BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to an optical device such a television lens capable of controlling a lens iris, an extender etc. by an electrical signal from a television camera and returning the lens status by an electrical signal to the camera. 
   2. Related Background Art 
   The television lens for broadcasting is capable of controlling lens operations such as iris, extender, tally etc. by electrical signals from the television camera, and returning the lens status such as positions of extender, iris, zooming and focusing to the television camera by electrical signals. 
   The exchange of such signals is executed by a connector provided at the junction between the camera and the lens, but the kind of the connector, the pin assignment to the signals and the signal level depend of the manufacturer of the television camera. 
   Also the mechanical configuration of the joint (hereinafter called mount) between the television camera and the lens depends of the manufacturer of the television cameras.  FIGS. 6 and 7  show different mount shapes adopted by different manufacturers A and B. For this reason, even a same lens is slightly modified for the respective television camera manufacturer. 
   To deal with such situation, in the lens unit, each manufacturers preparates a mount for mechanically adapting to different television cameras and provides a variation of set, adjustment, or replacement of the board in the lens for electrically adapting to different television cameras. 
   Thus, a lens of a same optical performance can be adapted to the different mechanical configurations and the different electrical interfaces of the cameras, with the minimum replacement of parts. 
     FIG. 5  shows a conventional lens system. 
   Electrical signals from a camera  8  are directly input to a main process circuit board (PCB)  43  of a lens  41 , through bidirectional connectors  7  and a mount  44  of the television lens and the television camera. The PCB  43  executes various operations such as auto focusing and auto iris control. 
   The mount  44  of the lens  41  is also provided with an auxiliary switch  45  and an indicator  46 , which are directly connected also to the PCB  43 . 
   For matching with the electrical interface adopted by each camera manufacturer, there are executed exclusive wiring and resetting of the main PCB  43 , or replacement to an exclusive circuit board and exclusive adjustment for the camera manufacturer. 
   In such method, however, the electrical interface has to be matched with each camera manufacturer, so that the electrical adjusting and setting methods can only be determined when the camera is determined. Consequently there are required various adjusting methods, leading to complicated electrical adjustment. 
   In case the lens is delivered to a rental company, such lens has to be mounted on the cameras of various manufacturers, so that the replacement of the above-mentioned mount and electrical interface is often executed by the user (rental company) who is sometimes required to execute complex electrical adjustments. 
   SUMMARY OF THE INVENTION 
   One aspect of the application is to provide an optical device capable of unifying the adjusting method and simplifying the switching of the electrical interface, in order to avoid such complexity in the electrical adjustments. 
   One aspect of the application is to provide an optical device adapted for connection with various camera, and comprising a connector for electrical connection with the camera, a process circuit, and an interface circuit connected between the process circuit and the connector, wherein the interface circuit is so constructed that the circuit characteristics or the standards for handling the interface or the signals are rendered switchable in order to adapt the process to different cameras. 
   One aspect of the application is to provide an optical device comprising designation means for designating a camera, wherein the aforementioned characteristics, interface or circuit characteristics are rendered switchable in accordance with the camera designated by the designation means. 
   Still other aspects of the present invention, and the features thereof, will become fully apparent from the following description of the embodiments, to be taken in conjunction with the attached drawings. 


