WO2013098288A1

WO2013098288A1 - Method for controlling a camera device, display device and camera device implementing such a method

Info

Publication number: WO2013098288A1
Application number: PCT/EP2012/076897
Authority: WO
Inventors: Jacques Delacoux
Original assignee: Transvideo
Priority date: 2011-12-29
Filing date: 2012-12-26
Publication date: 2013-07-04
Also published as: FR2985405A1; FR2985405B1

Abstract

The present invention relates to a method for controlling a camera device. It also relates to a display device and to a camera device implementing such a method. The camera device (140) comprises a support mechanism (144 - 150) for supporting a cinematographic camera (145) or camera of a similar kind. The support mechanism allows an operator to manoeuvre the camera (145) while monitoring the picture that said camera is currently taking on a display device (20; 147). A measurement of the relative inclination of the camera with respect to a reference axis of the scene being shot is taken (E1) so as produce (E2) an artificial horizon display on the device that displays the current view seen by said camera. The acceleration of the camera is taken into consideration (E3), said acceleration then being used in a later step (E4) of correcting the artificial horizon, said corrected artificial horizon finally being used in a step (E5) to display a corrected artificial horizon on said display device.

Description

"Control method of a camera, display device and camera device implementing such a method"

TECHNICAL FIELD OF THE INVENTION

The present invention relates to a method of controlling a camera. It also relates to a display device and a shooting device implementing such a method. STATE OF THE ART

In the state of the art, there are known filming devices, in particular for cinematographic shooting, which comprise a mechanism for supporting the camera and which are associated with at least one display and monitoring device. shooting, also called monitor or video monitor. The support mechanism makes it possible to move the camera in movements that must be perfectly satisfactory, in particular during the monitoring of the display device by the operator of the camera and by the director or other speakers during of a shoot composed of a series of shots.

Such cameras have already been presented which include an inclinometer mounted in mechanical relation with the camera of the camera. The inclinometer makes it possible to display an artificial horizon on a display device associated with the camera and whose display of the measurement of the inclination, which it provides, makes it possible to determine whether the camera on its camera device Shooting is correctly oriented during the relative movements of the camera and the scene being shot.

However, it was found that the camera movements biased the indication of the inclinometer and that, therefore, the display of the artificial horizon was erroneous in several shooting situations. The The present invention aims to remedy this disadvantage of the state of the art.

In the state of the art, we know the document "Tiffen - Steadicam Phantom - 2010" whose teachings are included in the preamble of claim 1. This document indicates the use of an artificial horizon in relation to a display device integral with the camera, the gyroscopes which are indicated in this document are not members of the artificial horizon of the display device. These gyroscopes perform an inertial control of the complete assembly in use on a cameraman.

The document A. lu. Ishlinskiiet al. "Vertical Gyroscope" refers to an artificial horizon for a vehicle. This artificial horizon is based on a vertical axis gyroscope. In this document, two types of gyroscopes are described: a first type of gyroscope, called "gyropendulum" that the document defines as a gyroscope that does not require a correction system; and a second type of gyroscope, called "inertial vertical pendulum" and which, by construction, needs a correction system. The fact that the second type of gyro requires a correction system has no reason to encourage the correction of the artificial horizon associated with a display monitor with a correction system as evoked in the "Tiffen" document.

BRIEF SUMMARY OF THE INVENTION For this purpose, the control method of a shooting device comprising a support mechanism of a cinematographic camera, and the support mechanism allowing an operator to maneuver the camera while monitoring the camera. current view of said camera on a display device of the device, the method comprising a step of measuring the relative inclination of the camera with respect to a reference axis of the scene of the shooting, then a step for producing an artificial horizon on the display device of the current view of said camera based on said tilt measurement. The method comprises a step of account of the acceleration of the camera, said acceleration being used during a subsequent step of correction of the horizon, said corrected horizon being then used during a step to display a corrected horizon on said display device.

According to other characteristics, the horizon correction step produces a corrected horizon HC which depends both on the artificial horizon generated H and on the acceleration taken into account A according to a determined correction function f () of the form: HC = f (H, A), said correction function f () being selected from a plurality of determined functions including in particular a trigonometric function and a linear function of the form: HC = H - k ^* Ax, in which Ax refers to at least one axial component of the acceleration A and k is a coefficient associated with the said axial component, the said coefficients and definitions of the correction functions f () being determinable by calibration, calibration and / or by manual selection. using a user interface available to the operator on the display device.

