JP2003029135A - Camera, camera system and photographic lens device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize improvement in focusing accuracy and the shortening of focusing time as far as possible, even when various photographic lenses are mounted, and also to secure the interchangeability of the photographic lens of an old system which will not cope with focusing control method by a plurality of focus detection systems. SOLUTION: This camera to/from which the photographic lens 200 can be attached/detached is provided with 1st and 2nd focus detection means 104 and 109, having a different system for detecting the focusing state of the lens 200, and a control means 111 for performing the focusing control of the lens 200, by using the detected result by the detection means 104 and 109. In the camera, the control means changes the focusing control method, conducted by using the detected result by either or both of the detection means 104 and 109 according to the information on the mounted lens 200.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a camera and a camera system in which a taking lens device can be attached and detached, and more particularly to a camera and a camera system having an automatic focusing function.

[0002]

2. Description of the Related Art In a conventional single-lens reflex camera that images an image on a silver salt film, a phase difference detection method is often used as a method for detecting the focus adjustment state of a photographing lens. Automatic focus adjustment (AF) using this phase difference detection method
The system operates as follows.

The light incident from the taking lens is reflected to the lower side of the camera by a sub-mirror attached to the back surface of a semi-transmissive main mirror arranged at an angle of 45 degrees with respect to the taking optical axis, and is reflected by a lens of a secondary optical system. It is separated into two images by and enters the pair of AF sensors.

The pair of AF sensors are arranged side by side, and the in-focus state, the front focus state, and the rear focus state are determined by the difference in the distance between the two images formed on the pair of AF sensors. Then, the focus adjustment lens is moved so that the image interval becomes an in-focus interval, and focusing is performed.

That is, since the relationship between the shift amount of two images and the image plane movement amount (defocus amount) is determined by the optical system, the defocus amount is obtained from the shift amount. Then, the amount of extension of the lens is obtained from the defocus amount, and the lens is moved to obtain the focus.

On the other hand, in a digital still camera or a video camera which captures an image in a two-dimensional image pickup device and outputs the image pickup signal or records it in a recording medium, the contrast is used as a method for detecting the focus adjustment state of the photographing lens. A method called a detection method or a mountain climbing method is often used.
There is a perturbation method (wobbling method) as one of the contrast detection methods, and the AF system based on this perturbation method generally operates as follows.

This AF system includes an image pickup system including a two-dimensional image pickup device, a system control unit including a calculation unit and a signal generation unit that generates a control signal for the lens, and a lens for moving the lens in the optical axis direction. The lens unit includes a control unit.

First, the image pickup system takes in image light,
It is output as an image pickup signal and sent to the system control unit, where the high frequency component contained in the image pickup signal is extracted. Then, the maximum value of this extraction signal is stored, the focus adjustment lens is moved in a certain direction, image light is similarly captured, and high frequency component extraction is performed.

At this time, if the maximum value of the extracted signal is larger than the previously stored value, it is assumed that the moving direction of the focus adjustment lens is close to the focusing surface, and the current value is stored again, Move the focusing lens in the same direction.

If the maximum value of the extracted signal this time is smaller than that of the previous time, it is assumed that the moving direction of the focus adjustment lens is away from the in-focus plane, and the value of this time is stored again and the focus adjustment lens is stored. Move in the opposite direction from the previous time,
Similarly, image light is taken in, high-frequency components are extracted, maximum values are compared, and finally the image plane is brought to the focusing surface.

As another method of the contrast detection AF, there is a trial method (including the whole area scan method). The configuration of this AF system is the same as that of the perturbation method described above.

First, the lens is sent to the closest end or the infinity end, and the lens is moved at an image plane interval in a direction in which the lens can move, with the lens as a starting point, and the image light is captured by the image pickup section and used as an image pickup signal. Output and send to system control section. Then, the system control unit extracts the high frequency component included in the image pickup signal and stores the maximum value.

This operation is repeated until the infinity end if the starting point is the closest end, and conversely if the starting point is the infinity end, until the closest end. Then, the maximum value among the stored maximum values, that is, the focus position with the highest contrast is obtained, and the lens is moved to the lens position corresponding to that point.

The applicant has proposed a camera equipped with two focus detection devices corresponding to the phase difference detection method and the contrast detection method, respectively. In addition, JP-A-11
In Japanese Patent Laid-Open No. 83474/1993, so-called active AF
It is a hybrid AF type camera having both a system and a passive AF system, and also proposes a technique for controlling the focus adjustment operation according to the use condition of the camera.

Further, Japanese Patent Application Laid-Open No. 9-181954 discloses an electronic still camera using a hybrid AF system for performing focus adjustment control in a phase difference detection method and a contrast detection method using an image pickup signal obtained by an image pickup device. Proposed.

[0016]

However, if only the AF system of the phase difference detection system is adopted in the digital camera, it corresponds to one pixel of the AF sensor due to the difference in size (area) of the silver salt film and the image pickup device. There arises a problem that the ratio of the image pickup surface becomes large, that is, the detection pixels become rough and the accuracy is lowered. To solve this problem,
The magnification of the AF optical system may be reduced, the pixel pitch of the AF sensor may be reduced, or the like, but the system configuration will be strict in terms of accuracy and costly.