   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a view showing a lens system embodying the present invention; 
       FIG. 2  is a block diagram showing the configuration of a camera interface board; 
       FIG. 3  is a flow chart showing a serial reception sequence from the main PCB; 
       FIG. 4  is a flow chart showing a serial transmission sequence to the main PCB; 
       FIG. 5  is a view showing a conventional lens system; 
       FIG. 6  is a view showing the configuration of the mount of a manufacturer A; 
       FIG. 7  is a view showing the configuration of the mount of a manufacturer B; 
       FIG. 8A  which is composed of  FIGS. 8A-1  and  8 A- 2  are tables showing data of an in-lens conversion table for different camera manufactures; 
       FIG. 8B  is a table showing content of bit signals of bit data camera answer for different camera manufactures and a part of the conversion data table; 
       FIG. 8C  is a table showing bit data before conversion; 
       FIG. 8D  is a table showing bit data converted with the conversion data of the manufacturer A; 
       FIG. 8E  is a table showing bit data converted with the conversion data of the manufacturer B; 
       FIG. 9  is a table showing the data format of communication between the lens and the camera interface board; 
       FIG. 10A  is a table showing communication commands from the main PCB  3  to the camera interface board  9 ; 
       FIG. 10B  is a table showing communication commands from the camera interface board  9  to the main PCB  3 ; 
       FIG. 11A  is a table showing transmission data addresses in a RAM  21 ; 
       FIG. 11B  is a table showing reception data addresses in the RAM  21 ; 
       FIG. 12  is a block diagram showing the configuration of the camera interface board in case of serial communication between the camera and the lens; 
       FIG. 13  is a flow chart showing a serial reception sequence from the main PCB; 
       FIG. 14  is a flow chart showing a serial transmission sequence to the main PCB; 
       FIG. 15  is a flow chart for zoom/focus control signals by a serial reception sequence from the camera; 
       FIG. 16  is a flow chart for lens on/off control by a serial reception sequence from the camera; 
       FIG. 17  is a flow chart showing a communication for transmitting to the camera; 
       FIG. 18  is a table showing correspondence between zooming, focusing and lens magnification; 
       FIG. 19  is a conversion table for lens on/off control data; 
       FIG. 20  is a position conversion table corresponding to iris F-number; 
       FIG. 21  is a table showing communication commands between the lens and the camera interface board; 
       FIG. 22A  is a table showing communication commands from the camera to the lens; 
       FIG. 22B  is a table showing communication commands from the lens to the camera; 
       FIG. 23A  is a table showing communication commands from the main PCB  3  to the camera interface board  9 ; 
       FIG. 23B  is a table showing communication commands from the camera interface board  9  to the main PCB  3 ; 
       FIG. 24A  is a table showing transmission data addresses of the RAM  21  to the main PCB  3 ; and 
       FIG. 24B  is a table showing transmission data addresses of the RAM  21  to the camera. 
   


   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   First Embodiment 
     FIG. 1  is a block diagram showing a lens system of a first embodiment. 
   The lens  1  in the present embodiment is divided into a main lens body  2  and a mount  4 . The main lens body  2  is provided with a main circuit board (PCB)  3 , which is a circuit board for controlling the lens. The PCB  3  is provided with a camera code switch  10 , which outputs a hexadecimal code corresponding to the camera manufacturer by a manual operation of a rotary switch, whereby the PCB  3  identifies the kind of the camera. 
   The mount  4  is provided with an auxiliary switch  5  and an auxiliary indicator  6 , which are connected to a camera interface board  9 . The television lens  1  and the television camera  8  are electrically connected through connectors  7 . The auxiliary switch  5  is used by the lens for controlling itself, and executes on/off control of lens tally and manual/servo switching of the extender. The auxiliary indicator  6  showing the positions of iris, zooming and extender of the lens. The electrical signals between the connectors  7  include analog signals and digital signals. The analog signal such as a position voltage for controlling the iris, zoom, focus and the like are transmitted from the camera to the lens, and voltages showing the current iris, zoom and focus positions are returns from the lens to the camera. These voltages are different from camera to camera. Digital signals from the camera execute switching operations, such as on/off control of the lens tally, 1X/2X switching of the extender, switching of the control mode for the lens iris, by binary values of 0V(L) and 5V(H), through exclusive pins assigned to the respective control items in the connector  7 . Also a digital signal from the lens to the camera indicates whether the extender is in the 1X  or 2X position, by binary values of 0V(L)=2X and 5V(H)=1X through an exclusive signal pin in the connector  7 . However the polarity of the signal, namely whether the switch is to be turned on at 0V(L) or 5V(H), is different from camera to camera. 
