Patent Publication Number: US-9413970-B2

Title: Camera and method of controlling operation of same

Description:
CROSS-REFERENCE TO RELATES APPLICATIONS 
     This application is a Continuation of PCT International Application No. PCT JP2013/064348 filed on May 23, 2013, which claims priority under 35 U.S.C. §119(a) to Japanese Patent Application No. 2012-146944 filed Jun. 29, 2012. Each of the above application is hereby expressly incorporated by reference, in its entirety, into the present application. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to a camera and to a method of controlling the operation thereof. 
     2. Description of the Related Art 
     There are instances where a camera is formed to include an optical viewfinder having an objective window facing the subject and an eyepiece window looked at by the user. The user decides the angle of view and takes a picture while looking at the optical viewfinder of the camera. 
     A finder unit implemented in the art makes it possible to display such information as a visual-field frame, which is displayed on the display screen of a liquid crystal display unit, by superimposing this information upon the optical image of a subject that can be seen by using an optical viewfinder (Patent Document 1). There is also a camera in which the image of a subject obtained from an optical viewfinder and the image of a subject obtained from a solid-state electronic image sensing device are displayed in separate areas within a finder (Patent Document 2). 
     Patent Document 1: Japanese Patent Application Laid-Open No. 2012-65294 
     Patent Document 2: Japanese Patent Application Laid-Open No. 2008-244511 
     When a camera is being shaken, the image of the subject captured by imaging will be blurred by such shaking motion. Nevertheless, there are instances where the user cannot tell that the captured image of the subject is blurred due to shaking merely by looking at the subject through the optical viewfinder. Consequently, even though the subject being viewed by the user may not be blurred, the image of the subject captured will be blurred. In Patent Documents 1 and 2 as well, the user cannot tell that the image of a subject affected by camera shake is in such a condition. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to arrange it so that even if a user is looking at a subject through an optical viewfinder, the user can ascertain the condition of the image of the subject that will be captured when the camera sustains camera shake. 
     According to the present invention, there is provided a camera comprising: an optical viewfinder formed on the front of the camera and having an objective window facing a subject and an eyepiece window for looking at the subject seen through the objective window; a solid-state electronic image sensing device for imaging the subject and outputting image data representing the image of the subject; a display unit for displaying a portion of the image of the subject, which is represented by the image data that has been output from the solid-state electronic image sensing device, on a display screen; and a deflecting unit for introducing the portion of the image of the subject, which is being displayed on the display screen of the display unit, to the eyepiece window so as to be superimposed upon the subject seen through the eyepiece window. 
     The present invention also provides an operation control method suited to the above-described camera. Specifically, the present invention provides a method of controlling operation of a camera which includes an optical viewfinder formed on the front of the camera and having an objective window facing a subject and an eyepiece window for looking at the subject seen through the objective window, the method comprising steps of: a solid-state electronic image sensing device imaging the subject and outputting image data representing the image of the subject; a display unit displaying a portion of the image of the subject, which is represented by the image data that has been output from the solid-state electronic image sensing device, on a display screen; and a deflecting unit introducing the portion of the image of the subject, which is being displayed on the display screen of the display unit, to the eyepiece window so as to be superimposed upon the subject seen through the eyepiece window. 
     In accordance with the present invention, a portion of the image of a subject captured by a solid-state electronic image sensing device is displayed on the display screen of a display unit. A portion of the displayed image of the subject is introduced to the eyepiece window of an optical viewfinder so as to be superimposed upon the optical image of the subject seen through the eyepiece window. Since the portion of the image of the subject captured by the solid-state electronic image sensing device is superimposed upon the optical image of the subject seen through the eyepiece window of the optical viewfinder, the user, by observing the superimposed state, can tell whether the captured image of the subject is blurry due to camera shake. Further, since what is superimposed on the optical image of the subject seen through the eyepiece window of the optical viewfinder is a portion of the captured image of the subject, the user can check the subject based upon the remaining portion of the image of the subject and can decide the angle of view. 
     The apparatus may further comprise a camera-shake detection device (camera-shake detection means) for detecting shaking of the camera; and a camera-shake notification device (camera-shake notification means) for notifying of camera shake in response to the fact that camera shake has been detected by the camera-shake detection device. 
     By way of example, the camera-shake notification device notifies of camera shake by displaying, on the display screen of the display unit, a character string to the effect that camera shake is taking place or an image representing the fact that camera shake is taking place, or by changing the form of a border, which encloses a portion of the image of the subject, in accordance with whether or not camera shake is taking place. 
