 10 m and infinity at the tele end), the positional relationship between the variator lens and the focusing lens changes from P to PA, PB, PC. Are controlled in order.

  The positions of PA to PC are positions where the interpolation ratio between the upper and lower stored loci LL1 and LL2 is constant.

  5). Next, an interchangeable lens system will be described. 2. Description of the Related Art Conventionally, an imaging device that can exchange a photographic lens has been widely used.

  FIG. 14 shows an example of an imaging system using interchangeable lenses. As described above, the interchangeable lens 900 uses a zoom lens having a four-group configuration in the order of convex / concave / convex / convex from the subject side. However, lenses having other configurations may be used.

  Reference numeral 911 denotes a fixed front lens, 912 denotes a variator lens that performs a zooming operation by moving in the optical axis direction, 936 denotes a diaphragm, 913 denotes a fixed afocal lens, and 914 denotes a focusing lens. The focusing lens 914 has both a focusing operation when the subject distance changes and a function as a compensator during zooming.

  Reference numerals 945, 952, and 937 denote driving sources for the variator, the aperture, and the focusing lens, respectively, and are driven and controlled by the lens microcomputer 910 via the driving circuits 961, 951, and 962, respectively.

  Three image sensors 1003 to 1005 such as CCDs are provided on the camera 1000 side, and signals output from the respective image sensors are amplified by amplifiers 1005 to 1007. These signals are input to the signal processing circuit 1152, where a video signal of a predetermined level is generated. The generated video signal is transmitted to the main body microcomputer 1009.

  The two microcomputers 910 and 1009 are connected by a communication path connected via the contacts 318 and 307. As a result, various signals are exchanged.

  For example, if the focus voltage for the above-described television signal autofocus is generated in the signal processing circuit 1152 on the camera 1000 side, the information is transmitted from the main body microcomputer 1009 to the lens microcomputer 910.

  Based on this signal information, the lens microcomputer 910 determines whether it is in-focus or out-of-focus (direction of blur and its degree), determines which speed the focusing lens is driven at, and a driving circuit 962. The focusing drive source 937 is driven via

  6). Next, the image sensor will be described. CCD image sensors, which are called 1/3 inch type and 1/4 inch type in consumer video cameras, have diagonal dimensions of about 6 mm and 4 mm. For example, 310,000 pixels are included in this size.

  In the digital still camera, a CCD having a ½ inch type (diagonal dimension of 8 mm) and having 2 million pixels is also used.

  In such a digital camera using a CCD having a large number of pixels, an image quality comparable to that of a photograph taken with a conventional film camera can be secured with a general small print size if conditions are met. .

  In such a video camera, the permissible circle of confusion is about 12 to 15 μm, and the digital still camera is about 7 to 8 μm, which is much smaller than the permissible circle of confusion 33 to 35 μm of the conventional 135 film format. .

  This is because the screen diagonal dimension is much smaller than 43 mm of the 135 film format as described above. This number is expected to become a smaller number when the pixel size of the CCD is further reduced.

  Considering from another viewpoint, in an imaging apparatus using a CCD, the focal length for obtaining the same angle of view becomes shorter as the image size is smaller than that of a 135 film camera.

  For example, the angle of view obtained with a standard focal length of 40 mm with a 135 film camera is 4 mm with an imaging device using a 1/4 inch CCD. For this reason, the depth of field when photographing with the same F value is extremely deep in an imaging device using these CCDs as compared with a film camera.

  On the other hand, as is well known, the depth of focus is obtained by the allowable circle of confusion x F value (aperture value). Therefore, for example, in the case of F2, the focal depth (one side) of the 135 film camera is 0.035 × 2 = 0.07 mm, whereas in the 1 / 2-inch imaging device, 0.007 × 2 = 0. It becomes as narrow as 014 mm.

  As described above, even with a CCD having the same diagonal dimension, for example, a 1/3 inch type CCD of 6 mm, the resolution is improved by increasing the number of pixels from 1 million to 2 million, and in the future, 3 million. It is for the purpose. For this reason, various types of specifications are known, such as those that emphasize the dynamic range and sensitivity without unnecessarily reducing the size of the pixels.

  7. Next, the light quantity adjustment method will be described. In an imaging device using an image sensor such as a CCD as an image sensor, such as a video camera or a digital still camera, the aperture is controlled automatically by a diaphragm so that the level of the luminance signal of the CCD is within a predetermined range. In general, a method for obtaining optimal exposure is generally used.

