Patent Publication Number: US-6342918-B1

Title: Image-shake correcting device having first and second correcting means and control means for proportionately applying same

Description:
The present application is a divisional application of application Ser. No. 08/870,022 filed Jun. 5, 1997, U.S. Pat. No. 5,982,421, which is a continuation application of application Ser. No. 08/350,096 filed Nov. 29, 1994. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an image-shake preventing device suitable for use in an image pickup apparatus, such as a video camera, and capable of correcting a shake (movement) of an image due to a vibration of the apparatus, or the like. 
     2. Description of the Related Art: 
     An electronic correcting system, an optical correcting system and the like have heretofore been known as a system for correcting a shake of an image in this kind of image-shake preventing device. The electronic correcting system is generally arranged to store in a memory an input image which immediately precedes the current input image, detect a shake of an image by detecting a variation of the image from the current input image and the previous input image stored in the memory, and vary an image reading position in the memory from which to read out a cut-out image so as to cancel the shake, thereby correcting the shake of the image. The optical correcting system generally includes a variable angle prism disposed in front of a lens and is arranged to turn the variable angle prism and bend the optical axis thereof so as to cancel a shake of an image, thereby correcting the shake of the image. 
     FIG. 1 is a block diagram showing the arrangement of a video camera having an image-shake preventing device of the conventional, electronic correction type. The arrangement shown in FIG. 1 includes an optical system  1  made up of predetermined constituent components, such as a focusing lens group provided for the purpose of focusing, a zooming lens group for varying a focal length of the optical system  1 , a compensation lens group, and an iris for adjusting the amount of light. An image pickup element  2  is made up of, for example, a two-dimensional CCD and is provided for converting an input light signal into an electrical signal and outputting the electrical signal. A sample-and-hold (S/H) circuit is provided for sampling and holding the electrical signal supplied from the image pickup element  2 , at intervals of a predetermined period, and an automatic gain control (AGC) circuit is provided for controlling the gain of the electrical signal outputted from the S/H circuit  3 . 
     The arrangement shown in FIG. 1 also includes an analog-to-digital (A/D) converter  5  for converting an analog signal outputted from the AGC circuit  4  into a digital signal, a Y/C separation circuit  6  for generating two kinds of delayed signals, i.e., a 1H delayed signal (H: horizontal synchronizing period) and a 2H delayed signal, from the signal outputted from the A/D converter  5 , and for performing computations on the 1H and 2H delayed signals to separate the signal outputted from the A/D converter  5  into a chrominance signal C and a luminance signal Y. A C process circuit  7  is provided; and for generating the chrominance signal C from the 2H delayed signal outputted from the Y/C separation circuit  6 , and a Y process circuit  8  is provided for generating the luminance signal Y from the 1H delayed signal outputted from the Y/C separation circuit  6  and performing edge enhancement, gamma correction and other predetermined processes on the luminance signal Y. 
     The arrangement shown in FIG. 1 also includes a first memory  9  for temporarily storing the chrominance signal C outputted from the C process circuit  7 , a second memory  10  for temporarily storing the luminance signal Y outputted from the Y process circuit  8 , a first digital-to-analog (D/A) converter  11  for converting the output signal (digital signal) of the first memory  9  into an analog signal, a second digital-to-analog (D/A) converter  12  for converting the output signal (digital signal) of the second memory  10  into an analog signal, a first signal output terminal  13  through which to output the signal outputted from the D/A converter  11 , and a second signal output terminal  14  through which to output the signal outputted from the D/A converter  12 . 
     The arrangement shown in FIG. 1 also includes a two-dimensional band-pass filter (BPF)  15  which is a spatial-frequency filter for extracting only a signal having a predetermined frequency band useful for detecting a motion vector, from the luminance signal outputted from the Y process circuit  8 , the BPF filter  15  serving to eliminate the high and low spatial frequency components of an image signal which are unsuitable for detecting a motion vector, a motion-vector detecting circuit  16  for detecting a motion vector indicative of movements of an image in horizontal (H) and vertical (V) directions from the output signal of the BPF filter  15 , a third memory  17  for temporarily storing the output signal of the BPF filter  15 , the output signal of the third memory  17  being inputted to the motion-vector detecting circuit  16 , and a memory-reading controlling circuit  18  for controlling the image reading position of each of the first and second memories  9  and  10  on the basis of the output of the motion-vector detecting circuit  16  so that shake of an image in the respective horizontal and vertical directions can be corrected. The image reading position of each of the first and second memory  9  and  10  is shifted in the direction of, and by the amount of a movement indicated by, the motion vector obtained in the motion-vector detecting circuit  16 , whereby the movements, i.e., shake, of the image in the horizontal and vertical directions can be cancelled. 
     The chrominance and luminance signals C and Y, the image shake of which has been corrected in the above-described manner, are respectively supplied from the first and second memories  9  and  10  to the D/A converters  11  and  12 . The chrominance and luminance signals C and Y are respectively converted by the D/A converters  11  and  12  and outputted through the first and second signal output terminals  13  and  14 . 
     FIG. 2 is a block diagram showing the arrangement of a video camera having an image-shake preventing device of the conventional, optical correction type. In FIG. 2, identical reference numerals are used to denote constituent parts identical to those shown in FIG. 1, and description thereof is omitted. Unlike the arrangement shown in FIG. 1, the memory-reading controlling circuit  18  is omitted from the arrangement shown in FIG. 2, and a variable angle prism (VAP)  19  is instead turnably disposed in front of the optical system  1  and a prism controlling circuit  20  is disposed for driving and controlling the variable angle prism  19 . The variable angle prism  19  has a structure in which a liquid of high refractive index is charged into the sealed space between two parallel flat plates, and is arranged to be able to change the direction of its optical axis, i.e., its apex angle, by varying the angle made by the two parallel flat plates. The prism controlling circuit  20  includes a vertical-direction control part (V-direction VAP controlling part)  20   a  for driving and controlling the variable angle prism  19  to correct a movement of an image in the vertical direction thereof and a horizontal-direction control part (H-direction VAP controlling part)  20   b  for driving and controlling the variable angle prism  19  to correct a movement of the image in the horizontal direction thereof. 
     A motion-vector detection signal indicative of a motion vector detected by the motion-vector detecting circuit  16  is inputted to the prism controlling circuit  20 , and the variable angle prism  19  is driven and controlled by the prism controlling circuit  20  so that shake of the image in the vertical and horizontal directions thereof can be corrected. 
