JP2013238746A - Camera body and camera system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce an influence by a change in image magnification caused by movement of a focus lens to quickly focus on an object even when the change in image magnification is large.SOLUTION: A camera body to and from which an interchangeable lens having a variable power lens and a focus lens can be attached and detached includes control means performing a micro amplitude operation of the focus lens with respect to the interchangeable lens, to permit an operation for focusing on an object, when the variable power lens and the focus lens are at predetermined positions respectively and when a change amount of image magnification when the focus lens is moved by a predetermined amount is a predetermined value or less, and permitting the operation for focusing on the object, without performing the micro amplitude operation of the focus lens with respect to the interchangeable lens, when the variable power lens and the focus lens are at the predetermined positions respectively and when the change amount of the image magnification is larger than the predetermined value.

Description

  The present invention relates to a camera body, and more particularly to a driving method of a focus lens when performing autofocus.

  Conventionally, as a focus autofocus (hereinafter referred to as AF) at the time of moving image shooting, a focus type AF (wobbling) is performed so that the focus lens is controlled to be guided to a focus position while determining a focus state from an imaging signal. There is. It is also known that when a lens with high optical sensitivity such as a focus lens is moved, an image magnification change is caused by the movement depending on the focal length and F value conditions. For this reason, there is a possibility that a change in image magnification becomes noticeable due to wobbling of the focus lens.

  Therefore, Patent Document 1 holds association information that associates information on the position of the zoom lens with information indicating a change in image magnification that occurs when the focus lens is controlled by wobbling, and based on this information, the wobbling information is stored. It discloses changing the amplitude or driving speed.

JP 2010-271696 A

  As described above, in Patent Document 1, the amplitude or speed during wobbling is changed based on a change in image magnification. Specifically, when it is determined that the change in the image magnification is larger than a predetermined value, the wobbling amplitude is decreased or the wobbling driving speed is decreased.

  However, in this method, if the change in image magnification is larger than a predetermined value, it takes time to find the focal point.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a camera body and a camera system that can reduce the influence of a change in image magnification accompanying the movement of a focus lens and can quickly focus on a subject even if the change in image magnification is large. That is.

  According to a first aspect of the present invention, in a camera body to which an interchangeable lens having a variable power lens and a focus lens can be attached and detached, the focus lens is located when the variable power lens and the focus lens are respectively in predetermined positions. When the amount of change in image magnification when the fixed amount is moved is less than or equal to a predetermined value, the interchangeable lens is allowed to operate the focus lens with a minute amplitude to focus on the subject, and the amount of change in image magnification is When it is larger than a predetermined value, it has control means for permitting an operation of focusing the subject on the interchangeable lens without operating the focus lens with a minute amplitude.

  In addition, according to a second aspect of the present invention, in a camera body in which a single focus interchangeable lens having a focus lens is removable, an image magnification change amount when the focus lens is moved by a predetermined amount at a predetermined position is a predetermined value or less. In this case, the focus lens is allowed to operate with a small amplitude with respect to the interchangeable lens, and the focus is adjusted with respect to the subject when the image magnification change amount is larger than the predetermined value. It has a control means for permitting the operation of focusing on the subject without operating the lens with a minute amplitude.

  According to a third aspect of the present invention, there is provided a camera system having an interchangeable lens and a camera body, wherein the interchangeable lens moves in the optical axis direction and a variable power lens that changes a focal length and moves in the optical axis direction. This corresponds to the amount of change in image magnification when the focus lens is moved by a predetermined amount when the focus lens for changing the in-focus state of the subject image, the variable power lens, and the focus lens are at predetermined positions, respectively. Storage means for storing information to be stored, and the camera body is based on information corresponding to the stored image magnification change amount, information on the position of the zoom lens, and information on the position of the focus lens When the obtained image magnification change amount is equal to or smaller than a predetermined value, the operation of focusing the subject on the interchangeable lens by operating the focus lens with a small amplitude is permitted. When the image magnification change amount obtained based on the stored information corresponding to the image magnification change amount, the information about the position of the variable magnification lens, and the information about the position of the focus lens is larger than the predetermined value, the interchangeable lens On the other hand, there is provided control means for permitting an operation of focusing the subject without operating the focus lens with a minute amplitude.