The method comprises comparing the acceleration taken into account A of the camera of the camera with a given acceleration profile selected, selected using the user interface on the display device so as to control the movements of the camera, in particular by displaying markers of movements simultaneously with the display of the artificial horizon corrected HC on said display device, and / or by the control of electromechanical actuators of the camera .

The invention also relates to a display device for implementing the control method, and comprising a user interface and a display screen. The device comprises:

a means for measuring the inclination and the acceleration of a camera, preferably composed of an inclinometer and an accelerometer integral with the display device, itself able to be secured to a camera device,

a circuit for generating an artificial horizon corrected on the display device by using both the inclination and the acceleration of the camera so as to correct the inclination as a function of the acceleration; and

means for displaying said corrected artificial horizon on the screen of the display device. The invention also relates to a shooting device for the implementation of the control method and comprising a support mechanism of a cinematographic camera, the support mechanism allowing an operator to maneuver the camera while monitoring the image. in progress of said camera on a display device, and means for taking into account the inclination of said camera with respect to a predetermined reference axis connected to a means for generating an artificial horizon intended to be superimposed on the image taken by the camera on said display device. The device further comprises means for taking into account the acceleration of said camera and an artificial horizon correction circuit which receives a signal representative of the artificial horizon generated by the means for generating an artificial horizon corrected according to a predetermined correction function f (), a signal representative of a corrected artificial horizon being received by means of transmitting a corrected artificial horizon to said display device.

According to other characteristics:

the means of taking account of the inclination comprises an inclinometer integral with a reference axis of said camera and / or the means of taking acceleration into account comprises an accelerometer integral with a reference axis of said camera and / or in that the means for taking account of the inclination and the means for taking acceleration into account are mounted on a display device mounted on the camera. the means for transmitting a corrected artificial horizon comprises radio frequency communication means for communicating at least one inclination signal, an acceleration signal, a signal representative of an artificial horizon, a signal representative of a corrected horizon, and / or a video signal generated by the camera to at least one display device comprising means for receiving said signal transmitted by the radio frequency communication means.

The device comprises a circuit for comparing at least one vector component of the instantaneous acceleration of the camera with an acceleration profile determined by program and / or by a user interface to activate a generator of a motion control signal camera having the generation of at least one active marker superimposed with the display of artificial horizon corrected on said display device and / or an electromechanical actuator control of the camera.

Other features and advantages of the present invention will be better understood from the description and the appended figures, among which:

- Figure 1 shows a block diagram explaining the method and the device according to a particular embodiment of the invention;

- Figure 2 shows the screen of a display device or display implemented according to the method of the invention;

- Figure 3 shows a shooting device adapted to implement the method of the invention;

- Figure 4 shows the screen of a display device or display of a camera according to another embodiment of the invention; and

FIG. 5 represents a variant added to the device described using FIG. 1 which makes it possible to control the generation of the markers. DETAILED DESCRIPTION OF THE FIGURES

In Figure 1, there is shown a block diagram explaining the method and the device according to a particular embodiment of the invention. As is known a camera has included an inclinometer 1, which is an electronic sensor whose output signal is dependent on the inclination of the sensor. The inclinometer is mounted on or in mechanical connection with the camera (not shown in Figure 1) so that the signal produced at the output of the inclinometer can display on an associated display device to the camera, an artificial horizon. The output signal of the inclination sensor 1 is inputted to a signal conditioning circuit 2 which is provided to adapt the inclination signal to the characteristics of the camera, especially in terms of resolution, scales and direction of inclination. More generally, such an arrangement is based on taking into account the inclination of the camera with respect to a reference axis such as the vertical of the location of the shooting. It is intended to deduce such a consideration of several different parameters such as an analysis of images, views, the camera to derive an inclination.

The conditioned signal from the signal conditioning circuit 2 is inputted to an artificial horizon generator 3 associated with the display device. The artificial horizon is then displayed in a graphical form or in a digital form or in the form of a plot superimposed on the current image of the shot.