     However, in an image-shake preventing device which relies on only a conventional electronic correcting system, shown in FIG. 1, which electronically corrects shake in the vertical and horizontal directions, it is necessary to make an image reading area smaller than the picture size of an image stored in the memory and it is, therefore, necessary to perform processing, such as enlargement and interpolation, for restoring the picture size of a read image to the original picture size. This leads to image degradation which is particularly noticeable in the case of a shake correction in the vertical direction, in which the number of available pixels is small. 
     In an image-shake preventing device which relies on only the conventional optical correcting system, as shown in FIG. 2, which optically corrects shake in the vertical and horizontal directions, although no substantial image degradation occurs, a special optical system and a control circuit therefor are needed. For this reason, the image-shake preventing device of the conventional optical correcting type has a higher price and a greater power consumption than that of the conventional electronic correcting type. 
     Japanese Laid-Open Patent Application No. Sho 63-166370 and the like disclose a purely electronic image-shake correcting device which is arranged to store a video signal outputted from an image pickup element (CCD) in an image memory or the like, detect an image shake from information about the video signal to find the amount of displacement of the image, and shift an image reading address of the image memory according to the amount of displacement of the image, thereby correcting the image shake. 
     It has also been proposed to provide a large-picture (area) image pickup element type of image-shake preventing device which includes a large-picture image pickup element having a larger picture area than a normal image pickup element. This type of image-shake preventing device is arranged to detect a movement by means of an acceleration sensor or the like and control a reading start position of an image which is stored in a field memory, without using a memory and according to a detection signal provided by the acceleration sensor, thereby correcting an image shake. 
     There is another optical type of image-shake preventing device in addition to the above-described image-shake preventing device which includes the variable angle prism (VAP) and is arranged to detect a movement by means of the acceleration sensor and optically correct an image shake. For example, an inertial pendulum type of image-shake preventing device (U.S. Pat. Nos. 2,959,088 and 2,829,557 and the like) is known. In the inertial pendulum type of image-shake preventing device, an inertial pendulum type of shake preventing lens having a two-axes gimbal structure is disposed around a master lens, and an image shake is cancelled by this shake preventing lens, thereby correcting the image shake. 
     SUMMARY OF THE INVENTION 
     A first object of the present invention which has been made in light of the above-described problems is to realize an image-shake correcting device which includes in combination an electronic correcting system and an optical correcting system so that it is possible to fully utilize the advantages of both correcting systems. 
     A second object of the present invention is to provide an image-shake correcting device which is capable of correcting an image shake without causing a substantial degradation in image quality and which has a small power consumption compared to an arrangement for optically correcting image shakes in both horizontal and vertical directions. 
     To achieve the above objects, in accordance with one aspect of the present invention, there is provided an image-shake correcting device which includes motion-vector detecting means for detecting a motion vector of an image in the horizontal and vertical directions thereof, optical correcting means for optically correcting a movement of the image in the vertical direction thereof, and electronic correcting means for electronically correcting a movement of the image in the horizontal direction thereof. 
     A third object of the present invention is to provide an image-shake correcting device capable of executing optimum shake correction control which can realize good characteristics at all times, by selectively controlling an optical image-shake correcting device and an electronic image-shake correcting device. 
     A fourth object of the present invention is to provide an image-shake correcting device capable of realizing optimum shake correction characteristics according to the statue of various photographic characteristics. 
     To achieve the above objects, in accordance with another aspect of the present invention, there is provided an image-shake correcting device which includes an electronic image-shake correcting device and an optical image-shake correcting device and is arranged to selectively control both of them according to individual shake frequencies. 
     A fifth object of the present invention is to provide an image-shake correcting device which can be adapted to any photographic status by switching the characteristics of image-shake correcting means according to the focal length of an image pickup apparatus. 
     A sixth object of the present invention is to provide an image-shake correcting device which is capable of selectively varying the proportion of the operations of a plurality of shake correcting means according to the amount of shake or the amount of correction of shake. 
     A seventh object of the present invention is to provide a video camera with the aforesaid image-shake correcting device. 
     The above and other objects, features and advantages of the present invention will become apparent from the following detailed description of preferred embodiments of the present invention, taken in conjunction with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a block diagram showing the arrangement of an electronic image-shake correcting device; 
     FIG. 2 is a block diagram showing the arrangement of an optical image-shake correcting device; 
     FIG. 3 is a block diagram showing a first embodiment of the present invention; 
     FIG. 4 is a block diagram showing the arrangement of an image pickup apparatus provided with an image-shake correcting device according to a second embodiment of the present invention; 
     FIG. 5 is a flowchart showing the control operation of a logic operation circuit used in the image-shake correcting device according to the second embodiment: shown in FIG. 4; 
     FIG. 6 is a flowchart showing the processing operation of the essential portion of the logic operation circuit used in the image-shake correcting device according to the second embodiment shown in FIG. 4; 
     FIG. 7 is a view of a conversion table which is used in an image-shake preventing device according to the second embodiment shown in FIG.  4  and shows the allocation of the control gains of individual correcting means with respect to a shake frequency; 
     FIG. 8 is a block diagram showing the arrangement of a video camera which is an image pickup apparatus provided with an image-shake preventing device according to a third embodiment of the present invention; 
     FIG. 9 is a view of a conversion table which is used in an image-shake preventing device according to a fourth embodiment and shows the allocation of the control gains of individual correcting means with respect to a shake frequency; 
     FIG. 10 is a block diagram showing the arrangement of a video camera which is an image pickup apparatus provided with an image-shake preventing device according to a fifth embodiment of the present invention; 
     FIG. 11 is a flowchart showing the control operation of the essential portion of a logic operation circuit used in the image-shake preventing device according to the fifth embodiment of the present invention; 
     FIG. 12 is a flowchart showing the detail of the control operation of the essential portion of the logic operation circuit used in the image-shake preventing device according to the fifth embodiment of the present invention; 
     FIG. 13 is a view of a conversion table which is used in the image-shake preventing device according to the fifth embodiment shown in FIG.  10  and shows the allocation of the control gains of individual correcting means with respect to a shake frequency; 
     FIG. 14 is a block diagram showing the arrangement of a video camera which is an image pickup apparatus provided with an image-shake preventing device according to a sixth embodiment of the present invention; 
     FIG. 15 is a view of a conversion table which is used in an image-shake preventing device according to a seventh embodiment and shows the allocation of the control gains of individual correcting means with respect to focal length; 
     FIG. 16 is a flowchart showing the control operation of a logic operation circuit used in an image-shake preventing device according to an eighth embodiment of the present invention; 
     FIG. 17 is a view of a conversion table which is used in the image-shake preventing device according to the eighth embodiment and shows the allocation of the control gains of individual correcting means with respect to image deviation; 
     FIG. 18 is a view of a conversion table which is used in an image-shake preventing device according to a ninth embodiment and shows the allocation of the control gains of individual correcting means with respect to image deviation; 
     FIG. 19 is a flowchart showing the control operation of a logic operation circuit used in an image-shake preventing device according to a tenth embodiment of the present invention; 
     FIG. 20 is a view of a conversion table which is used in the image-shake preventing device according to the tenth embodiment and shows the allocation of the control gains of individual correcting means with respect to a representative motion vector; and 
     FIG. 21 is a view of a conversion table which is used in an image-shake preventing device according to an eleventh embodiment and shows the allocation of the control gains of individual correcting means with respect to a representative motion vector. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Embodiments of an image-shake correcting device according to the present invention will be described below in detail with reference to the accompanying drawings. 