   In the lens  1 , the signal exchange between the main PCB  3  and the camera  8  connected to the lens  1  is executed through a camera interface board  9  incorporated in the mount  4 . 
   The signals from the camera  8 , supplied through the connector  7 , are received by the lens  1  at the camera interface board  9 . These signals are converted, in the camera interface board  9 , into the data format in the lens and are then transmitted as serial data to the main PCB  3 . All the data of both analog and digital signals are handled as serial data. The above-mentioned data format is a normalization for processing the analog and digital signals in the lens, by the PCB  3 . For example, in case the digital signal for tally on/off control to be processed in the PCB  3  is so selected that 0V(L) is for switch-on operation and 5V(H) is for switch-off operation while the digital signal from the camera interface is so formatted that 0V(L) is for switch-on operation and 5V(H) is for switch-on operation, the camera interface board  9  executes conversion to the inverted data. Also in case of an analog signal the camera interface board executes conversion of the command signals for iris, zooming and focusing, which are different from camera to camera, into voltage widths and reference voltage to be actually controlled in the PCB  3 . 
   On the other hand, the serial data supplied from the main PCB  3  to the camera interface board  9  are converted therein into analog and digital signals of the camera interface and are transmitted through the connectors  7  of both sides to the camera  8  connected to the television lens. 
   Also input or output of the signal to the main PCB  3  for the auxiliary switch  5  and the auxiliary indicator  6  of the mount  4  is executed by the serial communication between the camera interface board  9  and the main PCB  3 . 
   Consequently there only exists a serial communication line between the camera interface board  9  and the main PCB  3 , so that the number of the wiring can be reduced. 
   In case the camera  8  is changed from that of the manufacturer A to that of the manufacturer B, the mount  4  of the lens  1  is replaced from that of the manufacturer A as shown in  FIG. 6  to that of the manufacturer B as shown in  FIG. 7 , in order to enable mechanical coupling. The mount of the manufacturer A shown in  FIG. 6  and that of the manufacturer B shown in  FIG. 7  are mutually different in the mechanical shape, the number of pins in both connectors  7  and the pin assignment therein. The electrical configuration is different only in the wiring from the connector  7  to the camera interface board  9 . In such configuration, a camera manufacturer coder, set by a camera code switch  10  provided in the main PCB  3 , is transmitted therefrom by serial communication to the camera interface board  9 , whereby the camera interface can be switched automatically, and the main PCB  3  and the camera interface board  9  can be used in common. 
     FIG. 2  is a block diagram showing the configuration of the camera interface board  9 . 
   The camera interface board  9  is provided with a CPU  11 , a serial input/output circuit  12  for enabling serial communication between the CPU  11  and the main PCB  3  of the main lens body, and an A/D converter  14  and a D/A converter  15  for enabling analog signal exchange between the CPU  11  and the camera  8 . 
   At the output side of the D/A converter  15  there is provided an amplifier (AMP)  16 , for effecting conversion for matching the analog reference voltage of each camera. For effecting such conversion of the reference voltage, the camera interface board  9  is provide with plural reference voltages Ref 16 , Ref 17 , Ref 18 , corresponding to the adaptable cameras, and the level of the voltage outputted from the amplifier  16  is switched according to the shifting of an analog switch  20  by the CPU  11 . The switching is conducted for conversion to the output characteristics, corresponding to the camera, and can also be achieved by varying the gain of the amplifier instead of switching the reference voltage level. 
   A digital I/O interface  13  is provided for digital signal exchange with the camera  8 . The digital I/O interface  13  is also connected to the auxiliary switch  5  and the auxiliary indicator  6  of the mount  4  and handles all the digital signal exchange. For data storage, there are provided a RAM  21  and a ROM  22 . 
