JP2005140943A - Focusing-assisting device, drive unit, photographic lens, and photographic system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain information of a focus state at need during manual focusing operation, without inviting an increase in cost and in weight. <P>SOLUTION: In information for displaying the focus state of a photographic lens in a focusing assist device (drive unit 3) used for the photographic lens 2, provided with a focus lens 10 moved in response to manual operation, the focusing-assist device includes an information-generating means 12 for generating display information displaying change of the focus state accompanying the movement of the focusing lens, and an output means 36 for outputting the display information on a display means. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a focus assist device that displays an instruction display for a manual focus operation of a photographing lens.

  Many consumer cameras and photographic lenses often have an autofocus (AF) function. On the other hand, business cameras and photographic lenses used by professional photographers rarely have an AF function. This is because a professional photographer often intentionally obtains various focus states not only for focusing but also for video effects such as so-called blurring effects.

  However, for recent HD cameras, TV lenses with higher resolution and a shallow depth of field are often used. When such a lens with a shallow depth of field is used, especially in a portable type camera in which a photographer takes a picture on his / her shoulder, the cameraman focuses on an image displayed on a viewfinder (VF) mounted on the camera. Although the focus operation is performed while checking the state, it is difficult to determine whether or not the intended focus state is obtained in such a small image.

In view of this, a method for assisting (instruction) manual focus operation other than the AF function has been proposed. For example, in the photographing apparatus proposed in Patent Document 1, a part of the lenses in the photographing optical system is wobbled (micro reciprocating operation) during manual focusing, and the contrast signal obtained from the video signal is compared and calculated at this time. Information on whether the focus position is the front pin is the rear pin or in focus is displayed on the VF of the camera.
Japanese Patent Laid-Open No. 5-308552 (paragraphs 0017 to 0023, FIGS. 1 to 3 etc.)

  However, in the photographing apparatus proposed in Patent Document 1, a wobbling operation is performed when the switch is switched from autofocus to manual focus, and only the focus state at that time is displayed. For this reason, focus state information is not obtained when necessary during a manual focus operation.

  In addition, providing a lens that performs a wobbling operation in the photographing optical system restricts the degree of freedom in optical design, and at the same time requires a wobbling drive mechanism, resulting in an increase in cost and weight. .

  Further, in the conventional photographing apparatus such as Patent Document 1 described above, information indicating the moving direction of the focus lens for obtaining the focus can be obtained, but represents the focus state within the focus range (the depth of focus). You cannot get information.

  Especially in the case of an HD lens with a shallow depth, if the focus state in the in-focus range can be grasped, it can be confirmed that the subject is sufficiently in the in-focus range, or an extra object near the subject is in the in-focus range. You can also make a video that was removed from. In addition, by changing the F number or focal length, it is possible to predict or confirm whether or not blur will occur in advance, which is a guideline for focus adjustment when changing the aperture and zoom conditions. However, such information cannot be obtained with a conventional photographing apparatus.

  According to the present invention, focus state information can be obtained as needed during manual focus operation without incurring an increase in cost or weight, and further, information representing a focus state within a focus depth that has not been obtained in the past can be obtained. An object of the present invention is to provide a focus assist device, a drive unit, a photographing lens, and a photographing system.

  In order to achieve the above object, the present invention provides information for displaying a focus state of a photographic lens in a focus assist device used for a photographic lens having a focus lens that moves according to a manual operation. And an information generating unit that generates display information that also represents a change in the focus state accompanying the movement of the focus lens, and an output unit that outputs the display information to the display unit.

  Here, the information generation unit may generate the display information based on a video signal input from a camera that performs imaging using the imaging lens.

  The display information may display a focus state with respect to a focus state of the photographic lens and a focus state within a focus range (depth of field or depth of focus) of the photographic lens.

  In addition, the information generation means may be capable of generating a plurality of different display information, and a selection means for allowing the user to select display information to be output to the display means may be provided.

