Electronic motion picture camera

p0001The invention relates to an electronic motion picture camera with a receiving optics and a beam splitter which splits the received beam path in a leading to an optoelectronic image sensor recording beam path and a leading to an optical viewfinder viewfinder beam path.

p0002In electronic motion picture cameras recorded the useful signal is usually displayed as a monitor image in an electronic viewfinder or on a label attached to the camera screen. The thus reproduced recording image is used for example to control the sharpness. An electronic viewfinder has the disadvantage that the environment of the host image can not be observed. Thus, potentially interfering objects can not be detected outside the captured image section, before they enter the recorded image. Above all, the viewfinder, which are based on electronic displays, limited in reproduction quality.

p0003There are also electronic motion picture cameras are known which are provided with an optical viewfinder. With these cameras, part of the detected by the receiving optical light stream is fed into a sensor for receiving parallel-connected optical system that displays the same image recording for the cameraman, which is also recorded by the image sensor. This allows a high quality image of the viewfinder can be achieved. A disadvantage, however, that the cameraman no additional image information can be made available.

p0004From the <patcit id="pcit0001" dnum="US4330797A"><text>US-A-4330797</text></patcit> 18 and 19 are known to a television camera and a method according to the respective preamble of claims 1 and 2 or the claims.

p0005From the <patcit id="pcit0002" dnum="EP1343312A"><text>EP-A-1343312</text></patcit> is an electronic motion picture camera is known in which a rotating mirror shutter the received beam path is divided into a recording beam path and a viewfinder beam path, with a frosted glass and a finder optical system are arranged in the viewfinder beam path.

p0006The <patcit id="pcit0003" dnum="EP0152496A"><text>EP-A-0152496</text></patcit> describes an electronic camera with a beam splitter in the receiver beam path and a semitransparent mirror in the viewfinder beam path. By means of an electronic display, a combination of a binary and the analog video signal to be displayed, which can be observed by means of the half mirror in the viewfinder. The binary video signal indicates areas of overexposure or underexposure.

p0007It is therefore an object of the invention to provide an electronic motion picture camera whose finder has a high image quality and can be used flexibly for different Anförderungen regarding the reproduction of the recording image and other image information. A corresponding method is to be created.

p0008This object is achieved by a motion picture camera with the features of claim 1 or claim 2.

p0009Furthermore, this object is achieved by a method having the features of claim 18 or of claim 19.

p0010The receiving optical system forms the image being shot is along the recording beam path on the Imager and brings the Up also in the viewfinder display, the camera according to the invention, a hybrid viewfinder system with two superimposed beam paths has: In the viewfinder beam path of an optical viewfinder, an optical image mixer is integrated, the the representation of the detected by the receiving optical recording image and an additional image generated by an electronic display allows, the captured image and the auxiliary image can be presented to the viewer in the viewfinder as a single, unified motion picture. Thus, the high image quality of an optical viewfinder is combined with the possibility einzuspiegeln an additional image information in the viewfinder beam path by means of an electronic display or optically initiated otherwise.

p0011The additional image may assist the cameraman while recording so in many ways, the image information contained therein depending can be selected from the specific recording situation flexibly. The actual recording image and the auxiliary image can thereby be displayed alternately with a temporal overlap in the optical viewfinder optionally simultaneously, alternatively each other, alternating in time or.

p0012In particular, the electronic display for playback of motion pictures is designed to complement the product placed in the viewfinder to display actual recording image.

p0013Since the viewfinder is designed as an optical viewfinder, a high image quality is assured, without the known technical limitations of an electronic monitor image. Moreover, the optical viewfinder may be such configured that the imaged by the receiving optics towards the viewfinder and there observable image section is larger than the actually absorbed by the Imager image section of the recording picture, so that the cameraman can also observe the environment of the actual recorded image section.

p0014Saved motion picture sequences for a new recording to the actual recording image superimposed namely as a reference for the camera operator.

