JP5583049B2 - Lens device, TV camera system, and focusing assist method - Google Patents

Description

  The present invention relates to a lens apparatus, a television camera system, and a focusing assist method, and more particularly to a technique for reducing the depth of field in conjunction with a focus command to a focus demand of a television camera.

  According to Patent Document 1, when a camera is not connected to a VTR or the like, the send-back video output is switched by operating the VTRSW.

  According to Patent Document 2, when adjusting the focus with a conventional surveillance camera, an aperture is forcibly opened by inserting an ND filter (Neutral Density Filter) to reduce the amount of light according to the surrounding brightness. To do. When the switch is switched to the adjustment mode side, the aperture of the automatic aperture lens is forcibly opened, and the focus can be adjusted with a shallow depth of field.

  According to Japanese Patent Laid-Open No. 2003-260260, the resolution is reduced due to light diffraction by automatically inserting into and removing from the optical path of the ND filter according to the amount of incident light, and maintaining the opening degree of the iris 2 at a predetermined amount or more.

  According to Patent Document 4, when photographing in a wide-side region with a deep focal depth, the master lens group, the iris, and the ND filter are driven in conjunction by turning on the iris interlocking mode selection switch.

  According to Patent Document 5, the zoom lens is moved to change the depth of field.

  According to Patent Document 6, when the amount of light incident on the light receiving sensor is larger than a predetermined value, the variable ND filter is rotated toward a lower transmittance, and when it is smaller than the predetermined value, the variable ND filter is moved toward a higher transmittance. Rotate.

  According to Patent Document 7, when the initial setting switch is turned on, the lens iris (iris) is opened, the zoom is set to the tele end, and the focus lens is moved to adjust the focus. The initial setting switch may be provided on the lens body or on the television camera side. Further, the initial setting switch may be provided in a controller for remote operation, and an aspect in which the initial setting switch is added to another controller such as a focus controller or a zoom / extender controller is also possible. Further, the initial setting switch is configured to be linked with the power switch of the lens device in addition to the mode prepared as an operation means operated by the cameraman so that the initial setting switch is automatically turned on when the lens device is turned on. It is also possible to configure.

  Patent Document 8 shows an example of a Neutral Density (ND) filter.

  Other technologies related to the present application include Patent Documents 9 and 10.

Japanese Patent Laid-Open No. 11-168649 JP2003-234952 Japanese Patent Laid-Open No. 10-210487 JP 2006-195340 A JP 2004-170612 A JP-A-945311 Japanese Patent Laid-Open No. 11-127376 JP 2004-333554 A JP 2004-280048 JP Japanese Patent No. 3941078

  Normally, a television camera performs focusing immediately before recording or on-air, and uses an image in the best focus state. In this case, focusing is performed by moving the zoom to tele, and the out-of-focus is prevented by returning to the required angle of view. However, since this zooming operation requires time, the operation is difficult when there is no time.

  As in Patent Document 7, it is conceivable to open the lens iris (iris) in response to the initial setting switch being turned on and to zoom the telephoto end. However, depending on the location of the initial setting switch, quick operation is difficult.

  Further, as in Patent Document 7, when an initial setting switch is added to another controller or shared with a switch such as a power switch, the switch becomes unintended due to an erroneous operation of those switches, and is not suitable for shooting. May cause trouble.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide an apparatus and a method that can quickly open the aperture and move the zoom during focusing without causing trouble in shooting even if there is an erroneous operation.

  The present invention is a lens device of a television camera having a focus lens group, a zoom lens group, and a diaphragm, a feed back operation input unit for inputting a feed back video switching operation, a focus operation input unit for inputting a focus adjustment operation, A zoom operation input unit for inputting a zoom adjustment operation, a focus drive unit capable of moving the focus lens group according to the focus adjustment operation input to the focus operation input unit, and a zoom lens according to the zoom adjustment operation input to the zoom operation input unit If there is a zoom drive unit that can move the group, an aperture drive unit that drives the aperture to vary the aperture diameter of the aperture, and an input for the return video switching operation and an input for the focus adjustment operation, the zoom drive unit zooms Shallow including driving to the telephoto side of the lens group and / or opening of the aperture by the aperture drive unit To provide a lens device including a controller that performs processing for changing the depth of field, the.