  According to the present invention, since the display information of the focus state that changes with the movement of the focus lens is obtained, the user can see the focus direction, the focus position, the focus state within the focus range, etc. while viewing the information. Can be recognized. Moreover, since no special mechanism such as a wobbling mechanism is used, display information that assists in manual focus operation can be displayed as needed without incurring an increase in cost or weight.

  In particular, by displaying the focus state within the in-focus range, it is possible not only to check whether the subject is in the in-focus range, but also to create an image that removes extraneous objects near the subject from the in-focus range. Various video effects can be easily obtained. Also, by displaying the focus state within the in-focus range, it is possible to predict or confirm the occurrence of blurring when changing the F number or focal length. Also useful information.

  By mounting the focus assist device of the present invention on the drive unit, the above effects can be obtained without changing the configuration of the existing photographing lens and camera.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 shows the external appearance of a zoom camera system (photographing system) used for television photography or the like, which is Embodiment 1 of the present invention.

  In the figure, 1 is a TV camera, and 2 is a zoom lens (photographing lens) attached to the camera. In the zoom lens 2, a photographing optical system including a focus lens, a variable power lens, a diaphragm, and the like 3 described later is mounted.

  A drive unit 3 is mounted on the side surface of the zoom lens 2. The drive unit 3 houses a variable power lens in the zoom lens 2, a motor for driving a diaphragm, a detector for detecting the position of each lens, and the like. A zoom switch 4 and various operation switches are provided on the exterior surface of the drive unit 3.

  Reference numeral 5 denotes a focus ring for adjusting the position of the focus lens in the zoom lens 2, which is manually operated by the user.

  Reference numeral 6 denotes a cable for supplying power from the camera 1 to the drive unit 3 and for exchanging signals between the camera 1 and the drive unit 3.

  Reference numeral 8 denotes a video output terminal provided in the camera 1, from which a video image signal is output to the drive unit 3 via the cable 9. Reference numeral 7 denotes a viewfinder (hereinafter referred to as VF) provided in the camera 1, which is constituted by a liquid crystal display or the like.

  Next, in the zoom camera system, a configuration related to an assist function when performing manual focus adjustment will be described with reference to FIG. The zoom camera system includes a camera unit composed of a TV camera 1 and a lens unit composed of a zoom lens 2 and a drive unit 3.

  First, in the lens unit, 10 is a focus lens that can move in the optical axis direction, and 11 is a focus position detector mounted on the drive unit 3 in order to detect the position of the focus lens 10. When the focus ring 5 is rotated, the focus lens 10 is moved in the optical axis direction by a cam mechanism (not shown) or the like. Thereby, focus adjustment by manual operation is possible. Hereinafter, this focus adjustment is referred to as manual focus. The focus position detector 11 outputs an electrical signal according to the rotation transmitted from the focus ring 5 via a gear mechanism (not shown).

  Reference numeral 12 denotes a CPU as a controller that controls the drive unit 3. Based on the signal from the focus position detector 11, the CPU 12 detects the position of the focus lens 10 (hereinafter referred to as the focus position) and the movement direction (hereinafter referred to as the focus direction) corresponding to the rotational position of the focus ring 5.

  Reference numeral 15 denotes a variable power lens movable in the optical axis direction, and reference numeral 24 denotes a fixed relay lens. Reference numeral 16 denotes a zoom position detector for detecting the position of the zoom lens 15 and is mounted on the drive unit 3. When the zoom switch 4 provided in the drive unit 3 is operated, the zoom lens 15 is moved in the optical axis direction by a zoom motor (not shown). The zoom position detector 16 outputs an electrical signal in accordance with the rotation transmitted from the zoom motor via a gear mechanism (not shown). Based on the signal from the zoom position detector 16, the CPU 12 can detect the position and moving direction of the zoom lens 15 driven by the zoom motor.

  Reference numeral 17 denotes an aperture. A diaphragm position detector 18 detects the position (opening diameter or F number) of the diaphragm 17 and is mounted on the drive unit 3. When the aperture switch provided in the drive unit 3 is operated, the aperture diameter of the aperture 17 is changed by the aperture motor. The aperture position detector 18 outputs an electrical signal in accordance with the rotation transmitted from the aperture motor through a gear mechanism (not shown). The CPU 12 can detect the position and opening / closing direction of the diaphragm 17 driven by the diaphragm motor based on the signal from the diaphragm position detector 18.