On the other hand, in the AF system using only the contrast detection method, since the range of defocus amount that can be detected is narrow, it becomes difficult to detect the focus adjustment state when the focus is greatly deviated, and the wobbling or the whole area scan is performed. There is a problem in that the need arises and the time required for focus adjustment increases.

Further, in the case where both the phase difference detection method and the contrast detection method are provided to shorten the focusing time of the contrast detection method and improve the accuracy of the phase difference detection method, the focusing operation of the optical system is There is a problem that the interchangeability of the interchangeable lens of the old system, which is not compatible, cannot be ensured because the drive based on the detection method must be possible.

Further, in the conventional camera equipped with the hybrid AF described above, no technique has yet been proposed for reducing the time required for detecting the focus adjustment state and focusing operation in a single lens reflex type camera system.

Therefore, in the present invention, in a camera and a camera system in which the taking lens device is detachable, it is possible to improve the focusing accuracy and shorten the focusing time as much as possible for various types of taking lens devices. Further, it is intended to ensure compatibility of the photographing lens device of the old system that does not support a plurality of focus detection methods.

[0021]

In order to achieve the above object, the first invention of the present application is a camera in which the taking lens device is detachable and replaceable, and is for detecting the focus adjustment state of the taking lens device. A camera having first and second focus detection means of different systems and control means for performing focus adjustment control of a photographic lens device using detection results of the first and second focus detection means. To
The method of focus adjustment control performed by using the detection result of one or both of the first and second focus detecting means is changed according to the information on the mounted photographic lens device. .

As a result, information about the attached photographic lens device (for example, optical information such as focal length of the photographic lens device, depth of field, open F number, sensitivity of image plane displacement to movement of the focus lens group). It is possible to select the most suitable method as the focus adjustment control method for the taking lens device according to the specification information such as the focus adjustment control method supported by the taking lens device). It is possible to improve the focusing accuracy by using the two focus detecting means together, and to shorten the focusing time by not performing the unnecessary focus detecting operation.

Specifically, for example, a phase difference detection type focus detection means and a contrast detection type focus detection means are provided, and the focus adjustment control method is performed by using the detection result of the phase difference detection type focus detection means. A method of performing focus adjustment control, a method of performing focus adjustment control by using the detection result of the focus detection means of the contrast detection method, and a detection result of the focus detection means of the phase difference detection method, the subject is in a predetermined low contrast state. It is possible to change between at least two methods among the methods for performing the focus adjustment control by using the detection result of the focus detection means of the contrast detection method when it is determined that.

According to the second aspect of the present invention, the photographing lens device is a detachable camera, and the distance measuring means for detecting the distance to the object and the focus detecting means for detecting the focus adjustment state of the photographing lens device. In a camera having a control means for performing focus adjustment control of the photographic lens device using the detection results of the distance measuring means and the focus detection means, the control means is responsive to information about the photographic lens device mounted. The method of focus adjustment control performed using the detection result of one or both of the distance measuring unit and the focus detecting unit is changed.

As a result, information about the attached photographing lens device (for example, optical information such as the focal length of the photographing lens device, the depth of field, the open F number, and the sensitivity of the image plane displacement to the movement of the focus lens group). It is possible to select the most suitable focus adjustment control method for the shooting lens device according to the specification information such as the focus adjustment control method supported by the shooting lens device). It is possible to improve the focusing accuracy by using the focus detection means together, and to shorten the focusing time by not performing unnecessary distance measurement or focus detection operation.

Specifically, for example, as the method of focus adjustment control, there are a method of performing focus adjustment control using the detection result of the distance measuring means, and a method of performing focus adjustment control using the detection result of the focus detection means. It is possible to change between at least two methods of performing focus adjustment control using the detection result of the focus detection means after performing focus adjustment control using the detection result of the distance measuring means.

In the first and second aspects of the present invention, according to the focus adjustment control method supported by the taking lens device, the control means is caused to perform only the focus adjustment control, and other control is performed. It is possible to ensure compatibility of taking lens devices that do not support the method.

[0028]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) FIG. 1 shows the configuration of a camera system including a digital camera and a taking lens device according to a first embodiment of the present invention. In FIG. 1, reference numeral 100 denotes a camera body (camera referred to in the claims), and reference numeral 200 denotes an interchangeable photographing lens device (hereinafter, referred to as a photographing lens) that can be attached to and detached from the camera body 100.

In the photographing lens 200, the first lens group 2
01, a zoom lens group 202, a focus lens group 203, and a diaphragm 204. The taking lens 200 of this embodiment has a focal length of 28 to 200 mm,
The open F number is 3.5 to 5.6, and the open F number changes depending on the focal length.
It is a zoom lens provided with the drive mechanism and the drive circuit of 3.

A prism 101 having a fixed half mirror is provided in the camera body 100.

The light flux from the subject 400 passes through the lens groups 201 to 203 and the diaphragm 204 and enters the prism 101 in the camera body 100 as a photographing light flux.

In the taking lens 200, 205 is a diaphragm drive circuit, which controls the aperture diameter of the diaphragm 204 according to a signal from the lens CPU 207. An operation switch 206 is provided with a manual operation switch for zooming, focusing, aperture, a setting switch for auto / manual switching of focus, and the like.