But when the camera is animated with changing movements, for example with sudden changes of direction, the tilt sensor 1 reacts with inertia so that the indication of the inclination by the artificial horizon displayed is wrong. This situation then deceives the operator who manipulates the camera which relies on the view displayed on the display device associated with the camera with the displayed artificial horizon. To remedy this drawback, the device of the invention comprises an accelerometer 6 which produces a signal for measuring the instantaneous acceleration of at least one part integral with the camera. A conditioning circuit 7, similar to the conditioning circuit 2, receives the measurement signal of the acceleration coming from the accelerometer 6. An acceleration vectorization circuit 8 is, in one embodiment, connected at the output of the circuit of FIG. conditioning 7 so as to produce an acceleration vector which can be the projection of the acceleration measured on the reference direction of the inclination measured by the inclinometer 1. The two conditioned signals originating from the conditioning circuits 2 and 7 or 8 of vectorization of the acceleration are input to a correction circuit 10 of the artificial horizon which produces a signal representative of the artificial horizon corrected on the basis of the acceleration measured by the accelerometer 6, as will be described later.

The signal representative of the corrected artificial horizon is then provided at the input of a transmission circuit 11 to at least one display device (not shown in FIG. 1). If only one display device is provided, the transmission circuit 1 1 is a simple connector. In the case of a plurality of transmission devices, the transmission circuit 11 makes it possible to form a network of display devices in relation to the camera. We will now describe using this same figure 1, the control method of the invention. During a step E1, a measurement of the inclination of the camera with respect to a reference axis is carried out in a known manner, such as the vertical of the scene of the shot of views. During a step E2, a signal is generated representative of an artificial horizon to be displayed on at least one display device associated with the camera. These steps are well known in the state of the art. They are supplemented according to the invention by a step E3 measuring or taking into account the acceleration, and in particular the instantaneous acceleration of the camera.

At a given moment, a step E4 of artificial horizon correction produced on the sole basis of the measurement of the inclination is performed taking into account the acceleration taken into account. For this purpose, a corrected horizon HC is produced that depends both on the artificial horizon generated H (step E2, on the circuit 3) and on the acceleration detected or taken into account A (step E3, circuits 6-8 ) according to a determined function f () of the form: HC = f (H, A). The correction function f () is selected from a plurality of determined functions including a trigonometric function and a linear function of the form: HC = H - k ^* Ax.

In this formulation of the invention, Ax refers to at least one axial component of the acceleration A, and k is a coefficient associated with said axial component. The various coefficients and definitions of the correction functions f () are determinable by calibration, calibration and / or manual selection by means of a user interface (22) available to the operator on the display device ( 20; 147).

In one embodiment, the acceleration Ax is measured along a single aligned axis relative to a reference direction of the camera. Preferably, the correction function f () is a linear function of the form: HC = H - k ^* Ax.

In another embodiment, the acceleration A is measured along the three positioning axes of the camera space, one of the measurement axes of the acceleration being aligned with respect to a reference direction of the device shooting. The correction function f () is then chosen on the basis of the trigonometric projections of the actual displacement of the camera along the three axes of the accelerometer. Of course, as is known, the number of axes of the accelerometer can be increased, the axes are then not all aligned on the directions of the reference trihedron of the actual shooting space. The increase in their number and their distribution in the reference trihedron improves the resolution of the correction.

In Figure 2, there is shown the screen of a display device or display implemented according to the method of the invention. The display device 20 comprises a screen 21 on which is displayed an image or current view of the camera of the camera. A user interface 22 allows a user to adjust the various parameters of the display device and in particular to make superimposed on the image of the screen 21 an artificial horizon corrected HC consisting of a display as a graphic trace 24- 27 or as an icon and which is generated by the device and method described in Figure 1. According to the invention, this is the artificial horizon corrected HC calculated according to what has been described above.

In one embodiment, the artificial horizon has a path 24 representative of the inclination stroke to the right and to the left on either side of a mark 25 of a zero inclination position.

An instantaneous tilt marker in the form of a round mobile icon running along the path 24 is continuously updated by the method of tracking the tilt of the camera, performed according to the control method of the camera. 'invention.

When the method of the invention is implemented, the measured acceleration A comes as a deduction according to the aforementioned correction function f () of the indication 26 of the inclination which would be directly produced by the horizon generator 3 on the base of the only inclinometer 1. As a result, the inclination indication 27 is further to the left, thus closer to the neutral position if the acceleration of the movement of the camera is directed to the right. In one embodiment, the artificial horizon is directly traced on the horizon line or in an initialized and periodically realigned position on the horizon line, along a line 23.

