JPH04161934A - Adapter for replacement lens of camera - Google Patents

Abstract

PURPOSE:To match two different AE control systems and accomplish AE control of good performance by producing an auto-exposure control signal with an image signal processing circuit of a video camera equipped with function of auto-exposure control, and converting this control signal into another form of auto-exposure control signal to suit the replacement lens system for still camera equipped with function of auto-exposure control. CONSTITUTION:An AE control signal prepared from outputs of a camera encoder 5. camera signal processing circuit 4, etc., of a camera unit CM equipped with AE (auto-exposure) controllability and AF (auto-focusing) controllability is converted by a microcomputer 17 of a conversion adapter AD into another form of AE control signal to suit the system of a lens unit LS for a still camera equipped with AE and AF controllabilities. This permits matching two different AE control systems to enable a replacement lens according to the lens system for still camera to be used in the replacement lens system of video camera. Thus AE control of good performance is achieved.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention provides a method for connecting a video signal processing system of a video camera capable of automatic exposure control and an interchangeable lens system for a still camera capable of automatic exposure control. This invention relates to an adapter for interchangeable lenses.

[Prior Art] In recent years, in video movie systems, an interchangeable lens system for movies that can be used interchangeably with various lenses has been proposed, unlike a normal camera/lens integrated system. As such an interchangeable lens system, a system for a still camera such as a single-lens reflex camera is generally known, and various lenses for this system, including special lenses suited for various uses, have already been supplied to the market. However, since the video movie system is still in its introductory stage and the market has not yet been developed, it is not realistic to produce a wide variety of special lenses, which should be a feature of the interchangeable lens system, at this early stage. Therefore, it has become an effective means to use interchangeable lenses for still cameras such as the above-mentioned single-lens reflex cameras, which have already been introduced in the market and are recognized by users. In order to connect this video movie camera and still camera interchangeable lens, a conversion adapter is required mainly for the following reasons (a) to (C).

(a) Since the mounts for the video movie interchangeable lens system and the mounts for the still camera interchangeable lens system are different, it is necessary to match them.

(b) Since the distances between the imaging surfaces and the mounting positions of the video movie camera and the still camera are different, it is necessary to match the optical path difference.

(C) The video movie interchangeable lens system and the still camera interchangeable lens system have different communication formats for receiving and passing various data necessary for control, and also have different data formats/control formats. , it is necessary to achieve consistency.

Here, there are considerable differences between a video movie camera and a still camera in conditions such as their form, imaging conditions, and functions. Therefore, there are also differences in the AE (automatic exposure) control methods. Next, an outline of this AE control method will be explained.

First, the AE control system of a conventional camera-integrated VTR will be explained with reference to FIG. After the light intensity of the layered image light from the lens optics r2--entering needle 1-5 is adjusted by the Manolis diaphragm 2, a subject image is formed on the image pickup device 3, where it is photoelectrically converted. The signal obtained from the image sensor 3 is converted into a composite video signal for telephony by a camera signal processing circuit 4 and a camera encoder 5, and is output to the outside. At this time, the luminance signal Yy obtained from the camera (Z processing circuit 4) is integrated by the integrator 6, and the arithmetic unit 18 generates a difference signal from the reference level from the reference value generation circuit 19. This difference No. 15 is sent to the driver 13 as an AE control signal, and the iris diaphragm (diaphragm mechanism for W light adjustment) is controlled via the actuator 14.

Next, the AE control system in an interchangeable lens type VTR will be explained with reference to FIG. The camera unit CM is on the right side, and the lens unit LS is on the left side, with the mount part MT indicated by the dashed line in the center of the figure as a border. A subject image formed from the lens optical system 1 through the iris diaphragm 2 onto the imaging surface of the image sensor 3 is photoelectrically converted by the image sensor 3 and output as an image signal. The image signal supplied from the image sensor 3 to the camera signal processing circuit 4 is subjected to γ (comma) conversion, etc., and is taken out as a video signal of a color signal C and a luminance signal YA, and is sent to a camera encoder 5 such as an NTSC system. The video signal is then output from this camera section to the outside in the form of a composite video signal. Further, the brightness signal YA outputted from the camera signal processing circuit is sent to the AE circuit in order to generate an AE control signal for controlling the iris diaphragm 2 so as to obtain proper exposure according to the brightness state of the screen. Integral 56. Amplifier (AMP) 7
and is supplied to the DC level shift circuit 8. In this AE circuit, the input luminance signal YA is integrated by an integrator 6, amplified to a predetermined level by an amplifier 7, and then the reference level is set to a predetermined voltage by a DC level shift circuit 8. . Based on the level difference from this reference level, the method for setting the AE control data is to set the amplifier 7 so that the communication data as shown in FIG.
, and by adjusting the DC level shift circuit 8. The signal generated by the AE circuit is then
After being converted into a digital signal by the D converter 9, it is manually input to the camera side microcomputer (microcomputer) 1o.
The signal is transmitted as an AE control signal to the lens unit LS via the data communication path 21 at a predetermined timing.