  According to a fourth aspect of the present invention, there is provided a camera system having a single-focus interchangeable lens and a camera body, wherein the interchangeable lens moves in the optical axis direction and changes a focus state of a subject image. Storage means for storing information corresponding to an image magnification change amount when the focus lens is moved by a predetermined amount at a predetermined position, and the camera body corresponds to the stored image magnification change amount. When the amount of change in the image magnification obtained based on the information and information on the position of the focus lens is equal to or less than a predetermined value, an operation of focusing the subject on the interchangeable lens by operating the focus lens with a minute amplitude The image magnification change amount obtained based on the information corresponding to the stored image magnification change amount and the information on the position of the focus lens is greater than the predetermined value. If, having control means for permitting focuses operation on the subject of the focus lens to the interchangeable lens without small amplitude operation, characterized in that.

  According to the present invention, it is possible to reduce the influence due to the change in image magnification accompanying the movement of the focus lens, and to focus on the subject quickly even if the change in image magnification is large.

The figure showing the camera system of a present Example Communication between camera and lens and operation timing chart Diagram showing the effect of the screen due to image magnification change Relationship between image magnification change amount, focus lens position, magnification lens position, F value Flow chart on the interchangeable lens side of this embodiment Flowchart on the camera body side of this embodiment

  Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a block diagram of a camera system including an interchangeable lens and a camera body according to an embodiment of the present invention.

  The configuration of the camera system will be described below with reference to FIG. The camera system of the present invention includes an interchangeable lens 100 and a camera body 200.

  The interchangeable lens 100 can be attached to and detached from the camera body 200. The interchangeable lens 100 and the camera body 200 can be connected to each other by connecting their power supply pins and communication pins to each other so that bidirectional communication is possible. Become.

  The interchangeable lens 100 is divided into an optical member and a part that controls the optical member. The optical member includes a zoom lens 101 that moves in the optical axis direction to change the focal length, a focus lens 102 that moves in the optical axis direction to change the in-focus state of the subject image, and a diaphragm 103 that adjusts the amount of light. . An image is formed on the image sensor 201 of the camera body 200 while the amount of light is appropriately adjusted by these optical members.

  The optical member is controlled by an actuator such as a lens communication unit 104 for communicating with the camera microcomputer 202, a focus motor 105 for moving the focus lens 102, and a diaphragm motor 106 for driving the diaphragm 103. is there. A stepping motor or the like can be used for the focus motor 105 and the aperture motor 106.

  When a stepping motor is used, the position of the object can be detected by counting the amount of pulses driven after the reset operation. In the case of other actuators, the position of the focus lens and the aperture position can be detected by separately providing a position detection means.

  Further, there are a focus drive driver 107 for driving the focus motor 105 and an aperture drive driver 108 for driving the aperture motor 106. By controlling the focus drive driver 107 and the aperture drive driver 108 by the lens microcomputer 109, the optical member can be appropriately controlled.

  The zoom operation unit 110 operates the zoom lens 101 to change the focal length. For example, the zoom operation unit 110 and the zoom lens 101 operate in conjunction with each other through a mechanical member such as a zoom ring. The position can be adjusted. Further, there is a zoom position detecting means 111 constituted by a potentiometer for detecting the position of the variable power lens 101. The zoom lens position is converted into an electric signal and detected as digital data by an AD converter in the lens microcomputer 109. can do. Further, by storing correspondence data between the zoom lens position and the focal length in advance, the lens microcomputer 109 can acquire the focal length by referring to the result of the zoom position detecting unit 111.

  Further, by storing correspondence data between the focus lens position and the subject distance in advance, the lens microcomputer 109 can acquire the subject distance from the focus lens position.

  Similarly, by storing correspondence data between the aperture position and the F value (aperture value) in advance, the lens microcomputer 109 can acquire the F value from the aperture position.