     First Embodiment 
     FIG. 3 is a block diagram showing a first embodiment of the image-shake correcting device according to the present invention. In FIG. 3, identical reference numerals are used to denote constituent parts identical to those shown in FIGS. 1 and 2, and description thereof is omitted. 
     The arrangement shown in FIG. 3 differs from either of those shown in FIGS. 1 and 2 in that a variable angle prism (VAP)  19  and a prism controlling circuit  20 ′, for driving and controlling the variable angle prism  19  are added to the arrangement shown in FIG.  1 . The prism controlling circuit  20 ′ used in the first embodiment has only a vertical-direction control part (V-direction VAP controlling part)  20   a ′ for driving and controlling the variable angle prism  19  to correct a movement of an image in the vertical direction thereof, and does not have a horizontal-direction control part (H-direction VAP controlling part) for driving and controlling the variable angle prism  19  to correct a movement of the image in the horizontal direction thereof. The variable angle prism  19  is driven and controlled by the prism controlling circuit  20 ′, whereby only movement of the image in the vertical direction thereof can be optically corrected. Accordingly, the variable angle prism  19  and the prism controlling circuit  20 ′ constitute optical shake correcting means for optically correcting shake of the image in the vertical direction thereof. 
     A memory-reading controlling circuit  18 ′ used in the first embodiment is arranged to control the image reading positions of the respective first and second memories  9  and  10  so that only a movement of the image in the horizontal direction thereof can be corrected. Accordingly, the memory-reading controlling circuit  18 ′ constitutes electronic shake correcting means for electrically correcting shake of the image in the horizontal direction thereof. 
     Specifically, the feature of the first embodiment is that movement of the image in the vertical direction thereof is optically corrected by driving and controlling the variable angle prism  19 , while movement of the image in the horizontal direction thereof is electronically corrected by controlling the image reading positions of the respective first and second memories  9  and  10 . 
     The construction and operation of the other portion of the first embodiment are substantially identical to the construction and operation described previously in connection with each of FIGS. 1 and 2, and description thereof is omitted. 
     If a shake of an image in the vertical direction thereof is subjected to electronic shake correction, the quality of the image will be degraded because the number of pixels of the image is smaller in the vertical direction than in the horizontal direction. According to the first embodiment, since shake of the image in the vertical direction thereof is corrected by the optical shake correcting means, it is possible to correct shake of the image in the vertical direction thereof without a degradation of image quality. In the case of a shake of an image in the horizontal direction thereof, which can be corrected without a remarkable degradation in image quality by electronic shake correction because a larger number of pixels are available, the electronic shake correcting means is selected, so that it is possible to reduce power consumption compared to optical shake correction and it is also possible to simplify a driving system. 
     As described above in detail, according to the first embodiment of the image-shake preventing device, since the electronic correcting means corrects only movement of an image in the horizontal direction thereof, it is possible to eliminate the disadvantage of the conventional electronic correcting means arranged to correct movement of an image in both vertical and horizontal directions thereof, i.e., it is possible to prevent occurrence of a degradation in image quality due to the correction of image shake in the vertical direction thereof. In addition, since the optical correcting means corrects only movement of an image in the vertical direction thereof, it is possible to provide an inexpensive arrangement compared to the conventional optical correcting means arranged to correct movement of an image in both vertical and horizontal directions thereof. In addition, it is possible to adopt a compact control circuit. 
     Second to eleventh embodiments of the present invention will be described below in that sequence. Unlike the first embodiment in which movement of an image in the vertical and horizontal directions thereof are separately handled by the respective optical and electronic correcting means, each of the second to eleventh embodiments is arranged to adaptively control the proportion of the operation of the optical correcting means to that of the electronic correcting means according to various factors such as image pickup conditions, the frequency of a shake, the amount of a shake and the amount of correction. 
     A so-called hybrid system provided with both optical correcting means and electronic correcting means has a number of problems which will be described below. 
     For example, in the case of a conventional hybrid correcting system in which an image-shake correcting system having a feedback loop, such as the optical correcting means, and an image-shake correcting system employing an image memory are simply combined with each other, there is the problem that if the shake frequency is high or photography or the like is performed on a wide-angle side on which the amplitude of an image shake is small, a degradation in high-frequency characteristic due to a delay of the feedback loop tends to stand out under the influence of the image-shake correcting system having the feedback loop. On the contrary, if the shake frequency is low or photography or the like is performed on a telephoto side on which the amplitude of the image shake is large, an excessive correction beyond an optimum correction range tends to easily occur under the influence of the image-shake correcting system having a image memory. 
     The following embodiments have been made in light of the above-described problems, and their primary object is to provide an image-shake preventing device in which, although a plurality of correcting means are combined, it is possible to readily and securely effect flexible image-shake correction which can cope with various photographic statuses without causing degradation of a high-frequency characteristic, an excessive correction beyond an optimum correction range, or the like. 
     To achieve the above object, in accordance with the second embodiment, there is provided an image-shake preventing device which is arranged to detect a motion vector from an image signal and correct an image shake and which includes motion-vector detecting means for detecting motion vectors relative to temporally continuous images by performing a computation on a correlation between the temporally continuous images, shake-frequency computing means for computing the shake frequency of an image on the basis of the motion vectors detected by the motion-vector detecting means, first correcting means having a feedback loop and arranged to correct the image shake, second correcting means having a field memory and arranged to correct the image shake by using an image delayed by the field memory, and control means for varying the proportions of the amounts of shake correction to be respectively performed by the first and second correcting means, on the basis of the shake frequency of the image computed by the shake-frequency computing means. 