     In a case where a principal subject seen through the optical viewfinder and a principal subject image among subject images captured in the solid-state electronic image sensing device are displayed on the display screen of the display unit, the display unit may display a portion of the subject image on the display screen upon applying a parallax correction in such a manner that the principal subject image and the principal subject will coincide. 
     If the distance from the camera to the principal subject is equal to or greater than a predetermined distance, the display unit may, in a case where a principal subject seen through the optical viewfinder and a principal subject image among subject images captured in the solid-state electronic image sensing device are displayed on the display screen of the display unit, display a portion of the subject image on the display screen in such a manner that the principal subject image and the principal subject will coincide. 
     The apparatus may further comprise a recording control device (recording control means) for recording image data, which has been output from the solid-state electronic image sensing device, on a recording medium. 
     Other features and advantages of the present invention will be apparent from the following description taken in conjunction with the accompanying drawings, in which like reference characters designate the same or similar parts throughout the figures thereof. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a front view of a digital camera; 
         FIG. 2  is a back view of the digital camera; 
         FIG. 3  is a perspective view of the digital camera when viewed from the back; 
         FIG. 4  is a block diagram illustrating the electrical configuration of the digital camera; 
         FIG. 5  illustrates the positional relationship between a lens barrel and an optical viewfinder; 
         FIG. 6  illustrates a parallax angle between the lens barrel and the optical viewfinder; 
         FIG. 7  illustrates the structure of an optical viewfinder; 
         FIG. 8  illustrates the relationship between a digital camera and a principal subject; 
         FIG. 9  shows an optical image of a subject and an image displayed in an electronic viewfinder; 
         FIG. 10  illustrates an image obtained by superimposing an optical image of a subject and an image displayed in an electronic viewfinder; 
         FIG. 11  is an image displayed in an electronic viewfinder; 
         FIG. 12  illustrates an image obtained by superimposing an optical image of a subject and an image displayed in an electronic viewfinder; 
         FIGS. 13 and 14  are flowcharts illustrating processing executed by a digital camera; 
         FIG. 15  illustrates an image displayed in an electronic viewfinder; 
         FIG. 16  illustrates an image obtained by superimposing an optical image of a subject and an image displayed in an electronic viewfinder; 
         FIG. 17  illustrates an image displayed in an electronic viewfinder; 
         FIG. 18  illustrates an image obtained by superimposing an optical image of a subject and an image displayed in an electronic viewfinder; 
         FIG. 19  illustrates an image displayed in an electronic viewfinder; and 
         FIG. 20  illustrates an image obtained by superimposing an optical image of a subject and an image displayed in an electronic viewfinder. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       FIGS. 1 to 3 , which illustrate an embodiment of the present invention, show the external appearance of a digital camera  1 .  FIG. 1  is a front view,  FIG. 2  a back view and  FIG. 3  a perspective view when viewed from the back. 
     With reference to  FIG. 1 , a lens barrel  2  projects forwardly from the approximate center of the front side of the digital camera  1 . An optical viewfinder is constructed at the upper right of the digital camera  1  and is formed to include an objective window  3  facing a subject. A flash device  4  is provided on the left side of the objective window  3 . 
     A shutter-speed dial  6 , a power lever  7 , a shutter-release button  8  and an exposure dial  9  are provided on the top of the digital camera  1  on the left side thereof when viewed from the front. The shutter-speed dial  6  is a circular dial that is free to rotate. By rotating the shutter-speed dial  6 , the user can set a desired shutter speed. The power lever  7  can be moved through a prescribed angle rightward and leftward as seen from the front. By moving the power lever  7  through the prescribed angle, the user can turn the power supply of the digital camera  1  on and off. The power lever  7  has the shape of a ring with an interior space when viewed from the top (see  FIG. 3 ), and the shutter-release button  8  is provided within the space. The exposure dial  9  also is a circular dial that is free to rotate. By turning the exposure dial  9 , the user can correct the exposure. 
     With reference to  FIGS. 2 and 3 , a liquid crystal display device  12  is provided on the back side of the digital camera  1  substantially over the entirety thereof. An eyepiece window  11  constituting the above-mentioned optical viewfinder is formed on the back side of the digital camera  1  at the upper left thereof. A command lever  10  movable to the left and right is provided on the back side of the digital camera  1  at the upper right thereof. By manipulating the command lever  10 , the user can supply the digital camera  1  with a command such as an aperture adjustment command in steps of ⅓ EV when the camera is in the manual exposure mode. 
