Abstract:
An imaging apparatus includes the functions of conducting automatic exposure control and of conducting shake correction with respect to digital image data acquired by an image pickup unit. The imaging apparatus includes: a determining unit that determines whether or not the shake correction is being implemented; and a switching unit which, when it has been determined by the determining unit that the shake correction is being implemented, switches the shutter speed such that the shutter speed is raised in comparison to when it has been determined by the determining unit that the shake correction is not being implemented. An imaging method determines whether or not the shake correction is being implemented, and when it has been determined that the shake correction is being implemented, switches the shutter speed such that the shutter speed is raised in comparison to when it has been determined that the shake correction is not being implemented.

Description:
CROSS-REFERENCE TO RELATED APPLICATION  
       [0001]     This application claims priority under 35 USC 119 from Japanese Patent Application No. 2005-200457, the disclosure of which is incorporated by reference herein.  
       BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     The present invention relates to an imaging apparatus and an imaging method, and in particular to an imaging apparatus and an imaging method that include the function of conducting automatic exposure control and the function of conducting shake correction with respect to digital image data acquired by an image pickup unit.  
         [0004]     2. Description of the Related Art  
         [0005]     Conventionally, there has been technology that electronically conducts shake correction when a moving image is picked up. As this type of technology, Japanese Patent Application Publication (JP-A) No. 11-98420 proposes an electronic shake correction apparatus configured to prevent the deterioration of correction performance resulting from changes in the shutter speed.  
         [0006]     However, even when the apparatus proposed in JP-A No. 11-98420 is used, shake or subject-shake within one frame occurs when the shutter speed is low at the time of shake correction when conducting moving image imaging. For this reason, when the shutter speed is low, a sharp image cannot be obtained in one frame and oftentimes a moving image after shake correction becomes not sharp. Moreover, assuming that this shake correction is conducted in view of the correlation between frames on the basis of moving vectors, the appropriate correlation between frames becomes incalculable due to shake occurring within one frame. Thus, the problem that the precision of the shake correction deteriorates can also occur.  
         [0007]     In view of these circumstances, the present invention provides an imaging apparatus and an imaging method where image quality deterioration resulting from shake is suppressed and with which a sharp image can be obtained.  
       SUMMARY OF THE INVENTION  
       [0008]     A first aspect of the invention provides an imaging apparatus including the function of conducting automatic exposure control and the function of conducting shake correction with respect to digital image data acquired by an image pickup unit, the imaging apparatus comprising: a determining unit that determines whether or not the shake correction is being implemented; and a switching unit which, when it has been determined by the determining unit that the shake correction is being implemented, switches the shutter speed such that the shutter speed is raised in comparison to when it has been determined by the determining unit that the shake correction is not being implemented.  
         [0009]     A second aspect of the invention provides an imaging apparatus including the function of conducting automatic exposure control and the function of conducting shake correction with respect to digital image data acquired by an image pickup unit, the imaging apparatus comprising: a determining unit that determines whether or not the shake correction is being implemented; a switching unit which, when it has been determined by the determining unit that the shake correction is being implemented, switches the shutter speed such that the shutter speed is raised in comparison to when it has been determined by the determining unit that the shake correction is not being implemented; an adjusting unit that adjusts the sensitivity of the image pickup unit; a changing unit which, when it has been determined by the determining unit that the shake correction is being implemented, changes the sensitivity of the image pickup unit such that the sensitivity is raised in comparison to when it has been determined by the determining unit that the shake correction is not being implemented; a shutter speed detecting unit that detects the shutter speed; a limiting unit that limits the shutter speed such that the shutter speed detected by the shutter speed detecting unit becomes equal to or greater than a predetermined speed when it has been determined by the determining unit that the shake correction is being implemented; and a warning unit that issues a warning when a shutter speed less than the predetermined speed has been detected by the shutter speed detecting unit.  