     In the above-described arrangement, on the basis of the shake frequency of the image computed by the shake-frequency computing means, the control means varies the proportion of the amount of shake correction to be performed by the first correcting means to the amount of shake correction to be performed by the second correcting means in an overall image-shake correction. 
     Second Embodiment 
     The second embodiment of the present invention will be described below with reference to FIGS. 4 to  6 . FIG. 4 is a block diagram showing the arrangement of a video camera which is an image pickup apparatus provided with the second embodiment of the image-shake preventing device according to the second embodiment of the present invention. 
     In the arrangement shown in FIG. 4, a variable angle prism (VAP)  101 , which is turnably arranged, constitutes first correcting means which has a feedback loop and serves to correct an image shake. The VAP  101  is driven and controlled by VAP driving means  102 . The VAP driving means  102  includes a VAP driving circuit (driver)  102   a , a VAP driving coil  102   b  and a VAP damping coil  102   c , and is controlled by a control signal outputted from a logic operation circuit  120  which will be described later. A VAP apex angle sensor  103  is provided for detecting the apex angle of the VAP  101 , and the detection signal of the VAP apex angle sensor  103  is inputted to the logic operation circuit  120  which will be described later. The VAP driving means  102  is arranged to drive the VAP  101  in both vertical and horizontal directions thereof. 
     The arrangement shown in FIG. 4 also includes a focusing lens group  104  provided for the purpose of focusing, a zooming lens group  105  for varying the focal length, a compensation lens group  106 , an iris  107  for adjusting the amount of light, an image pickup element  108  made up of, for example, a two-dimensional CCD and provided for converting a light signal inputted through the lens groups  104  to  106  and the iris  107  into an electrical signal and outputting the electrical signal, a sample-and-hold (S/H) circuit  109  for holding the electrical signal outputted from the image pickup element  108 , and an automatic gain control (AGC) circuit  110  for automatically controlling the gain of the signal outputted from the S/H circuit  109 . 
     The arrangement shown in FIG. 4 also includes an analog/digital (A/D) converter  111  for converting an analog signal outputted from the AGC circuit  110  into a digital signal, a delay (2HDLY) circuit  112  for receiving the output signal of the A/D converter  111  and delaying a color-difference line-sequential signal outputted from the image pickup element  108  by two horizontal scanning periods, a chrominance signal generating (C process) circuit  113  for receiving the output signal of the 2HDLY circuit  112  and generating a chrominance (C) signal, a low-pass filter (LPF)  114  for receiving the output signal of the 2HDLY circuit  112  and eliminating a chrominance signal contained in the luminance signal Y, and an enhancer  115  for receiving the output signal of the LPF  114  and enhancing a high-frequency component thereof. 
     The arrangement shown in FIG. 4 also includes a gamma (γ) correction circuit  116  for receiving the output signal of the enhancer  115  and performing gamma correction thereof, a two-dimensional band-pass filter (BPF)  117  which is a spatial frequency filter for receiving the output signal of the gamma correction circuit  116  and eliminating a signal having a predetermined frequency band from the received signal, and a motion-vector detecting circuit  118  for receiving both the output signal of the BPF  117  provided for extracting only the frequency band required for shake detection and the output signal of a first field memory  119  which will be described later, and detecting a motion vector of an image on the basis of a variation between two pictures which temporally differ from each other. The motion-vector detecting circuit  118  is a circuit which is based on a matching computation, and, in the second embodiment, it is preferable that the motion-vector detecting circuit  118  adopt a detection method which can execute real-time processing. The first field memory  119  is arranged to receive the output signal of the BPF  117 . The first field memory  119  serves as a delay circuit for delaying the luminance signal Y by a predetermined time (in the second embodiment, a one-field period), and is arranged to store the luminance signal Y contained in a field which immediately precedes the current field, thereby enabling a matching computation on the previous and current fields. By this matching computation, it is possible to obtain the direction and the amount of movement of the image. 
     The logic operation circuit  120  controls the entire image pickup apparatus by performing predetermined kinds of signal processing, and is formed by a microcomputer. The logic operation circuit  120  receives the output signals of the VAP apex angle sensor  103  and the motion-vector detecting circuit  118  and controls the VAP driving circuit  102   a  and a memory-reading controlling circuit  121  on the basis of the output signals, thereby causing the VAP driving circuit  102   a  and the memory-reading controlling circuit  121  to perform optical shake correction and electronic shake correction, respectively. 
     The logic operation circuit  120  computes the amount of correction required for optically correcting the direction and the amount of movement of the image due to shake, on the basis of motion vector information outputted from the motion-vector detecting circuit  118 . Then, the logic operation circuit  120  supplies the computed amount of correction to the VAP driving means  102  and drives the VAP driving coil  102   b  via the VAP driving circuit  102   a , thereby causing the VAP  101  to operate. In this manner, it is possible to optically correct movement of the image due to shake. 
     A second field memory  122  receives and stores the chrominance signal C outputted from a C process circuit  113  and the luminance signal Y outputted from the gamma correction circuit  116 . The memory-reading controlling circuit  121  controls a position and an area in the second field memory  122  from which to read out image information, on the basis of movement correction information outputted from the logic operation circuit  120 . The second field memory  122  and the memory-reading controlling circuit  121  constitute second correcting means. 
     Specifically, the logic operation circuit  120  computes, on the basis of the motion vector information outputted from the motion-vector detecting circuit  118 , the direction and the amount in which the image is to be shifted to correct for movement of the image on the second field memory  122 , and the memory-reading controlling circuit  121  controls a position and an amount in the second field memory  122  from which to read out the image information, on the basis of the direction and the amount in which the image is to be shifted, thereby cancelling the movement of the image. 
     An electronic-zoom circuit  123  receives the output signals of the second field memory  122  and the logic operation circuit  120  and converts the image into an image of desired size. Specifically, since a movement of an image is corrected by shifting an area on the second field memory  122  from which to read out the image, the picture size of the read-out image becomes smaller than that of the image stored in the second field memory  122 . To cope with this problem, the electronic-zoom circuit  123  performs the processing of enlarging the read-out image up to the original picture size. 