  Known diaphragm devices include those using two diaphragm blades having a diamond-shaped opening, and iris diaphragms using five or six blades.

  By the way, when the aperture diameter becomes small, there arises a problem that the image quality deteriorates due to diffraction. For this reason, in these image pickup apparatuses, it is a general practice to limit the aperture opening diameter control range to a range in which image quality deterioration does not occur or does not cause a significant problem.

  This is because the microcomputer grasps the current aperture value and does not use the aperture on the side smaller than the predetermined F value.

  However, if such a restriction is applied to the usable aperture range, it becomes difficult to optimally adjust the light amount with only the aperture for a wide range of brightness of the actual field.

  For this reason, an ND filter is integrally attached to the aperture blades, and the aperture opening is covered by the ND filter when the aperture diameter is reduced, so that the brightness can be adjusted with the same aperture control (for example, open to F8). The range is being expanded. In some cases, a method of making the charge accumulation time (shutter speed) of the CCD variable is combined.

  The ND filter has a dedicated drive source in addition to the one that is integrally attached to the diaphragm blades and driven as described above, and the amount of insertion into the optical path is controlled separately from the diaphragm. Some are.

  8). Next, the photographing lens will be described. The photographic lens is designed and manufactured so as to obtain the necessary resolution performance (MTF performance) determined by the pixel pitch of the CCD used.

  The photographing lens has an effective image circle determined by the size of the CCD.

  The imaging apparatus configured as described above is designed so that many functions are optimized based on the CCD specifications.

  First, with respect to AF, the focal point is determined with the peak of the high frequency component of the video signal obtained from the CCD. Therefore, the amount of movement in one step when the focus lens is driven by the stepping motor is set based on the permissible circle of confusion determined by the pixel pitch of the CCD and the open F value of the aperture.

  Further, when the best focus direction is searched for by so-called wobbling (small reciprocating drive in the optical axis direction) of the lens, the wobbling amount corresponding to the F value is also determined by the permissible circle of confusion (and thus the CCD specification). Furthermore, the level for determining whether the focus is in focus or not is also determined in relation to the CCD.

  For AE, the F value at which image degradation occurs due to small aperture diffraction is determined by the pixel pitch of the CCD. The exposure is controlled so as not to use the smaller aperture side than the F value.

  The effective image circle is designed so as not to be distorted according to the size of the CCD when designing and manufacturing the lens. As for the resolution performance, the design value is determined from the pixel pitch specification of the CCD at the time of designing and manufacturing the lens.

In this way, even in an imaging device with interchangeable lenses, it is designed so that good imaging performance can be obtained for all interchangeable lenses, depending on the specifications of the CCD used by the imaging device. The
JP-A-1-321416

  However, a CCD is a film itself in terms of a film camera. Therefore, depending on the purpose of shooting, characteristics (for example, the number of pixels, sensitivity, dynamic range) differ depending on the specifications even with the same image size, such as whether high image quality is required even with low sensitivity as described above, or whether high sensitivity is required. come.

  In addition, with the improvement of semiconductor manufacturing technology, the size of a pixel has been reduced year by year as the CCD has been improved.

  Under such circumstances, even if an interchangeable lens imaging system that assumes a single CCD is determined, the entire system will soon become obsolete with the evolution of the CCD, or a new lens will be added each time the latest CCD is used. May need to be redesigned.

  Also, if a lens that always satisfies the maximum performance of the CCD is prepared, it is necessary to obtain a sufficient MTF even when assuming the CCD with the highest pixel size. Therefore, a user who does not require the image quality up to that point uses an over-performance lens (in many cases, the lens becomes larger when the MTF is increased).

  In view of the above, an object of the present invention is to enable a proper image to be efficiently recorded on the imaging device side in accordance with various performances of the photographing lens device.

  As a result, even when the lens does not have sufficient performance to satisfy the maximum performance of the CCD, an image obtained according to the lens can be recorded. Therefore, the usable range of the combination of the lens and the camera is expanded, and as long as the mounting conditions (mechanism and flange back value) are met, it is possible to efficiently capture an image without failure.

  In order to achieve the above object, according to the first aspect of the present invention, the photographic lens device can be exchanged, and is an imaging device that captures an image with an imaging element. MTF (Modulation Transfer Function: so-called resolution performance or contrast reproducibility) characteristic data corresponding to at least one of the focal length and F value is received, and based on the received MTF characteristic data and pixel pitch information of the image sensor, Control means for setting a use limit F value at which small aperture diffraction occurs is provided by the photographing lens apparatus that can be adjusted by a light amount adjusting means provided in the photographing lens apparatus.