         [0010]     A third aspect of the invention provides an imaging method including the function of conducting automatic exposure control and the function of conducting shake correction with respect to digital image data acquired by an image pickup unit, the imaging method comprising: determining whether or not the shake correction is being implemented; and when it has been determined that the shake correction is being implemented, switching the shutter speed such that the shutter speed is raised in comparison to when it has been determined that the shake correction is not being implemented.  
         [0011]     Other aspects, features and advantages of the present invention will become apparent from the following description taken in conjunction with the accompanying drawings. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]     Preferred embodiments of the present invention will be described in detail based on the following figures, in which:  
         [0013]      FIG. 1  is a diagram showing the exterior of a digital camera according to an embodiment of the invention;  
         [0014]      FIG. 2  is a block diagram showing the configuration of relevant portions of an electrical system of a digital camera according to a first embodiment of the invention;  
         [0015]      FIG. 3A  is a program diagram when a shake correction mode is unset;  
         [0016]      FIG. 3B  is a program diagram where shutter speed is maintained at a speed equal to or greater than a shake limit shutter speed;  
         [0017]      FIG. 3C  is a program diagram when ISO sensitivity is raised;  
         [0018]      FIG. 4  is a flow chart showing the flow of processing in the digital camera according to the first embodiment of the invention;  
         [0019]      FIG. 5  is a flow chart showing the flow of processing in a digital camera according to a second embodiment of the invention;  
         [0020]      FIG. 6  is a block diagram showing the configuration of relevant portions of an electrical system of a digital camera according to a third embodiment of the invention;  
         [0021]      FIG. 7  is a flow chart showing the flow of processing in the digital camera according to the third embodiment of the invention;  
         [0022]      FIG. 8  is a flow chart showing the flow of processing in a digital camera according to a fourth embodiment of the invention; and  
         [0023]      FIG. 9  is a diagram showing an LCD when a warning is displayed in the fourth embodiment. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0024]     Embodiments of the present invention will be described in detail below with reference to the drawings. Here, a case will be described where the invention is applied to a digital camera  10  that includes the functions of imaging both still images and moving images.  
         [0025]     First, the external configuration of the digital camera  10  according to an embodiment of the invention will be described with reference to  FIG. 1 .  
         [0026]     The digital camera  10  includes a front surface disposed with a lens  21  for imaging a subject image, a flash  44  that emits light (image fill-in light) onto a subject as needed at the time of imaging, and a viewfinder  20  that is used in order to determine the composition of the subject to be imaged. Further, the digital camera  10  is provided in its top surface with a release button (shutter)  56 A that is depressed when executing imaging, a power switch  56 B, and a mode switch  56 C.  
         [0027]     The release button  56 A of the digital camera  10  according to the present embodiment is configured such that two stages of depression are detectable. The first is when the release button  56 A is depressed to an intermediate position (“half-depressed”), and the second is when the release button  56 A is depressed to a final depressed position beyond the intermediate position (“fully depressed”).  
         [0028]     In the digital camera  10 , when the release button  56 A is half-depressed, an automatic exposure (AE) function is activated and exposure conditions (shutter speed, aperture value) are set. Then, an auto focus (AF) function is activated and focus is adjusted. Then, when the release button  56 A is fully depressed, exposure (imaging) is conducted.  
         [0029]     The mode switch  56 C is rotated when setting the mode to any of a still image imaging mode where imaging of a still image is conducted, a moving-image imaging mode where imaging of a moving image is conducted, a shake correction mode where shake correction is conducted, and a playback mode where a subject image is played back on a later-described liquid crystal display (hereinafter referred to as LCD)  38 . The mode switch  56 C is also configured such that it can be set to a shutter speed priority mode when it is rotated and set to the shake correction mode.  
         [0030]     The digital camera  10  is also provided in its rear surface with an eyepiece portion of the viewfinder  20 , the LCD  38  for displaying imaged subject images and menu screens, and an arrow cursor button  56 D. The arrow cursor button  56 D is configured to include four arrow buttons representing the four moving directions of up, down, right, and left in the display region of the LCD  38 .  