  The focus driving unit moves the focus lens group according to the input of the focus adjustment operation after executing the change process.

  When a predetermined time has elapsed from completion of the input of the focus adjustment operation, the control unit finishes driving the zoom lens group to the tele side by the zoom drive unit and / or opening the aperture by the aperture drive unit, and returns to the original state. Return.

  The control unit adjusts the shift of the focus position caused by returning the zoom lens group and / or the aperture to the original state with a correction value corresponding to the original state.

  A light-blocking member that limits the amount of light passing through the lens device to an arbitrary value, a light-blocking drive unit that changes the amount of light limited by the light-blocking member, and a subject that responds to the opening of the aperture when the aperture is opened by executing the change process A light amount detection unit that detects an increase in the light amount of the image, and the control unit controls the light shielding drive unit to change the light amount limited by the light shielding member so as to cancel the increase in the light amount detected by the light amount detection unit.

  The light quantity detection unit emits a light emission amount corresponding to an increase in the aperture diameter of the diaphragm, and receives the light emission from the light emission unit through the light shielding member, and detects the light emission amount from the light emission unit. An incremental detector.

  Preferably, when the aperture is opened by executing the changing process, the aperture position detecting unit detects an aperture position corresponding to the aperture diameter of the aperture before and after the aperture is opened, and the light amount detecting unit is the aperture position detecting unit. The increase in the amount of light of the subject image is detected according to the change in the aperture position before and after the aperture opening detected in (1).

  The light shielding member includes a variable ND (Neutral Density) filter.

  The focus drive unit moves the focus lens group according to the input of the focus adjustment operation after executing the change process, and the control unit adjusts the amount of light by the light shielding member when a predetermined time has elapsed from the completion of the input of the focus adjustment operation. End the restriction and return to the original state.

  The present invention relates to the above-described lens device, a TV camera body that is connected to the lens device, converts the subject image formed on the imaging surface via the lens device into a video signal, and outputs the video signal. It is possible to selectively display one of a return video signal input unit for inputting a return video signal which is a video signal and a return video signal input from the return video signal input unit or a video signal output from the TV camera body. The monitor is equipped with a monitor that displays the video signal output from the TV camera body when there is an input for the return video switching operation and an input for the focus adjustment operation at the same time. A TV camera system that displays video signals sent back.

  The present invention includes a focus lens group, a zoom lens group, an aperture, a feed back operation input unit that inputs a feed back video switching operation, a focus operation input unit that inputs a focus adjustment operation, and a zoom operation that inputs a zoom adjustment operation. An input unit, a focus drive unit capable of moving the focus lens group according to a focus adjustment operation input to the focus operation input unit, and a zoom drive unit capable of moving the zoom lens group according to a zoom adjustment operation input to the zoom operation input unit And a diaphragm drive unit that drives the diaphragm to vary the aperture diameter of the diaphragm. The lens device includes a step of inputting a return video switching operation, a step of inputting a focus adjustment operation, and a transmission video switching operation. Zoom lens group by zoom drive when input and focus adjustment operation are input simultaneously Provides a focusing assist how to perform the step of executing the process of changing to the shallow depth of field, including the opening of the diaphragm by driving and / or diaphragm driver to the telephoto side.