  As a result, the amount of light is adjusted by the light amount adjusting means in the photographing lens device in accordance with the resolution performance of the mounted photographing lens device, for example, within a range where small aperture diffraction does not occur, and a high-quality image is recorded. Is possible.

  Specifically, for example, if the control unit is configured to set the maximum F value that can be adjusted by the light amount adjusting unit based on the information related to the received MTF, the information is transmitted to the photographing lens device. Good.

1 is a block diagram illustrating a configuration of an imaging system that is a first embodiment of the present invention. FIG. It is an operation | movement flowchart of the camera main body which comprises the imaging system of the said 1st Embodiment. It is a flowchart which shows operation | movement of the imaging | photography system which is 2nd Embodiment of this invention. It is a block diagram which shows the structure of the imaging system which is 3rd Embodiment of this invention. It is a graph which shows the relationship between the correctable angle and focal distance in the said 3rd Embodiment. It is a flowchart which shows operation | movement of the imaging | photography system which is 3rd Embodiment of this invention. It is a flowchart which shows operation | movement of the imaging | photography system which is 3rd Embodiment of this invention. It is sectional drawing of the imaging lens used for the conventional video camera. It is a block diagram which shows the structure of the conventional imaging system. It is a figure for demonstrating the principle of the automatic focus adjustment using the conventional television signal. It is a figure for demonstrating the principle of the automatic focus adjustment using the conventional television signal. It is a figure for demonstrating the principle of the automatic focus adjustment using the conventional television signal. It is a figure for demonstrating an example of the map data of the conventional zoom tracking. It is a block diagram which shows the structure of the conventional interchangeable lens type imaging system.

  FIG. 1 shows a main part configuration of an imaging system according to the first embodiment of the present invention. This imaging system includes a camera body (imaging device) and a photographing lens that can be exchanged for the camera body.

  First, the configuration on the photographing lens side will be described. In FIG. 1, reference numerals 111 to 114 denote four lens groups constituting the photographing lens. The photographic lens of this embodiment is a zoom lens having four convex and concave lens groups in order from the subject side. However, the photographing lens device of the present invention is not limited to the photographing lens having this lens group configuration.

  Reference numeral 111 denotes a fixed front lens group, and 112 denotes a variator lens group that changes its focal length (zooms) by changing its position in the optical axis direction. Reference numeral 113 denotes a fixed afocal lens group, and reference numeral 114 denotes a focus compensator having a function of a compensator and a function of a focusing lens that keeps the subject distance in focus constant during zooming.

  Reference numeral 136 denotes an aperture unit (light amount adjusting means) inserted in the optical path of the photographing lens, and adjusts the amount of light passing by operating the IG meter 413 as a drive source to change the aperture area (aperture diameter). Is.

  Reference numeral 145 denotes a zoom motor for driving the variator lens group 112. In this embodiment, a stepping motor is used. The zoom motor 145 rotates by a predetermined angle according to a predetermined step pulse applied by the zoom drive circuit 161.

  As for the mechanism for converting the rotation of the zoom motor 145 into the movement of the variator lens group 112, the configuration described in FIG.

  Further, by continuously counting the number of steps input to the motor for driving the zoom motor 145, the absolute position of the lens group 112 in the optical axis direction can be encoded. For this purpose, it is necessary to always arrange the lens group 112 at a predetermined position at the start of counting. In this embodiment, a zoom reset switch for detecting that the lens group 112 is positioned at a predetermined initial position. 501 is provided.

  That is, a variator encoder is configured by counting pulses input to the zoom motor 145 continuously from an initial position where the zoom reset switch 501 is turned on by a zoom counter 503 provided in the lens microcomputer 410. .

  In addition, the focus lens group 114 is driven by a focus motor 137 including a stepping motor in this embodiment. The focus driving circuit 162, the focus reset switch 502, and the focus counter 507 are the same as those provided for the variator lens group 112.

  In addition, the lens microcomputer 410 includes a storage unit 506, a control unit 504, and a communication unit 508.

  In addition to map data for performing zoom tracking, the storage unit 506 stores MTF characteristic data and effective image circle data of the photographing lens. Further, the control unit 504 has a setting unit 505 for setting the small aperture limit F value.