     Accordingly, if the magnitude of movement of an image is small, the amount in which an image reading area on the second field memory  122  is to be shifted may be small, so that the image reading area can be made large. Therefore, the ratio at which the image is enlarged may be small. However, if the magnitude of movement of the image is large, the image reading area needs to be made small because the amount of shifting of the image reading area on the second field memory  122  needs to be large. Therefore, the ratio at which the image is enlarged is made large. To execute such control, the logic operation circuit  120  is arranged to compute the amount of shifting of the image according to a motion vector and transmits an image enlargement ratio according to the computed amount of shifting to the electronic-zoom circuit  123 . 
     A digital/analog (D/A) converter  124  is provided for converting a digital signal outputted from the electronic-zoom circuit  123  to an analog signal. The image signal made up of the corrected luminance and chrominance signals Y and C, which is outputted from the electronic-zoom circuit  123 , is outputted through a signal output terminal  125 . 
     The operation of the image pickup apparatus having the above-described arrangement will be described below. 
     An image of a subject  126  sequentially passes through the VAP  101 , the lens groups  104  to  106  and the iris  107  and is formed on an image pickup surface of the image pickup element  108 . The formed image of the subject  126  is photoelectrically converted by the image pickup element  108 . The S/H circuit  109  holds the output signal of the image pickup element  108 , and the AGC circuit  110  executes automatic gain control. The A/D converter  111  performs A/D conversion of the output signal of the AGC circuit  110 . The 2HDLY circuit  112  separates the color-difference line-sequential signal outputted from the image pickup element  108  into a 1H delayed signal and a 2H delayed signal, and sends the respective 1H and 2H delayed signals to a luminance signal processing part (which includes the LPF  114  and so on) and a chrominance signal processing part (which includes the C process circuit  113  and so on). The 2H delayed signal sent to the chrominance signal processing part (which includes the C process circuit  113  and so on) is inputted to the C process circuit  113 , and the C process circuit  113  generates the chrominance signal C and writes the chrominance signal C into the second field memory  122 . 
     In the meantime, the 1H delayed signal sent to the luminance signal processing part (which includes the LPF  114  and so on) is inputted to the LPF  114 , and the LPF  114  eliminates a carrier component from the color-difference line-sequential signal to perform separation of the luminance signal Y. The enhancer  115  performs the processing of enhancing the high-frequency component of the luminance signal Y, such as the edge of the image of the subject  126 , for the purpose of improving image quality. Normally, in such processing, a quadratic differential of the video signal (luminance signal Y) is added to the original luminance signal Y. Then, the gamma correction circuit  116  executes the processing of preventing saturation of the high-light portion of the luminance signal Y and expanding the dynamic range thereof. The BPF  117  extracts a spatial frequency component which is useful for detecting a motion vector. 
     Since the high- and low-frequency components of an image signal are generally unsuitable for detecting a motion vector, they are eliminated by the BPF  117 . In the second embodiment, only a sign bit is outputted from the BPF  117 . This means that the luminance signal Y is converted into a two-level signal by using a DC level as a threshold. Accordingly, the luminance signal Y which has passed through the BPF  117  is a two-level signal represented by one bit. 
     The motion-vector detecting circuit  118  detects a motion vector of the image on the basis of the signals inputted from the BPF  117  and the first field memory  119 , and inputs the detected motion vector signal to the logic operation circuit  120 . Also, an apex-angle signal indicative of the apex angle of the VAP  101 , which is detected by the VAP apex angle sensor  103 , is inputted to the logic operation circuit  120 . The logic operation circuit  120  calculates a deviation from a reference position of the image at that time instant in accordance with the flowchart shown in FIG. 5 which will be described later, on the basis of the motion vector signal (the horizontal and vertical components of a motion vector at a predetermined position in the picture) and the apex-angle signal. Then, the VAP  101  is subjected to feedback loop control on the basis of the deviation, and the VAP  101  is driven and controlled in a predetermined state by the VAP driving means  102  to bend the optical axis, thereby correcting image shake. 
     Then, to correct image shake of high frequency and small amplitude which is not completely corrected only by driving and controlling the VAP  101  (VAP control) in the above-described manner, the following control is performed. Specifically, the memory-reading controlling circuit  121  controls the image reading position of the second field memory  122  on the basis of a control signal outputted from the logic operation circuit  120  (field memory control), thereby correcting image shake. The image outputted from the second field memory  122  is converted into an image of desired size by the electronic-zoom circuit  123 . In this manner, the image whose image shake is finally corrected is obtained. The corrected image signal is D/A converted by the D/A converter  124 , and the analog signal is outputted through the signal output terminal  125 . 
     The operation of the logic operation circuit  120  provided in the image-shake preventing device according to the second embodiment will be described below with reference to FIGS. 4 and 5. FIG. 5 is a flowchart showing the operation of the logic operation circuit  120 . In Step S 1 , the logic operation circuit  120  reads the output signal of the motion-vector detecting circuit  118  (the horizontal and vertical components of a motion vector at a predetermined position in a picture) on a field-by-field basis. Then, the process proceeds to Step S 2 , in which the logic operation circuit  120  detects, at a plurality of positions per picture, a plurality of motion vectors from a movement of an image in a plurality of fields, and performs predetermined processing, such as an averaging or weighting computation, on the plurality of motion vectors, thereby computing one representative motion vector. The predetermined processing includes the processing of evaluating the reliability of each of the motion vectors, the processing of determining a target area to be controlled, and the like. 
     Then, the process proceeds to Step S 3 , in which the logic operation circuit  120  integrates the representative motion vector to find a deviation from a reference position in the picture (the amount of displacement of the image), thereby producing an image-shake correction signal. Then, the process proceeds to Step S 4 , in which the logic operation circuit  120  finds a shake frequency from the deviation of the image obtained in Step S 3  and sets the control gain of each of the first and second correcting means to an optimum state on the basis of the shake frequency. Then, the process proceeds to Step S 5 , in which image-shake correction by the control of the VAP  101  (VAP control) or image-shake correction by the control of the second field memory  122  is executed on the basis of the amount of image-shake correction which is the deviation of the image obtained in Step S 3  and the control gain set in Step S 4 . After that, the logic operation circuit  120  brings the process to an end. 