  Reference numeral 19 denotes an extender lens that can be taken in and out of the photographing optical system. The drive unit 3 is also provided with an extender detector 20 for detecting whether or not the extender lens 19 is inserted in the photographing optical system, and the CPU 12 is based on a signal from the extender detector 20. The insertion state and non-insertion state of the extender lens 19 are detected.

  In the drive unit 3, reference numeral 25 denotes a mode changeover switch such as a multi-position changeover type or a circulation changeover type for changing an assist display mode, which will be described later. / Off switch. Reference numeral 35 denotes a video input terminal to which a video image signal from the camera 1 is input via the cable 9. Reference numerals 36 and 37 denote power input / signal input for connecting the cable 6 provided in the drive unit 3 and the camera 1, respectively. Output terminal.

  Next, in the camera unit, reference numeral 13 denotes an image sensor such as a CCD or CMOS sensor that photoelectrically converts a subject image formed by the photographing optical system. An output signal from the image sensor 13 is converted into a digital video image signal by the video processing circuit 22 via the sampling hold circuit 14 and the A / D converter 21. The digital video image signal is displayed as an image on the VF 7 via the VF drive circuit 23.

  Next, the focus assist operation in the CPU 12 during manual focus will be described using the flowchart of FIG.

  First, in step (abbreviated as S in the figure) 1, the CPU 12 determines whether or not the display changeover switch 26 is turned on. If it is turned on, the process proceeds to step 2. If it is not turned on, step 1 is repeated.

  In step 2, the CPU 12 captures the video image signal generated by the video processing circuit 22 of the camera 1 via the cable 9 and the video input terminal 35, and extracts a high-frequency component of the video image signal, so that the captured image is captured. A focus signal indicating a contrast value is calculated (generated) for each frame.

  FIG. 3 shows the relationship between the focus position and the contrast value (focus signal). As shown in the figure, the value of the contrast signal 27 becomes the maximum value MAX when the focus position becomes the in-focus position. On the other hand, the contrast value becomes lower than the maximum value MAX as the distance from the in-focus position increases. Therefore, the direction of the in-focus position can be known by observing the moving direction of the focus lens 10 and the change in the contrast signal. Also, near the in-focus position, the increase rate of the contrast value changes while decreasing, so when the increase rate of the contrast signal decreases to a predetermined value or when the increase / decrease change of the contrast signal is reversed (the contrast signal is almost the maximum). It is possible to determine that the focus position is almost at the in-focus position. The focus position in the in-focus state can be detected through the focus position detector 11.

  In display modes 3 and 4 to be described later, the CPU 12 also calculates a depth (focus range) at which focus can be obtained. There are two depths of the photographing optical system: depth of field and depth of focus. Of these, the depth of field is determined by the object distance, the F number, the focal length, and the diameter of the allowable circle of confusion.

  Therefore, the CPU 12 determines the rear cover based on the zoom position detected by the zoom and aperture position detectors 16 and 18, the aperture position and the diameter of the predetermined permissible circle of confusion and the focus position detected as described above. Determine the depth of field and forward depth of field. Further, since the F-number changes even with or without the extender lens 19, the signal from the extender detector 20 is also used for depth calculation. By using the calculated depth and focus position information, it is also possible to obtain information representing the focus state within the focus range.

  Thus, the focus assist information as the display information indicating the focus direction, the focus position, and the focus state within the focus range is displayed from the CPU 12 together with the display pattern information generated by the display pattern generation unit 32 from the signal input / output terminal. 36 and 37 and the cable 6 are transmitted to the VF drive circuit 23 by serial communication. The VF drive circuit 23 that has received the focus assist information and the display pattern information displays them on the VF7.

  Next, in step 3, the display mode set by the display mode changeover switch 26 is read. The display pattern generation unit 32 of this embodiment generates four display patterns for displaying focus assist information. The display pattern (display mode) can be selected by the user using the display mode changeover switch 26 as desired or necessary. The CPU 12 proceeds to steps 4 to 7 according to the read display mode, and generates focus assist information according to the display mode.