  Next, the configuration on the camera body side will be described. Reference numeral 221 denotes an image sensor (imaging device: hereinafter referred to as a CCD) composed of a CCD. However, the image sensor in the present invention is not limited to a CCD.

  The CCD 221 is driven by a CCD drive circuit 513. A video signal (captured image) obtained by charge accumulation for each pixel obtained from the CCD 221 is converted into a digital signal by the A / D converter 509 and then subjected to predetermined signal processing (amplification and gamma correction) by the camera signal processing circuit 510. Etc.) is given. The video signal subjected to this signal processing is taken out only in the vicinity of a predetermined center by the AF gate 230, processed into information relating to the high frequency component of the Y signal by the AF signal processing circuit 231, and then sent to the camera microcomputer 409.

  Further, the signal processed into information on the high-frequency component of the Y signal passes through a block (not shown), and is then processed into a signal for determining whether the video signal is at a predetermined level, and is sent to the camera microcomputer 409. It is captured.

  Values relating to the high frequency components of these video signals and signals relating to the level of the video signal are communicated between the lens microcomputer 410 and the camera microcomputer 409 via the mount. Upon receiving these signals, the lens microcomputer 410 drives the aperture unit 136 and the focus lens group 114 in order to obtain an in-focus state or an optimal exposure state.

  Reference numeral 511 denotes an image processing circuit, which further applies an electronic zoom process to the video signal generated by the camera signal processing circuit 510 to change the image cutout size or to cut out an image for electronic camera shake correction (not shown). Change the position. In addition to these, the image resolution is converted to change the file size (data size) for image recording, or the compression processing is performed to convert the data size of the photographed image (electronic data). Furthermore, there is a case where processing for correcting distortion aberration of the lens is performed.

  A recording system 512 records the output (electronic data) of the image processing circuit 511 on a recording medium. As the recording medium, a card, a disk, a tape, or the like is used.

  As with the lens microcomputer 410, the camera microcomputer 409 is provided with a control unit 517, a communication unit 518, and a storage unit 519. The storage unit 519 stores information on the size (effective diagonal length) of the CCD, the number of pixels, the pixel pitch, and the like.

  Further, all the states of the switches operated by the user on the camera body side are input to the camera microcomputer 409. In the present embodiment, states such as a trigger switch 513, a zoom switch 514, a recording definition setting switch 515, and a moving image / still image mode switching switch 516 are input.

  As described above, in the imaging system configured such that the photographing lens can be exchanged with respect to the camera body, communication is performed between the lens microcomputer 410 and the camera microcomputer 409 via the communication contact provided on the mount. At this time, information related to the MTF characteristics on the lens side (hereinafter referred to as MTF related information) is transmitted to the camera body side.

  Note that the MTF-related information here may be raw MTF characteristic data, or information replaced with several levels based on the MTF characteristic data value. Furthermore, some conversion result that facilitates subsequent signal processing may be transmitted. In other words, any form may be used as long as it is information related to MTF.

  Here, there are various levels of image definition, such as VGA, XGA, and SXGA. Depending on how much MTF this photographing lens has, the image data file corresponding to which level of definition can be used. Whether or not sufficient resolution can be satisfied.

  For example, the following may occur depending on whether or not the photographing lens can sufficiently resolve a resolution of 50 / mm on the image plane (for example, MTF 50% or more). If the photographic lens can sufficiently resolve the resolution of 50 lenses / mm on the image plane, there may be a clear difference between the VGA recording and the XGA recording (the lens performance is XGA or more). . If the photographic lens cannot sufficiently resolve the resolution of 50 lenses / mm on the image plane, the recording lens will eventually obtain only the same resolution as when VGA recording is performed (the lens performance is VGA). Only class).

  On the other hand, the file size of the image information to be recorded becomes larger as the definition becomes higher, and the capacity of the recording medium set in the camera body is consumed.

  Therefore, in the present embodiment, necessary and sufficient recording is performed according to the performance of the photographing lens by setting an optimal recording file size in the camera microcomputer 409 based on the MTF related information transmitted from the lens microcomputer 410. I am doing so.

  The camera microcomputer 409 generates an image data having a necessary and sufficient (minimum) file size in the image processing circuit 511 by instructing an optimum file size for the image definition indicated by the MTF related information from the photographing lens. To do.

  Further, in the present embodiment, the camera microcomputer 409 sets a use limit F value (maximum F value) at which small aperture diffraction occurs in the photographic lens based on the MTF characteristic data from the photographic lens, and uses this information as the photographic lens. Send to.