     FIGS. 8A-1  and  8 A- 2  show the configuration of a data conversion table, which is composed of zoom gain data (16 bits), zoom reference voltage data (16 bits), focus gain data (16 bits), focus reference voltage data (16 bits), iris gain data (16 bits), iris reference voltage data (16 bits), camera control data (8 bits) and camera answer data (8 bits), provided corresponding to camera codes which in turn correspond to the camera manufacturers or makers. 
   The serial data are composed of a command portion and a data portion, as shown in  FIG. 9 . 
     FIG. 3  is a flow chart showing a serial reception sequence from the main PCB  3 , to be executed in the camera interface board  9  shown in  FIG. 2 . 
   Data input from the serial input/output circuit  12  are read out by the CPU  11  (S 1 ), and there is discriminated whether the command portion of the serial data is a camera code command (S 2 ). As shown in  FIG. 10A , the commands include a camera code command, an analog data output iris command, an analog data output zoom command, an analog data output focus command, a digital I/O output command, and an indicator data command. The analog data output iris command, the analog data output zoom command and the analog data output focus command will be explained collectively as analog data output commands. 
   If the command portion is a camera code command, the data portions stored in the RAM  21  (S 6 ). Then, based on a voltage selection table ( FIGS. 8A-1  and  8 A- 2 ) set according to the camera code stored in the ROM  22 , the analog switch  20  is shifted to a reference voltage corresponding to the camera, among the reference voltages Ref 17  to Ref 19 . Thus the reference value for the analog voltage to the camera is automatically switched. As shown in  FIG. 8A , the camera codes are set from 0 to F corresponding to the manufacturers A to O, and are set by the camera code switch  10  of the main PCB  3 . Referring to  FIGS. 8A-1  and  8 A- 2 , the CPU  11  shifts the analog switch  20  in such a manner that the reference voltage Ref 17  is selected for the manufacturer A and the reference voltage Ref 18  is selected for the manufacturer B. If the command portion is not a camera code command, there is discriminated whether it is an analog output data command (S 3 ). 
   If it is an analog output data command, the data of the data portion are read out. Then, based on the camera code stored in the RAM  21 , the level of the analog data is converted according to the conversion table ( FIGS. 8A-1  and  8 A- 2 ) of the ROM  22  (S 7 ). The conversion is executed in the following manner. As an example, in case of conversion for zooming in  FIGS. 8A-1  and  8 A- 2 , the zoom gain is ‘833’ corresponding to the camera code  0  for the manufacturer A. The zoom data ZOOM — DATA are supposed to indicate the difference from the reference voltage. The ZOOM — DATA is multiplied by 833 and divided by 1000. If the entire operating voltage range 6V is the voltage in the lens, there is executed a calculation 6×833/1000=4.998V, thereby achieving a conversion to the output of 5V. 
   The data thus obtained is converted by the D/A converter  15  into an analog voltage (S 8 ), which is outputted to the camera through the amplifier  16 . As the amplifier is subjected to the switching of the reference voltage by the analog switch  20 , a voltage corresponding to the sum of such reference voltage and the output of the D/A converter  15  is supplied to the camera. This means that the conversion of the reference voltage and the gain is executed corresponding to the camera. 
   If the command portion is not an analog output data command, there is discriminated whether it is a digital I/O output command (S 4 ). If it is a digital I/O output command, the data portion is read out, then converted by the conversion table in the ROM  22 , according to the camera code stored in the RAM  21  (S 9 ), and the converted data are outputted to the digital I/O interface  13  (S 10 ). 