  Here, each display mode will be described. On the screen 28 in the display mode 1 shown in FIG. 4 set when the process proceeds to step 4, a bar graph 28 a corresponding to the magnitude of the contrast signal calculated for each frame is displayed as the focus assist information 1. When the focus ring 5 is operated and the focus position approaches the in-focus position, the bar graph 28a extends in the MAX direction, and when the focus position moves away from the in-focus state, the bar graph 28a contracts in the MIN direction. By observing the change of the bar graph (contrast value) 28a while operating the focus ring 5 (moving the focus lens 10), the user can confirm the in-focus direction and the in-focus position.

  On the screen 29 in the display mode 2 shown in FIG. 5 set when the process proceeds to step 5, if the contrast value is increased by operating the focus ring 5 and moving the focus lens 10, one of the focus assist information 2 is displayed. The up arrow indicator 29a blinks. On the contrary, when the contrast value decreases, the down arrow indicator 29b blinks as one of the focus assist information 2. As a result, it is possible to know the change in focus state (increase / decrease in contrast value) accompanying the movement of the focus lens 10, and as a result, the in-focus direction can be known. In the in-focus state, the circle indicator 29c is turned on as one of the focus assist information 2 and the blinking of the arrow indicators 29a and 29b disappears. In the display mode 1 shown in FIG. 4, there is a case in which it is difficult to understand the slight increase / decrease in the contrast signal in the small screen in the VF 7, but in the display mode 2 shown in FIG. 5 such a delicate contrast value. And the direction of the blinking arrow indicators 29a and 29b can be confirmed.

  In the display modes 1 and 2 shown in FIGS. 4 and 5, the in-focus direction is not directly displayed, but the user can recognize the in-focus direction by looking at the change in display content. . In these display modes 1 and 2, the focus assist information can be generated only by the video image signal without the focus position detector 11.

  In the display mode 3 shown in FIG. 6 set when the process proceeds to step 6, an increase / decrease in the contrast value due to the movement of the focus lens 10 by operating the focus ring 5 is an arrow indicator as one of the focus assist information 3. Displayed by blinking 30a, 30b. Further, it is displayed as one of the focus assist information 3 that the in-focus state is indicated by turning on the circle indicator 30c. For example, when the contrast value increases when the focus ring 5 is rotated rightward (clockwise) as viewed from the user holding the camera, the operation direction of the focus ring 5 determined based on the output of the focus position detector 11 Is displayed in the direction of increasing contrast value, that is, the in-focus direction, the right arrow indicator 30a blinks. When the focus determination based on the contrast value is made, the blinking of the arrow indicator 30a disappears, and instead, as one of the focus assist information 3, the circle indicator 30c is turned on to indicate that it is in focus. .

  Further, in this display mode 3, the CPU 12 calculates the subject distance according to the focus position detected based on the output of the focus position detector 11, and the subject distance is displayed in the display area 30 d as one of the focus assist information 3. Is displayed. Further, the CPU 12 calculates the depth of field from the subject distance in the in-focus state, and displays the rear depth of field (the infinity side end of the focusing range) and the forward depth of field in the display areas 30e and 30f, respectively. (The closest end of the focusing range) is displayed as focus assist information paired with the subject distance. At this time, even if the focus ring 5 is operated, if the subject distance displayed in the display area 30d is within the depth of field displayed in the display areas 30e and 30f, the focus state is maintained. Continue to light up. Then, by observing which distance within the depth of field displayed in the display areas 30e and 30f the subject distance displayed in the display area 30d is, the user can adjust the focus state within the in-focus range ( Whether it ’s just in focus, close to infinity, or close.

  In this way, by grasping the focus state within the in-focus range, it is possible not only to check whether the subject is sufficiently within the in-focus range, but also to remove extraneous objects near the subject from the in-focus range. Video creation is also possible. Furthermore, since the depth of field information displayed in the display areas 30e and 30f changes by linking to the zoom position, F number, and extender insertion information, the focal length (zoom position) and F number are changed after focusing. Even if the extender lens 19 is inserted or removed, it can be confirmed whether or not the subject is in the in-focus range. It is also possible to predict whether or not the subject can be placed in the in-focus range after the change by looking at the focus state in the in-focus range before the change.