     Provided below the command lever  10  are an AF (autofocus)/AB (autoexposure) lock button  13 , a command dial  14 , a menu/OK button  15 , a back button  16  and a RAW button  17 , etc. 
     With reference primarily to  FIG. 3 , the shutter-speed dial  6 , power lever  7 , shutter-release button  8  and exposure dial  9  are provided on the top of the digital camera  1  on the right side thereof (the right side when viewed from the back), as mentioned above. The power lever  7  is formed to have a projection  7 A projecting toward the front side. The power supply of the digital camera  1  can be turned on and off by grasping the projection  7 A and moving it to the right or left. 
     By bringing an eye close to the eyepiece window  11  of the optical viewfinder and looking at the eyepiece window  11 , the user can view a subject through the objective window  3  and eyepiece window  11  and can decide the camera angle. 
       FIG. 4  is a block diagram illustrating the electrical configuration of the digital camera  1 . 
     The overall operation of the digital camera  1  is controlled by a CPU  20 . 
     As mentioned above, the digital camera  1  is provided with operating switches  23  such as the shutter-speed dial  6 , power lever  7  and exposure dial  9 . Signals from the operating switches  23  are input to the CPU  20 . Further, a signal indicating whether the power supply has been turned on or off by the power lever  7  also is input to the CPU  20 . A changeover signal from a changeover switch  21  for switching between a shooting mode and a playback mode also is input to the CPU  20 . 
     The digital camera  1  includes a solid-state electronic image sensing device  34 . A zoom lens  31 , iris  32  and focusing lens  33  are provided in front of the solid-state electronic image sensing device  34 . The zoom lens  31  has its amount of zoom controlled by a motor driver  37 , the iris  32  has its aperture value controlled by a motor driver  38 , and the focusing lens  33  has its focus position controlled by a motor driver  39 . 
     When the image of a subject is formed on the photoreceptor surface of the solid-state electronic image sensing device  34 , the solid-state electronic image sensing device  34  is controlled by a timing generator  40  and a video signal representing the image of the subject is output from the solid-state electronic image sensing device  34 . The video signal that has been output from the solid-state electronic image sensing device  34  is subjected to correlated double sampling in a CDS (Correlated Double Sampling) amplifier circuit  35 . The CDS amplifier circuit  35  outputs the resultant video signal, which is converted to digital image data in an analog/digital conversion circuit  36 . 
     The digital image data is input to an AF (autofocus) detection circuit  46  via an image input controller  41 . A focusing control signal is generated based upon the entered digital image data, and the focusing control signal generated is input to the CPU  20 . The motor driver  39  is controlled based upon the focusing control signal so that the focusing lens  33  is positioned. The AF detection circuit  46  also calculates the distance to a principal subject specified by a AF target frame  94 , described later. If necessary, the digital camera  1  would be provided with a rangefinding device for measuring the distance to the principal subject. Further, the digital image data that has been output from the image input controller  41  is input to an AE (autoexposure)/AWB (automatic white balance)  47  as well. The AE/AWB detection circuit  47  generates an exposure control signal and a white balance adjustment signal. The exposure control signal generated is input to the CPU  20 . The motor driver  38  is controlled based upon the exposure control signal, whereby the aperture value of the iris  32  is controlled. Further, the white balance adjustment signal generated in the AE/AWB detection circuit  47  is input to an image signal processing circuit  42 . Image data that has been output from image input controller  41  also is input to the image signal processing circuit  42  as well. The image signal processing circuit  42  subjects the image data to a white balance adjustment based upon the white balance adjustment signal. 
     Image data that has been output from the image signal processing circuit  42  is applied to a liquid crystal display device  12  via a video encoder  44 . The captured image of the subject is displayed on the display screen of the liquid crystal display device  12 . 
     As mentioned above, the digital camera includes an optical viewfinder  60 . 