  The present invention includes a focus lens group, a zoom lens group, an aperture, a feed back operation input unit that inputs a feed back video switching operation, a focus operation input unit that inputs a focus adjustment operation, and a zoom operation that inputs a zoom adjustment operation. An input unit, a focus drive unit capable of moving the focus lens group according to a focus adjustment operation input to the focus operation input unit, and a zoom drive unit capable of moving the zoom lens group according to a zoom adjustment operation input to the zoom operation input unit And a lens device that drives the diaphragm to vary the aperture diameter of the diaphragm, and a lens device that is connected to the lens device, and the subject image formed on the imaging surface via the lens device is converted into a video signal. The TV camera body that converts and outputs, and the send-back video that inputs the send-back video signal that is currently being broadcast or recorded A television camera system comprising: a signal input unit; and a monitor capable of selectively displaying either one of the return video signal input from the return video signal input unit or the video signal output from the TV camera body. When there is a step of inputting a video switching operation, a step of inputting a focus adjustment operation, and an input of a feed back video switching operation and an input of a focus adjustment operation, the zoom drive unit drives the zoom lens group to the tele side and If there is a step of changing to a shallow depth of field including opening of the aperture by the aperture drive unit, and an input of the return video switching operation and an input of the focus adjustment operation at the same time, the TV camera body output When the video signal is displayed on the monitor and there is only an input for switching back video, the video signal is sent back. Provides a focusing assist method for performing the step of displaying the data, the.

  According to the present invention, when there is an input of the return video switching operation and an input of the focus adjustment operation at the same time, the shallow driving including the driving of the zoom lens group to the tele side by the zoom driving unit and / or the opening of the diaphragm by the aperture driving unit is performed. The change process to the depth of field is executed. The photographer can focus accurately and quickly by reducing the depth of field by simultaneously inputting the return video switching operation and the focus adjustment operation.

  Also, according to the present invention, when there is an input for the return video switching operation and an input for the focus adjustment operation at the same time, the video signal output from the TV camera body is displayed on the monitor, and there is only an input for the return video switching operation. The sent back video signal is displayed on the monitor. The photographer can perform accurate and quick focusing while watching the monitor while reducing the depth of field by simultaneously performing the input of the return video switching operation and the input of the focus adjustment operation.

External view showing one embodiment of a TV camera system The block diagram of the lens apparatus and television camera system which concern on 2nd Embodiment. Flowchart of focusing assist process Block diagram of a lens apparatus according to the second embodiment

<First Embodiment>
FIG. 1 is an external view showing an embodiment of a television camera system to which the present invention is applied. As shown in the figure, a television camera 10 is a television camera mainly used for broadcasting or business use, and is composed of a lens device 12 and a camera body 14 and is mounted on a pedestal stand (not shown). It is supported by.

  The pan head is extended with two left and right bread sticks, a focus demand (focus controller) 26 is installed on the grip part of the right bread stick, and a zoom demand is placed on the grip part of the left bread stick. (Zoom controller) 20 is installed. At the time of shooting, the cameraman holds the focus demand 26 with the right hand and the zoom demand 20 with the left hand.

  The lens device 12 is provided with an RS-232C (which may be another communication format) interface 15 for connection with peripheral devices or external devices. Further, the lens device 12 is provided with an RS-485 interface 16 for connecting to the focus demand 26 and the zoom demand 20.

  The RS-232C interface 15 receives a return video signal that is currently being recorded or aired from another camera body or a television studio master system.

  The focus demand 26 is provided with a rotatable focus knob 30. When focus control is performed by manual focus (MF), when the focus knob 30 is rotated, a focus corresponding to the rotation position is obtained. A focus control signal for instructing movement of a focus lens group 64a (described later) with the position as a target position is given from the focus demand 26 to the lens device 12. As a result, the focus lens of the lens device 12 moves to the target position commanded by the focus control signal.

  The zoom demand 20 is provided with a rotatable thumb ring 34. When the thumb ring 34 is rotated in the left-right direction, the zoom lens group 64b (to be described later) uses a zoom speed corresponding to the rotation position as a target speed. A zoom control signal instructing movement is given from the zoom demand 20 to the lens device 12. As a result, the zoom lens group 64b of the lens device 12 moves at the target speed commanded by the zoom control signal.

  Although not shown in the figure, the focus demand 26 is provided with various operation members related to autofocus (AF), and control of an AF frame indicating a subject range to be focused by AF (AF target range). An AF frame control device (AF frame automatic tracking device) for performing (change of position and the like) is incorporated, and various operation members of the AF frame control device are also provided in the focus demand 26.