  The memory 112 as storage means stores data corresponding to the image magnification change amount when the focus lens 102 is moved by a predetermined amount at a certain magnification lens position and a certain focus lens position. That is, information corresponding to the amount of change in image magnification when the focus lens 102 is moved by a predetermined amount when the variable magnification lens 101 and the focus lens 102 are at predetermined positions is stored. Here, the specified amount can be the amount of movement of the focus lens 102 when the specified defocus amount (F = 1, Δ = specified amount) is moved, for example. Further, if Δ is based on the confusion circle of the optical system of the interchangeable lens, it can be normalized in the same way even when the optical system of the interchangeable lens is changed.

  As described above, the zoom lens position and the focal length, and the focus lens position and the subject distance are in a corresponding relationship. Therefore, for example, instead of the zoom lens position and the focus lens position, data corresponding to the image magnification change amount corresponding to the focal distance and the subject distance may be used.

  In the camera body 200, an image sensor 201 that forms an image of light passing through the interchangeable lens 100 and converts it into an electrical signal is disposed. The video signal converted into an electrical signal by the image sensor 201 is sent to the video processing unit 203, and video processing such as luminance adjustment, video size change, white balance adjustment, color adjustment, and the like is performed to produce an appropriate video. Video information appropriately processed by the video processing unit 203 is sent to a display unit 204 such as a liquid crystal panel as an output unit, or a recording unit 205 including a semiconductor storage device, a hard disk, a magnetic tape, etc. The The video data processed by the video processing unit 203 is sent to the AF unit 206 and the AE unit 207.

  The AF unit 206 extracts contrast data from the video information, generates focus evaluation value information for determining how much the image is focused, and generates information for controlling the focus lens 102 of the interchangeable lens 100. Further, the AE unit 207 extracts luminance information from the video information, generates AE evaluation information for determining whether the exposure is over or under, and generates information for controlling the diaphragm 203 of the interchangeable lens 100. Also, the camera microcomputer 202 that performs control in the camera body 200 communicates with the lens communication unit 104 of the interchangeable lens 100 via the camera communication unit 208. The camera body 200 receives information inside the interchangeable lens 100, such as current focus lens position information, variable magnification lens position information, aperture information, and the like. Then, based on the information and the information of the AF unit 206, the AE unit 207, and the image processing unit 203, information for controlling each lens is transmitted to the interchangeable lens 100 side via the camera communication unit 208. Then, the interchangeable lens 100 controls each lens based on the transmitted information.

  Next, communication between the interchangeable lens 100 and the camera body 200 and various operation timings will be described with reference to FIG.

  In FIG. 2, various operations are arranged vertically, the horizontal axis represents the passage of time, and various operations (a) to (f) in the passage of time are schematically described.

  The LTC of (a) represents communication from the interchangeable lens 100 to the camera body 200, and the High period represents the period during which data is transmitted from the interchangeable lens 100 to the camera body 200. Similarly, CTL in (b) represents communication from the camera body 200 to the interchangeable lens 100, and a High period represents a period during which data is transmitted from the camera body 200 to the interchangeable lens 100.

  The AF drive command generation in (c) represents the timing for generating the AF drive command for the interchangeable lens 100 within the camera body 200, and the generation period is represented by a rectangle. Similarly, the AF drive command in (d) represents a process for actually driving the focus lens in the interchangeable lens 100 based on the AF drive command received from the camera body 200, and each period for driving the focus lens is shown in FIG. It is represented by a rectangle. Here, the process for driving the focus lens is to send the focus lens target position and drive speed to the focus drive driver 107 to prepare for the focus lens drive.

  In the image magnification calculation of (e), the period during which the image magnification change amount is calculated is represented by a rectangle.

  The focus lens position in (f) schematically represents how the focus lens position changes according to the focus lens drive command specified by the AF drive command in (d). The vertical direction represents the position of the focus lens.

  Further, communication between the interchangeable lens 100 and the camera body 200 is periodically performed according to the accumulation time of the image sensor.

  A series of flows will be described. At the timing when LTC is High (<1> in FIG. 2), the focus lens position and the image magnification change amount are transmitted from the interchangeable lens 100 to the camera body 200 by communication. The camera body 200 calculates an AF evaluation value from the video data obtained by the image sensor 201.