     The optical viewfinder  60  has an eyepiece lens  66  provided in front of the eyepiece window  11 . A prism  63  formed to have a half-mirror  64  is provided in front of the eyepiece lens  66 . The half-mirror  64  is formed so as to have a 45-degree angle of incidence with respect to optical axis C 3  of the optical viewfinder  60 . An OVF (optical viewfinder) shutter (which may be a mechanical shutter or a liquid crystal shutter)  62  and an objective lens  61  are provided in front of the prism  63 . The optical viewfinder  60  is further provided with an electronic viewfinder  65 . Data representing various information and the like that are output from the video encoder  44  are input to the electronic viewfinder  65 , where this information and the like are displayed. By inputting image data, which has been obtained by imaging, to the electronic viewfinder  65  when the OVF shutter  62  has closed, the image of the subject obtained by imaging is displayed on the display screen of the electronic viewfinder  65 . 
     When the OVF shutter  62  is open, the image of a subject OB formed by the objective lens  61  and eyepiece lens  66  can be seen through the eyepiece window  11 . Further, when various information is displayed on the display screen of the electronic viewfinder  65  when the OVF shutter  62  is open, light rays representing this information are reflected by the half-mirror  64  so that the user can see the information. Information and the like displayed on the display screen of the electronic viewfinder  65  can be seen upon being superimposed upon the optical image of the subject formed by the objective lens  61 , etc. 
     In particular, according to this embodiment, a portion of the image of the subject captured by the solid-state electronic image sensing device  34  can be displayed in a portion of the electronic viewfinder  65  in a state in which the OVF shutter  62  is open. The portion of the image of the subject displayed in the electronic viewfinder  65  is superimposed upon the optical image of the subject seen through the objective window  3 . If camera shake is non-existent, the portion in the electronic viewfinder and the optical image of the subject seen through the objective window  3  should not be offset from each other, but they will be offset if camera shake occurs. By observing the state of overlap, the user can tell whether camera shake is present or not. 
     An eye sensor  67  is mounted in the vicinity of the eyepiece window  11 . The eye sensor  67  detects that the eye of user has been brought near the eyepiece window  11 , whereupon the OVF shutter  62  opens so that the optical image of the subject OB can be viewed through the eyepiece window  11 . If the eye sensor  67  has not detected that the eye of the user has been brought near the eyepiece window  11 , the OVF shutter  62  closes. The image of the subject is displayed on the liquid crystal display device  12  and the user decides the camera angle while viewing the image of the subject being displayed on the liquid crystal display device  11 . Even if the eye sensor  67  has detected that the eye of the user has been brought near the eyepiece window  11 , the OVF shutter  62  can be turned off, image data representing the image of the subject can be input to the electronic viewfinder  65 , and the image of the subject displayed in the electronic viewfinder  65  can be viewed through the eyepiece window  11 . 
     The digital camera  1  further includes such circuits as a face detection circuit  48 , a moving-body detection circuit  49  and a camera-shake detection circuit  55 . The camera-shake detection circuit  55  is s circuit for detecting whether the digital camera  1  is experiencing camera shake. 
     When the shutter-release button  8  is pressed, image data that has been output from the image signal processing circuit  42  as described above is stored temporarily in a memory  50 . The image data is read out of the memory  50  and is input to a compression processing circuit  43 , which proceeds to execute prescribed compression processing. The compressed image data is applied to and stored temporarily in the memory  50 . The compressed image data is read out of the memory  50  and is recorded on a memory card  52  by a memory card controller  51 . 
     When the playback mode is set, image data that has been recorded on the memory card  52  is read out and the image represented by the read image data is displayed on the display screen of the liquid crystal display device  12 . 
     Furthermore, image data representing information displayed in the electronic viewfinder  65  and data representing various information also have been stored in the memory  50 . By reading out these items of data and applying them to the electronic viewfinder  65  via the video encoder  44 , various information is displayed on the display screen of the electronic viewfinder  65 . 
       FIG. 5  illustrates the relationship between the lens barrel  2  and the objective window  3  when the digital camera  1  is viewed from the front. 
     The lens barrel  2  has an optical axis C 2 . The optical axis C 2  and the optical axis C 3  of the optical viewfinder  60  (objective window  3 ) are a distance d apart and parallax exists between them. Consequently, there are instances where an offset develops between the optical image seen through the eyepiece window  11  and the image of the subject captured by the lens barrel  2 . As described above, when a portion of the image of the subject captured by the solid-state electronic image sensing device  34  is displayed in the electronic viewfinder  65  and this is superimposed upon the optical image of the subject formed via the objective window  3 , there are instances where, owing to the aforesaid parallax, the portion of the image of the subject displayed in the electronic viewfinder  65  and the optical image of the subject will not coincide even if camera shake is non-existent. In this embodiment, therefore, if camera shake is non-existent, then a parallax correction is applied as necessary in such a manner that the portion of the image of the subject displayed in the electronic viewfinder  65  and the optical image of the subject will coincide. 