A lens CPU 207 exchanges information with the camera CPU (control means) 111 via the lens communication circuit 211 and the camera communication circuit 102, and controls the entire control of the photographing lens 200. .

Reference numeral 208 denotes a focus drive circuit. In this embodiment, it is composed of a motor and its drive circuit, and drives the focus lens group 203 in the optical axis direction according to a signal from the lens CPU 207.

A focal length detection circuit 209 detects the focal length by detecting the position of the zoom lens group 202. In this embodiment, the zoom lens position is set to 3
It is detected by a gray code pattern of two divisions.

Reference numeral 210 is a memory circuit, which is configured to have a ROM. The storage circuit 210 stores an ID (product model number, serial number, etc.) of the taking lens 200, focal length information, focus sensitivity which is a ratio of an image plane displacement amount to a movement amount of the focus lens group 203 for each focal length, and the like. It is stored and read by the lens CPU 207 at any time.

Next, in the camera body 100, the photographing light flux transmitted through the fixed half mirror of the prism 101 is
An image is formed on the image pickup surface of the image pickup device 108 such as CCD or CMOS. In addition, in the fixed half mirror of the prism 101, a part (for example, 1/3) of the photographing light amount branches upward and enters the pentaprism 103.

A light beam (not shown) branched in the pentaprism 103 enters a focus detecting device 104 which is a first focus detecting means. The focus detection device 104 detects the focus adjustment state of the photographing lens 200 by a detection method called a phase difference detection method.
It is equivalent to that used in silver salt cameras and the like. In this embodiment, the focus detection device 104 is Fn.
o. The light flux of 8 is used, the light flux is divided into two, and each is subjected to image detection by a line sensor. Then, the detection signal from the first focus detection device 104 is output to the camera CPU 111.

On the other hand, the light flux that has passed through the pentaprism 103 passes through the finder optical system 106 and is visually recognized by the photographer as an optical finder image.

The image pickup device 108 photoelectrically converts the incident light and outputs an electric signal. This output signal is amplified and is output to the camera C as a digital video signal (imaging signal).
It is output to the PU 111.

The camera CPU 111 uses this video signal to form a moving image or a still image. Further, the digitized video signal is, apart from the output to the camera CPU 111, the AF processing circuit 1 as the second focus detection means.
It is also output to 09.

In the AF processing circuit 109, the high frequency component contained in the image data of one screen of the digital video signal is extracted through a high pass filter (HPF) or the like, and the arithmetic processing of cumulative addition or the like is performed on this. Be done. As a result, the AF evaluation value corresponding to the amount of contour components on the high frequency side is calculated, and it becomes possible to detect the focus adjustment state of the photographing lens 200 by the so-called contrast detection method (hereinafter referred to as focus detection). The AF evaluation value is the camera C
It is output to the PU 111. In this way, the camera 100
In (1), the camera is equipped with a hybrid AF having means for detecting the focus of the taking lens 200 by two different detection methods, a phase difference detection method and a contrast detection method.

In the present embodiment, basically, the defocus amount is calculated by the phase difference detection method, converted into the movement amount of the focus lens group 203 to drive the focus lens group 203, and then the contrast detection method. The focus adjustment control method for making fine adjustment for focusing is used.

However, if the taking lens is of a type that does not allow fine driving (wobbling) for the contrast detection method, final fine adjustment cannot be performed. For this reason, in the camera CPU 111 of the present embodiment, when using a photographing lens that does not support minute driving (that is, does not support the focus adjustment control method by the contrast detection method) such as the old type, the contrast is increased. Fine adjustment by the detection method is not performed, meaningless focus detection operation is prevented, and the time required for focus detection and focusing operation is shortened. The specific operation contents of the camera CPU 111 will be described later.

In the camera body 100, a photometry circuit 105 transmits photometry information to the camera CPU 111. Reference numeral 107 has a two-step switch, which outputs a signal (SW1 signal) for starting photometry, focus detection, and focus adjustment operations when the first-step switch is turned on, and the image pickup (exposure by the image sensor 108 is performed when the second-step switch is turned on. ) A release switch circuit for outputting a signal (SW2 signal) for starting the start to the camera CPU 111.

In addition to the communication with the lens CPU 207 described above, the camera PU 111 controls the display circuit 112 for displaying the image taken by the image pickup device 108, the set shooting conditions and the shooting mode, and various shootings. Setting switch circuit 113 for setting conditions, shooting mode, etc.
It is in charge of various controls on the camera body side such as control for input from the camera, checking of remaining capacity of the power supply 110, and sharing of power. Further, a video signal memory, various buffer memories, and the like are also included in the camera CPU 111.

In the interchangeable lens system of the silver salt single-lens reflex camera, the film format used is fixed, and the permissible circle of confusion diameter is approximately 35 μm. In accordance with this, the focusing accuracy and the like of the taking lens are set. It had been.

However, in the system of the digital camera as in this embodiment, the area (size) of the image pickup element 108 is not fixed to one, and the number of pixels of the image pickup element 108 is different. The diameter also differs depending on the camera, and the focus detection accuracy is required to be higher than that of a silver salt single lens reflex camera.