     The processing of Step S 4 , which constitutes part of the gist of the present invention, will be described in more detail with reference to FIG.  6 . FIG. 6 is a flowchart showing the detail of the processing routine of Step S 4  of FIG.  5 . In Step S 11  of FIG. 6, the amount of displacement of the image obtained in Step S 3  of FIG. 5 is subjected to a frequency analysis according to the capability of the present control system, such as the operation of counting the frequency of cross points relative to a predetermined reference value, thereby providing the shake frequency of the image. In Step S 12 , the respective control gains of the VAP control and the field memory control are determined according to the shake frequency of the image obtained in Step S 11 , on the basis of a conversion table of FIG. 7 which shows the allocation of the control gains with respect to the shake frequency. In FIG. 7, the vertical axis and the horizontal axis represent correction (control) gain and shake frequency, respectively. As is apparent from FIG. 7, the conversion table is set so that the proportion of the field memory control, i.e., the electronic shake correction to be performed by the second correcting means, in an overall image-shake correction becomes larger in a higher-frequency area, whereas, in a lower-frequency area, the proportion of the VAP control, i.e., the optical shake correction to be performed by the first correcting means, in the overall image-shake correction becomes larger. 
     In general, a low-frequency image shake tends to become large in amplitude, while a high-frequency image shake tends to become small in amplitude. Accordingly, it is desirable that an image shake of smaller amplitude be corrected in a higher-frequency area, while an image shake of larger amplitude be corrected in a lower-frequency area. 
     According to the second embodiment, in the image-shake preventing device in which the optical, first correcting means utilizing the VAP control and the electronic, second correcting means utilizing the field memory control are combined, the shake frequency of an image is calculated by a method which can be executed by the present control system, and the respective control gains of the VAP control and the field memory control are made to vary so that the proportion of the optical shake correction to be performed by the VAP control in an overall image-shake correction, which VAP control is capable of correcting an image shake of large amplitude, can be made larger in a lower-frequency area, while the proportion of the electronic shake correction to be performed by the field memory control in the overall image-shake correction can be made larger in a higher-frequency area, which field memory control realizes a good correction characteristic capable of correcting an image shake of small amplitude. Accordingly, it is possible to perform image-shake correction which utilizes as fully as possible the respective advantages of the first and second correcting means. 
     Third Embodiment 
     The third embodiment of the present invention will be described below with reference to FIG.  8 . 
     FIG. 8 is a block diagram showing the arrangement of a video camera provided with an image-shake correcting device according to the third embodiment of the present invention. In FIG. 8, identical reference numerals are used to denote constituent parts identical to those used in the second embodiment described above with reference to FIG.  4 . The arrangement shown in FIG. 8 differs from that shown in FIG. 4 in that the VAP  101 , the VAP driving means  102 , the VAP apex angle sensor  103  and the image pickup element  108  are omitted from the arrangement shown in FIG. 4 and, instead, a large-picture image pickup element  108 ′ having a larger area than a normal image pickup element and an image-pickup-element-reading controlling circuit  127  are provided. The large-picture image pickup element  108 ′ and the image-pickup-element-reading controlling circuit  127  constitute the first correcting means which has a feedback loop and serves to correct image shake. The image-pickup-element-reading controlling circuit  127  varies the reading address of the large-picture image pickup element  108 ′ to cut out an image from an arbitrary area of the large-picture image pickup element  108 ′, thereby effecting image-shake correction. 
     The other arrangement, operation, effects and advantages of the third embodiment are substantially identical to those of the second embodiment described previously, and description thereof is omitted. 
     Fourth Embodiment 
     The fourth embodiment of the present invention will be described below with reference to FIG.  9 . FIG. 9 is a view of a conversion table which shows the allocation of the control gains with respect to the shake frequency in an image-shake preventing device according to the fourth embodiment of the present invention. In the fourth embodiment, the relation between the shake frequency and the allocation of the control gains is made to vary not linearly as in the case of the second embodiment but in a manner expressed by an exponential function. 
     The other arrangement, operation, effects and advantages of the fourth embodiment are substantially identical to those of the second embodiment described previously, and description thereof is omitted. 
     Fifth Embodiment 
     The fifth embodiment of the present invention will be described below with reference to FIGS. 10 through 13. According to the fifth embodiment, there is provided an image-shake preventing device which is arranged to detect a motion vector from image signal and correct an image shake in real time. The image-shake preventing device includes first correcting means having a feedback loop and arranged to correct image shake, second correcting means having a field memory and arranged to correct image shake by using an image delayed by the field memory, focal-length reading means for reading a focal length of an optical system, and control means for varying the proportions of individual image-shake corrections to be performed by the first and second correcting means in an overall image-shake correction, on the basis of information indicative of the focal length read by the focal-length reading means. FIG. 10 is a block diagram showing the arrangement of a video camera provided with image-shake correcting device according to the fifth embodiment of the present invention. In FIG. 10, identical reference numerals are used to denote constituent parts identical to those used in the second embodiment described above with reference to FIG.  4 . The arrangement shown in FIG. 10 differs from that shown in FIG. 4 in that a position encoder  128  for detecting the position of the zooming lens group  105  is added to the arrangement shown in FIG. 4. A position signal about the zooming lens group  105 , which is detected by the position encoder  128 , is inputted to the logic operation circuit  120 . Incidentally, the construction and operation of the other portions of the fifth embodiment shown in FIG. 10 are substantially identical to the construction and operation of the second embodiment described previously. 
     The operation of the logic operation circuit  120  provided in the image-shake preventing device according to the fifth embodiment will be described below with reference to FIGS. 10 and 11. FIG. 11 is a flowchart showing the operation of the logic operation circuit  120 . In Step S 21 , the logic operation circuit  120  reads the output signal of the motion-vector detecting circuit  118  (the horizontal and vertical components of a motion vector at a predetermined position in a picture) on a field-by-field basis. Then, the process proceeds to Step S 22 , in which the logic operation circuit  120  performs predetermined processing on the read plurality of motion vectors at positions in a plurality of fields, thereby computing one representative motion vector. The predetermined process includes the processing of evaluating the reliability of each of the motion vectors, the process of determining a target area to be controlled, and the like. 
     Then, the process proceeds to Step S 23 , in which the logic operation circuit  120  integrates the representative motion vector to find a deviation from a reference position in the picture (the amount of displacement of the image), thereby producing an image-shake correction signal. Then, the process proceeds to Step S 24 , in which the logic operation circuit  120  sets the control gain of each of the first and second correcting means to an optimum state on the basis of the position signal about the zooming lens group  105  outputted from the position encoder  128 , i.e., the focal-length signal about the optical system. Then, the process proceeds to Step S 25 , in which image-shake correction by the control of the VAP  101  (VAP control) or image-shake correction by the field memory control is executed on the basis of the amount of image-shake correction which is the deviation of the image obtained in Step S 23  and the control gain set in Step S 24 . After that, the logic operation circuit  120  brings the process to an end. 