  A viewfinder 36 that is a display device is installed on the camera body 14. Since the viewfinder 36 displays an image of the subject photographed by the television camera 10, the cameraman operates the focus demand 26 and the zoom demand 20 while viewing the image, so that the subject can be selected with a desired composition. You can shoot. In the following description, the term “captured video” or “captured image” refers to a video or an image currently captured by the television camera 10.

  In addition, an image of the AF frame indicating the position, size, and shape (aspect ratio) where the AF frame is currently set is superimposed on the captured image displayed on the viewfinder 36. When focus control is performed by AF, it is possible to know which range of subjects in the captured image can be focused. The focus control of MF and AF can be switched by a focus mode switch or the like provided in the focus demand 26.

  The zoom demand 20 is provided with a return switch (RET-SW) 35. The RET-SW 35 is a switch for sending a video signal back to the camera body 14 from another camera body or a television studio master system via the RS-232C interface 15. When the RET-SW 35 is turned on (generation of a return signal request), the on-air signal is sent to the camera body 14 and displayed on the viewfinder 36. When the RET-SW 35 is off, the video output from the video signal processing circuit 71 is displayed on the viewfinder 36. The RET-SW 35 may be a lock type (on-press continues until it is pressed again) or a non-lock type (on-state continues as long as the press continues).

  FIG. 2 is a block diagram of the television camera 10.

  The lens device 12 includes a photographic lens 64 that is attached to a lens mount of the camera body 14, and the photographic lens 64 forms an image of the subject on the imaging surface of the image sensor 70 of the camera body 14. Yes. The photographing lens 64 is provided with movable parts for adjusting photographing conditions such as a focus lens group 64a, a zoom lens group 64b, a variable ND (Neutral Density) filter 64c, an aperture 64d, and a master lens group 64e as its constituent elements. These movable parts are electrically driven by a drive system such as a motor (servo mechanism). For example, the focus lens group 64a and the zoom lens group 64b move in the direction along the optical axis L, and the focus (subject distance) adjustment is performed by moving the focus lens group 64a, and the zoom lens group 64b moves. Thus, the focal length (zoom magnification) is adjusted.

  The variable ND filter 64c has a plurality of continuous or stepwise transmittances, and by changing an applied voltage or mechanically rotating, an arbitrary transmittance is selected from among them, The received light amount of the subject image formed on the image sensor 70 is adjusted.

  In the AF-related system, it is sufficient that at least the focus lens group 64a can be driven electrically, and the other movable parts may be driven only manually.

  The lens device 12 includes a lens CPU 65 and an AF unit 66. The lens CPU controls the entire lens device 12. The AF unit 66 is a processing unit for acquiring information necessary for performing focus control (automatic focus adjustment) by AF, and includes an AF processing unit 27, an AF imaging circuit, and the like (not shown). Has been.

  Further, in the lens device 12, in order to suppress an increase in the amount of light received by the image pickup device 70 due to the driving of the diaphragm 64d by a focusing assist process described later, the amount of received light is kept constant by adjusting the density (light attenuation rate) of the variable ND filter 64c. A light amount adjusting unit 50 is provided.

  On the side of the variable ND filter 64c, there are provided a light shielding plate 60a and a light shielding plate 60b that shield subject light branched from the optical path upstream and downstream of the stop 64d. The LED 61 and the light receiving element 62 are installed separately from the optical path of the photographing lens 64 by a light shielding plate 60a and a light shielding plate 60b. Therefore, the light receiving element 62 receives only the light of the LED 61 without receiving the subject light branched from the optical path. The light emission amount of the LED 61 is steady.

  The lens CPU 65 determines a target density (dimming rate) of the variable ND filter 64c that works in conjunction with the increase in the aperture diameter of the stop 64d and cancels the exposure amount increment ΔEV that increases accordingly. The lens CPU 65 inputs a digital signal corresponding to the determined density to the D / A converter 63. This digital signal is converted into a voltage signal by the D / A converter 63 and applied to the drive system of the variable ND filter 64c. Thereby, the density of the variable ND filter 64c is adjusted.