         [0031]     On the back surface of the digital camera  10  are also provided a menu button that is depressed when displaying a menu screen on the LCD  38 , an enter button that is depressed when entering the operation content up to that point in time, a cancel button that is depressed when canceling the prior operation content, and a flash button that is depressed when setting the flash conditions of the flash  44 .  
         [0032]     Next, the configuration of the relevant portions of the electrical system of the digital camera  10  according to the present embodiment will be described with reference to  FIG. 2 .  
         [0033]     The digital camera  10  is configured to include an optical unit  22  that includes the lens  21 , a charge coupled device (CCD)  24  disposed at the rear side of the optical axis of the lens  21 , and an analog signal processor  26  that conducts various kinds of analog signal processing with respect to inputted analog signals.  
         [0034]     The digital camera  10  is also configured to include an analog/digital converter (ADC)  28 , which converts inputted analog signals to digital data, and a digital signal processor  30 , which conducts various kinds of digital signal processing with respect to inputted digital data.  
         [0035]     The digital signal processor  30  internally houses a line buffer with a predetermined capacity and conducts control that causes inputted digital data to be directly stored in a predetermined region of a later-described memory  48 .  
         [0036]     The output end of the CCD  24  is connected to the input end of the analog signal processor  26 , the output end of the analog signal processor  26  is connected to the input end of the ADC  28 , and the output end of the ADC  28  is connected to the input end of the digital signal processor  30 . Consequently, predetermined analog signal processing is undertaken by the analog signal processor  26  to an analog signal representing a subject image outputted from the CCD  24 , the analog signal is converted by the ADC  28  into digital image data (data of the colors of red (R), green (G) and blue (B), as will be described later), and the digital image data is inputted to the digital signal processor  30 .  
         [0037]     The digital signal processor  30  according to the present embodiment includes amplifiers (not shown), which correspond to the respective colors of red, green and blue, and a sensitivity adjuster  31 , which conducts sensitivity adjustment by setting the values of the digital gains corresponding to the ISO sensitivities set with respect to the amplifiers.  
         [0038]     The sensitivity adjuster  31  may also be disposed in the analog signal processor  26 .  
         [0039]     The digital camera  10  is also configured to include: an LCD interface  36  that generates, and supplies to the LCD  38 , a signal for causing subject images and menu screens to be displayed on the LCD  38 ; a microprocessing unit (MPU)  40  that controls the operation of the entire digital camera  10 ; a moving vector calculating circuit  42  that calculates moving vectors; the memory  38  that stores digital image data obtained by imaging; and a memory interface  46  that controls access with respect to the memory  48 .  
         [0040]     The shake correction in the shake correction mode of the present embodiment is conducted by deriving the correlation between frames based on the moving vector that the moving vector calculating circuit  42  has calculated, but the moving vector calculating circuit  42  may also be substituted with a gyro sensor that detects the direction in which the digital camera  10  moves, and the amount that the digital camera  10  moves, from a predetermined position.  
         [0041]     The memory  48  is configured to include a program diagram storage  49  that stores plural program diagrams per ISO sensitivity. The program diagrams represent the manner of switching between the shutter speed and the aperture value. That is, the program diagrams control the AE function and are uniquely programmed for each digital camera characteristic.  
         [0042]      FIGS. 3A  to  3 C show examples of the program diagrams.  FIG. 3A  shows a first program diagram  3 A,  FIG. 3B  shows a second program diagram  3 B, and  FIG. 3C  shows a third program diagram  3 C. In each of these program diagrams, the horizontal axis represents the shutter speed, the vertical axis represents the aperture value, and the slanted axis represented by one-dot chain lines represents the Ev value (exposure value). Ev is a photometric unit, and the Ev value represents subject brightness.  
         [0043]     The shutter speed has a threshold where the potential for shake to occur increases. This is called the shake limit shutter speed. The shake limit shutter speed is the inverse of the focal distance of the lens, and is determined dependently on the lens. For example, in the first program diagram  3 A shown in  FIG. 3A , the shutter speed indicated by arrow  3 AS is the shake limit shutter speed.  