       FIG. 6  illustrates a case where principal subject OB is seen (imaged) via the lens barrel  2  and how the subject OB is seen through the eyepiece window  11  of the optical viewfinder  60 . 
     As mentioned above, the distance between the optical axis C 2  of the lens barrel  2  and the optical axis C 3  of the eyepiece window  11  is d. Let D represent the distance from the lens barrel  2  to the principal subject OB. Accordingly, a parallax angle θ defined by a line from the lens barrel  2  to the object OB and a line from the eyepiece window  11  to the object OB is θ=arctan(d/D). That is, in a case where the principal subject OB is viewed through the lens barrel  2 , the principal subject OB that appears in front can be seen from the eyepiece window  11  with an offset equivalent to the parallax angle θ. 
       FIG. 7  illustrates the structure of the optical viewfinder  60 . The diagram at the top of  FIG. 7  illustrates the optical viewfinder  60  in a planar view in a manner similar to  FIG. 4 , and the diagram at the bottom of  FIG. 7  illustrates the optical viewfinder  60  in three dimensions. Components  FIG. 7  identical with those shown in  FIG. 4  are designated by like reference characters. 
     As shown in  FIG. 6 , when the principal subject OB is viewed through the eyepiece window  11 , it is offset from the optical axis of the optical viewfinder  60  by the parallax angle θ. Therefore, in order to make the portion of the image of the subject displayed in the electronic viewfinder  65  coincide with the optical image of the subject formed through the objective window  3 , the portion of the image of the subject need only be displayed upon being offset by the parallax angle θ. It goes without saying that the direction in which the portion of the image of the subject is offset through the above-mentioned angle is decided in accordance with the positional relationship between the positions where the eyepiece window  11  and lens barrel  2  are placed and the position where the optical viewfinder  60  is placed. 
       FIG. 8  illustrates the positional relationship among the digital camera  1  and principal subjects OB 1 , OB 2  and OB 3  as viewed in a plane. 
     If the principal subject OB 1  is at a position comparatively far from the digital camera  1 , then a parallax angle formed with the optical axis of the objective window  3  will be θ 1  in a case where the principal subject OB 1  is viewed from the eyepiece window  11 . Similarly, if the principal subject OB 2  is at an intermediate position that is neither far from nor close to the digital camera  1 , then a parallax angle formed with the optical axis of the objective window  3  will be θ 2  in a case where the principal subject OB 2  is viewed from the eyepiece window  11 . Furthermore, if the principal subject OB 3  is at a position close to the digital camera  1 , then a parallax angle formed with the optical axis of the objective window  3  will be θ 3  in a case where the principal subject OB 3  is viewed from the eyepiece window  11 . These parallax angles θ 1 , θ 2  and θ 3  are related as follows: θ 1 &lt;θ 2 &lt;θ 3 . Since the parallax angle will be small if the distance from the digital camera  1  is great, as is the case with the principal subject OB 1 , there will be almost no offset between the optical image of the subject seen through the objective window  3  and the portion of the image of the subject displayed in the electronic viewfinder  65 , as mentioned above. This means that the above-mentioned parallax correction need not necessarily be applied in a case where the distance from the digital camera  1  is great, as is the case with the principal subject OB 1 . 
     Shown at the top of  FIG. 9  is an example of a subject image  85  formed optically through the objective window  3 . 
     When the eye of the user is brought near the eyepiece window  11  and the OVF shutter  62  opens, the user sees the optical subject image  85  formed by the objective lens  61  and eyepiece lens  66 . 
     Shown at the bottom of  FIG. 9  is an example of an image  88  displayed in the electronic viewfinder  65 . 
     When the eye of the user is brought near the eyepiece window  11  and this is sensed by the eye sensor  67 , the image  88  shown at the bottom of  FIG. 9  is displayed on the display screen of the electronic viewfinder  65 . 
     A visual-field frame  90  indicating a picture-taking zone is formed on the image  88 . 