This is because (1) generally, the area of the image pickup device is smaller than the filming range of the film because of cost reasons, etc. (2) The output image size is arbitrarily set by the photographer due to the function of the digital camera. This is because there is a reason that it can be set to a large value with.

In this embodiment, the image sensor 108 is used.
Is a so-called APS with a pixel pitch of 9 microns and 27 mm
A -C size image sensor is used. Therefore, the permissible circle of confusion diameter of 18 μm that is worthy of focusing at the time of focus adjustment is set as the minimum pitch (4 pixels represent one point, which corresponds to about 2 pixels in the vertical and horizontal directions). This is because the point image does not affect the output image because the point image is within the pixel range even if finer focus detection and focusing control are performed.

FIG. 2 shows the focus sensitivities S for each of the 32-division focal lengths stored in the storage circuit 210 in the taking lens 200. The camera CPU 111 uses the information on the focus sensitivity S to perform focus adjustment control.

In this embodiment, the focus sensitivity is 1.
If the number exceeds 7, the accuracy cannot be ensured only with the phase difference detection method, so the fine adjustment of the contrast detection method is always performed. Note that the switching of the focus adjustment control method based on the focus sensitivity and the numerical value of the reference value may be changed depending on the focus extension amount, the stop position accuracy of the focus drive circuit 208 (and the drive mechanism), and the detection accuracy of the focus detection device. .

FIG. 3 is a flowchart mainly showing the focus adjustment control operation of the camera CPU 111 in this embodiment.

First, in step (abbreviated as S in the figure) 01, the camera CPU 111 acquires lens ID information from the memory circuit 210 through the lens CPU 207 when the taking lens 200 is mounted on the camera body 100, and this lens The taking lens 200 is a hybrid A from the ID information.
It is determined whether or not the lens is compatible with the F control method. If the lens is a non-compatible lens, the process proceeds to step 25 to perform focus adjustment control using only the phase difference detection method. On the other hand, if the lens is compatible with hybrid AF, the process proceeds to step 02.

At step 02, the camera CPU 111
Determines whether the SW1 signal has been input from the release switch circuit 107, and if not input, waits at this step. When the SW1 signal is input, step 03
Then, the photometering circuit 105 is caused to perform photometry of the object, the result is taken in, and the shutter speed, aperture value, sensitivity, etc. at the time of exposure are set.

Steps 04 and 0 after step 03
In 5, 06, the camera CPU 111 uses the lens C.
Information on the side of the taking lens is fetched through the PU 207, and operation is performed based on this fetched information. First, in step 04, the current open F-number information is received, and when the open F-number exceeds 5.6 and is dark, the depth of field is deep, and the accuracy difference between the phase difference detection method and the contrast detection method and the focus lens position. Since the influence of accuracy becomes inconspicuous, the focus adjustment control is performed in the mode in which the focus detection by the contrast detection method is not performed for the purpose of shortening the focusing time, and the step 18 is performed through the step 18
Proceed to.

On the other hand, if the open F number is brighter than 5.6, the routine proceeds to step 05. In the taking lens 200 of the present embodiment, the open F number is always 5.6 or less, and therefore the process always proceeds to step 05.

In step 05, it is determined whether the value of the focus sensitivity S shown in FIG. 2 is 1.7 or less, and 1.7 is determined.
If the following is true, the focus lens position accuracy under focus drive based on the focus detection result by the phase difference detection method will not cause any actual damage, so focus control is performed in a mode in which focus detection by the contrast detection method is not performed. Step 0
Proceed to step 18 via 6.

When the value of the focus sensitivity S is larger than 1.7, there is a high possibility that the required stop position accuracy of the focus lens group 203 cannot be ensured, so focus adjustment control using a contrast detection method is performed. So proceed to step 07.

However, in the present embodiment, before proceeding to step S18, in step 06, the current focal length is 30 based on the information from the focal length detecting circuit 209 of the photographing lens.
It is determined whether or not it is on the telephoto side of 0 mm, and if it is on the telephoto side of 300 mm, the contrast detection method should be used together because the depth of field becomes shallow, so step 0
Proceed to 7. In addition, in the taking lens 200 of the present embodiment,
Since 300 mm is out of the variable range of the focal length, it does not proceed to this step.

In this embodiment, when the SW1 signal is input and the focal length is within the wide-angle end and the second divided zone from the wide-angle end, the process proceeds to step 18 (FIG. 2).
reference).

At step 07, the camera CPU 111
Calculates the defocus amount using the detection result from the phase difference detection type focus detection device 104. Then, based on the calculated result, in step 08, it is determined whether or not the subject is in a low contrast state equal to or lower than a predetermined contrast state, and in the low contrast state, it takes time to detect the focus. Therefore, the process proceeds to step 13 in order to shift to the focus detection using the contrast detection method which is more accurate than the phase difference detection method and whose sensitivity can be changed.