         [0044]     The first program diagram  3 A in  FIG. 3A  is a program diagram that is used when the shake correction mode is unset when the ISO sensitivity has been set to ISO  200 . The shake limit shutter speed in this program diagram is determined by the focal distance of the lens during ordinary imaging.  
         [0045]     The second program diagram  3 B in  FIG. 3B  is a program diagram that is used when the shake correction mode has been set when the ISO sensitivity has been set to ISO  200 .  
         [0046]     The third program diagram  3 C in  FIG. 3C  is a program diagram when the ISO sensitivity has been set to ISO  800 .  
         [0047]     The digital camera  10  is also configured to include an external memory interface  50  for enabling a portable memory card  52  to be accessed by the digital camera  10  and a compression/expansion circuit  54  that compresses and expands digital image data.  
         [0048]     In the digital camera  10  of the present embodiment, a Flash Memory is used as the memory  48 , and Smart Media® is used as the memory card  52 .  
         [0049]     The digital signal processor  30 , the LCD interface  36 , the MPU  40 , the memory interface  46 , the external memory interface  50  and the compression/expansion circuit  54  are interconnected via a system bus. Consequently, the MPU  40  can control the operation of the digital signal processor  30  and the compression/expansion circuit  54 , can cause various types of information to be displayed on the LCD  38  via the LCD interface  36 , and can access the memory  48  and the memory card  52  via the memory interface  46  and the external memory interface  50 . The MPU  40  also switches between the program diagrams stored in the program diagram storage  49 .  
         [0050]     A timing generator  32  that generates, and supplies to the CCD  24 , a timing signal for driving mainly the CCD  24  is disposed in the digital camera  10 , and the driving of the CCD  24  is controlled by the MPU  40  via the timing generator  32 .  
         [0051]     A motor drive  34  is disposed in the digital camera  10 , and the driving of a focusing motor, a zoom motor and an aperture drive motor disposed in the optical unit  22  is also controlled by the MPU  40  via the motor drive  34 .  
         [0052]     That is, the lens  21  according to the present embodiment includes plural lenses, is configured as a zoom lens whose focal distance can be changed (varied), and is disposed with an unillustrated lens drive mechanism. The focusing motor, the zoom motor and the aperture drive motor are included in this lens drive mechanism, and these motors are driven by drive signals supplied by the control of the MPU  40  from the motor drive  34 .  
         [0053]     Various types of buttons and switches (called “operational unit  56 ” in  FIG. 2 ), such as the release button  56 A, the power switch  56 B, the mode switch  56 C, the arrow cursor button  56 D and the menu button, are connected to the MPU  40 , and the MPU  40  always grasps the status of operation with respect to the operation unit  56 . The flash  44  is also connected to the MPU  40 , and the emission of the imaging fill light by the flash  44  is also controlled by the MPU  40 .  
         [0054]     Next, the action of the first embodiment will be described.  
         [0055]     First, the CCD  24  conducts imaging via the optical unit  22  and sequentially outputs to the analog signal processor  26  analog signals of red, green and blue representing the subject image. The analog signal processor  26  administers analog signal processing such as correlated double sampling with respect to the analog signals inputted from the CCD  24 , and then sequentially outputs the processed analog signals to the ADC  28 .  
         [0056]     The ADC  28  converts the analog signals of red, green and blue inputted from the analog signal processor  26  to 12-bit signals of red, green and blue (digital image data), and then sequentially outputs the digital image data to the digital signal processor  30 . The digital signal processor  30  accumulates in its line buffer the digital image data sequentially inputted from the ADC  28 , and directly stores the digital image data in a predetermined region of the memory  48 .  