  Specifically, first, the F value at which small aperture diffraction occurs is calculated from the MTF related information transmitted from the lens microcomputer 410 and the information (pixel pitch information) regarding the CCD pixel pitch set in the camera microcomputer 409. Then, this F value or a slightly smaller F value is set as the use limit F value.

  For example, it is assumed that the photographing lens is assumed to have a specific size of 3 million pixel CCD, and the limit F value of the 3 million pixel CCD is set to F5.6. Even at that time, if the camera body side has 2 million pixel CCDs of the same size, if it can be used up to F8, the setting in the setting unit 505 of the small aperture limit F value on the photographing lens side is replaced from the reference F5.6 to F8 . Thereby, exposure adjustment in a wider range is possible.

  In addition, the camera microcomputer 409 of the present embodiment displays information on the file size or image definition set on the camera body side on the finder display unit 232 configured by an electronic finder (LCD finder or electronic view finder). Thus, the information is transmitted to the photographer.

  Here, in the camera body of this embodiment, the photographer can arbitrarily set the image definition to be used through the recording definition setting switch 515. In this case, when the photographer sets the image definition corresponding to the high-quality recording that is mismatched (excessive) with respect to the performance of the photographing lens, a warning is displayed on the finder display unit 232. This warning operation is determined and executed according to the flowchart of FIG. 2 described later.

  In addition, the storage unit 506 of the photographing lens according to the present embodiment stores MTF characteristic data corresponding to at least one of the focal length and the F value. This makes it possible to set a more optimal file size and use limit F value on the camera body side, compared to the case of using typical MTF characteristic data that does not depend on the focal length or F value, and is more efficient. Image recording can be performed.

  This is because the MTF characteristic data usually varies depending on the focal length and the F value, and even if the MTF is such that the performance of the CCD cannot be fully obtained under certain conditions, it may be satisfied under other conditions. Therefore, the lens microcomputer 410 (storage unit 506) has MTF characteristic data that takes into account the focal length and F value, and information related to the MTF characteristic data according to the situation of the focal length and F value at that time is stored in the camera microcomputer. 409. As a result, it is possible to efficiently record an image with the highest image quality within a necessary and sufficient range on the camera body side.

  Next, the operation of the camera microcomputer 409 will be described using the flowchart of FIG. First, in step 601, a request to transmit MTF related information is transmitted to the lens microcomputer 410 in step 602, and MTF related information transmitted from the lens microcomputer 410 is obtained in response thereto.

  The MTF related information transmitted at this time is based on the MTF characteristic data corresponding to the focal length and F value of the photographing lens at that time.

  In step 603, the optimum recording file size Va is determined as described above based on the obtained MTF related information on the lens side.

  In step 604, it is determined whether the recording definition setting on the camera body side is in the auto mode. In the auto mode, the recording file size Va determined in step 603 is used, so that the performance of the photographing lens can be maximized, and an optimum setting that does not use an unnecessarily large file size. Become. In this case, in step 605, the used file size V is set to Va.

When the used file size V is set, when the photographer operates the trigger switch 513 to trigger the recording operation, image recording is performed with the definition of the file size V.

  On the other hand, if it is determined in step 604 that the mode is not the auto mode (manual mode), the file size Vm set by the photographer is read in step 606. In the manual mode, the setting value of the photographer is given priority, so the used file size V is set to Vm in step 607.

  In step 608, the file size Va set by the camera microcomputer 409 based on the MTF related information is compared with the file size Vm set by the photographer. If Va is larger, the file size set by the photographer corresponds to sufficient definition in terms of lens performance, and the process returns to step 602 as it is.

  On the other hand, even if the file size Vm set by the photographer is set to a high definition in terms of lens performance, it is determined that there is no difference from the image quality recorded with a setting smaller than that (high definition image definition or less). If this is the case (Va <Vm), a warning to that effect is displayed on the finder display unit 232 in step 609.

  By seeing this warning, the photographer notices that the recording medium capacity is wasted, and the data size used can be brought closer to the optimal setting by reducing the recording precision set manually. it can.

  In this embodiment, the definition of the image recorded by the photographer can be set manually. However, the file size may be set manually.