In Figure 3, there is shown a camera which the method of the invention is particularly suitable. This system, known as Steadycam®, is described in particular in US-A-5435515. Carried by an operator, as shown in Figure 3, the camera 140 essentially comprises a harness 142 on which is mounted an articulated arm 150 with a return spring in a neutral position. The articulated arm 150 comprises at least two articulated levers 148 and 149 capable of movement in a horizontal plane relative to the normal upright position of the operator.

At the free end of the arm 149 is disposed a bearing in which can slide vertically a support column 144 of a camera 145 by a first upper end of the column 144. At a second end, lower in Figure 3, the column 144 is mounted an elongated plate whose one end mainly carries a display device 147, similar to the display device 20 shown in FIG. 2. A second end of the elongated plate, opposite the first end of the plate, carries a source of electrical power for powering the camera 145 and the display device 147. The camera 145 of the camera 140 can follow movements in the horizontal plane by the movements printed using articulated arms 148 and 149 and movements in the vertical direction 120, in one direction or the other, the operator himself being motionless in a determined posture born, or mobile for example in a moving movement.

The display device 147 is electronically connected to the camera 145 so that the operator who carries the camera 140 has at all times the exact image taken by the camera 145. artificial horizon on the display device to warn the operator of positions and postures that come out of the positions and postures of the camera 140 that correspond to the program of the current shooting.

The operator can then rectify the inclination in a desired position or posture, changing his own posture or manipulating the articulated bottom 148, 149 or the column 144. According to the invention, the camera of Figure 3 is completed by an inclinometer 100 and an accelerometer 1 10, which are similar to the inclinometer 1 and the accelerometer 6 of the device of Figure 1. In a preferred embodiment of the invention, they are mounted mechanically integral with the camera 145. They thus make it possible to generate an artificial horizon on the display device 147, mounted on the actual camera. The movement of the camera is directly detected by the inclinometer 100 and the accelerometer 1 10 mounted on the display device 147. The artificial horizon is corrected on the basis of the measurements of the accelerometer 1 10 according to the method and circuit described in Figure 1.

To this end, the inclinometer 100 and the accelerometer 1 10 are connected by suitable electrical connections to two input ports of the display device 147. Each input port is then connected to the signal conditioning circuit 2 or 7 of the device described in Figure 1, depending on whether it is the inclinometer signal or the accelerometer signal. Thus, it is to be understood that, in one embodiment, all the means and circuits described with the help of FIG. 1 are installed inside the housing of the display device 147.

When the inclinometer and / or the accelerometer is mounted directly on or inside the casing containing the display device 147, it is then avoided to have one or two electrical connection cables between the one or more sensors. tilt or acceleration and the circuitry of the device described in Figure 1.

In another embodiment, the signal from each of the sensors 100, 1 10, or preferably from each of the signal conditioning circuits 2 and / or 7, or the transmission circuit of the corrected artificial horizon 1 1 of the device described in Figure 1 is provided at the input of a radiofrequency communication device or the like, which comprises a radiofrequency transmitter and a transmitting antenna so that the and / or the selected signals are transmitted to at least one display device provided with a radiofrequency receiving antenna and a radio frequency communication device which comprises a radio frequency receiver adapted to receive and decode the signal and / or the signals emitted by the communication device with transmitter of the device shot 140 proper.

Most often, the video signal generated by the camera 145 of the camera 140 is also transmitted to the various remote display devices by means of the radiofrequency communication device of the camera.

In such an embodiment, the control of the camera is remotely at least partially. If the control of the camera is partial, one or more devices are then available to other people than the operator of the camera. This is the case of the director, and his director of photography in particular.

If the control of the camera is completely remote, the camera is then remotely controlled and includes electromechanical actuators to allow remote control movements. This is the case of a camera mounted on a telescopic arm and / or articulated at the end of which is mounted the camera of the two inclination and acceleration sensors as well as the radiofrequency communication device with transmitter described above.

In such an arrangement, at least one display device, such as the device 20 (Figure 2) or the device 147 (Figure 3), is then placed at a distance from the camera of the camera, at the disposal of the camera. operator, the director and / or his director of photography, or any other person planned at the filming location. These display devices each cooperate with a device for receiving radiofrequency emissions from the camera according to the invention.