  A voltage signal corresponding to the amount of light received by the light receiving element 62 from the LED 61 is converted into a digital signal by the A / D converter 69 and input to the lens CPU 65. The lens CPU 65 calculates the current density (dimming rate) of the variable ND filter 64c from the received light amount. This can be calculated by dividing the received light amount by the steady light emission amount of the LED 61. The lens CPU 65 compares the current density of the variable ND filter 64c with the target density, determines again the target density (dimming rate) so as to eliminate the difference, and outputs a control signal corresponding to the determined density. The voltage is applied to the drive system of the variable ND filter 64c via the D / A converter 63. This drive system further selects the transmittance corresponding to this control signal, so that the density of the variable ND filter 64c is adjusted, and the amount of light received by the image sensor 70 is maintained before and after the aperture 64d is opened. Adjusted.

  The camera body 14 is provided with an interface (I / F) 52 for connecting to the lens device 12 with a cable so that various signals can be exchanged by serial communication between the lens CPU 65 and the body CPU 72 through the SCI 68/73. It has become.

  Accordingly, various control signals sent from the main body CPU 72 of the camera main body 14 are given to the lens CPU 65, and processing according to the control signals is executed by the lens CPU. For example, when an instruction for focus control (AF mode) by AF is given, focus control by AF is performed based on a focus evaluation value obtained from an AF unit (not shown), and focus control by MF (MF mode). Is given, the focus control by MF is performed in accordance with a focus position command signal given based on the operation of a focus knob (not shown).

  The video signal processing circuit 71 digitally processes the video signal output from the image sensor 70, converts it into an HDTV signal, and outputs it to the viewfinder 36.

  The SCIs 68 and 73 are interface circuits for performing serial communication between the lens device 12 and the camera body 14. In this communication, various commands, the AF frame information, and the like are transmitted and received.

  FIG. 3 shows a flowchart of a focusing assist process executed by the television camera system. This process is performed before video recording and on-air.

  In S1, based on a control signal output in accordance with an operation on an operation means (not shown), the movable part other than the focus lens group 64a, for example, the zoom lens group 64b is electrically driven in accordance with a predetermined operation by the operator.

  In S <b> 2, the lens CPU 65 determines whether or not a manual focus (MF) operation has been performed on the focus knob 30 of the focus demand 26. If Yes, the process proceeds to S3. If No, the process proceeds to S10.

  In S3, the lens CPU 65 drives the focus lens group 64a in response to the MF operation and starts focusing.

  In S4, the lens CPU 65 determines whether or not the RET-SW 35 is turned on in addition to the MF operation (whether or not there is a focusing assist request). If Yes, the process proceeds to S5. If No, the process proceeds to S11.

  The focusing assist request is generated on condition that both the focus operation and the RET-SW 35 are turned on, and the process proceeds to S5. In S5, the lens CPU 65 instructs the drive system to move the zoom lens group 64b to the telephoto end.

  In S6, the lens CPU 65 instructs the drive system to open the aperture 64d. S5 and S6 are processes for reducing the depth of field in order to quickly and accurately perform manual focusing. For this purpose, it is sufficient that at least one of S5 and S6 is executed, but preferably both are executed as shown.

  In S7, the lens CPU 65 selects the density of the variable ND filter 64c and adjusts the amount of received light so that the light amount does not change before and after the aperture 64d is opened via the light amount adjusting unit 50.

  In S8, the lens CPU 65 sets an assist flag stored in a RAM (not shown) to ON. Further, when the assist CPU is turned on, the lens CPU 65 switches the video signal output to the viewfinder 36 from the video signal sent back via the I / F 52 to the video signal via the video signal processing circuit 71. However, if the video signal via the video signal processing circuit 71 has already been output to the viewfinder 36 when the assist flag is turned on, this switching is unnecessary, and the video signal output via the video signal processing circuit 71 is not output. continue.

  In S9, the lens CPU 65 starts measuring time with a timer (not shown). Thereafter, the process returns to S1.

  In S10, it is determined whether or not a predetermined time, for example, 0.3 seconds has elapsed since the start of time measurement in S9. In the case of Yes, it progresses to S11, and in No, it returns to S9.