p0015A particular advantage is obtained by using a rotating mirror shutter as a beam splitter in the receiver beam path: In this case, the rotation of the mirror shutter inevitably leads to an intermittent hide the light that falls on the image sensor. In the camera according to the invention, these blanking intervals of time over those time intervals in which the incident light is deflected in the direction of the viewfinder can be reduced. The thus caused flickering in the viewfinder can namely be compensated by the fact that on the electronic display and the optical vision mixer the recorded by the sensor recording image is introduced into the viewfinder beam path.

p0016Preferably, the illustrated camera is designed as a digital electronic motion picture camera with the image sensor downstream digitizer.

p0017Further embodiments of the invention are recited in the dependent claims. The invention will now be described by way of example only with reference to the drawings wherein like elements are denoted by the same reference numerals.<dl id="dl0001" compact="compact"><dt>FIGS. 1-8</dt><dd>show various embodiments of an electronic motion picture camera, and only the <figref idrefs="f0003">Fig. 3</figref> and <figref idrefs="f0004">4</figref> illustrate embodiments of the invention.</dd></dl>

p0018<figref idrefs="f0001">Fig. 1</figref> shows a first embodiment of an electronic motion picture camera. This has a receiving optical system 11, which images the recorded motion picture along a receive beam path. 13 By means of serving as a beam splitter mirror shutter 15 which can be driven by a drive unit 17 to a rotational movement, the incident along the reception beam path 13 light is alternately transmitted in the direction of a recording beam path 19 or deflected toward a viewfinder beam path 21st For this purpose, the mirror shutter 15 a passband 23 and a mirrored blanking 25th

p0019An image captured by the receiving optical system 11 receiving image is thus alternately displayed along the receiving beam path 19 to an optoelectronic image sensor 27 and is deflected along the finder optical path 21 to be placed in an optical viewfinder 29 to display. The receiving sensor 27 is formed for example by a CCD or CMOS imager, and he has a signal output 31 for outputting a reception signal.

p0020In the viewfinder beam path 21 a focusing screen 33 is located on the the detected by the receiver optics 11 Recording Picture is taken, unless the blanking 25 of the mirror shutter 15 is in the receive beam. 13 The result of the focusing screen 33 a real image that can look through the viewfinder 29 of the camera man.

p0021In the viewfinder beam path 21, an optical image mixer 35 is further arranged the 33 allowed one hand the observation of the focusing screen through the viewfinder 29 and on the other hand brings a reproduced from an electronic display 37 additional picture in the viewfinder 29 to display. By means of the optical image mixer 35 is therefore the focusing screen image superimposed on the auxiliary image of the electronic display 37, wherein a viewer with a corresponding adjustment of the two optical branches the two superimposed images appear in the viewfinder 29 as a single image. For this purpose, the display 37 and the focusing screen 33 are arranged in the same object plane or focal position of the viewfinder 29th

p0022The optical image mixer 35 is formed for example by a partially transparent mirror. The electronic display 37 is, for example, by a liquid crystal monitor, an LCD monitor (thin film transistor) or a CRT monitor (CRT, cathode ray tube) formed. It has a signal input 39, via which the additional image and corresponding image signals can be supplied.

p0023The use of an optical viewfinder 29 in conjunction with a focusing screen 33 ensures high quality of the viewfinder image. Despite the use of a finder optical system the cameraman can in the viewfinder 29 by the display 37 and the image mixer 35 an additional image are displayed, to thereby support the inclusion in diverse and flexible ways.

p0024In particular, it is possible that at the electronic display 37 motion pictures or still images are reproduced, which complement the recording picture intermittently shown on the TV screen 33 time, so that a 15 might evoked by the rotation of the mirror shutter flicker of recording image formed is avoided. The electronic display 37 and the optical vision mixer 35 can also be used to indicate a just recorded motion picture sequence in the viewfinder 29 for control purposes. Alternatively or additionally, 35 any other image information can be reflected into the viewfinder beam path 21 by the display 37 and the image mixer.

p0025Another advantage of this camera is that in preparing a recording, while the mirror shutter 15 is still standing and the passband 23 is located in the received beam path 13, an image in the viewfinder 29 can be seen: The receiving sensor 27 may provide a received signal during recording preparations which is for example used to test and reference purposes. At the same time, despite standing mirror shutter 15, an image observation in the viewfinder 29 is possible by the reception signal of the receiving sensor is supplied 27 via the signal input 39 of the electronic display 37 and is brought by this via the optical vision mixer 35 in the viewfinder 29 to display.