On the other hand, when the contrast is not low, the process proceeds to step 09, and a control signal is sent to the lens CPU 207 for performing focus adjustment control (focus lens drive) based on the calculated defocus amount. The camera CPU 111 also operates the focus detection device 104 of the phase difference detection method to calculate the defocus amount at any time during the driving of the lens, and in step 10, the calculated defocus amount and the focus lens group 203. Is driven, and after driving by the defocus amount, the process proceeds to step 11. In step 11, each information is acquired again from the taking lens, and the process proceeds to step 12.

In step 12, steps 04, 05,
The respective information acquired in 06 and the respective information acquired in step 11 are compared, and if changed, the process returns to step 02.
If there is no change, the process proceeds to step 13 to detect the focus by the contrast detection method and calculate the defocus amount.

In this embodiment, the focus lens group 203 already exists near the in-focus position because the focus detection is performed by the contrast detection method after the phase difference detection method except in the low contrast state. Therefore, in most cases, the defocus amount can be calculated by the contrast detection method.

After calculating the defocus amount, the process directly proceeds to step 14, and the lens CPU is driven so as to drive the focus lens group 203 based on the calculated defocus amount.
A control signal is sent to 207. On the other hand, if it is in the low contrast state or if the defocus amount cannot be calculated depending on the type of subject, in step 14, a control signal is sent to the lens CPU 207 in order to finely drive (wobble) the focus lens group 203. The focus is sent out, focus detection is performed by the contrast detection method, and the focus determination is performed in step 15 based on the result. If no focusing result is obtained, the process returns to step 13.

If it is determined in step 15 that the object is in focus,
In step 16, it is determined whether or not the SW2 signal has been input from the release switch circuit 107. If no SW2 signal has been input, the flow returns to step S15 to wait while looking at the in-focus state. When the SW2 signal is input, step 1
7, the exposure control of the image sensor 108 is performed.

Next, the control starting from step 18 is based on the information from the taking lens, when the depth of field of the taking lens is deep or when the precision of the stop position of the focus lens is not severe, the focus width is wide and the focus is in focus. For the purpose of shortening the time, the control mode in which focus detection by the contrast detection method is not performed is shown.

First, in step 18, as in step 07, the defocus amount by the phase difference detection method is calculated. In step 19, based on the result, step 08
Similar to the above, it is determined whether or not the subject is in a low contrast state, and if it is in a low contrast state, it takes time to detect the focus. In order to make the transition, the process proceeds to step 13.

If it is not in the low contrast state, the process proceeds to step 20, and a control signal is sent to the lens CPU 207 for performing focus adjustment control (focus lens drive) based on the calculated defocus amount. Even during this lens driving, the camera CPU 111 performs a focus detection operation at any time to calculate the defocus amount, and in step 21, the lens is driven by the calculated defocus amount to determine whether or not the lens is in focus. Determine whether.

After driving the focus lens group 203 by the defocus amount, the camera CPU 111 proceeds to step 22, acquires information from the taking lens 200 again, and proceeds to step 23. In step 23, the information acquired in steps 04, 05, 06 is compared with the information acquired in step 22, and if the information has been changed, step 02
Return to. If there is no change, go to step 24,
It is determined whether or not the SW2 signal is input from the release switch circuit 107, and if it is not input, the process returns to step 21 and waits while watching the in-focus state. If the SW2 signal is input, the process proceeds to step 17 to control the exposure of the image sensor 108.

Next, the operation starting at step 25 is an operation when a photographic lens which is not compatible with the hybrid AF is attached. Specifically, since there is a gear train in the focus drive and there is backlash. The control mode is for a shooting lens that does not support wobbling drive, or a shooting lens that has a focus lens stop position accuracy of only 35 μm for a silver salt single-lens reflex camera.

In this case, the focusing accuracy is determined by the hybrid AF.
Although it is inferior to the case of using a compatible lens, if the output of the captured image is limited to some extent (for example, up to A5 size),
You can get the shooting results that you can appreciate. Therefore, in the present embodiment, instead of prohibiting the mounting of such a lens that does not support hybrid AF, compatibility is ensured to broaden the shooting conditions and expand the shooting opportunities.

In step 25, as in step 07, the defocus amount is calculated from the result of the phase difference detection type focus detection device 104. In step 26, a control signal is sent to the lens CPU 207 in order to drive the focus lens group 203 based on the calculated defocus amount. The camera CPU 111 calculates the defocus amount by performing the focus detection operation at any time during the driving of the lens, and in step 27, determines whether or not the focus lens group has been driven by the calculated defocus amount. ,
When the focusing result is obtained by driving the defocus amount,
Go to step 28.

In step 28, it is determined whether or not the SW2 signal is input from the release switch circuit 107, and if it is not input, the process returns to step 27 and waits while watching the in-focus state. When the SW2 signal is input, step 17
Then, the exposure control of the image sensor 108 is performed.

As described above, according to the present embodiment, when the mounted photographing lens is compatible with hybrid AF and satisfies a certain optical condition (shooting condition), the phase difference detection method and the contrast detection method are used. Since the focus adjustment control using both and is performed, the focus can be obtained with high accuracy. In addition, when the above conditions are not satisfied, focus detection by the contrast detection method is not performed, and focus adjustment control is performed only by focus detection by the phase difference detection method, so the focusing time can be shortened.