         [0057]     The digital image data stored in the predetermined region of the memory  48  is read by the digital signal processor  30  in response to the control by the MPU  40 , white balance adjustment is conducted by applying a digital gain corresponding to a predetermined physical quantity, and gamma processing, sharpness processing and sensitivity adjustment are conducted to generate 8-bit digital image data.  
         [0058]     Then, the digital signal processor  30  undertakes YC signal processing on the generated 8-bit digital image data, generates a luminance signal Y and chroma signals Cr and Cb (called a “YC signal” below), and stores the YC signal in a region of the memory  48  different from the aforementioned predetermined region.  
         [0059]     The LCD  38  is configured such that it can also be used as a viewfinder to display a moving image (through-image) obtained by continuous imaging with the CCD  24 . When the LCD  38  is used as a viewfinder, the generated YC signals are sequentially outputted to the LCD  38  via the LCD interface  36 . Thus, the through-image is displayed on the LCD  38 .  
         [0060]     Here, when the still image imaging mode has been set, the AE function is activated and the exposure conditions are set as described above at the timing when the release button  56 A is half-depressed by the user. Then, the AF function is activated so that the focus is adjusted. Then, image fill-in light is emitted from the flash  44  as needed at the timing when the release button  56 A is fully depressed. The YC signal stored in the memory  48  is compressed at that point in time in a predetermined compression format (in the present embodiment, the JPEG format) by the compression/expansion circuit  54  and is recorded as a digitized file in the memory card  52  via the external memory interface  50 .  
         [0061]     When the moving-image imaging mode has been set, the image fill-in light is emitted from the flash  44  as needed at the timing when the release button  56 A is fully depressed. Then, the YC signal stored in the memory  48  is compressed in a predetermined compression format (in the present embodiment, the Motion JPEG format) by the compression/expansion circuit  54  and is recorded in the memory card  52  via the external memory interface  50 . The recording operation ends at the timing when the release button  56 A is again fully depressed. The moving-image data representing the moving image is recorded in the memory card  52  as a digitized file by this operation.  
         [0062]     Incidentally, the digital camera  10  of the first embodiment is disposed with the function of switching between the program diagrams by setting the shake correction mode. The action of the portion relating to this function will be described in detail in accordance with the flow chart of  FIG. 4 .  
         [0063]     First, it is determined in step  100  by the determination of the MPU  40  whether or not the mode switch  56 C has been rotated and set to the shake correction mode. When the mode switch  56 C has been set to the shake correction mode and the determination in step  100  is YES, then the processing moves to step  102 , and when the determination in step  100  is NO, then the processing moves to step  108 .  
         [0064]     In step  102 , it is determined whether or not imaging has been initiated. When imaging has been initiated and the determination in step  102  is YES, then the processing moves to step  104 , and when the determination in step  102  is NO, then step  102  is repeated and the same determination is again conducted.  
         [0065]     In step  104 , the program diagram is switched to the second program diagram  3 B, and the shutter speed is switched and the aperture value is changed on the basis of the second program diagram  3 B.  
         [0066]     Next, it is determined in step  106  whether or not imaging has ended. When imaging has ended and the determination in step  106  is YES, then the processing of the flow chart ends, and when the determination in step  106  is NO, then the processing moves to step  104 .  
         [0067]     When the determination in step  100  is NO and the processing moves to step  108 , it is determined whether or not imaging has been initiated. When imaging has been initiated and the determination in step  108  is YES, then the processing moves to step  110 , and when the determination in step  108  is NO, then step  108  is repeated and the same determination is again conducted.  
         [0068]     In step  110 , the program diagram is switched to the first program diagram  3 A, and the shutter speed is switched and the aperture value is changed on the basis of the first program diagram  3 A.  
         [0069]     Next, it is determined in step  112  whether or not imaging has ended. When imaging has ended and the determination in step  112  is YES, then the processing ends, and when the determination in step  112  is NO, then the processing moves to step  110 .  
         [0070]     In this manner, in the first embodiment, when the shake correction mode has been set, the shutter speed is increased, shake within one frame can be prevented, image quality deterioration resulting from shake is suppressed, and a sharp image can be obtained.  