p0026Preferably, the camera is equipped with an adjusting device, by the reproduction of the additional image of the electronic display 37 can be adjusted relative to the captured image shown on the TV screen 33rd By such adjustment, for example, the size, position, orientation, or other geometric properties of the additional image can be adjusted to achieve a geometry identical superimposed on the captured image in the viewfinder 29th Preferably, this adjustment is done electronically.

p0027Of course, it is different from the illustration in accordance with <figref idrefs="f0001">Fig. 1</figref> also possible that the focusing screen 33, the optical image mixer 35 and the viewfinder 29 is L-shaped are arranged so that the image mixer 35 the imaged on the focusing screen 33 Up in the direction of the sensor 29 deflects, while the additional screen of the electronic display 37, for example, a straight line is represented by the image mixer 35 towards the viewfinder 29th

p0028The use of ground glass 33 is not mandatory. Instead, the receiving optical system 11 can produce a virtual image in the viewfinder beam path 21, which can be viewed in the viewfinder 29, together with the additional image display 37th

p0029Instead of the mirror shutter 15 can in principle also be provided a beam splitter which splits the incident luminous flux continuously.

p0030<figref idrefs="f0002">FIG. 2</figref> shows a development of the embodiment of <figref idrefs="f0001">Fig. 1</figref>, In this one the receiving sensor 27 downstream signal processing device 41 is provided. This prepares the received signal of the receiving sensor 27, for example, by amplification and preferably by additional digitization. The conditioned signal is the one at the signal output 31 is output as a useful signal and transmitted to the other of the electronic display 37th

p0031The electronic display 37 can thus reflect the current reception signal of the receiving sensor 27 in real time as an additional image. Thereby, in the optical image mixer 35 the 27 recorded picture image that captured image superimposed on the image sensor or time supplemented, which is imaged by the receiving optics 11 via the rotating mirror shutter 15 at the screen 33rd Thus, observable in the viewfinder 29 Up appears especially quiet, without annoying flickering.

p0032Optionally, a controller 43 is provided which controls the drive unit 17 of the mirror shutter 15, the receiving sensor 27 and the electronic display 37 synchronized such that the viewfinder 29 is substantially alternating, ie exactly alternately or with a time overlap that of the receiving optical system 11 via mirror shutter 15 shown on the TV screen 33 up and reproduced from the electronic display 37 receiving signal of the receiving sensor 27 can be observed.

p0033In the <figref idrefs="f0002">FIG. 2</figref> Controller 43 shown is also ansteueren so the drive unit 17 of the mirror shutter 15 that the receiving optical system 11, the recording image depicts solely on the receiving sensor 27 during a recorded image sequence. In other words, the mirror shutter 15 is temporarily brought to a standstill, so that the passage region 23 is in the received beam path. 13 Because the captured image is then no longer displayed on the TV screen 33, causes the controller 43 that the display 37 representing the current signal received by the receiving sensor 27 as an additional image throughout the image sequence. The viewfinder 29 thus serves as a purely electronic viewfinder. This is in low light conditions particularly advantageous because the entire received light can be fully directed to the Imager 27th

p0034<figref idrefs="f0003">Fig. 3</figref> shows a development, in which the image sensor 27 and a signal processing device 41, an image storage device 45 is connected downstream. This supplies at a signal output 31 the processed receive signal of the pickup sensor 27. A further signal output is connected to an input of the electronic display 37th Thus, moving picture data or still image data, which have been recorded at an earlier time by receiving sensor 27 and stored in the image storage device 45, are shown on the electronic display 37 and thus observed in the optical viewfinder 29th The image storage device 45 thereby enables viewing a previously recorded motion picture sequence in the viewfinder 29, an additional screen monitor is required without the need for.

p0035A particular advantage of the embodiment according to <figref idrefs="f0003">Fig. 3</figref> is that while a new recording the recorded image shown on the TV screen 33 a previously 27 recorded motion picture sequence can be overlaid by means of the receiving sensor, for example, the cameraman to provide a reference for the camera operator.