In the present embodiment, the case where the file size Va set by the camera microcomputer 409 based on the MTF related information is compared with the file size Vm set by the photographer in the flowchart of FIG. 2 has been described. In this case, the image definition corresponding to the file size Va may be compared with the image definition set by the photographer.
(Second Embodiment)
In the first embodiment, the MTF related information based on the MTF characteristic data on the photographing lens side is transmitted to the camera body side, and the camera body side has the smallest file within the range where the lens performance can be maximized based on this information. Enabled to record by size. In this embodiment, not MTF related information but information related to the effective image circle of the taking lens (hereinafter referred to as effective image circle related information) is transmitted from the lens side to the camera body side.

  In the present embodiment, data of the effective image circle diameter of the photographing lens is stored in the storage unit 506 of the lens microcomputer 410 shown in FIG. Further, this data is stored as a value of an effective image circle diameter corresponding to the focal length of the photographing lens and the F value.

  The lens microcomputer 410 transmits this effective image circle related information to the camera microcomputer 409 via the mount. The effective image circle related information to be transmitted may be raw effective image circle data or information obtained by appropriately converting the same as the MTF related information of the first embodiment.

  Here, for example, if the effective diagonal length of the CCD 221 included in the camera body is 6 mm, the entire screen obtained from the CCD is recorded if a photographing lens having an effective image circle diameter of 6 mm or more is attached thereto. You can shoot images that can't be worn without waste.

  However, when a photographing lens having an effective image circle diameter of 4 mm is attached, the corner of the screen is cut (blackened and no image is present). In such a case, in the camera microcomputer 409, first, based on the effective image circle-related information of the taking lens transmitted from the lens microcomputer 410, a range in which a clear image can be cut out (image acquisition range on the CCD 221). Determine. Then, the image processing circuit 511 sets the cutout range, so that it is possible to perform image recording without waste.

  Further, in the present embodiment, an image captured in the clipping range set by the image processing circuit 511 is displayed on the finder display unit 232 to show a field angle substantially the same as the recorded field angle, and to the photographer. Inform about information.

  For example, even if a photographing lens designed with an effective image circle diameter of 4 mm is attached to a camera body having a CCD with a diagonal length of 6 mm, only a range with a diagonal length of 4 mm on the CCD is cut out. For this reason, even if they have the same focal length (for example, f = 5 mm), it is not necessary to cut out an image using a photographing lens having an effective image circle diameter of 6 mm, and there is only an effective image circle diameter of 4 mm. Therefore, there is a difference in the angle of view from the case where image clipping is necessary.

  For example, when the angle of view is converted into the focal length of a 135 film formatted photographing lens, even if f = 5 mm, if the effective image circle diameter is 6 mm, it is about 43 mm, and if the image is cut out with an effective image circle diameter of 4 mm, about 55 mm.

  In other words, in this embodiment, the angle of view is unified with the focal length of the 135 film format that is familiar to many users. Thus, even if lenses having various effective image circle diameters are attached, the angle of view that can be taken without any trouble is calculated and displayed, thereby avoiding confusion for the user.

  For this purpose, in the camera microcomputer 409, the effective image circle diameter A indicated by the effective image circle-related information transmitted from the photographing lens, and the focal length information f of the photographing lens transmitted from the lens side in the same manner. A simple calculation may be performed based on the diagonal length information C of the CCD 221 of the camera body itself.

  That is, when A <C, approximately f × 43 / A, and when C <A, approximately f × 43 / C, the angle of view at that time is converted into the focal length of the 135 film format. Here, “43” is the diagonal length of 135 film.

  The calculation result is displayed on the finder display unit 232 by the camera microcomputer 409.

  Next, the operation of the camera microcomputer 409 in this embodiment will be described using the flowchart of FIG.

  First, in step 611, the effective image circle information A possessed by the lens is obtained in step 612 through communication through the contact point from the lens side.

  In step 613, the effective image circle information (effective image circle diameter) A is compared with the value of the effective diagonal length C of the image sensor such as a CCD on the camera side. As a result of this comparison, if the effective diagonal length C of the CCD 221 is larger (it will be lost with the lens), an ineffective cutout range is set in step 614.

  When the effective image circle on the lens side covers the CCD (when the effective image circle diameter A is larger than the effective diagonal length C), in step 615, the clipping setting is canceled (released). If it is, leave it as is).

Note that when electronic image stabilization is turned on, a standard clipping range may be set.
(Third embodiment)
FIG. 4 shows the configuration of an imaging system that is the third embodiment of the present invention. Note that in the imaging system of the present embodiment, constituent elements that are common to the imaging system of the first embodiment are denoted by the same reference numerals as in the first embodiment and are not described.