On the other hand, even when a photographic lens of an old system whose focusing precision does not correspond to the focus adjustment control method by the contrast detection method is attached, the focusing control for the focusing precision of this photographic lens is provided. Therefore, the compatibility of this taking lens can be ensured.

In the present embodiment, the focus detection means are separately provided at different positions, but the AF and the contrast detection method using the phase difference detection method by using the image pickup signals obtained by the same image pickup device. You may perform AF using.

(Second Embodiment) FIG. 4 shows a second embodiment of the present invention.
1 illustrates a configuration of a camera system including a digital camera and a photographing lens according to an embodiment. The first
The same components as those in the first embodiment are designated by the same reference numerals as those in the first embodiment and will not be described.

The camera 300 of this embodiment is provided with a distance measuring device 501 for measuring the distance to a subject and an AF processing circuit 109 equivalent to the second focus detecting means of the first embodiment. .

The distance measuring device 501 includes a light emitting diode that emits infrared light toward a subject, a light position detecting element (PSD) as a light receiving element that receives reflected light of the light emitted by the light emitting diode from the subject, and the like. The camera CPU 500 outputs a signal corresponding to the PSD output.
It is a so-called active AF device that outputs to.

The camera CPU 500 uses the distance measuring device 50.
Based on the output signal from 1, the focus adjustment control of the taking lens 200 is performed.

The camera CPU 500 uses the communication circuits 102 and 211 to connect the lens C to the lens C, as in the first embodiment.
Information is exchanged with the PU 207.

Further, the AF processing circuit 109 performs focus detection by the contrast detection method as in the first embodiment.

FIG. 5 shows a flowchart of the focus adjustment control operation mainly by the camera CPU 500 in this embodiment.

First, step (abbreviated as S in the figure) 31
Then, the camera CPU 500 uses the release switch circuit 10
It is determined whether or not the SW1 signal is input from 7, and when it is not input, this step stands by. When the SW1 signal is input, the process proceeds to step 32, the photometry circuit 105 is caused to perform photometry of the object, and the result is taken in to set the shutter speed, aperture value, sensitivity, etc. at the time of exposure.

At step 33, the camera CPU 111
Receives the current open F number information of the taking lens 200 through the lens CPU 207, and when the open F number exceeds 5.6 and is dark, the depth of field is deep, and the accuracy difference between the active AF method and the contrast detection method is noticeable. Since it disappears, for the purpose of shortening the focusing time,
In order to perform focus adjustment control in a mode in which focus detection by the contrast detection method is not performed, the process proceeds from step 35 to step 46.

On the other hand, if the open F number is brighter than 5.6, it proceeds to step 34. In the taking lens 200 of the present embodiment, the open F number is always 5.6 or less, so the process always proceeds to step 34.

In step 34, it is judged whether or not the value of the focus sensitivity S shown in FIG. 2 is 1.7 or less, and 1.7 is determined.
If the following is true, the accuracy of the focus lens position under focus drive based on the focus detection result by the active AF method will not cause any actual damage, so that step 46 through step 46 will be performed.
Proceed to.

When the value of the focus sensitivity S is larger than 1.7, the focusing accuracy is severe, so that the active A
In order to use both the F method and the contrast detection method, the process proceeds to step 36.

However, in the present embodiment, before the operation proceeds to step S46, in step 35, the current focal length is 30 based on the information from the focal length detection circuit 209 of the photographing lens.
It is determined whether or not it is on the telephoto side of 0 mm, and if it is on the telephoto side of 300 mm, the contrast detection method should be used together because the depth of field becomes shallow, so step 0
Proceed to 7. In addition, in the taking lens 200 of the present embodiment,
Since 300 mm is out of the variable range of the focal length, it does not proceed to this step.

In this embodiment, when the SW1 signal is input and the focal length is within the wide-angle end and the second divided zone from the wide-angle end, the process proceeds to step 36 (FIG. 2).
reference).

Next, in step 36, active AF is performed.
The defocus amount is calculated from the result of the distance measuring device 501 of the method. Then, based on this result, the process proceeds to step 37, and a control signal is sent to the lens CPU 207 for performing focus adjustment control (focus lens drive) of the focus lens group 203 based on the calculated defocus amount.

Then, in step 38, it is determined whether or not the focus lens group 203 has been driven by the calculated defocus amount, and after driving by the defocus amount, the process proceeds to step 39, and information is again acquired from the taking lens 200. Then, the process proceeds to step 40. In Step 40, Step 3
The information acquired in 3, 34, and 35 is compared with the information acquired in step 39, and if changed, the process returns to step 31. If there is no change, the process proceeds to step 41, where focus detection is performed by the contrast detection method to calculate the defocus amount.

In this embodiment, since focus detection by the contrast detection method is performed after focus detection by the active AF method, the focus lens group 203 already exists near the in-focus position, so in most cases The defocus amount can be calculated by the contrast detection method. When the defocus amount can be calculated, the control signal is sent to the lens CPU 207 for performing focus adjustment control based on the defocus amount as it is in step 42.