In Figure 4, there is shown the screen of a display device or display of a camera according to another embodiment of the invention. It is substantially identical to the screen shown in Figure 2 and the same elements have the same reference numbers and will not be described further.

In this embodiment, the accelerometer 1 10 of the camera of Figure 3 has several measurement axes. In particular, the accelerometer admits a vertical axis relative to the horizontal plane of the natural movements caused by the articulated arms 148, 149, vertical axis which is then associated with the column 144.

In the control method of the invention, it is then expected to measure the vertical acceleration. The operator who monitors the screen 21 (FIG. 4) of his display device (147, FIG. 3) is warned that he prints an upward movement along the arrow 120 (FIG. views, thanks to a pair of markers (icons) in the form of arrows 30 and 31. Since the vertical movement is directed upward (arrow 120, FIG. 3), the activated marker marked in bold is the marker 30 disposed above the graphical path 24 of the inclinometer displayed on the screen, while the marker 31 disposed below the graphic path 24 is inactive shown in fine line. In an exemplary embodiment, the markers are consisting of graphic icons generated by a control device (not shown) of the screen, the graphic icons being two triangles of which the first (30) is pointed up, and the second (31) is pointed downwards to indicate a upward or downward movement of the camera.

Such an arrangement is particularly effective to allow the operator to simultaneously control the inclination of his camera and a vertical movement he prints. Such an arrangement makes it possible, for example, to avoid that, during a tracking shot, for example in reverse with the aid of the camera of FIG. 3, the operator does not realize a plane in which the frame of the camera image is lower at the end of the tracking than at the beginning, or the opposite. For this purpose, in FIG. 5, there is shown a variant of the device described using FIG. 1 which makes it possible to control the generation of the markers 30 and 31 as a function of the detection of a vertical movement of the camera 145 of the camera 140. In general, this arrangement is provided to activate a generator 42 of a camera movement control signal comprising the generation of at least one marker 30, 31 active in superposition with displaying the corrected artificial horizon 24-27 on said display device and / or controlling electromechanical actuators of the camera. At the output of the accelerometer 6 of the device described with reference to FIG. 1 (or preferably of its conditioning circuit 7), the component Az is taken along the vertical axis associated with the accelerometer. The vertical acceleration signal Az is supplied at the input of a voltage comparator 40 whose other input is connected to a generator buffer 41 with a comparison threshold value S + / S-. The values S + and S- are provided for upward (S +) or downward (S-) movements and are entered by the operator or the director on the user interface 20 of the display device 20 ( Figure 4). If the voltage measuring the acceleration Az is greater than the threshold value S °, the comparator 40 generates a control voltage of the marker generator 42 which then selects the icon 30 that it activates in a determined location above the path 24 of the inclinometer displayed on the screen of the display device.

In another embodiment, one or more other directions than the vertical direction are monitored on the model of the aforementioned control of the vertical acceleration Az. In the previous embodiments, a zero acceleration is monitored at a constant time in at least one determined direction. In other embodiments, it is intended to monitor a non-zero acceleration value of the camera. For this purpose, the value of the threshold value generator 41 of the device of FIG. 5 is modified by the operator with the aid of a selected program, or of a value entered manually before the image is taken by the operator. operator or by the director on the user interface 22 of the display device (Figure 4). Likewise, it is provided in other embodiments, that the threshold value varies over time during the execution of the shooting so as to allow determined profiles of movements of the camera during the shooting. . The solution is particularly useful for a shooting device equipped with electromechanical actuators for setting in motion and for an automatism to interpret the output signal of the comparator 40 of the device of FIG. 5.

It should be noted that the camera may comprise several cameras, for example together in a stereoscopic system. Note that the camera may also include motorized parts allowing certain movements that are then controlled under at least partial control of the artificial horizon corrected. This is for example the case when the camera of the kind of that of Figure 3 is carried by an operator who moves on an automatic or semi-automatic vehicle as a self-balanced platform such as that described in particular in US-A-5,971,091. In this case, the signal representative of the corrected artificial horizon is also transmitted to a device for controlling the attitude and / or movement of the actuators according to a predetermined program of overall movement of the camera.