p0036Alternatively or additionally, the electronic display 37 or in connection with such data buffer may comprise a signal input 39, to which an external storage device 47 can be connected to supply the electronic display 37 motion picture data or still image data reproduced by the optical image mixer 35 in the viewfinder 29 as an additional image to be. By connecting an external storage device 47, it is particularly possible to reproduce on the electronic display 37 mathematically generated or edited image elements that should be included in the post-recording. By these pixels are already visible during the recording of the cameraman, this may account for the interaction of the real scene with the virtual pixels. The camera work is thereby greatly facilitated, and it is avoided that a recorded motion picture sequence subsequently turns out to be unsuitable for the desired post.

p0037Particularly advantageously, the explained Fade an additional motion picture sequence in the optical viewfinder 29 is thus for the so-called compositing, ie for recording the subject against a blue background (blue screen) for the subsequent overlaying of several different designs in the post. For example, if the recording of a real actor in front of a blue screen to be superimposed later with an artificial or trick technically generated illustration of another figure (eg, an alien, or the like), so can already during the recording of the real actor in front of the blue screen the cameraman the representation artificially generated are displayed by the electronic display 37 in the optical viewfinder 29th The cameraman can thus observe the real recording and Pullout representation of trick technical subject simultaneously and affect the camera accordingly, thus ensuring that the final overlaying the real and the artificial scene in the post will be trouble.

p0038<figref idrefs="f0004">Fig. 4</figref> shows a modification of the embodiment according to <figref idrefs="f0003">Fig. 3</figref>, With this, an evaluation and control device 49 whose input is connected to a the Imager 27 downstream signal processing device 41st On the output side, the evaluation and control device 49 is connected to an image memory 45, which is connected to the electronic display 37th

p0039The evaluation and control device 49 is such configured to 37 controls the timing of reproduction of a data stored in the image memory 45 motion picture sequence on the electronic display, depending on the camera running. In a simple case, the motion picture sequence is played once the evaluation and control device 49 detects the start of the camera is running or a recording by the recording sensor 27th The evaluation and control device 49 may also be configured in such a way that it evaluates the current reception signal of the receiving sensor 27 with respect to a moving object within the receiving frame and in response thereto, the playback frequency controls, with the image storage means 45 stored moving picture data or still image data to the electronic display 37 are reproduced.

p0040In the image storage device 45 may, as in connection with <figref idrefs="f0003">Fig. 3</figref> explained, for example, a previously recorded motion picture sequence to be stored, which serves as a reference for the camera, or the data stored in the image memory 45 image data corresponding to the virtual image elements that should be included in the post-recording. The evaluation and control device 49 is capable, playback of stored image data (start and end points, running speed) to control a function of the camera running and / or from the reception signal of the receiving sensor 27, to ensure synchronization of the stored events with the real recording.

p0041Also in the embodiment according to <figref idrefs="f0004">Fig. 4</figref> can on the electronic display 37 einzuspielenden image data alternatively originate from an external storage device. In this case, the auxiliary image is fed via a signal input 39 of the camera, wherein the image storage device 45 may serve as a data buffer.

p0042<figref idrefs="f0005">Fig. 5</figref> shows an embodiment in which the display 37 is input is connected to an image generator 51, which generates as an additional image to be reproduced on the display 37, for example, screen area indicia image format markings, other graphical information or alphanumeric information.

p0043For example, the display 37 and the image mixer 35, by means of the image generator 51, the captured image shown on the TV screen 33, a frame can be superimposed, which marks the image section of the associated image format according to the destination of recording (cinema or television). Thus, a permanent mark of the focusing screen 33 or replacement of differently labeled faceplates 33 is not required. In the image information generated by the image generator 51 may be an alphanumeric identification of the set aperture or the set depth of field for example.

p0044Optionally, the image generator 51 whose input side is connected to an evaluation and control device 49, the input side is in turn connected to the receiving sensor 27 or an associated signal processing device. The evaluation and control device 49 evaluates the received signal of the receiving sensor 27 in terms of predetermined brightness or sharpness values ​​and causes the image generator for generating corresponding brightness range markings or of field markings that are displayed on the electronic display 37th Thus, the observed at the focusing screen 33 receiving image from the sensor image specially prepared electronic image superimposed to indicate the cameraman to areas with a certain brightness or sharpness (modulation frequency). These areas can be marked by the image generator 51, for example by hatching.