At this time, the data communication path 21 is connected to the lens-side microcomputer 11, and all communication data is once received by the lens-side microcomputer 11, converted to an analog signal by the D/A converter 12, and then sent to the driver circuit 13. Supplied. The iris diaphragm 2 is then controlled via the actuator 14. A transmitted to this lens unit LS
FIG. 8 shows representative values when E control data is allocated, for example, in 8 bits (256 steps). As shown in this figure, each level difference is expressed by an EV (aperture) value; for example, +IEV indicates that the optimum exposure should be stopped down by IEV (so-called one aperture). Further, the AE sub-control reference value is set to 32 in this case, and it is assumed that the iris does not move when this data is used. Then, on the lens side, as described above, the control data transmitted from the camera side is converted back into an analog signal by the D/A converter 12, and the actuator 14 is driven through the driver 13, and the iris diaphragm 2
to drive. As described above, by digitally encoding and transmitting the control signal that includes the iris drive stop based on the level of the video signal as AE control information, it is possible to ignore the difference in apparent gain of the camera. Similarly, differences in camera dynamic range are not a problem. Furthermore, since the reference values are unified in a predetermined coat, compatibility is maintained.

Finally, the AE control method in the still camera will be explained using FIG. 9. The imaging light incident from the lens optical system 1 is adjusted in light intensity by the iris diaphragm 2 as described above, and then passes through the photometry element 3A for performing partial/average photometry.
and is manually applied to the photometric element 3B for performing spot photometry. The outputs of the photometric elements 3A and 3B are amplified by amplifiers 7A and 7B, respectively, and then input to the photometric circuit 23. In this photometry circuit 23, the photocurrent is converted into a logarithmically compressed voltage, which is then applied to the camera-side microcomputer 10. Then, the camera-side microcontroller 10 controls various AE modes (shutter-priority AE, aperture-priority AE, depth-priority AE, etc.).
Exposure calculation is performed to find the appropriate exposure according to the mode), and the result of this exposure calculation is the difference between the shooting aperture and the maximum aperture,
That is, it is determined as a value corresponding to the number of aperture stages. This aperture stage number is sent to the lens-side microcomputer 11 of the lens unit LS via the data transmission line 21.

The number of aperture stages inputted from the camera side is converted into the number of steps of the stepping motor (M) 20 by the lens side microcomputer 11, and the driver 1
3, a stepping motor 14 is driven. As a result, the iris diaphragm 2 opens and closes, and exposure control is performed.

At this time, the relationship between the stepping motor 20 and the iris diaphragm 2 is such that, for example, the iris diaphragm changes by 1/8 step per rotation of the rotor of the stepping motor 14 by one pitch.

[Fi problem to be solved by the invention] By the way, in the above control method, the AE control method in the interchangeable lens system for a video movie camera calculates the difference value between the reference light amount and the current light amount on the lens side. The lens side controls the amount of light by driving the diaphragm mechanism analogously from the current position based on the difference value, and finally controls the reference amount of light and the actual amount of incident light to be equal. It has become. In addition, the AE control method in the interchangeable lens system for still cameras uses the difference between the absolute value information of the current aperture and the absolute value information of the target aperture from the camera side. ) and sends the converted data to the lens side, which controls the light amount by digitally driving the aperture mechanism with a specified number of pulses, and finally adjusts the aperture (light amount) to the user's intended aperture (light amount). It is a method of controlling so that For this reason, AEf! from the camera side in an interchangeable lens system for a video movie camera! There was a problem in that the data for 1 Jal could not be directly used as data for AE control of the interchangeable lens in the still camera interchangeable lens system, and AE sub-control could not be performed.