  In this embodiment, a shake sensor 530 is provided on the camera body side, and a signal corresponding to the shake of the camera body output from the shake sensor 530 is taken into the camera microcomputer 409.

  Note that a piezoelectric vibration gyro or the like is used as the shake sensor 530. In this embodiment, two shake sensors for detecting a rotational component in the longitudinal (pitch) direction and detecting a rotational component in the lateral (yaw) direction are used. Provided.

  In the conventional electronic shake correction, the range to be cut out as an image from all effective CCD screens based on the rotation amount of the camera body obtained from the shake sensor and the focal length and CCD size at that time Was determined (moved). Thus, the subject is aligned between successive images, and image blur is corrected.

  At this time, there is no problem as long as the CCD is sufficiently large, but the size of the CCD is limited. For this reason, 100% correction cannot be performed for a very large shake angle. Rather, in order to prevent an uncomfortable feeling in the moving image, software is devised in the vicinity of the cutout limit position of the image so that a natural image and It is trying to become.

  In the present embodiment, such an electronic shake correction function uses the effective image circle-related information transmitted from the photographing lens side, and a range that can be corrected by electronic shake correction (an image cutout range can be moved). The possible range: movement allowable range) and the position where the above-mentioned software correction is applied are optimized. This prevents the image from being distorted even when the camera body capable of lens replacement has various effective image circles of the photographing lens.

  In particular, when the effective image circle of the photographic lens changes depending on the focal length, F value, etc., an electronic shake correction operation is performed based on information sent from the photographic lens side including those conditions.

  FIG. 5 shows the relationship between the focal length of the photographic lens and the shake angle that can be corrected by electronic shake correction. The horizontal axis in FIG. 5 represents the focal length of the photographic lens, and the vertical axis represents the shake angle that can be corrected by electronic shake correction.

  In the electronic shake correction, if the angle is converted assuming that the movable amount of the image cutout range on the CCD is constant, the larger shake angle becomes the maximum shake angle that can be corrected on the wide side and the smaller shake angle on the telephoto side.

  Here, the alternate long and short dash line in the figure indicates that the effective image circle of the photographic lens is secured at any focal length with respect to the effective size of the CCD (when such a camera body and photographic lens are combined). The shake angle which can be corrected according to the focal length is shown.

  On the other hand, the solid line in the figure is smaller than the total effective screen of the CCD, although the effective image circle does not fall below the cut-out angle of view in the CCD when the focal length is in the range from wide to middle (focal length of points W to A). Become. Correction can be made according to the focal length when the camera body and the photographic lens are combined such that the effective image circle of the photographic lens is larger than the effective size of the CCD on the telephoto side from the focal length of the point A. The deflection angle is shown.

  In this case, the maximum shake angle that can be corrected differs depending on the focal length (if the movable amount of the image cutout range on the CCD is fixed, the image is distorted). Therefore, the camera microcomputer 409 limits the movement of the image cutout range so that the image cutout range moves only within a range corresponding to the maximum shake angle that can be corrected according to the focal length at that time.

  In this manner, first, the allowable movement range of the image cutout range corresponding to the focal length is determined from the effective image circle related information transmitted from the photographing lens. Then, the position of the image cut-out range is determined based on the output from the shake sensor within the allowable movement range and taking into consideration that the moving image does not feel uncomfortable. Accordingly, it is possible to realize an electronic shake correction function that does not cause an image blur while ensuring the maximum correctable shake angle according to the focal length at that time.

  In the characteristics indicated by the solid line, the correctable angle is minimized at a focal length slightly wider than the tele side, but this is only an example because it depends on the optical design.

  In FIG. 5, a two-dot chain line indicates a combination of a photographic lens and a camera body in which electronic shake correction cannot function on the wide side from point B. On the wide side from the point B is an area where the effective image circle is just below the image cutout size, or in some cases the cutout size must be reduced to match the effective image circle of the photographic lens.

  Further, from point B to point C, the effective image circle is larger than the cutout range, but the entire CCD screen cannot be covered. Therefore, although shake correction functions, correction for a sufficiently wide shake angle may not be possible.

  Further, between the point C and the telephoto end, the lens has an effective image circle larger than the entire CCD screen. Therefore, shake correction is performed within this range.

  That is, in the present embodiment, the electronic shake correction function is driven or the drive is limited (the movement allowable range is set to zero) based on the effective image circle related information that the photographing lens has. Accordingly, it is possible to realize an electronic shake correction function that does not cause image blurring while ensuring the maximum correctable shake angle in a focal length region where shake correction is possible.