p0045According to an advantageous embodiment, the evaluation and control device 49 may compare the received signal of the receiving sensor 27 for the individual pixels of the recording picture, for example by means of a comparator in each case with an upper brightness threshold or a lower brightness threshold or with the two aforementioned brightness thresholds. In this case, the evaluation and control device 49 to calculate or determine within which the pixels of the recording picture, or at least for a majority of the pixels the respective received signal exceeds the upper brightness threshold or falls below the lower brightness threshold at least a brightness range of the recording image. The image generator 51 generates corresponding brightness range labels, such as those already mentioned hatchings due to the thus determined brightness ranges. This brightness range markings are thus produced on the display 37 and are thus in the optical viewfinder 29 as warnings superimposed on the captured image visible.

p0046The generation and display of such brightness range markings just in motion picture cameras with an optoelectronic image sensor is important because this is generally a lower brightness dynamic has as a traditional photochemical film, the thresholds for critical upper and lower brightness values ​​are sensor-dependent. It is therefore advantageous if the cameraman image areas can be displayed, in which the recorded brightness values ​​of the subject could prove problematic, so the cameraman can take account of the warnings discussed or screen area indicia during the camera operator. This feature is important on the one for a test run in order optionally to be able to change the set (for example, by a sunlight reflecting coffeepot is moved into the shade). Secondly, this function for the actual, final acceptance is important because the cameraman thus has a control option that actually no problematic brightnesses also be recorded while recording. If on the other hand only after the recording - namely the sighting of the recorded scene - would turn out that problematic brightness values ​​or ranges have been recorded, a subsequent again to record the scene would usually very costly, if not impossible, because the set may have to be adjusted again ,

p0047It is important that the cameraman himself - and not any other person - can observe the described brightness range markings, in the optical viewfinder. The cameraman can thus even keep control of the Helligkeitsaussteuerung recording picture and possibly affect the camera accordingly, and he does not have this without the use of conventional optical viewfinder 29th It is also important that the cameraman is not only received a simple warning, but appears concretely in which the screen of the error occurs.

p0048Of importance is the function of displaying the screen labels and particular brightness range markings for which is already associated with <figref idrefs="f0003">Fig. 3</figref> mentioned compositing, ie for recording the subject against a blue screen. Again, it is in fact important that the division of the recording image in different color or brightness areas - so the quality of segmenting - can be monitored and controlled. For example, it can be problematic when a person with a green or even blue garment before the blue screen filmed. By explained comparing the received signals with respective thresholds cinematographer potentially critical areas of the image can be displayed.

p0049For said application of the compositing it is advantageous if the reception signals of the receiving sensor 27 are compared for the different image points in each case with respect to the colors red, green and blue having different threshold values, as for example, the reception signals of the color blue are more critical than the reception signals of the color Green. It must also not necessarily of each color compared with a brightness threshold value are performed. For example, such a comparison for the color red in terms of compositing not mandatory.

p0050<figref idrefs="f0006">Fig. 6</figref> shows a modification of the embodiment according to <figref idrefs="f0005">Fig. 5</figref>Wherein a distance measuring device 53 is provided in addition. This is for example formed by an infrared probe or a laser rangefinder. The distance measuring device 53 is connected to an evaluation and control device 49 that the Imager is the input side 27 and output side to an image generator 51 for the electronic display 37th

p0051The distance measuring device 53 is able to measure the distance of the camera to an object within the recorded object space. The corresponding measuring signal can be evaluated by the evaluation and control device 49 at different distance ranges of the object space and therefore the recorded by the image sensor 27 receiving image. Depending on this evaluation, the evaluation and control device 49 causes the image generator 51 to generate corresponding distance range markings, which are reproduced by the electronic display 37 and thus superimposed on the focusing screen image.