   The conversion is executed in the following manner, based on a conversion table shown in  FIG. 8B . In the illustrated table, each operation to be executed in the opposite polarity, such as 5V(H signal), is represented by “1”, while that in the same polarity, such as 0V (L signal), is represented by “0”. In case of setting for the camera of the manufacturer A, there is calculated the exclusive sum (EXOR) of the bit data of the conversion table corresponding to the camera code  0  and the digital I/O output command data ( FIG. 8C ) from the main PCB  3 , and such exclusive sum (EXOR) is according to the converted data to be outputted to the camera ( FIG. 8D ). Also in case of setting for the camera of the manufacturer B, the conversion is achieved ( FIG. 8E ) by calculating the exclusive sum (EXOR) of the data of the conversion table corresponding to the camera code  1  and the digital I/O output command data ( FIG. 8C ) from the main PCB  3 . Thus converted data is supplied to the digital I/O  13  to output the answer data of the lens, corresponding to the camera. 
   It is to be noted, however, that the data bits correspond to the output bit of the digital I/O in hardware. 
   If the step S 4  identifies that the command portion is not a digital I/O output command, there is discriminated whether it is an indicator data command (S 5 ). If it is an indicator data command, the auxiliary indicator  6  provided in the lens mount is renewed by the digital I/O  13  (S 11 ). 
   After the sequence from S 2  to S 5 , the sequence returns to S 1  to read out and process next data in a similar manner. 
     FIG. 4  is a flow chart showing a serial transmission sequence to the main PCB  3 , to be executed by the camera interface board  9  shown in  FIG. 2 . 
   The serial data are composed, as shown in  FIG. 9 , of a command portion and a data portion. 
   The commands include a mount auxiliary switch digital I/O data command, a camera input digital I/O data command, a camera analog iris data command, a camera analog zoom data command, and a camera analog focus data command ( FIG. 10B ). 
   The input from the auxiliary switch  5  is stored by the digital I/O  13  in the CPU  11 , and the data is written into a mount switch input of the transmission data address in the RAM  21  shown in  FIG. 11 . 
   Then the digital input signal from the camera is read from the digital I/O  13  and is converted into data in the lens. 
   This conversion is executed in the following manner, utilizing the conversion table shown in  FIG. 8B . 
   In case of setting for the camera of the manufacturer A, there is calculated the exclusive sum (EXOR) of the bit data of the conversion table corresponding to the camera code  0  and the camera input digital I/O data ( FIG. 8C ) from the main PCB  3 , as such exclusive sum (EXOR) is according to the converted in-lens data ( FIG. 8D ). Also in case of setting for the camera of the manufacturer B, the conversion is achieved ( FIG. 8E ) by calculating the exclusive sum (EXOR) of the data of the conversion table corresponding to the camera code  1  and the camera input digital I/O data ( FIG. 8C ) from the main PCB  3 . Thus converted data is written into a control signal from the camera to the lens, in the transmission data address of the RAM  21  shown in  FIG. 11B  (S 13 ). 
   Then the analog signal from the camera is converted by the A/D converter  14  into the in-lens data and stored in the CPU  11  (S 14 ). The conversion is executed in the following manner. As an example, in case of conversion for zooming in  FIG. 8A , the zoom gain is ‘833’ corresponding to the camera code  0  for the manufacturer A. The read zoom data ZOOM — DATA are supposed to indicate the difference from the reference voltage. The ZOOM — DATA is multiplied by 1000 and divided by 833. If the entire operating voltage range of 5V is the voltage in the camera, there is executed a calculation 6×1000/833=6.002V, thereby achieving a conversion to the input of 6V. In addition to the zooming explained above, iris and focusing can be processed in a similar manner. The converted data is written into the iris control, zoom control and focus control from the camera of the transmission data address in the RAM  21  shown in  FIG. 11B  (S 14 ). 
   Then, the main PCB  3  adds a command for data identification to the data of each transmission data address of the RAM  21  shown in  FIG. 11B , and these data are transmitted in succession to the main PCB  3  through the serial input/output circuit  12  (S 15 ). 
   The sequence from S 12  to S 15  is executed repeatedly, and such transmission procedure allows the main PCB  3  to process the normalized data in the lens, even if the camera is changed. 