Claims

A method of controlling a camera (140) having a support mechanism (144-150) of a movie camera (145), and the support mechanism for an operator to maneuver the camera (145). ) while monitoring the current view of said camera on a display device (20; 147) of the device, the method comprising a step (E1) of measuring the relative inclination of the camera with respect to a reference axis of the shooting scene, then a step (E2) for producing an artificial horizon on the device for displaying the current view of said camera on the basis of said tilt measurement, the method being characterized in that it comprises a step (E3) of taking into account the acceleration of the camera, said acceleration being used during a subsequent step (E4) of correction of the horizon, said corrected horizon being then used when a step (E5) for displaying a horizon corrected on said display device (20; 147).

2 - Control method according to claim 1, characterized in that the step (E4) correction of the horizon produces a corrected horizon HC which depends both on the artificial horizon generated H and the acceleration taken in account A according to a determined correction function f () of the form: HC = f (H, A), said correction function f () being selected from among a plurality of determined functions including in particular a trigonometric function and a linear function of the form: HC = H - k * Ax, in which Ax refers to at least one axial component of the acceleration A and k is a coefficient associated with said axial component, said coefficients and definitions of the correction functions f () being determinable by calibration, calibration and / or manual selection using a user interface (22) available to the operator on the display (20; 147). 3 - Control method according to claim 2, characterized in that it consists in comparing the acceleration taken into account A of the camera of the camera to a given profile of acceleration allowed, selected with the aid of the user interface (22) on the display device (20; 147) so as to control the movements of the camera, in particular by displaying movement markers (30, 31) simultaneously with the display (24-27) of the corrected artificial horizon (HC) on said display device (20; 147), and / or by the control of electromechanical actuators of the camera (140).

4 - Display device (20; 147) for implementing the method according to any one of claims 1 to 3, and comprising a user interface (22) and a display screen (21), characterized in that 'it comprises :

a means for measuring the inclination and the acceleration of a camera, preferably composed of an inclinometer (1; 100) and an accelerometer (6; 1 10) integral with the camera device; display (20; 147), itself able to be secured to a camera,

a circuit (3, 8, 10) for generating an artificial horizon corrected on the display device by using both the inclination and the acceleration of the camera so as to correct the tilt as a function of acceleration; and

means (11, 23-27) for displaying said corrected artificial horizon on the screen (21) of the display device (20; 147).

5 - Shooting device for the implementation of the method according to any one of claims 1 to 3 and comprising a support mechanism (144-150) of a cinematographic camera (145), the support mechanism allowing an operator to maneuver the camera (145) while monitoring the current image of said camera on a display (20; 147), and means (1, 2) for taking into account the tilt of said camera with respect to a predetermined reference axis connected to means (3) for generating an artificial horizon to be superimposed on the image taken by the camera on said display device (20; 147), characterized in that it further comprises a means (6-8) for taking into account the acceleration of said camera and a correction circuit of the horizon artificial device which receives a signal representative of the artificial horizon generated by the means (3) for generating an artificial horizon corrected according to a predetermined correction function f (), a signal representative of a corrected artificial horizon being received by a transmission means a corrected artificial horizon (1 1) for said display device (20; 147).

6 - Device according to claim 5, characterized in that the means for taking into account the inclination comprises an inclinometer (3; 100) integral with a reference axis of said camera and / or the means for taking account of the acceleration comprises an accelerometer integral with a reference axis of said camera and / or in that the means for taking into account the inclination (1; 100) and the means for taking acceleration into account (6 -8; 1 10) are mounted on a display device (147) mounted on the camera (147).

7 - Device according to one of claims 5 to 6, characterized in that the transmitting means of a corrected artificial horizon (1 1) comprises a radio frequency communication means for communicating at least one inclination signal, a signal d an acceleration, a signal representative of an artificial horizon, a signal representative of a corrected horizon and / or a video signal generated by the camera (145) to at least one display device (20; means for receiving said signal transmitted by the radiofrequency communication means. 8 - Device according to any one of claims 5 to 7, characterized in that it comprises a comparison circuit (40) of at least one vector component (Az) of the instantaneous acceleration of the camera to a profile of (S +, S-) determined acceleration by program and / or user interface (22) for activating a generator (42) of a camera motion control signal including the generation of at least one marker (30); , 31) active in superposition with the display of the corrected artificial horizon (24-27) on said display device and / or an electromechanical actuator control of the camera.