p0052In this way, the cameraman is delivered in the viewfinder 29 a "depth map" available, which - for example, by different colors (false color), by hatching or by representing different distance ranges with different brightness - rapid identification of the object distances and / or the focal plane allows. This setting a desired depth of field will be facilitated in particular. Of course, several distance measuring devices 53 may be provided to detect the different distance ranges of recording image quickly and with high resolution.

p0053<figref idrefs="f0007">Fig. 7</figref> shows an embodiment with a photodetector 55, which measures the brightness of the image imaged by the receiving optics 11 on the ground glass 33rd The photodetector 55 is connected to a brightness control means 57 which regulates the brightness of the playback of the additional image on the electronic display 37 depending on the measured brightness of the focusing screen image. The brightness control device 57 may for example be configured such that the imaged by the receiving optics 11 Up and hereby superimposed auxiliary image of the electronic display 37 are perceived by the viewer with the same brightness or with a constant brightness difference.

p0054Instead of the illustrated brightness control device 57 with photodetector 55 may also have a simple brightness control device may be provided which is connected to the electronic display 37 to adjust the brightness of the playback of the additional image to a desired value can.

p0055For the embodiment according to <figref idrefs="f0001">Fig. 1</figref> it is preferred if the optical image mixer 35 - for example in the form of a partially transparent mirror - both the recording picture imaged by the receiving optics 11 at the screen 33 and the additional image of the electronic display is capable of directing 37 simultaneously towards the viewfinder 29th

p0056<figref idrefs="f0008">Fig. 8</figref> shows this alternative embodiment in which the optical image mixer 35 either the imaged by the receiving optics 11 Up, or the auxiliary image of the electrical display 37, or at the same time the recording image and the auxiliary image deflected towards the viewfinder 29th For this purpose, the video mixer 35 a fully permeable portion 59, a fully reflecting portion 61 and a partially reflecting / partially transmitting portion 63 have, which are selectively inserted into the viewfinder beam path 21st For example, the three sections 59, 61, 63 may be disposed at an image mixer carousel, is brought by the rotation of the desired portion in the viewfinder beam path 21st

p0057As an alternative to such a carousel, the video mixer 35 also allow a continuous variation of the division ratio so that the viewer, the relative proportions of the two templates, ie the time correction of the focusing screen 33 receiving image and reproduced by the display 37 additional image can be shifted against each other , For example, the video mixer 35 have a liquid mirror with controllable permeability, so that depending on the arrangement of the liquid crystals, a greater proportion of the recording picture, or a larger proportion of the additional image towards the viewfinder 29 is steered.

p0058Finally, it is to be noted that in connection with the <figref idrefs="f0001 f0002 f0003 f0004 f0005 f0006 f0007 f0008">FIGS. 1-8</figref> described embodiments can be combined together to employ 37 more versatile the video mixer 35 and the display.

LIST OF REFERENCE NUMBERS

p0059<dl id="dl0002" compact="compact"><dt>11</dt><dd>receiving optics</dd><dt>13</dt><dd>Received beam path</dd><dt>15</dt><dd>mirror shutter</dd><dt>17</dt><dd>drive unit</dd><dt>19</dt><dd>Recording beam path</dd><dt>21</dt><dd>Finder beam path</dd><dt>23</dt><dd>Passband</dd><dt>25</dt><dd>blanking</dd><dt>27</dt><dd>Imager</dd><dt>29</dt><dd>viewfinder</dd><dt>31</dt><dd>signal output</dd><dt>33</dt><dd>focusing screen</dd><dt>35</dt><dd>optical vision mixer</dd><dt>37</dt><dd>electronic display</dd><dt>39</dt><dd>signal input</dd><dt>41</dt><dd>Signal processing means</dd><dt>43</dt><dd>controller</dd><dt>45</dt><dd>Image storage means</dd><dt>47</dt><dd>external storage device</dd><dt>49</dt><dd>Evaluation and control device</dd><dt>51</dt><dd>image generator</dd><dt>53</dt><dd>Distance measuring device</dd><dt>55</dt><dd>photodetector</dd><dt>57</dt><dd>Brightness control device</dd><dt>59</dt><dd>fully permeable section</dd><dt>61</dt><dd>fully reflecting section</dd><dt>63</dt><dd>partially reflecting / partially transparent portion</dd></dl>