         [0071]     Next, a digital camera  10  according to a second embodiment of the invention will be described.  
         [0072]     Reference numerals that are the same as those in the first embodiment will be given to portions having basically the same configuration as those in the first embodiment, and description of those portions will be omitted.  
         [0073]     The digital camera  10  of the second embodiment is equipped with the function of increasing the shutter speed by raising the ISO sensitivity when the shake correction mode has been set. The action of the portion relating to this function will be described in detail in accordance with the flow chart of  FIG. 5 .  
         [0074]     First, it is determined in step  150  by the determination of the MPU  40  whether or not the mode switch  56 C has been rotated and set to the shake correction mode. When the mode switch  56 C has been set to the shake correction mode and the determination in step  150  is YES, then the processing moves to step  152 , and when the determination in step  150  is NO, then the processing moves to step  162 .  
         [0075]     In step  152 , a warning is displayed on the LCD  38  questioning the user whether the user wants to raise the ISO sensitivity in order to raise the correction precision.  
         [0076]     Next, it is determined in step  154  whether or not the ISO sensitivity is to be raised as a result of the user being prompted by the warning in step  152 . When the ISO sensitivity is to be raised and the determination in step  154  is YES, then the processing moves to step  156 , and when the determination in step  154  is NO, then the processing moves to step  162 .  
         [0077]     In step  156 , it is determined whether or not imaging has been initiated. When imaging has been initiated and the determination in step  156  is YES, then the processing moves to step  158 , and when the determination in step  156  is NO, then step  156  is repeated and the same determination is again conducted.  
         [0078]     In step  158 , the program diagram is switched to the third program diagram  3 C, and the shutter speed is switched and the aperture value is changed on the basis of the third program diagram  3 C.  
         [0079]     That is, the sensitivity is adjusted by the sensitivity adjuster  31 , and the ISO sensitivity is raised from ISO 200 to ISO 800. Then, the shutter speed that had been 1/30, before the processing of step  158  is conducted, as indicated by arrow  3 AS in  FIG. 3A  is increased to the shutter speed of 1/125 indicated by arrow  3 CS in  FIG. 3C  as a result of the ISO sensitivity being raised in step  158 . Meanwhile, the aperture value remains unchanged at 2.8 in step  158 .  
         [0080]     Next, it is determined in step  160  whether or not imaging has ended. When imaging has ended and the determination in step  160  is YES, then the processing of the flow chart ends, and when the determination in step  160  is NO, then the processing moves to step  158 .  
         [0081]     When the determinations in step  150  and step  154  are NO and the processing moves to step  162 , it is determined whether or not imaging has been initiated. When imaging has been initiated and the determination in step  162  is YES, then the processing moves to step  164 , and when the determination in step  162  is NO, then step  162  is repeated and the same determination is again conducted.  
         [0082]     In step  164 , the program diagram is switched to the first program diagram  3 A, and the shutter speed is switched and the aperture value is changed on the basis of the first program diagram  3 A.  
         [0083]     Next, it is determined in step  166  whether or not imaging has ended. When imaging has ended and the determination in step  166  is YES, then the processing of the flow chart ends, and when the determination in step  166  is NO, then the processing moves to step  164 .  
         [0084]     In this manner, in the second embodiment, the shutter speed can be increased by raising the ISO sensitivity. Thus, shake within one frame can be prevented, image quality deterioration resulting from shake is suppressed, and a sharp image can be obtained.  
         [0085]     Next, a digital camera  10  according to a third embodiment of the invention will be described.  
         [0086]     Reference numerals that are the same as those in the first embodiment will be given to portions having basically the same configuration as those in the first embodiment, and description of those portions will be omitted.  
         [0087]     The third embodiment is one where the mode is set to a shutter speed priority mode during the shake correction mode.  