On the other hand, when the defocus amount cannot be calculated depending on the type of the subject, a control signal is sent to the lens CPU 207 to finely drive (wobbling) the focus lens group 203 in step 42, and the focus is detected by the contrast detection method. The detection is performed, and the focus determination is performed in step 43 based on the detection result. If no focusing result is obtained, the process returns to step 41.

If it is determined in step 43 that the object is in focus,
In step 44, it is determined whether or not the SW2 signal has been input from the release switch circuit 107. If no SW2 signal has been input, the flow returns to step S43 to wait while looking at the in-focus state. When the SW2 signal is input, step 4
5, the exposure control of the image sensor 108 is performed.

Next, the control starting at step 46 is based on the information from the taking lens, when the depth of field of the taking lens is deep or when the accuracy of the stop position of the focus lens is not severe, the focus width is wide and the focus is in focus. For the purpose of shortening the time, the control mode in which focus detection by the contrast detection method is not performed is shown.

First, in step 46, as in step 36, the defocus amount by the phase difference detection method is calculated. In step 47, based on the result, step 37
Similarly to the above, the lens CP is used to perform focus adjustment control (focus lens drive) based on the calculated defocus amount.
Send a control signal to U207.

Then, in step 48, the camera CPU
Reference numeral 111 denotes the defocus amount and the focus lens group 20.
3 is driven, and after driving by the defocus amount, the process proceeds to step 49, and the photographing lens 200
Information is acquired from step S50 and the process proceeds to step S50. Step 50
Then, the information acquired in steps 33, 34, and 35 is compared with the information acquired in step 49, and if changed, the process returns to step 31. If there is no change, the process proceeds to step 51, where the release switch circuit 107 switches to SW2.
It is determined whether or not a signal has been input. If no signal has been input, the process returns to step 49 and waits while watching the in-focus state. SW2
If the signal is input, the process proceeds to step 45, and the exposure control of the image sensor 108 is performed.

As described above, according to the present embodiment, when the attached photographing lens satisfies a certain optical condition (photographing condition), the focus adjustment control using both the active AF method and the contrast detection method is performed. Therefore, the focus can be obtained with high accuracy. Moreover, when the above conditions are not satisfied, focus detection by the contrast detection method is not performed,
Since the focus adjustment control is performed only by the active AF method, the focusing time can be shortened.

Incidentally. In the above-mentioned two embodiments, the threshold values for discriminating the focal length, the open F-number, the focus sensitivity, etc., which are the information obtained from the taking lens, are appropriately set according to the pixel pitch of the image sensor, the stop position accuracy of the focus lens drive, etc. Numerical values other than those described in this embodiment may be used.

In the above two embodiments, the case where the phase difference detection method, the contrast detection method, and the active AF method are combined has been described, but other methods (for example, passive AF method) may be combined.

Further, the optical condition described in the above two embodiments may be changed or added so that the focus adjustment control by only the contrast detection method can be performed.

In the first embodiment, the case where the camera of the type compatible with the hybrid AF is identified by the lens ID information acquired from the taking lens through communication has been described. Protrusions and recesses for each type are provided nearby, and a switch that is turned on by the engagement of these protrusions and recesses with the vicinity of the mount on the camera body side is provided. Based on the signal from this switch, the camera CPU determines the type of the taking lens. May be determined.

[0106]

As described above, according to the first aspect of the present invention, an optimum method for controlling focus adjustment for a photographing lens device is selected according to information about the mounted photographing lens device. The first and second
It is possible to improve the focusing accuracy by using the focus detecting means in combination, and to shorten the focusing time by not performing an unnecessary focus detecting operation.

Further, according to the second aspect of the present invention, it is possible to select an optimum focus adjustment control method for the photographic lens device according to the information about the attached photographic lens device. It is possible to improve the focusing accuracy by using together with the focus detection means and to shorten the focusing time by not performing unnecessary distance measurement or focus detection operation.

Further, according to the first and second aspects of the present invention, if the control means is caused to perform only the focus adjustment control according to the focus adjustment control method supported by the taking lens device, the other It is possible to ensure the compatibility of the taking lens device that is not compatible with the control method.

[Brief description of drawings]

FIG. 1 is a block diagram of a camera system according to a first embodiment of the present invention.

FIG. 2 is a table showing ROM information relating to focus sensitivity of a photographing lens which constitutes the camera system.

FIG. 3 is a flowchart showing an operation of a camera that constitutes the camera system.

FIG. 4 is a block diagram of a camera system according to a second embodiment of the present invention.

FIG. 5 is a flowchart showing an operation of a camera that constitutes the camera system of the second embodiment.