  Then, based on the position of the focus lens 102 sent from the interchangeable lens 100 and the calculated AF evaluation value, the position, direction, amount, and speed of the next movement of the focus lens are set in the AF drive command generation period (in FIG. 2). <2>). The calculated information (position or direction, amount, speed) is transmitted as an AF drive command from the camera body 200 to the interchangeable lens 100 at a timing when LTC is High (<3> in FIG. 2).

  In response to this, the interchangeable lens 100 performs a process of actually operating the focus lens 102 during the AF drive command period (<4> in FIG. 2). Then, before the timing of the next High of LTC (<5> in FIG. 2) comes, a position (predicted position) where the focus lens 102 is expected to arrive at the timing of High next to LTC is calculated. Further, the current zoom lens position is acquired by the zoom position detecting means 111. Then, the interchangeable lens 100 selects data corresponding to the current zoom lens position and focus lens position from data corresponding to the image magnification change amount stored in the memory 112 in advance. Then, using the selected data and the current F value, the image magnification change amount corresponding to the current F value of the interchangeable lens 100 is acquired. The image magnification change amount corresponding to the F value may be obtained by simply multiplying the data corresponding to the current zoom lens position and the focus lens position by the current F value, or by multiplying some coefficient. Good. As described above, the F value has a correspondence relationship with the aperture position. Therefore, here, the aperture position may be used instead of the F value. Then, at the High timing next to LTC (<5> in FIG. 2), the calculated information of the predicted position of the focus lens 102 and the image magnification change amount is transmitted from the interchangeable lens 100 to the camera body 200.

  By repeating such a series of operations, information on the image magnification change amount according to the current state of the interchangeable lens 100 when the focus lens is moved by a predetermined amount is periodically (for example, in V cycle). 200 side can be notified.

  Further, for example, when the image magnification change amount calculated in the period <6> in FIG. 2 exceeds a predetermined magnitude, it is considered that the change in the angle of view due to the wobbling operation becomes large. Therefore, in this case, at the timing of t1 in FIG. 2, the camera body 200 changes from the wobbling AF in which the focus lens 102 is operated with a small amplitude to the non-wobbling AF in which the focus lens 102 is not operated with a small amplitude. Thereby, it is possible to perform appropriate focus control with less change in the angle of view. Here, the non-wobbling AF may be an AF method that searches the peak value of the contrast while scanning the focus lens in the optical axis direction as long as it is an AF method that focuses the subject without operating the focus lens with a minute amplitude. A phase difference AF method may be used.

  Here, what the image magnification change is will be described. In general, the image magnification change is an image change that occurs when the optical system of the lens is changed. For example, the change rate of the angle of view when the variable power lens is moved in the optical axis direction is defined as an image magnification change amount. For example, if the zoom lens is moved to the Wide side, the angle of view becomes larger as shown in FIG. 3A, and if it is moved to the Tele side, it moves as shown in FIG. 3B. It becomes smaller with respect to the angle of view before making it. Thus, the amount of change in image magnification represents how much the angle of view changes before and after changing the optical system. The image magnification change amount may be, for example, a change rate of the entire screen or a diagonal change rate. The standard can be defined by the rate of change of video if the definition is the same.

  Next, correspondence between the image magnification change amount and various optical systems will be described with reference to FIG.

  In FIG. 4A, the horizontal axis represents the focus lens position, the vertical axis represents the image magnification change amount, and the image magnification change amount with respect to the focus lens position is shown. Here, it is assumed that the zoom lens position and the aperture position are fixed. As can be seen from the figure, the image magnification change amount decreases as the focus lens is moved so that the subject distance changes from the infinite side to the close side.

  FIG. 4B shows the image magnification change amount with respect to the magnification lens position, with the magnification lens position on the horizontal axis and the image magnification change amount on the vertical axis. Here, the focus lens position and the aperture position are considered fixed. As can be seen from the figure, the amount of change in image magnification increases as the zoom lens is moved so that the focal length changes from the Wide side to the Tele side.