  In the display mode 4 shown in FIG. 7 set when the process proceeds to step 7, as in the display mode 3 in FIG. 6, the increase or decrease of the contrast value (ie, the focus lens 10 is moved by operating the focus ring 5). Is displayed as one of the focus assist information 4 by blinking of the arrow indicators 31a and 31b. The bar index 31c represents the width of the focus range (depth) and is always displayed with a constant width.

  When the in-focus state is determined from the change in contrast value, the blinking of the arrow indicators 31a and 31b disappears, and the circle indicator 31d is turned on instead.

  Here, the CPU 12 calculates the subject distance and the depth of field in the same manner as in the display mode 3, and determines which distance the subject distance is within the depth of field. Then, the display position of the circular index 31d with respect to the bar index 31c is determined so as to indicate the position (ratio) of the subject distance within the depth of field. Thereby, one piece of focus assist information 4 is formed. For example, when the focus state in the in-focus range is the just-focus state, the circle index 31d is displayed at the upper center of the bar index 31c. Further, when the focus lens 10 moves from this state and the focus state within the in-focus range deviates from the just-focus state, the circular index 31d moves to a position corresponding to the focus state (for example, a position 31d '). When the focus state exceeds the focus range, the circle indicator 31d is turned off and the arrow indicator 31a or 31b flashes instead. In this display mode 4, as compared with the display mode 3 described with reference to FIG. 6, it is possible to visually display the state in which the focus state is within the in-focus range.

  In the display modes 3 and 4, the information indicating the focus range may be the depth of field or the depth of focus. In the case of the focal depth, there is no need to provide the zoom position detector 16.

  Next, in step 8, the focus assist information generated in steps 4 to 7 is transmitted to the VF drive circuit 23. The VF drive circuit 23 displays the focus assist information superimposed on the video image on the VF7.

  In this embodiment, when the focus assist information is required, the display on / off switch 25 provided in the drive unit 3 is turned on, so that the focus assist information is displayed in the display mode set by the display mode changeover switch 26. The focus assist information disappears when the switch 25 is turned off. Thereby, when the focus assist information is unnecessary, it does not interfere with the video monitor on the VF7.

  In the present embodiment, the case where four display modes are provided has been described. However, only one display mode or another number of display modes may be provided.

  In this embodiment, since the focus assist information that changes with the movement of the focus lens 10 is displayed, the user can view the focus direction, the focus position, and the focus state within the focus range while viewing the focus assist information. Can be recognized.

  Further, in this embodiment, since focus assist information is obtained without using a wobbling mechanism, the weight and size of the drive unit 3 and the lens unit including the drive unit 3 are not increased, and the entire lens unit and camera system are inexpensive. Can be configured. Further, since the focus assist information is generated by the drive unit 3, the drive unit 3 can be used for an expensive camera and a zoom lens that have been conventionally used.

  FIG. 9 shows the appearance of a zoom camera system that is Embodiment 2 of the present invention. In the present embodiment, the same components as those in the first embodiment are denoted by the same reference numerals as those in the first embodiment, and the description is omitted.

  In the first embodiment, the video video signal supply line from the video processing circuit 22 to the VF drive circuit 23 and the video video signal supply line from the video processing circuit 22 to the drive unit 3 are separate systems. Then, the video image signal is first supplied from the video processing circuit 22 to the drive unit 3 via the cable 41, and focus assist information is superimposed on the video image signal and supplied to the VF drive circuit 23 via the cable 42.

  In this case, the video output terminal 8 provided in the camera 1 can be used for other purposes. Further, the focus assist information can be transmitted to the camera 1 without being restricted by the communication protocol of the cable 6 connecting the camera 1 and the drive unit 3.