[Explanation of symbols]

100,300 Camera body 101 prism 102 camera communication circuit 103 Penta prism 104 Focus detection device 105 Photometric circuit 106 finder optical system 107 Release switch circuit 108 image sensor 109 AF processing circuit 110 power supply 111,500 camera CPU 112 display circuit 113 Setting switch circuit 200 interchangeable shooting lens 201 first lens group 202 Zoom lens group 203 Focus lens group 204 aperture 205 diaphragm drive circuit 206 operation switch 207 lens CPU 208 Focus drive circuit 209 Focal length detection circuit 210 memory circuit 211 Lens communication circuit 400 subjects 501 range finder

Front page continued (51) Int.Cl. ⁷ Identification code FI theme code (reference) H04N 5/232 G03B 3/00 A (72) Inventor Takashi Suzuki 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. In-house (72) Inventor Masanori Ishikawa 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Seiichi Kashiwaha 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. F Terms (reference) 2H011 AA03 BA21 BA31 BB04 CA01 CA21 2H051 AA00 BA02 BA47 DA02 EB06 EB13 EB20 EC04 EC05 2H101 EE08 EE23 EE24 5C022 AA11 AB29 AB66 AC54 AC69 AC74

Claims (23)

[Claims] 1. A camera in which a taking lens device is attachable / detachable and replaceable, and first and second focus detecting means having different systems for detecting a focus adjustment state of the taking lens device, and the first and second focus detecting means. And a control unit for performing focus adjustment control of the photographic lens device by using the detection result of the focus detection unit, the control unit according to information on the mounted photographic lens device. A camera, characterized in that a method of focus adjustment control performed by using a detection result by one or both of the second focus detection means is changed. 2. The control means obtains information about the photographing lens device by communicating with the attached photographing lens device, and selects one of the first and second focus detection means according to the obtained information. The camera according to claim 1, wherein a method of focus adjustment control performed by using a detection result of one or both focus detection means is changed. 3. The camera according to claim 2, wherein the information regarding the taking lens device is information regarding a focal length of the taking lens device. 4. The camera according to claim 2, wherein the information regarding the taking lens device is information regarding a depth of field of the taking lens device. 5. The camera according to claim 2, wherein the information regarding the taking lens device is information regarding an open F number of the taking lens device. 6. The camera according to claim 2, wherein the information on the photographing lens device is information on the sensitivity of image plane displacement to the movement of the focus lens group in the photographing lens device. 7. The camera according to claim 2, wherein the information about the taking lens device is information about a focus adjustment control method supported by the taking lens device. 8. An image pickup device for picking up a subject image through the photographing lens device, wherein the first and second focus detection means respectively detect differently using an image pickup signal obtained by the image pickup device. 8. The camera according to claim 1, wherein the camera is of a system. 9. The control means uses a method of focus adjustment control, which performs focus adjustment control using a detection result of the first focus detection means, and a detection result of the second focus detection means. Focus adjustment control method and the second result when it is determined that the subject is in a predetermined low contrast state using the detection result of the first focus detection means.
9. The camera according to claim 1, wherein the method is changed between at least two methods of performing focus adjustment control using the detection result of the focus detection means of. 10. The first focus detecting means is a phase difference detecting focus detecting means, and the second focus detecting means is a contrast detecting focus detecting means. 9. The camera according to any one of 9. 11. A camera in which a taking lens device is attachable / detachable and replaceable, and distance measuring means for detecting a distance to a subject,
A camera having focus detection means for detecting a focus adjustment state of the photographing lens device and control means for performing focus adjustment control of the photographing lens device using detection results of the distance measuring means and the focus detection means, The means changes the method of focus adjustment control performed by using the detection result of one or both of the distance measuring means and the focus detecting means, according to information about the mounted photographing lens device. . 12. The control means obtains information about the taking lens device by communicating with the attached taking lens device, and one of the distance measuring means and the focus detecting means is obtained according to the obtained information. The camera according to claim 11, wherein a method of focus adjustment control performed by using detection results of both of them is changed. 13. Information relating to the taking lens device includes:
The camera according to claim 12, wherein the information is about a focal length of the photographing lens device. 14. Information relating to the taking lens device comprises:
The camera according to claim 12, wherein the information is information regarding a depth of field of the taking lens device. 15. Information relating to the taking lens device comprises:
The camera according to claim 12, wherein the information is information regarding an open F number of the taking lens device. 16. Information relating to the taking lens device comprises:
13. The camera according to claim 12, wherein the information is information regarding the sensitivity of the image plane displacement to the movement of the focus lens group in the photographing lens device. 17. Information relating to the taking lens device comprises:
The camera according to claim 12, wherein the information is information regarding a focus adjustment control method supported by the taking lens device. 18. An image pickup device for picking up a subject image through the taking lens device, wherein the focus detection means is of a detection system using an image pickup signal obtained by the image pickup device. The camera according to any one of claims 11 to 17. 19. The control means performs a focus adjustment control method using the detection result of the distance measuring means, and a focus adjustment control using the detection result of the focus detection means. At least two of the method and the method of performing focus adjustment control using the detection result of the focus detection means after performing focus adjustment control using the detection result of the distance measuring means are changed. The camera according to any one of claims 11 to 18. 20. The focus detection means is a focus detection means of a contrast detection method.
The camera according to any one of 1 to 19. 21. A camera according to any one of claims 1 to 20, and a taking lens device which can be attached to and detached from the camera, wherein the information about the taking lens device is attached to the camera. And a taking lens device capable of performing focus adjustment control by the control means. 22. The camera system according to claim 21, wherein the taking lens device is compatible with a plurality of focus adjustment control methods by the control means. 23. A photographic lens device attachable to and detachable from the camera according to claim 1, wherein information on the photographic lens device attached to the camera is transmitted to the camera, and A photographing lens device, wherein focus control can be controlled by a control means.