  In S11, the lens CPU 65 determines whether or not the assist flag is on. In the case of Yes, it progresses to S12, and in No, it returns to S9.

  In S12, the lens CPU 65 instructs the drive system so that the zoom lens group 64b returns to the position before the RET-SW 35 is pressed. In response to this instruction, the zoom lens group 64b is driven and the angle of view is restored.

  The shift of the focus position accompanying the return of the position of the zoom lens group 64b may be automatically corrected. For example, the position correction amount of the focus lens group 64a corresponding to the movement amount from the original position of the zoom lens group 64b to the telephoto end is stored in advance in the EEPROM of the lens device 12, and the lens CPU 65 performs zooming after the return. By driving the focus lens group 64a by a position correction amount corresponding to the original position of the lens group 64b, the shift of the focus position is corrected.

  In S13, the lens CPU 65 instructs the drive system so that the aperture 64d returns to the opening diameter before the RET-SW 35 is pressed.

  The shift of the focus position accompanying the return of the aperture diameter of the stop 64d may be automatically corrected. For example, the position correction amount of the focus lens group 64a corresponding to the difference between the original aperture diameter of the aperture 64d and the aperture diameter at the time of opening is stored in advance in the EEPROM of the lens device 12, and the lens CPU 65 stores the aperture after the return. The focus lens group 64a is driven by a position correction amount corresponding to the original aperture diameter of 64d, thereby correcting the focus position shift.

  In S14, the lens CPU 65 instructs the drive system so that the variable ND filter 64c returns to the density before the RET-SW 35 is pressed.

  In S15, the lens CPU 65 turns off the assist flag. Then, the process returns to S9.

  Although illustration is omitted, when the RET-SW 35 is simply turned on without any MF operation (when a return signal request is generated), the lens CPU 65 generates a return signal request via the I / F 52. In addition to the notification, a return video signal is sent to the main body CPU 72. When receiving the request generation notification, the main body CPU 72 switches the video signal output to the viewfinder 36 from the video signal via the video signal processing circuit 71 to the return video signal via the I / F 52.

  With the above processing, when the photographer turns on the RET-SW 35 and generates a focus assist request simultaneously with the focus operation, the depth of field becomes shallow due to the zoom side movement and / or the opening of the aperture. Since the RET-SW 35 is originally provided at a place where the lens apparatus 12 is easily operated, such as the zoom demand 20, the photographer can reduce the depth of field without operating a specially provided operating means. In addition, the manual focus operation can be performed quickly and with high accuracy.

  Even when the aperture 64d is opened due to the generation of a focus assist request, the exposure adjustment due to the opening is prevented by adjusting the density of the variable ND filter 64c, and the photographer who performs the focusing operation while viewing the image of the viewfinder 36 Will not be adversely affected.

  Furthermore, even if a focus assist request is generated by mistake, the shooting depth is small since the original depth of field is restored if a predetermined time elapses without performing the MF operation. Alternatively, even if a return signal request is generated by mistake in order to generate a focus assist request, only an on-air signal is displayed on the viewfinder 36, and shooting trouble is small.

  Further, when only the MF operation is performed (Yes in S2 and No in S4), focus adjustment that is not linked to the zoom lens group 64b or the aperture 64d is possible.

Second Embodiment
FIG. 4 shows a main part of the lens device 120 constituting the television camera system according to the second embodiment of the present invention. Although not shown, the lens device 120 is connected to the camera main body 14 similar to that of FIG. 1 via the SCI 68 similarly to the lens device 12, and the focus demand 26 and the zoom demand via the RS-485 interface 16. 20 is connected to form a TV camera system.

  The lens device 120 includes a light amount adjustment unit 500 instead of the light amount adjustment unit 50 of the first embodiment. Other configurations are the same as those in the first embodiment. Among the blocks provided in the light amount adjustment unit 500, the same blocks as those in the first embodiment are denoted by the same reference numerals.