     An area occupying about one-third of the visual-field frame  90  on the right side thereof is delimited as a confirmation display area  89 . A portion of the image of the subject captured by the solid-state electronic image sensing device  34  in the manner described above is being displayed in the confirmation display area  89 . In the example shown at the bottom of  FIG. 9 , the portion of the image of the subject captured by the solid-state electronic image sensing device  34  in a state in which camera shake is taking place is being displayed in the confirmation display area  89 . The image within the confirmation display area  89 , therefore, is blurry to due to camera shake. The image of the subject captured by the solid-state electronic image sensing device  34  is not being displayed within the visual-field frame  90  with the exception of the confirmation display area  89 . The confirmation display area  89  is formed to have a border  89 A so that the user can ascertain that this area is the confirmation display area  89 . 
     Numerals  92  indicating the number of photos that can be taken and a character  93  indicating image size are being displayed at the upper right of the visual-field frame  90 . Further, an AF target mark  94  is being displayed at the center of the visual-field frame  90 . The subject specified by the AF target mark  94  is a principal subject. An exposure correction bar  95  is being displayed at the lower left of the visual-field frame  90 . Furthermore, a depth-of-field display bar  96 , a character  97  indicative of exposure mode, shutter speed  98 , aperture value  99  and ISO sensitivity  100  are being displayed below the visual-field frame  90 . 
       FIG. 10  illustrates an image obtained by superimposing the image  88 , which is displayed in the electronic viewfinder  65  shown at the bottom of  FIG. 9 , upon the optical image  85  shown at the top of  FIG. 9 . 
     Light rays representing the portion of the image of the subject within the confirmation display area  89  as well as information such as the visual-field frame  90  displayed on the electronic viewfinder  65  reach the eye of the user, who is looking at the eyepiece window  11 , owing to the half-mirror  64 . The user, therefore, can see an image that is the result of superimposing the information such as the visual-field frame  90 , which is being displayed on the electronic viewfinder  65 , upon the optical image  85  representing the image of the subject, as shown in  FIG. 9 . 
     In particular, according to this embodiment, a portion of the image of the subject captured by the solid-state electronic image sensing device  34  is displayed in the confirmation display area  89 , and this portion of the image of the subject is superimposed upon the optical image of the subject seen through the objective window  3 . Since the image of the subject captured by the solid-state electronic image sensing device  34  will be blurred in the presence of camera shake, the portion of the image of the subject displayed in the electronic viewfinder  65  will also be blurred (the image within the confirmation display area  89  is blurry also in the example shown in  FIG. 10 ). By viewing the portion of the subject of the image within the confirmation display area  89 , the user can tell that camera shake is taking place. 
     In particular, in the area on the left side of confirmation display area  89  in visual-field frame  90 , the optical image of the subject formed via the objective window  3  can be seen as is without the image of the subject captured by the solid-state electronic image sensing device  34  being displayed. Therefore, by comparing the optical image of the subject and the image of the subject that is being displayed in the confirmation display area  89 , the user can readily ascertain camera shake if such camera shake is taking place. Further, it may be arranged so that the border  89 A of the confirmation display area  89  turns red if camera shake is detected by the camera-shake detection circuit  55  and turns blue if camera shake is not detected. By thus changing the form of display of the border  89 A of the confirmation display area  89  in accordance with absence or presence of camera shake, the user can readily whether or not camera shake is taking place. 
       FIG. 11  is an example of the image  88  displayed in the electronic viewfinder  65 . This view corresponds to the view at the top of  FIG. 9 . 
       FIG. 11  is an example of the image  88  displayed in the electronic viewfinder  65  when camera shake is not taking place. Since there is no camera shake, the portion of the image of the subject within the confirmation display area  89  will not be blurry. 
       FIG. 12  is an example of an image obtained by superimposing the image  88 , which is displayed in the electronic viewfinder  65  shown in  FIG. 11 , upon the optical image of the subject (see the view at the top of  FIG. 9 ) formed via the objective window  3 . The example shown in  FIG. 12  corresponds to the view shown in  FIG. 10 . 
     In the example shown in  FIG. 12 , unlike the example of  FIG. 10 , camera shake is not taking place and therefore the image within the confirmation display area  89  is not blurry. By confirming that the image within the confirmation display area  89  is not blurry, the user can tell that the image of the subject captured using the solid-state electronic image sensing device  34  also is not blurry. For example, the border  89 A is made to turn blue. 
       FIG. 13  is a flowchart illustrating processing executed by the digital camera  1 . It is assumed here that the camera has been set to the imaging mode. 