     The processing of Step S 24 , which constitutes part of the gist of the present invention, will be described in more detail with reference to FIG.  12 . FIG. 12 is a flowchart showing the details of the processing routine of Step S 24  of FIG.  11 . In Step S 31  of FIG. 12, the focal-length signal outputted from the position encoder  128  is inputted to the logic operation circuit  120 , and in Step S 32  the actual focal length of the optical system is determined on the basis of the focal-length signal obtained in Step S 31 . Then, the process proceeds to Step S 33 , in which the respective control gains of the VAP control and the field memory control are determined according to the focal length determined in Step S 32 , on the basis of a conversion table of FIG. 13 which shows the allocation of the control gains with respect to the focal length. In FIG. 13, the vertical axis and the horizontal axis represent correction (control) gain and focal length, respectively. As is apparent from FIG. 13, the conversion table is set so that the proportion of the field memory control, i.e., the electronic shake correction to be performed by the second correcting means, in an overall image-shake correction becomes larger on a wider-angle side, whereas, on a more telephoto side, the proportion of the VAP control, i.e., the optical shake correction to be performed by the first correcting means, in the overall image-shake correction becomes larger. 
     In general, as the focal length is closer to its telephoto end, an image shake tends to increase. Accordingly, it is desirable that an image shake of smaller amplitude be corrected on the wider-angle side, while an image shake of larger amplitude be corrected on the more telephoto side. 
     According to the fifth embodiment, in the image-shake preventing device in which the optical, first correcting means utilizing the VAP control and the electronic, second correcting means utilizing the field memory control are combined, the focal length of the optical system is monitored to appropriately vary the respective control gains of the VAP control and the field memory control so that the proportion of the optical shake correction to be performed by the VAP control in an overall image-shake correction, which VAP control is capable of correcting an image shake of large amplitude, can be made larger on a more telephoto side, while the proportion of the electronic shake correction to be performed by the field memory control in the overall image-shake correction can be made larger on a wider-angle side, which field memory control realizes a good correction characteristic capable of correcting an image shake of small amplitude. Accordingly, it is possible to perform image-shake correction which utilizes as fully as possible the respective advantages of the first and second correcting means. 
     Sixth Embodiment 
     The sixth embodiment of the present invention will be described below with reference to FIG.  14 . 
     FIG. 14 is a block diagram showing the arrangement of a video camera provided with an image-shake correcting device according to the sixth embodiment of the present invention. In FIG. 14, identical reference numerals are used to denote constituent parts identical to those used in the fifth embodiment described above with reference to FIG.  10 . The arrangement shown in FIG. 14 differs from that shown in FIG. 10 in that the VAP  101 , the VAP driving means  102 , the VAP apex angle sensor  103  and the image pickup element  108  the arrangement omitted from the arrangement shown in FIG.  10  and are instead is provided with a large-picture image pickup element  108 ′ having a larger area than a normal image pickup element, an image-pickup-element-reading controlling circuit  127  and a position encoder  128  for detecting the position of the zooming lens group  105 . A position signal about the zooming lens group  105 , which is detected by the position encoder  128 , is inputted to the logic operation circuit  120 . The large-picture image pickup element  108 ′ and the image-pickup-element-reading controlling circuit  127  constitute the first correcting means which has a feedback loop and serves to correct an image shake. The image-pickup-element-reading controlling circuit  127  varies the reading address of the large-picture image pickup element  108 ′ to cut out an image from an arbitrary area of the large-picture image pickup element  108 ′, thereby effecting image-shake correction. 
     The other arrangement, operation, effects and advantages of the sixth embodiment are substantially identical to those of the fifth embodiment described previously, and description thereof is omitted. 
     Seventh Embodiment 
     The seventh embodiment of the present invention will be described below with reference to FIG.  15 . FIG. 15 is a view of a conversion table which shows the allocation of the control gains with respect to the focal length in an image-shake preventing device according to the seventh embodiment of the present invention. In the seventh embodiment, the relation between the focal length and the allocation of the control gains is made to vary not linearly as in the case of the fifth embodiment but in a manner expressed by an exponential function. 
     The other arrangement, operation, effects and advantages of the seventh embodiment are substantially identical to those of the fifth embodiment described previously, and description thereof is omitted. 
     Eighth Embodiment 
     The eighth embodiment of the present invention will be described below with reference to FIGS. 16 and 17. According to the eighth embodiment, there is provided an image-shake preventing device which is arranged to detect a motion vector from an image signal and correct image shake in real time. The image-shake preventing device includes motion-vector detecting means for detecting motion vectors relative to temporally continuous images by performing a computation on a correlation between the temporally continuous images, absolute-deviation computing means for computing an absolute deviation from a reference point of a current image by adding together the motion vectors detected by the motion-vector detecting means, first correcting means having a feedback loop and arranged to correct the image shake, second correcting means having a field memory and arranged to correct the image shake by using an image delayed by the field memory, and control means for varying the proportions of individual image-shake corrections to be performed by the first and second correcting means in an overall image-shake correction, on the basis of the absolute deviation from the reference point of the current image computed by the absolute-deviation computing means. The arrangement of a video camera which is an image pickup apparatus provided with the image-shake preventing device according to the eighth embodiment of the present invention is substantially identical to that of the previously-described second embodiment shown in FIG. 4, and the following description will be made with reference to FIG. 4 as well. FIG. 16 is a flowchart showing the operation of the logic operation circuit  120  provided in the image-shake preventing device according to the eighth embodiment. In Step S 41 , the logic operation circuit  120  reads the output signal of the motion-vector detecting circuit  118  (the horizontal and vertical components of a motion vector at a predetermined position in a picture) on a field-by-field basis. Then, the process proceeds to Step S 42 , in which the logic operation circuit  120  performs predetermined processing on the read plurality of motion vectors at positions in a plurality of fields, thereby computing one representative motion vector. The predetermined processing includes the process of evaluating the reliability of each of the motion vectors, the process of determining a target area to be controlled, and the like. 