         [0088]     As shown in  FIG. 6 , the digital camera  10  is disposed with a shutter speed detecting unit  58  that measures the shutter speed. The shutter speed detecting unit  58  is configured to receive from the timing generator  32  a timing signal for driving the CCD  24  and to measure the shutter speed on the basis of the exposure time of the CCD  24 .  
         [0089]     In the third embodiment, the digital camera  10  includes a function where the shutter speed is maintained at a speed equal to or greater than the shake limit shutter speed as a result of the shutter speed detecting unit  58  measuring the shutter speed, and where the shutter speed detecting unit  58  outputs a signal when the shutter speed becomes less than the shake limit shutter speed. The action of the portion relating to this function will be described in detail in accordance with the flow chart of  FIG. 7 .  
         [0090]     First, it is determined in step  200  by the determination of the MPU  40  whether or not the mode switch  56 C has been rotated and set to the shake correction mode. When the mode switch  56 C has been set to the shake correction mode and the determination in step  200  is YES, then the processing moves to step  202 , and when the determination in step  200  is NO, then the processing moves to step  216 .  
         [0091]     In step  202 , a warning is displayed on the LCD  38  questioning the user whether the user wants to switch the mode to the shutter speed priority mode in order to raise the correction precision.  
         [0092]     Next, it is determined in step  204  whether or not the mode is to be switched to the shutter speed priority mode as a result of the user being prompted by the warning in step  202 . When the mode is to be switched to the shutter speed priority mode and the determination in step  204  is YES, then the processing moves to step  206 , and when the determination in step  204  is NO, then the processing moves to step  216 .  
         [0093]     In step  206 , it is determined whether or not imaging has been initiated. When imaging has been initiated and the determination in step  206  is YES, then the processing moves to step  208 , and when the determination in step  206  is NO, then step  206  is repeated and the same determination is again conducted.  
         [0094]     In step  208 , the program diagram is switched to the second program diagram  3 B, and the shutter speed is switched and the aperture value is changed on the basis of the second program diagram  3 B.  
         [0095]     In step  208 , the third program diagram  3 C may be used rather than the second program diagram  3 B.  
         [0096]     Next, it is determined in step  210  whether or not the shutter speed measured by the shutter speed detecting unit  58  is equal to or greater than the shake limit shutter speed. When the shutter speed is equal to or greater than the shake limit shutter speed and the determination in step  210  is YES, then the processing moves to step  212 , and when the determination in step  210  is NO, then the processing moves to step  214 .  
         [0097]     In step  212 , the shutter speed is corrected to the shake limit shutter speed.  
         [0098]     Next, it is determined in step  214  whether or not imaging has ended. When imaging has ended and the determination in step  214  is YES, then the processing of the flow chart ends, and when the determination in step  214  is NO, then the processing moves to step  208 .  
         [0099]     When the determinations in step  200  and step  204  are NO and the processing moves to step  216 , it is determined whether or not imaging has been initiated. When imaging has been initiated and the determination in step  216  is YES, then the processing moves to step  218 , and when the determination in step  216  is NO, then step  216  is repeated and the same determination is again conducted.  
         [0100]     In step  218 , the program diagram is switched to the first program diagram  3 A, and the shutter speed is switched and the aperture value is changed on the basis of the first program diagram  3 A.  
         [0101]     Next, it is determined in step  220  whether or not imaging has ended. When imaging has ended and the determination in step  220  is YES, then the processing of the flow chart ends, and when the determination in step  220  is NO, then the processing moves to step  218 .  
         [0102]     In this manner, in the third embodiment, the shutter speed is maintained at a speed equal to or greater than the shake limit shutter speed, whereby shake within one frame can be prevented, image quality deterioration resulting from shake is suppressed, and a sharp image can be obtained.  
         [0103]     Next, a digital camera  10  according to a fourth embodiment will be described.  
         [0104]     Reference numerals that are the same as those in the first embodiment will be given to portions having basically the same configuration as those in the third embodiment, and description of those portions will be omitted.  