  In FIG. 4C, the horizontal axis represents the F value, the vertical axis represents the image magnification change amount, and the image magnification change amount with respect to the F value is shown. Here, the zoom lens position is fixed, and the subject distance is changed to L1, L2, and L3 (L1 <L2 <L3). As can be seen from the figure, the amount of change in image magnification increases as the aperture is reduced from the Open side to the Close side (F value is increased). Further, as the subject distance becomes shorter, the change in the image magnification change amount becomes steep.

  In this way, the image magnification change amount changes as the magnification lens position, the focus lens position, and the F value change.

  Therefore, on the interchangeable lens 100 side, the image magnification change amount data per FΔ multiplied by the current effective F value with respect to the image magnification change amount data per confusion circle Δ corresponding to the current zoom lens position and focus lens position. Is sent to the camera body 200 side.

  The camera body 200 calculates a wobbling amplitude amount when the focus lens 102 performs a wobbling operation. If the calculated wobbling amplitude amount is, for example, 1 / 4FΔ, the image magnification change amount with respect to 1 / 4FΔ is calculated. When the image magnification change amount is larger than a predetermined value, the change in the angle of view can be reduced by changing the AF driving method as described above.

  Next, the operation flow of the interchangeable lens and the camera body will be described using the flowcharts of FIGS. The flowchart in FIG. 5 shows the operation of the interchangeable lens. The flowchart in FIG. 6 shows the operation of the camera body.

  First, the operation of the interchangeable lens will be described with reference to FIG. The operation of the interchangeable lens starts from S501. In S502, an AF drive command is received from the camera body and the focus lens is controlled. Then, after driving the focus lens based on the AF drive command, various states of the optical member in the interchangeable lens are detected and calculated in S503. The various states include a zoom lens position, a focus lens position, an F value, and the like. In step S504, the image magnification change amount is calculated based on various states, and the image magnification change amount calculated in step S505 is transmitted to the camera body. Thereby, the image magnification change amount in the current state of the interchangeable lens can be transmitted to the camera body.

  Next, the operation of the camera body will be described with reference to FIG. The operation of the camera body starts from S601. First, in S602, the image magnification change amount in the current state of the interchangeable lens is received from the interchangeable lens. In step S603, the camera body calculates a wobbling amplitude amount. In step S604, the wobbling amplitude amount calculated in step S603 and the image magnification change amount acquired in step S602 are used to calculate an image magnification change amount when the wobbling amplitude amount is moved. calculate. In step S605, it is determined whether the image magnification change amount calculated in step S604 is greater than a predetermined value. If it is greater than the predetermined value, it is determined that the influence of the change in the angle of view is large, and the process proceeds to S606, where the AF mode is set to non-wobbling AF, and the focusing operation by non-wobbling is permitted for the interchangeable lens. If it is equal to or smaller than the predetermined value in S605, the process proceeds to S607. In S607, the AF mode is set to wobbling AF, and a focusing operation by wobbling is permitted for the interchangeable lens. Next, in AF set in S606 or S607, an AF drive command for the interchangeable lens is transmitted in S608. Thus, the camera body determines the AF operation method according to the image magnification change amount.

  As described above, when the image magnification change amount is larger than the predetermined value, since the focusing operation is performed by the non-wobbling AF, the subject is faster than the case where the wobbling amplitude is reduced or the driving speed is lowered. It becomes possible to focus on.

  Further, in the case of the wobbling operation, the image magnification change repeatedly occurs in accordance with the operation, so that the user may feel uncomfortable depending on the size. However, in the case of non-wobbling AF, even if a change in image magnification occurs, it does not occur repeatedly. Therefore, it is possible to reduce the influence due to the change in image magnification.

  In the above-described embodiments, the interchangeable zoom lens has been described, but an interchangeable single focus lens can be similarly implemented. In this case, since the zoom lens does not exist, it is sufficient to have data corresponding to the image magnification change amount when the specified focus lens movement amount is moved at a certain focus lens position.