     Then, the process proceeds to Step S 43 , in which the logic operation circuit  120  integrates the representative motion vector to find a deviation from a reference position in the picture (the amount of displacement of the image), thereby producing an image-shake correction signal. Then, the process proceeds to Step S 44 , in which the logic operation circuit  120  sets the control gain of each of the first and second correcting means to an optimum state on the basis of an absolute value (absolute deviation) of the deviation of the image obtained in Step S 43 . Then, the process proceeds to Step S 45 , in which image-shake correction by the control of the VAP control and image-shake correction by the field memory control are executed on the basis of the amount of image-shake correction which is the deviation of the image obtained in Step S 43  and the control gains set in Step S 44 . After that, the logic operation circuit  120  brings the process to an end. 
     The processing of Step S 44 , which constitutes part of the gist of the present invention, will be described in more detail with reference to FIG.  17 . FIG. 17 is a view of a conversion table which shows the allocation of the control gains with respect to the image deviation. In FIG. 17, the vertical axis and the horizontal axis represent a correction gain and the image deviation, respectively. As is apparent from FIG. 17, as the image deviation becomes larger, the proportion of the VAP control, i.e., the optical shake correction by the first correcting means, in an overall image-shake correction is made larger, while, as the image deviation becomes smaller, the proportion of the field memory control, i.e., the electronic shake correction by the second correcting means, in the overall image-shake correction is made larger. Accordingly, in Step S 44  of FIG. 16, the control gains of the VAP control and the field memory control according to the absolute value of the image deviation are set in accordance with the conversion table of FIG.  17 . 
     Ninth Embodiment 
     The ninth embodiment of the present invention will be described below with reference to FIG.  18 . FIG. 18 is a view of a conversion table which shows the allocation of the control gains with respect to the image deviation in an image-shake preventing device according to the ninth embodiment of the present invention. In the ninth embodiment, the relation between the image deviation and the allocation of the control gains is made to vary not linearly as in the case of the eighth embodiment but in a manner expressed by an exponential function. 
     The other arrangement, operation, effects and advantages of the ninth embodiment are substantially identical to those of the eighth embodiment described previously, and description thereof is omitted. 
     Tenth Embodiment 
     The tenth embodiment of the present invention will be described below with reference to FIGS. 19 and 20. The arrangement of a video camera which is an image pickup apparatus provided with an image-shake preventing device according to the tenth embodiment of the present invention is substantially identical to that of the previously-described second embodiment shown in FIG. 4, and the following description will be made with reference to FIG. 4 as well. FIG. 19 is a flowchart showing the operation of the logic operation circuit  120  provided in the image-shake preventing device according to the tenth embodiment. In Step S 51 , the logic operation circuit  120  reads the output signal of the motion-vector detecting circuit  118  (the horizontal and vertical components of a motion vector at a predetermined position in a picture) on a field-by-field basis. Then, the process proceeds to Step S 52 , in which the logic operation circuit  120  performs predetermined processing on the read plurality of motion vectors at positions in a plurality of fields, thereby computing one representative motion vector. The predetermined process includes the processing of evaluating the reliability of each of the motion vectors, the process of determining a target area to be controlled, and the like. 
     Then, the process proceeds to Step S 53 , in which the logic operation circuit  120  integrates the representative motion vector to find a deviation from a reference position in the picture (the amount of displacement of the image), thereby producing an image-shake correction signal. Then, the process proceeds to Step S 54 , in which the logic operation circuit  120  sets the control gain of each of the first and second correcting means to an optimum state on the basis of an absolute value of the representative motion vector obtained in Step S 52 . Then, the process proceeds to Step S 55 , in which image-shake correction by the VAP control and image-shake correction by the field memory control are executed on the basis of the amount of image-shake correction which is the deviation of the image obtained in Step S 53  and the control gains set in Step S 54 . After that, the logic operation circuit  120  brings the process to an end. 
     The processing of Step S 54 , which constitutes part of the gist of the present invention, will be described in more detail with reference to FIG.  20 . FIG. 20 is a view of a conversion table which shows the allocation of the control gains of the respective correcting means with respect to the representative motion vector. In FIG. 20, the vertical axis and the horizontal axis represent the correction (control) gain and the representative motion vector, respectively. As is apparent from FIG. 20, if the representative motion vector, i.e., the amplitude of a shake at a particular time instant is large, the proportion of the VAP control, i.e., the optical shake correction by the first correcting means, in an overall image-shake correction is made large, while, if the amplitude of a shake at a particular time instant is small, the proportion of the field memory control, i.e., the electronic shake correction by the second correcting means, in the overall image-shake correction is made large. Accordingly, in Step S 54  of FIG. 19, the control gains of the VAP control and the field memory control according to the absolute value of the representative motion vector are set in accordance with the conversion table of FIG.  20 . 
     According to the tenth embodiment, there is provided an image-shake preventing device which is arranged to detect a motion vector from an image signal and correct image shake in real time. The image-shake preventing device includes motion-vector detecting means for detecting motion vectors relative to temporally continuous images by performing a computation on a correlation between the temporally continuous images, first correcting means having a feedback loop and arranged to correct the image shake, second correcting means having a field memory and arranged to correct the image shake by using an image delayed by the field memory, and control means for varying the proportions of individual image-shake corrections to be performed by the first and second correcting means in an overall image-shake correction, on the basis of information indicative of the motion vectors relative to the temporally continuous images, which are detected by the motion-vector detecting means. 
     Eleventh Embodiment 
     The eleventh embodiment of the present invention will be described below with reference to FIG.  21 . FIG. 21 is a view of a conversion table which shows the allocation of the control gains of the respective correcting means with respect to the representative motion vector in an image-shake preventing device according to the eleventh embodiment of the present invention. In the eleventh embodiment, the relation between the representative motion vector and the allocation of the control gains is made to vary not linearly as in the case of the tenth embodiment but in a manner expressed by an exponential function. 
     The other arrangement, operation, effects and advantages of the eleventh embodiment are substantially identical to those of the tenth embodiment described previously, and description thereof is omitted. 
     According to any of the second to eleventh embodiments, it is possible to appropriately vary the respective control gains of the first and second correcting means so that the proportion of image-shake correction to be performed by the first correcting means in an overall image-shake correction, which means is capable of correcting an image shake of large amplitude, can be made large if the amount of an image shake at a particular time instant is large, while, if such an amount is small, the proportion of image-shake correction to be performed by the second correcting means in the overall image-shake correction can be made large, which means realizes a good correction characteristic capable of correcting an image shake of small amplitude. Accordingly, although a plurality of correcting means are combined, it is possible to readily and reliably effect flexible image-shake correction which can cope with various photographic states without causing degradation of a high-frequency characteristic, an excessive correction beyond an optimum correction range, or the like.