  FIG. 10 shows the appearance of a zoom camera system that is Embodiment 2 of the present invention. In the present embodiment, the same components as those in the first embodiment are denoted by the same reference numerals as those in the first embodiment, and the description is omitted.

  In the first embodiment, focus assist information is displayed on the VF 7 of the camera 1. However, in this embodiment, a dedicated external display device (liquid crystal display or the like) 50 provided separately from the VF 7 is connected to the dedicated cable 51 from the drive unit 3. The focus assist information is output via and displayed.

  When using an old-type camera that cannot communicate focus assist information due to restrictions on the communication interface, it can be dealt with by providing a dedicated external display device 50 as in this embodiment. As shown in the drawing, the display device 50 can be mounted not only in the vicinity of the VF 7 but also at an arbitrary position so as to be able to correspond to various shooting styles. The display device 50 is not limited to a liquid crystal display, and may be any device that can display focus assist information, such as an LED.

  In each of the above embodiments, the case where the focus lens 10 is mechanically driven (by a cam mechanism or the like) according to the manual operation of the focus ring 5 has been described. However, the manual operation of the focus ring 5 is electrically detected, The present invention can also be applied when the focus lens 10 is driven by a motor based on the detection signal.

  Further, when the drive unit has two modes of the auto focus mode and the manual focus mode, the focus assist function may be operated only in the manual focus mode.

  Further, in each of the above embodiments, the case where the focus assist function is mounted on the drive unit has been described. However, the focus assist function is mounted on a photographic lens (for example, a so-called large lens) that integrally includes the components in the drive unit. Also good.

1 is an external view of a zoom camera system that is Embodiment 1 of the present invention. FIG. 1 is a block diagram showing a system configuration of Embodiment 1. FIG. Explanatory drawing of a contrast signal. FIG. 6 is a diagram for explaining a display mode 1 of focus assist information in the first embodiment. FIG. 6 is a diagram for explaining a display mode 2 of focus assist information in the first embodiment. FIG. 6 is a view for explaining a display mode 3 of focus assist information in the first embodiment. FIG. 6 is a diagram for explaining a display mode 4 of focus assist information in the first embodiment. 5 is a flowchart illustrating a procedure of a focus assist operation in the first embodiment. FIG. 6 is an external view of a zoom camera system that is Embodiment 2 of the present invention. FIG. 6 is an external view of a zoom camera system that is Embodiment 3 of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Camera 2 Zoom lens 3 Drive unit 7 Viewfinder 10 Focus lens 15 Variable magnification lens 17 Aperture 19 Extender lens 24 Relay lens 50 External display device

Claims (9)

A focus assist device used for a photographing lens having a focus lens that moves according to a manual operation,
Information generating means for generating display information which is information for displaying a focus state of the photographing lens and also represents a change in the focus state accompanying movement of the focus lens;
A focus assist device comprising: output means for outputting the display information to the display means.   The focus assist apparatus according to claim 1, wherein the information generation unit generates the display information based on a video signal input from a camera that performs imaging using the imaging lens.   The focus assist apparatus according to claim 1, wherein the display information is information for displaying a focus state with respect to a focus state of the photographing lens.   The focus assist apparatus according to claim 1, wherein the display information is information for displaying a focus state within a focusing range of the photographing lens. The information generating means is capable of generating a plurality of different display information,
5. The focus assist device according to claim 1, further comprising a selection unit that selects display information to be output from the output unit from among the plurality of display information. A drive unit that is mounted on a photographic lens having a focus lens and has an actuator that drives the focus lens; and an operation unit that outputs a drive command of the focus lens by the actuator according to a user's operation,
6. A drive unit comprising the focus assist device according to claim 1. A focus lens,
An actuator for driving the focus lens;
An operation means for outputting a drive command of the focus lens by the actuator according to a user's operation;
A photographic lens comprising the focus assist device according to claim 1. A photographic lens having a focus lens;
A drive unit according to claim 6;
A camera for taking a picture using the taking lens;
An imaging system comprising: display means for displaying the display information from the focus assist device. The taking lens according to claim 7;
A camera for taking a picture using the taking lens;
An imaging system comprising: display means for displaying the display information from the focus assist device.

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