     When the power supply is turned on by the power lever  7  of the digital camera  1 , whether the user is looking at the eyepiece window  11  of the optical viewfinder  60  is checked by the eye sensor  67 , as described above (step  71 ). If the eye of the user cannot be sensed by the eye sensor  67  (“NO” at step  71 ), it is judged that the user is not looking at the eyepiece window  11  of the optical viewfinder  60 . Consequently, the image of the subject obtained by imaging is displayed on the liquid crystal display device  12  (step  72 ). 
     If the eye of the user is sensed by the eye sensor  67  and it is judged that the user is looking at the eyepiece window  11  of the optical viewfinder  60  (“YES” at step  71 ), the camera is set to a sensor detection display changeover/OVF mode (step  73 ). The OVF shutter  62  opens and the user looking at the eyepiece window  11  can see the optical image of the subject. 
     Next, it is determined whether the camera-shake detection mode has been set by a mode setting switch (not shown) included among the operating switches  23  (step  74 ). If the camera-shake detection mode has not been set (“NO” at step  74 ), a portion of the image of the subject is not displayed in the electronic viewfinder  65 . Prescribed information such as the visual-field frame is displayed in the electronic viewfinder  65  and this information is displayed in a form superimposed upon the optical image of the subject formed via the objective window  3  (the usual hybrid display is presented)(step  75 ). 
     If the camera-shake detection mode has been set (“YES” at step  74 ), AF processing is executed using the AF detection circuit  46  (step  76 ). In AF processing, the distance to a principal subject is calculated. The parallax angle is calculated, as described above, using the calculated distance to the principal subject and the distance from the optical axis of the lens barrel  2  to the optical axis of the objective window  3 , and an amount of parallax, which is an amount of offset for shifting the portion of the image of the subject displayed in the electronic viewfinder  65 , is calculated (step  77 ). 
     The portion of the image of the subject obtained by imaging is displayed in the electronic viewfinder  65  upon being shifted by the calculated amount of parallax. The image displayed in the electronic viewfinder  65  and the image of the subject formed optically via the objective window  3  are superimposed in the manner shown in  FIG. 10  or  FIG. 12  (step  78 ). 
     If camera shake occurs (“YES” at step  79 ), as shown in  FIG. 10 , then camera shake is detected by the camera-shake detection circuit  55  and the border  89 A of the confirmation display area  89  turns red. As a result, the user is notified of the fact that the digital camera  1  is undergoing camera shake (step  80 ). If camera shake is not detected (“NO” at step  79 ), then the border  89 A of the confirmation display area  89  turns blue. As a result, the user is notified of the fact that the digital camera  1  is not undergoing camera shake (step  81 ). 
     The processing from step  71  onward is repeated unless the power supply is turned off or unless the mode is changed to one other than the imaging mode (step  82 ). 
     In the foregoing embodiment, amount of parallax is calculated and a parallax adjustment applied if the camera-shake mode has been set. However, a parallax adjustment need not be applied in a case where the distance to the principal subject is equal to or greater than a predetermined distance, as mentioned above. It goes without saying that it may be arranged so that a parallax adjustment is performed even if there is a long distance to the principal subject. 
       FIG. 14 , which illustrates a modification, is a flowchart showing processing executed by the digital camera  1 . Processing steps shown in  FIG. 14  identical with those shown in  FIG. 13  are designated by like step numbers and need not be described again. 
     In the embodiment shown in  FIG. 13 , whether camera shake is taking place or not is checked by the camera-shake detection circuit  55  and the user is notified of the absence or presence of camera shake. In the embodiment shown in  FIG. 14 , however, the user is not notified of the absence or presence of camera shake. Here the user judges whether camera shake is taking place or not by observing the state of the image within the confirmation display area  89 . 
       FIGS. 15 and 16  illustrate another modification. 
       FIG. 15 , which is an example of an image  88 A displayed in the electronic viewfinder  65 , corresponds to the diagram at the top of  FIG. 9  and to  FIG. 11 . Items shown in the diagram at the top of  FIG. 9 , etc., identical with those shown in  FIG. 15  are designated by like reference characters and need not be described again. 
     In  FIG. 15 , a comparatively small confirmation display area  111  is formed at the lower right of the visual-field frame  90 , and the confirmation display area  111  is formed to have a border  111 A. Whereas the confirmation display area  89  shown at the top of  FIG. 9  occupies approximately one-third of the visual-field frame  90 , the confirmation display area  111  being displayed in the image  88 A shown in  FIG. 15  is comparatively small. A portion of the image of the subject captured by the solid-state electronic image sensing device  34  is thus displayed in the comparatively small confirmation display area  111 . 