  Further, in the above-described embodiment, the image magnification change amount is calculated based on the zoom lens position, the focus lens position, and the F value with the interchangeable lens, and is transmitted to the camera body side. However, for example, data corresponding to the image magnification change amount from the interchangeable lens in the initial communication is received by the camera body and stored in the memory, and based on the variable magnification lens position, the focus lens position, and the F value transmitted from the interchangeable lens. The camera body may be configured to calculate the image magnification change amount.

DESCRIPTION OF SYMBOLS 100 Interchangeable lens 101 Variable magnification lens 102 Focus lens 103 Diaphragm 104 Lens communication part 109 Lens microcomputer 112 Memory 200 Camera main body 202 Camera microcomputer

Claims (6)

In the camera body in which an interchangeable lens having a variable power lens and a focus lens can be attached and detached,
When the amount of change in image magnification when the focus lens is moved by a predetermined amount when the variable magnification lens and the focus lens are at predetermined positions is less than a predetermined value, the focus lens is slightly moved with respect to the interchangeable lens. An operation of allowing the subject to be focused by performing an amplitude operation, and when the amount of change in the image magnification is greater than the predetermined value, an operation of focusing the subject on the interchangeable lens without causing the focus lens to perform a minute amplitude operation. A camera body having control means for permitting the operation. In the camera body with a detachable single-focus interchangeable lens with a focus lens,
When the amount of change in image magnification when the focus lens is moved by a predetermined amount at a predetermined position is less than or equal to a predetermined value, the operation of focusing the subject on the interchangeable lens by operating the focus lens with a minute amplitude is permitted. And a camera body having control means for permitting the interchangeable lens to focus on a subject without operating the focus lens with a small amplitude when the image magnification change amount is larger than the predetermined value. . In a camera system having an interchangeable lens and a camera body,
The interchangeable lens is
A zoom lens that moves in the direction of the optical axis to change the focal length;
A focus lens that moves in the direction of the optical axis and changes the focus state of the subject image;
Storage means for storing information corresponding to an amount of change in image magnification when the focus lens is moved by a predetermined amount when the variable magnification lens and the focus lens are respectively at predetermined positions;
Have
The camera body is
When the image magnification change amount obtained based on the information corresponding to the stored image magnification change amount, the information on the position of the variable power lens, and the information on the position of the focus lens is less than a predetermined value, On the other hand, an operation of focusing the subject by operating the focus lens with a minute amplitude is permitted, information corresponding to the stored image magnification change amount, information regarding the position of the zoom lens, and information regarding the position of the focus lens When the image magnification change amount obtained based on the above is larger than the predetermined value, the interchangeable lens has a control unit that permits an operation to focus the subject without causing the focus lens to perform a minute amplitude operation.
A camera system characterized by that. The interchangeable lens is
An aperture for adjusting the amount of light,
The image magnification change amount is acquired based on the information corresponding to the stored image magnification change amount, information on the position of the variable power lens, information on the position of the focus lens, and information on the aperture value of the diaphragm. The camera system according to claim 3, further comprising an acquisition unit. In a camera system having a single focus interchangeable lens and a camera body,
The interchangeable lens is
A focus lens that moves in the direction of the optical axis and changes the focus state of the subject image;
Storage means for storing information corresponding to an image magnification change amount when the focus lens is moved by a predetermined amount at a predetermined position;
Have
The camera body is
When the image magnification change amount obtained based on the information corresponding to the stored image magnification change amount and the information on the position of the focus lens is equal to or smaller than a predetermined value, the focus lens is moved to a minute amplitude with respect to the interchangeable lens. The image magnification change amount obtained based on the information corresponding to the stored image magnification change amount and the information on the position of the focus lens is greater than the predetermined value. A control means for permitting the subject to focus on the subject without moving the focus lens by a minute amplitude with respect to the interchangeable lens,
A camera system characterized by that. The interchangeable lens is
An aperture for adjusting the amount of light,
Obtaining means for acquiring the image magnification change amount based on the information corresponding to the stored image magnification change amount, the information on the position of the focus lens, and the information on the aperture value of the diaphragm. The camera system according to claim 5.

Images