         [0105]     The digital camera  10  of the fourth embodiment is disposed with the function of issuing a warning that the shutter speed has become equal to or greater than the shake limit shutter speed and that there is a greater potential for shake. The action of the portion relating to this function will be described in detail in accordance with the flow chart of  FIG. 8 .  
         [0106]     First, it is determined in step  250  by the determination of the MPU  40  whether or not the mode switch  56 C has been rotated and set to the shake correction mode. When the mode switch  56 C has been set to the shake correction mode and the determination in step  250  is YES, then the processing moves to step  252 , and when the determination in step  250  is NO, then the processing moves to step  262 .  
         [0107]     In step  252 , it is determined whether or not imaging has been initiated. When imaging has been initiated and the determination in step  252  is YES, then the processing moves to step  254 , and when the determination in step  252  is NO, then step  252  is repeated and the same determination is again conducted.  
         [0108]     In step  254 , the program diagram is switched to the second program diagram  3 B, and the shutter speed is switched and the aperture value is changed on the basis of the second program diagram  3 B.  
         [0109]     Next, it is determined in step  256  whether or not the shutter speed measured by the shutter speed detecting unit  58  is equal to or greater than the shake limit shutter speed. When the shutter speed is equal to or greater than the shake limit shutter speed and the determination in step  256  is YES, then the processing moves to step  258 , and when the determination in step  256  is NO, then the processing moves to step  260 .  
         [0110]     In step  258 , the LCD  38  receives the signal outputted by the shutter speed detecting unit  58  via the LCD interface  36 , whereby the LCD  38  displays a warning such as the one indicated by arrow  9 W in  FIG. 9 .  
         [0111]     Next, it is determined in step  260  whether or not imaging has ended. When imaging has ended and the determination in step  260  is YES, then the processing of the flow chart ends, and when the determination in step  260  is NO, then the processing moves to step  254 .  
         [0112]     When the determination in step  250  is NO and the processing moves to step  262 , it is determined whether or not imaging has been initiated. When imaging has been initiated and the determination in step  262  is YES, then the processing moves to step  264 , and when the determination in step  262  is NO, then step  262  is repeated and the same determination is again conducted.  
         [0113]     In step  264 , the program diagram is switched to the first program diagram  3 A, and the shutter speed is switched and the aperture value is changed on the basis of the first program diagram  3 A.  
         [0114]     Next, it is determined in step  266  whether or not imaging has ended. When imaging has ended and the determination in step  266  is YES, then the processing of the flow chart ends, and when the determination in step  266  is NO, then the processing moves to step  264 .  
         [0115]     In this manner, in the fourth embodiment, a warning is displayed when the shutter speed has reached the shake limit shutter speed, whereby shake within one frame can be prevented, image quality deterioration resulting from shake is suppressed, and a sharp image can be obtained.  
         [0116]     In the preceding embodiments, a case was described where the shutter speed was changed as a result of switching the program diagram, but the present invention is not limited thereto. For example, the present invention can also be configured such that the shutter speed is directly increased or increased by an arithmetic expression. In these cases also, effects that are the same as those of the preceding embodiments can be obtained.  
         [0117]     Further, in the foregoing embodiments, a case was described where a predetermined speed of the shutter speed was used as the shake limit shutter speed, but the present invention is not limited thereto. For example, a value where a predetermined coefficient is multiplied by a predetermined value set by AE can also be the predetermined speed of the shutter speed. In this case also, effects that are the same as those of the preceding embodiments can be obtained.  
         [0118]     Moreover, in the foregoing embodiments, a case was described where a warning was issued by display on the LCD  38 , but the present invention is not limited thereto. For example, the warning can also be issued by a speaker (not shown) or by lighting a LED lamp (not shown). In these cases also, effects that are the same as those of the preceding embodiments can be obtained.  
         [0119]     While the present invention has been illustrated and described with respect to specific embodiments thereof, it is to be understood that the present invention is by no means limited thereto and encompasses all changes and modifications which will become possible without departing from the spirit and scope of the present invention.