       FIG. 16  corresponds to  FIG. 10 or 12  and illustrates an image obtained by superimposing the image  88 A, which is displayed in the electronic viewfinder  65  shown in  FIG. 15 , upon the optical image  85  of the subject formed via the objective window  3 . 
     In the confirmation display area  111 , the portion of the image of the subject displayed in the electronic viewfinder  65  and captured by the solid-state electronic image sensing device  34  is superimposed upon the optical image  85  of the subject. If the image within the confirmation display area  111  is blurry, the user can tell that camera shake is taking place. 
     The form of display of the border  111 A of the confirmation display area  111  can be changed in accordance with absence or presence of camera shake in a manner similar to that set forth above. 
       FIGS. 17 and 18  illustrate yet another modification. 
       FIG. 17 , which is an example of an image  88 B displayed in the electronic viewfinder  65 , corresponds to the diagram at the top of  FIG. 9  and to  FIGS. 11 and 15 . Items shown in the diagram at the top of  FIG. 9 , etc., identical with those shown in  FIG. 17  are designated by like reference characters and need not be described again. 
     In  FIG. 17 , the region within the AF target frame  94  is defined as a confirmation display area  121 . The confirmation display area  121  also is formed to have a border  121 A. The border  121 A may of course be the same as that of the AF target frame  94 . A portion of the image of a subject captured by the solid-state electronic image sensing device  34  is displayed in the confirmation display area  121 . 
       FIG. 18  corresponds to  FIG. 10, 12 or 16  and illustrates an image obtained by superimposing the image  88 B, which is displayed in the electronic viewfinder  65  shown in  FIG. 17 , upon the optical image  85  of the subject formed via the objective window  3 . 
     In the confirmation display area  121 , which corresponds to the region within the AF target frame  94 , the portion of the image of the subject displayed in the electronic viewfinder  65  and captured by the solid-state electronic image sensing device  34  is superimposed upon the optical image  85  of the subject. If the image within the confirmation display area  121  is blurry, the user can tell that camera shake is taking place. Since the user decides the camera angle so as to bring a desired principal subject into correspondence with the AF target frame  94  and also views the image within the AF target frame  94 , the user can tell spontaneously whether the image within the confirmation display area  121  is out of focus. Without being aware of it, the user is able to recognize whether camera shake is taking place. 
       FIGS. 19 and 20  illustrate a further modification. 
       FIG. 19 , which is an example of an image  88 C displayed in the electronic viewfinder  65 , corresponds to the diagram at the top of  FIG. 9  and to  FIGS. 11, 15 and 17 . Items shown in the diagram at the top of  FIG. 9 , etc., identical with those shown in  FIG. 19  are designated by like reference characters and need not be described again. 
     In  FIG. 19 , a comparatively small confirmation display area  131  having a border  131 A has been defined. Further, in the image  88 C shown in  FIG. 19 , a camera-shake icon  132  indicating the presence of camera shake is being displayed within the visual-field frame  90  at the lower right thereof. Thus, it may be arranged so that, in a case where camera shake has been detected by the camera-shake detection circuit  55 , an icon or the like indicating the presence of camera shake is displayed. It goes without saying that a portion of the image of the subject captured by the solid-state electronic image sensing device  34  is displayed within the confirmation display area  131 . 
       FIG. 20  corresponds to  FIG. 10, 12, 16 or 18  and illustrates an image obtained by superimposing the image  88 C, which is displayed in the electronic viewfinder  65  shown in  FIG. 19 , upon the optical image  85  of the subject formed via the objective window  3 . 
     In the confirmation display area  131 , the portion of the image of the subject displayed in the electronic viewfinder  65  and captured by the solid-state electronic image sensing device  34  is superimposed upon is taking place, the image within the confirmation display area  131  will be out of focus and, as described above, the camera-shake icon  132  will be displayed. The user can ascertain the presence of camera shake by checking the camera-shake icon  132 . 
     In the foregoing embodiments, an audio tone may be used to notify the user if camera shake is taking place. In such case the digital camera  1  would be provided with a speaker. 
     As many apparently widely different embodiments of the present invention can be made without departing from the spirit and scope thereof, it is to be understood that the invention is not limited to the specific embodiments thereof except as defined in the appended claims.