The present invention was made to solve the above-mentioned problems by matching two different AE control methods, and using the interchangeable lens of the interchangeable lens system for still cameras in the interchangeable lens system of the video camera. The object of the present invention is to obtain an adapter for an interchangeable lens of a camera that enables good AE sub-control.

[Means to solve the problem]

The camera interchangeable lens adapter of the present invention is compatible with an interchangeable lens system for a still camera capable of automatic exposure control by transmitting an automatic exposure control signal generated from the output of a video signal processing circuit of a video camera capable of automatic exposure control. The device is equipped with a signal converting means for converting the automatic exposure control signal into an automatic exposure control signal.

[Effect]

In the camera interchangeable lens adapter of the present invention, due to the function of the signal conversion means, when viewed from the video camera,
Interchangeable lenses for still cameras can be handled just like interchangeable lenses for video cameras, and there is no need to be aware of the differences between the lenses. Further, the interchangeable lens for a still camera operates as if it were processing data from a still camera, and can be used as a lens without any modification.

(Embodiment) FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention. Components that are the same as those of the above-mentioned conventional example are given the same reference numerals and detailed explanations will be omitted. In the same figure, 1 of the 2 trees
Mount part MT1. shown by the dotted chain line. The parts divided by MT2 are, from the right, a camera unit CM, a conversion adapter AD, and a lens unit LS, each of which is equipped with a microcomputer 10, 17, and 11. Then, the conversion microcomputer 17 of the conversion adapter AD converts the AE
The AE control signal generated from the output of the video signal processing circuit (camera signal processing circuit 4, camera encoder 5, etc.) of a video movie camera (camera unit CM) capable of control and AF (automatic focusing) control is A signal conversion means is configured to convert the signal into an AE control signal compatible with an interchangeable lens system for a still camera (a system of lens unit LS) capable of control and AF control.

In the camera unit CM, the AF control signal generated by the AE circuit is finally converted into a digital signal by the A/D converter 9 in the same manner as shown in FIG. 7, and then input to the camera side microcomputer 10. The data processing described below is performed.

At that time, whether the reference level output of the reference value generation circuit 19 is A/
It is taken into the camera-side microcomputer 10 via the D converter 16 as a reference value Yr, and is processed together with the output Yc of the A/D converter 9. This calculation process is as follows.

Di= (Yc-Yb) / (Yr-Yb)
x Dc--...= (1) Data i: Data for AE control (Diris) YC: Signal for AE control input to the camera side microcomputer Yc at reference level Yb: When image sensor light is blocked Yc level Dc: AE control data at reference level (center value) The above calculated AE control data Di is sent to the conversion adapter AD via the data communication path 21 at a predetermined timing.
E is sent as a control signal (X is sent).

At this time, the data communication path 21 is connected to the conversion microcomputer 17 of the conversion adapter via a direct connection point (not shown) of the mount MTI.
All communication data is once received by this conversion microcomputer 17. For example, if the control data to be transmitted is assigned in 8 bits (256 steps), and the representative value (Da) is set to 32 considering the general characteristics of the video signal and iris diaphragm 2, then each representative value is The values are shown in FIG. 8 already mentioned. In FIG. 8, each level difference is expressed by an EV value. For example, +IEV indicates that the optimum exposure should be stopped down by IEV (so-called one aperture). Also, A.E.
In this case, the control reference value is set to 32, and it is assumed that the iris diaphragm 2 does not move when using this data. The AE control data D i (Diris) is
It is set based on the communication data transmitted from the camera body, taking into consideration the level difference, the control direction code, etc.

FIG. 2 shows the specific processing operations of the camera unit CM mentioned above, and shows the processing contents of the camera-side microcomputer 10.

First, in step S1, the output of the video signal level of the AE circuit is taken in via the A/D converter 9, and at the same time, in step S
At step 2, the reference level output of the reference value generation circuit 19 is read through the A/D converter 16. Then, in step S3, the above-mentioned equation (1) is calculated (video signal level - black level)/
(Reference level - Black level) x 32 is executed to obtain AE control data Di. Next, in step S4, some V
Wait until the input timing of nync (video vertical synchronization signal), and when the input is complete, select the chip select signal in step S5. Send from unit CM to conversion adapter AD (serial communication), step S
Step 7 resets the chip select word.