   In the present embodiment, the camera interface board  9  is provided in the mount  4 , but it may also be provided outside the mount  4 . Also the main PCB  3  is provided with the camera code switch  10  for changing the setting in case the camera is changed, but it is also possible to provide the camera interface board  9  with such camera code switch  10  whereby the camera interface board  9  executes signal conversion by directly recognizing the camera setting and returns the camera code to the main PCB  3  by serial communication. 
   Also in the present embodiment, the camera interface board  9  executes conversion of the data to or from the camera and the ROM  22  for the data conversion tables is provided in the camera interface board  9 , but it is also possible to execute the data conversion in the main PCB  3  and to provide the main PCB  3  with the ROM  22  for the data conversion tables. 
   Second Embodiment 
   The second embodiment is different from the first embodiment in such configuration of the camera interface board that the electrical interface between the camera and the lens is achieved by serial communication.  FIG. 12  is a block diagram showing the configuration of the camera interface board in case the electrical interface is achieved by serial communication. 
   The camera interface board  9  is provided with a CPU  11 , a serial input/output circuit  12  for serial communication between the CPU  11  and the main PCB  3  of the main lens body, and a camera serial input/output circuit  23  for serial communication between the CPU  11  and the camera  8 . The CPU  11  is connected to a RAM  21  for data storage and a ROM  22  for table data. 
   The CPU  11  is further connected to a digital I/O interface  13 , for the auxiliary switch  5  and the auxiliary indicator of the mount  4 . 
   The serial signal supplied from the camera  8  through the connectors  7  is input into by the CPU  11  through the camera serial input/output circuit  23  of the camera interface board  9 . The CPU  11  converts the signal into a data format in the lens and transmits it to the main PCB  3  through the serial input/output circuit  12 . 
   The commands from the camera to the lens include, as shown in  FIG. 22A , an iris F number control command, a zoom focal length control command, a focus object distance control command, and a lens on/off control command. 
   The data format mentioned above is a normalization process for actual data processing in the lens. As an example, in case the zoom control data is transmitted from the camera  8  in the form of a focal length, there is executed the conversion into an in-lens position signal for moving the lens to a zoom position corresponding to such focal length. In the following description, the wide angle end and the telephoto end of the lens are respectively represented by 0 and 0xffff.  FIG. 15  is a flow chart showing the sequence in case the camera interface board receives zoom control data from the camera. When zoom control data by the focal length is received from the camera (S 31 ), the camera interface board reads out the lens code stored in the RAM  21 . 
   The lens code is transmitted from the main PCB  3  to the camera interface board and is stored in the RAM  21 . After the reading of the lens code, a zoom data converting table corresponding to such lens code is selected (S 32 ), and conversion is made by interpolating calculation utilizing the data of such table. This conversion provides zoom position data in the lens. This data is stored in the zoom control of the data address in the RAM  21  for transmission to the main PCB, shown in  FIG. 23A  (S 33 ).  FIG. 19  shows a zoom position data table of the lens corresponding to the focal length control data, wherein “•” indicates omission of the intermediate data. 
   Similar conversion (data interpolation) is executed for the focus with the table shown in  FIG. 18  and for the iris with the table shown in  FIG. 20 , and the normalized control data in the lens are stored in the focus control and iris control of the data addresses in the RAM  21  for transmission to the main PCB  3 , shown in  FIG. 24A . 
   Also in case a lens on/off control command is received, there is executed conversion, based on a conversion table stored in the ROM  22 , into data to be actually usable in the lens. 
     FIG. 16  is a flow chart showing the process sequence in case the lens on/off control command is received from the camera.  FIG. 21  shows a data conversion table for the commands 0x80 to 0x8f. The table contains bit conversion data for converting these commands into bit data, and mask data required for renewing such bit data. The command can be converted into the data format in the lens, by applying following process to the data for transmission to the lens. For transmission, there is calculated AND of the RAM data which are transmission data to the lens and the mask data, and then calculated OR of thus obtained data and the bit conversion data to prepare renewed RAM data. In this manner there is achieved inverse conversion from the bit data to the command. 