  Next, the operation of the lens microcomputer 410 in the present embodiment will be described using the flowchart of FIG. 6, and the operation of the camera microcomputer 409 of the present embodiment will be described using the flowchart of FIG.

  In FIG. 6, when starting at step 616, the value of the focal length f set at that time is detected at step 617, and then, at step 618, an effective image circle at the value of f is determined. This is a method of providing a table in which the relationship as shown in FIG. 5 is stored in the microcomputer and reading from the table.

  In step 619, the determined effective image circle information is communicated to the camera microcomputer.

  In FIG. 7, when the process starts in step 620, the effective image circle A communicated in step 619 of the flowchart of FIG. 6 is received from the lens side in step 621.

  In step 622, it is determined whether or not camera shake correction (IS) is ON. If OFF, it is equivalent to the transition to step 613 in FIG. 3, and the same processing as in steps 614 and 615 in FIG. 3 is performed.

  If IS is ON, in step 624, how much the cutout position can be moved up, down, left and right from the center of the effective screen of the CCD 221 is determined by, for example, the number of scanning lines and the number of pixel columns. Then, the range that can be moved without being lost is determined from the effective image circle information A. At this time, the values of the effective image circle information A and the CCD diagonal length information C are used.

  Then, the value of how much the cutout position can be changed is communicated to an IS microcomputer or the like that controls the camera shake correction function in step 625. On the basis of this value, the IS microcomputer side performs control so that the moving image does not feel uncomfortable as described above.

  As described above, according to the first and third aspects of the present invention, the data size for recording the captured image is set to the data size corresponding to the information related to the MTF received from the photographing lens device. . Therefore, an image can be recorded with an optimum use data size (file size) corresponding to the resolution performance of the mounted photographic lens device, that is, without waste, and efficient image recording can be performed.

  When the data size or image definition can be selected by the user, the data size corresponding to the selected data size or image definition is determined based on the information related to the MTF received by the control means. A warning operation may be performed when the data size is larger than the set data size. Accordingly, it is possible to reliably notify the user that the shooting is inefficient.

  Further, according to the second and fourth inventions of the present application, the adjustment range (command) of the light amount adjusting means provided in the photographic lens device based on the information (command) related to the MTF received from the photographic lens device. Variable setting is made. For this reason, it is possible to record a high-quality image by adjusting the light amount by the light amount adjusting means in the photographing lens device in an optimum range according to the resolution performance of the mounted photographing lens device, for example, within a range where small aperture diffraction does not occur. it can.

  In the first to fourth aspects of the invention, if the MTF related information received from the photographing lens device is information corresponding to at least one of the focal length and the F value of the photographing lens device, more efficient photographing can be performed. It can be performed.

  According to the fifth and seventh inventions of the present application, the size of the image acquisition range on the image sensor is variably set based on the information related to the effective image circle received from the photographing lens device. . Therefore, it is possible to record an image in an image acquisition range that is optimal in accordance with the effective image circle of the mounted photographic lens device, that is, wasteless and incapable of losing images, and is efficient and inevitable. Recording can be performed.

  According to the sixth and seventh aspects of the present invention, the image acquisition range is moved on the image sensor for electronic image blur correction based on information related to the effective image circle received from the photographing lens device. The allowable movement range is set variably. For this reason, it is possible to set an optimum movement allowable range corresponding to the effective image circle of the mounted photographing lens device, that is, wasteless and incapable of losing an image, and perform effective shake correction without being distorted. be able to.

  Note that if the information related to the effective image circle received from the photographic lens device is information related to the effective image circle corresponding to at least one of the focal length and the F value of the photographic lens device, more effective image shake is achieved. Correction can be performed.

111-114 Lens group 221 CCD
409 Camera microcomputer 410 Lens microcomputer 506 Storage unit 511 Image processing circuit unit 512 Image recording system 515 Recording definition setting switch

Claims (2)

The imaging lens device can be replaced, and is an imaging device that captures an image with an imaging device,
Receiving MTF characteristic data corresponding to at least one of a focal length and an F value of the photographic lens device from the mounted photographic lens device;
Based on the received MTF characteristic data and pixel pitch information of the image sensor, a use limit F value at which small aperture diffraction is generated by the photographing lens device that can be adjusted by a light amount adjusting means provided in the photographing lens device. An imaging apparatus comprising control means for setting.   An imaging system comprising the imaging device according to claim 1 and the imaging lens device.