  A GCA (gain control amplifier) unit 67 provided in the light amount adjustment unit 500 transmits the transmittance of the variable ND filter 64c so as to keep the output (DC signal) of the light receiving element 62 at a predetermined level during the above-described focusing assist process. Control the selection of

  On the other hand, the lens CPU 65 controls the light emission amount of the LED 61 in conjunction with the opening of the aperture 64d. That is, control is performed to increase the light emission amount of the LED 61 as the aperture diameter of the stop 64d increases. The GCA unit 67 applies a voltage signal that decreases the transmittance (increases the light attenuation rate) to the variable ND filter 64c according to the increase in the amount of light received by the light receiving element 62. Thereby, the increment ΔEV of the exposure amount due to the increase in the aperture diameter of the stop 64d is canceled out. As described above, the present TV camera system can also perform the focusing assist process shown in FIG. 4 and can be kept constant without increasing the amount of light received by the image sensor 70 by opening the aperture during focusing.

  Alternatively, the lens CPU 65 detects the aperture position (F value) before and after the aperture 64d is opened by a known aperture position detection means such as a Hall element, and cancels the exposure amount increment ΔEV corresponding to the change in the aperture position. The selection of the transmittance of the variable ND filter 64c may be controlled.

  12: Lens device, 14: Camera body, 26: Focus demand, 35: RET-SW, 36: Viewfinder, 64: Shooting lens, 50: Light quantity adjustment unit, 65: Lens CPU, 72: Body CPU

Claims (10)