As described above, information for AE control is created in the camera unit CM. Here, the conversion microcomputer 17 in the conversion adapter AD converts the data based on the AE control data (relative difference data) created on the camera side and sent via the data communication path 21 as described above. It is necessary to convert the data into absolute aperture difference data that can be used by the lens unit LS. Therefore, the relationship between the AE control transmission data and the EV value based on FIG. 8 becomes a graph as shown in FIG. 3. Of course, the conversion method at this time could be to convert the diagram into an arithmetic expression and execute it, but when considering the capabilities and costs of the microcomputer, it is not a good idea to have the microcomputer perform complex calculations. Therefore, convert the values calculated in advance (or from the graph) into conversion table 1.
It is practical to have it as 5. For example, if the minimum resolution of the aperture drive mechanism in the lens group of a still camera interchangeable lens system is set to, for example, 1/8 step (if a pulse motor is used, the aperture will change by 1/8 step with one pulse drive of the pulse motor. Further, FIG. 4 shows a conversion table 15 in which the aperture changes by one aperture, that is, IEV by eight pulses. In the figure, only the absolute value of the pulse number is shown.

The pulse number data obtained from FIG. 4 above is transmitted to the lens side as an AE control signal via the data communication path 22. At this time, the data communication path 22 is connected to the mount section MT2.
It is connected to the lens-side microcomputer 11 via a direct connection point (not shown), and all communication data is once received by the lens-side microcomputer 11.

FIG. 5 is a flowchart showing specific processing operations of the conversion adapter described above, and shows the processing contents of the conversion microcomputer 17.

First, in step S11, the chip select input of the microcomputer 17 is confirmed, and if it is selected, the process goes to step S1.
2, the AE control data is serial-parallel converted and taken in.

Next, in step 513, the corresponding number of drive pulses is determined from the conversion table 15 based on the captured data. Then, in step 514, the driving direction of the pulse motor (stellar pink motor 20) is determined by checking the magnitude relationship with the reference value based on the above data, and in step S15, it is confirmed whether the lens side is in a communication standby state. At this time, if it is in the standby state, the data on the number of driving pulses and the driving direction are converted from parallel to serial in step S16, and the conversion adapter A
D is serially transmitted to the lens side, and in step S17, it is confirmed that the driving on the lens side is completed.

As described above, AE control information is converted in the conversion adapter AD. At this time, as the processing of the lens unit LS, since the above processing is performed by the conversion adapter AD, the data transmission path 2 is transferred from the conversion microcomputer 17.
The data sent via 2 is no different from the data sent from the still camera (format).

Therefore, it is no longer possible to perform operations within the normal processing range.

In this way, the relative drive value for AE control transmitted from the video camera to the converter is converted into an absolute drive value that can control (drive) the interchangeable lens group for the still camera, so two different AE controls are possible. The system can be matched, the interchangeable lens of the still camera interchangeable lens system can be used in the interchangeable lens system of the video camera, and good AE sub-control can be achieved.

(Effects of the Invention) As described above, according to the present invention, it is possible to use an interchangeable lens of an interchangeable lens system for a still camera in an interchangeable lens system of a video camera, and it is possible to obtain an effect that good AE sub-control is possible. .

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention, FIG. 2 is a flowchart showing the processing operation of the camera unit in FIG. 1, and FIG. 3 is a diagram showing the relationship between iris control data and EV value. , FIG. 4 is a diagram showing an example of the conversion table shown in FIG. 1, FIG. 5 is a flowchart showing the processing operation of the conversion adapter shown in FIG. 1, and FIG. 6 is a block diagram showing the configuration of the camera-integrated VTR. , FIG. 7 is a block diagram showing the configuration of an interchangeable lens type VTR, and FIG. 8 is a diagram showing the relationship between the video signal and iris control data in the VTR shown in FIG. 7.
FIG. 9 is a block diagram showing the configuration of the still camera. ! ......Lens optical system 2----Iris diaphragm 3=--Image sensor 4-=Camera signal processing circuit 5--Camera encoder i o---Camera side microcomputer 1
1--Lens side microcomputer 13...
Driver 14--Stepping motor 15--Conversion table 17--Conversion microcomputer (signal conversion means) 19---Reference value generation circuit

Claims (1)

[Claims] Signal conversion that converts the automatic exposure control signal generated from the output of the video signal processing circuit of a video camera capable of automatic exposure control into an automatic exposure control signal compatible with an interchangeable lens system for a still camera capable of automatic exposure control. An adapter for an interchangeable lens of a camera, characterized in that it is equipped with a means.