     FIG. 14  is a flow chart showing the sequence for the communication from the camera interface board  9  to the main PCB  3 . The commands in this communication include, as shown in  FIG. 23B , an iris control command, a zoom control command, a focus control command, a lens on/off control command, and a mount switch input data command. The iris control command, the zoom control command and the focus control command will be collectively called analog data commands. The input from the auxiliary switch  5  is read from the digital I/O  13  (S 28 ), and the data are stored in the mount switch input of the transmission data address to the main PCB  3 , shown in  FIG. 24A  (S 29 ). The iris control, zoom control, focus control and on/off control from the camera to the lens, stored in the transmission data addresses to the main PCB  3 , as shown in  FIG. 24A , are stored after data conversion at the reception of the commands from the camera. These commands are respectively given headers for data identification and are transmitted in succession to the main PCB  3  through the serial input/output circuit  12  (S 30 ). 
     FIG. 13  is a flow chart showing the sequence of communication from the main PCB  3  to the camera interface board  9 , to be executed in the interface board  9  shown in  FIG. 12 . The communication commands from the main PCB  3  to the camera interface board  9  include, as shown in  FIG. 23A , a lens code command, an iris follow command, a zoom follow command, a focus follow command, an answer command to the camera in response to on/off command, and an indicator data command. The iris follow command, zoom follow command and focus follow command will be collectively called analog output data commands. 
   When the camera interface board reads out the received data (S 17 ), there is discriminated whether it is a lens code command (S 18 ), and, if it is a lens code command, the lens code is stored in the RAM  21  (S 19 ). This lens code is used for conversion for zoom and focus controls. 
   If it is not a lens code command, there is discriminated whether it is an analog output data command (S 19 ). If it is an analog output data command, the lens code stored in the RAM  21  is read out. Then an interpolating calculation is executed with the conversion tables shown in  FIGS. 18 and 20  for conversion into the F-number control in case of iris, the focal length in case of zooming or the object distance in case of focusing, and the obtained data are stored in the iris F-number follow, zoom focal length follow or focus object distance follow of the data addresses for transmission to the camera in the RAM  21 , shown in  FIG. 23B  (S 24 ). 
   If the command is not an analog output data command, there is discriminated whether it is an answer code for the lens on/off state (S 20 ). 
   If it is an answer command, data of the RAM  21 , different from the preceding one, are converted into a command. The conversion is executed utilizing the conversion table in the ROM  22  shown in  FIG. 21 , and the command after conversion is stored in a transmission buffer for transmission to the camera. If the command is not an answer command, there is discriminated whether it is an indicator turn-on command (S 21 ), and, if so, the data for the indicator in the mount are renewed. 
     FIG. 17  is a flow chart showing the sequence of communication to the camera. The transmission command to the camera include, as shown in  FIG. 22B , an iris F-number follow command, a zoom focal length follow command, a focus object distance follow command, and a lens control on/off answer command. The iris F-number follow command, zoom focal length follow command and focus object distance follow command will be collectively called analog data commands. At the interval for transmitting the analog data command, data are received from the RAM  21  shown in  FIG. 24B  and are transmitted, together with a header for data identification, to the camera (S 40 ). When there is no interval, the lens control on/off answer command is transmitted if it is present in the transmission buffer (S 41 ). 
   As explained in the foregoing, the mount incorporating the camera interface board of the configuration shown in  FIG. 12  allows to convert the data transmitted from the camera by serial communication into the normalized data of the format in the lens.
This invention provides a lens device to be mounted on a television camera and capable of executing appropriate process even when it is used in combination with the cameras of different characteristics. The lens device has an interface circuit of which characteristics are switchable according to the camera to be used, whereby the characteristics of the lens device match those of the television camera used.