A lens device for a television camera having a focus lens group, a zoom lens group, and a diaphragm,
A feed back operation input unit for inputting a feed back video switching operation;
A focus operation input section for inputting a focus adjustment operation;
A zoom operation input section for inputting a zoom adjustment operation;
A focus drive unit capable of moving a focus lens group in accordance with a focus adjustment operation input to the focus operation input unit;
A zoom drive unit capable of moving the zoom lens group according to a zoom adjustment operation input to the zoom operation input unit;
An aperture drive unit that drives the aperture to vary the aperture diameter of the aperture; and
When there is an input of the return video switching operation and an input of the focus adjustment operation at the same time, the shallowness includes driving the zoom lens group to the tele side by the zoom driving unit and / or opening the aperture by the aperture driving unit. A control unit that executes a change process to the depth of field;
A variable ND (Neutral Density) filter that limits the amount of light passing through the lens device to an arbitrary value;
A light-shielding drive unit that changes the amount of light limited by the variable ND filter;
When the aperture is opened by executing the change process, a light amount detection unit that detects an increase in the amount of light of the subject image according to the opening of the aperture;
Equipped with a,
The control unit is a lens device that controls the light shielding drive unit to change the light amount limited by the variable ND filter so as to cancel out the increment of the light amount detected by the light amount detection unit .   The lens apparatus according to claim 1, wherein the focus driving unit moves the focus lens group in accordance with an input of the focus adjustment operation after executing the change process.   The control unit finishes driving the zoom lens group to the tele side by the zoom driving unit and / or opening the aperture by the aperture driving unit when a predetermined time has elapsed from completion of input of the focus adjustment operation. The lens device according to claim 2, wherein the lens device is restored to its original state.   The lens apparatus according to claim 3, wherein the control unit adjusts a shift in a focus position caused by returning the zoom lens group and / or the diaphragm to an original state with a correction value corresponding to the original state. . The light amount detector is
A light emitting unit that emits a light emission amount according to an increase in the aperture diameter of the diaphragm;
A light intensity increment detecting unit that receives light emitted from the light emitting unit via the variable ND filter and detects an increment of a light emission amount from the light emitting unit;
The lens device according to claim 1, comprising: When the aperture is opened by the execution of the change process, the aperture position detecting unit detects an aperture position corresponding to the aperture diameter of the aperture before and after the aperture is opened,
The light amount detection unit, according to claim 1 for detecting the amount increment of the object image in response to changes in throttle position before and after the detected said aperture opening was of the diaphragm-position detector Lens device. The focus driving unit moves the focus lens group in accordance with an input of the focus adjustment operation after the execution of the change process,
The control unit according to any one of claims 1 to 6 , wherein when a predetermined time elapses from completion of input of the focus adjustment operation, the control unit ends the light amount limitation by the variable ND filter and returns to the original state. The lens device described. The lens device according to any one of claims 1 to 7 ,
A television camera body connected to the lens device and converting a subject image formed on the imaging surface through the lens device into a video signal and outputting the video signal;
A send-back video signal input unit for inputting a send-back video signal which is a video signal currently being broadcast or recorded;
A monitor capable of selectively displaying any one of the return video signal input from the return video signal input unit or the video signal output from the television camera body;
With
The monitor displays the video signal output from the TV camera body when there is an input for the return video switching operation and an input for the focus adjustment operation at the same time, and when there is only an input for the return video switching operation, A television camera system for displaying the return video signal. A lens device for a television camera having a focus lens group, a zoom lens group, and a diaphragm, a return operation input unit for inputting a return image switching operation, a focus operation input unit for inputting a focus adjustment operation, and zoom adjustment A zoom operation input unit for inputting an operation, a focus drive unit capable of moving a focus lens group according to a focus adjustment operation input to the focus operation input unit, and the zoom according to a zoom adjustment operation input to the zoom operation input unit A zoom driving unit capable of moving the lens group, a diaphragm driving unit that drives the diaphragm to vary the aperture diameter of the diaphragm, and a variable ND (Neutral Density) filter that limits the amount of light passing through the lens device to an arbitrary value And a light-shielding drive unit that changes the amount of light limited by the variable ND filter. ,
A step of inputting a return video switching operation;
A step of inputting a focus adjustment operation;
When there is an input of the return video switching operation and an input of the focus adjustment operation at the same time, the shallowness includes driving the zoom lens group to the tele side by the zoom driving unit and / or opening the aperture by the aperture driving unit. Performing a change process to the depth of field;
Changing the amount of light limited by the variable ND filter;
Detecting the increment of the light amount of the subject image according to the opening of the aperture when the aperture is opened by the execution of the change process;
Controlling the light-shielding drive unit and changing the amount of light limited by the variable ND filter so as to cancel the increment of the detected amount of light;
Focusing assist method to execute. A lens device for a television camera having a focus lens group, a zoom lens group, and a diaphragm, a return operation input unit for inputting a return image switching operation, a focus operation input unit for inputting a focus adjustment operation, and zoom adjustment A zoom operation input unit for inputting an operation, a focus drive unit capable of moving a focus lens group according to a focus adjustment operation input to the focus operation input unit, and the zoom according to a zoom adjustment operation input to the zoom operation input unit A zoom driving unit capable of moving the lens group, a diaphragm driving unit that drives the diaphragm to vary the aperture diameter of the diaphragm, and a variable ND (Neutral Density) filter that limits the amount of light passing through the lens device to an arbitrary value And a light-shielding drive unit that changes the amount of light limited by the variable ND filter ; A TV camera body connected to the lens device and converting a subject image formed on the imaging surface via the lens device into a video signal and outputting the video signal; and a return video signal which is a video signal currently being broadcast or recorded And a monitor capable of selectively displaying either the return video signal input from the return video signal input unit or the video signal output from the TV camera body. TV camera system
A step of inputting a return video switching operation;
A step of inputting a focus adjustment operation;
When there is an input of the return video switching operation and an input of the focus adjustment operation at the same time, the shallowness includes driving the zoom lens group to the tele side by the zoom driving unit and / or opening the aperture by the aperture driving unit. Performing a change process to the depth of field;
When there is an input for the return video switching operation and an input for the focus adjustment operation at the same time, the video signal output from the TV camera body is displayed on the monitor, and when there is only an input for the return video switching operation, Displaying a return video signal on the monitor;
Changing the amount of light limited by the variable ND filter;
Detecting the increment of the light amount of the subject image according to the opening of the aperture when the aperture is opened by the execution of the change process;
Controlling the light-shielding drive unit and changing the amount of light limited by the variable ND filter so as to cancel the increment of the detected amount of light;
Focusing assist method to execute.

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