JP2008187614A - Photographing apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To shorten the time to focusing in auto-focus operation in response to a shutter operation in a photographing apparatus which drives an imaging device by supplying a vertical transfer pulse and a horizontal transfer pulse to the imaging device and iteratively carries out processing for sweeping away electric charges and exposing an imaging plane. <P>SOLUTION: In the photographing apparatus, a frame rate in driving an imaging device is variably set to a value corresponding to an exposure time in response to a shutter operation. A plurality of horizontal lines A which is not utilized for auto-focus processing, among a plurality of horizontal lines constituting one frame, are transferred faster than a transfer velocity for a plurality of horizontal lines B which is utilized for auto-focus processing. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a photographing apparatus such as a digital still camera provided with an image pickup device composed of a CCD or the like.

In recent years, digital still cameras having a solid-state imaging device composed of a CCD or the like have become widespread.
FIG. 2 shows a configuration of an interline transfer type solid-state imaging device (1) used in a digital still camera. In the solid-state imaging device (1), a color filter array is provided on a plurality of photosensors arranged in a matrix to form an imaging surface composed of a plurality of pixels (11), and a plurality of pixels arranged in the vertical direction. A plurality of vertical registers (12) for transferring the charges of the pixels (11) in the column in the vertical direction, and a horizontal register (13) for outputting the charges transferred by these vertical registers (12) in a cycle of one horizontal period; Is provided.

The solid-state imaging device (1) has an input terminal 8 for a first vertical transfer pulse Vφ1 having a first phase, an input terminal 7 for a second vertical transfer pulse Vφ2 having a second phase, and a third phase. A pair of third vertical transfer pulses Vφ3A and Vφ3B, input terminals 6 and 5, an input terminal 4 of a fourth vertical transfer pulse Vφ4 having a fourth phase, and a pair of fifth vertical transfer pulses Vφ5A and Vφ5B having a fifth phase Input terminals 3 and 2 and an input terminal 1 for a sixth vertical transfer pulse Vφ6 having a sixth phase. By supplying each vertical transfer pulse to these input terminals, the electric charge accumulated in the vertical register (12) is transferred to the horizontal register (13).
The solid-state imaging device (1) includes a pair of first horizontal transfer pulses Hφ1A and Hφ1B input terminals 21 and 16 and a pair of second horizontal transfer pulses Hφ2A obtained by inverting the first horizontal transfer pulse, respectively. Hφ2B input terminals 22 and 17 are provided. By supplying each horizontal transfer pulse to these input terminals, the charges transferred from the vertical register (12) to the horizontal register (13) are output to the outside.
Further, the solid-state imaging device (1) has an input terminal 19 for a sub-pulse φSUB for performing an electronic shutter operation for sweeping out charges accumulated in the pixels before exposure of the imaging surface to the outside (resetting to the ground level). Is provided.

In a conventional digital still camera, it is possible to set a monitor mode in which an image (through image) photographed by the solid-state imaging device (1) is displayed on a monitor at a period of 1/60 seconds.
FIG. 8 shows an operation when the shutter button is pressed in a monitor mode set in a conventional digital still camera, and vertical transfer pulses Vφ1 to Vφ6, horizontal transfer pulses Hφ1A, Hφ1B supplied to the solid-state imaging device. , Hφ2A, Hφ2B, and sub-pulse φSUB. In FIG. 8, SHT is a shutter pulse generated when the shutter button is pressed, and VD is a vertical synchronization pulse. The vertical transfer pulse, horizontal transfer pulse, and sub-pulse are rectangular pulses, and one block of the horizontal transfer pulse in FIG. 8 represents a series of horizontal transfer pulses.
As illustrated, the solid-state imaging device includes a first vertical transfer pulse Vφ1, a second vertical transfer pulse Vφ2, a third vertical transfer pulse Vφ3A, Vφ3B, a fourth vertical transfer pulse Vφ4, a fifth vertical transfer pulse Vφ5A, Vφ5B, and Six vertical transfer pulses Vφ6 are continuously supplied, and a series of first horizontal transfer pulses Hφ1A and Hφ1B and second horizontal transfer pulses Hφ2A and Hφ2B are intermittently supplied in a cycle of one vertical period. As a result, the charge accumulated in the pixel is transferred as will be described later.

  When the shutter button is pressed, in the first vertical period (# 1V), a series of sub-pulses φSUB is supplied to the solid-state imaging device, and the charge accumulated in the pixels is swept away, and then the imaging surface is exposed. It is. Subsequently, in the second vertical period (# 2V), the charges accumulated in the pixels by the exposure performed in the first vertical period are transferred, and the exposure time and autofocus are based on the image signal obtained thereby. Calculation of the evaluation value is started. In addition, after a series of sub-pulses φSUB is supplied to the solid-state imaging device and the charges accumulated in the pixels are swept away, the imaging surface is exposed.

Next, in the third vertical period (# 3V), after the calculation is continued, the exposure time and autofocus evaluation value obtained by the calculation are set. In addition, the charge accumulated in the pixels by the exposure performed in the second vertical period is transferred, and the calculation of the exposure time and the autofocus evaluation value is started based on the image signal obtained thereby. Further, after a series of sub-pulses φSUB is supplied to the solid-state imaging device and the charges accumulated in the pixels are swept away, the imaging surface is exposed.
Subsequently, in the fourth vertical period (# 4V), after the calculation is continued, the exposure time and autofocus evaluation value obtained by the calculation are set. Further, the charge accumulated in the pixels by the exposure performed in the third vertical period is transferred, and the calculation of the exposure time and the autofocus evaluation value is started based on the image signal obtained thereby. Further, after a series of sub-pulses φSUB is supplied to the solid-state imaging device and the charges accumulated in the pixels are swept away, the imaging surface is exposed. At this time, the exposure time and autofocus evaluation value set in the third vertical period are reflected. Similarly, exposure, transfer, calculation and setting are performed in parallel in one vertical period.

  As described above, in a conventional digital still camera, when the shutter button is pressed, a series of shooting operations of exposure, transfer, calculation, and setting are executed with three vertical periods shifted by one vertical period, so that an optimal exposure time is obtained. When the autofocus evaluation value is obtained, the photographing operation for image recording is started.

  Also, in the conventional digital still camera, when the operation of pressing the shutter button halfway (half-press) is performed, the autofocus evaluation value is calculated based on the image signal captured from the solid-state image sensor, and the result Based on the above, a focusing operation (lens motor drive) is executed (see, for example, Patent Document 1). Here, among the plurality of horizontal lines constituting one frame, for example, the plurality of horizontal lines constituting the screen area at the center of the imaging surface are used for the autofocus processing. The frame rate is set to 120 fps, which is twice the normal 60 fps, by performing transfer at the normal speed for the lines, and transferring the other plurality of horizontal lines at a speed higher than the normal speed.

FIG. 7A shows a vertical synchronization pulse VD, a vertical transfer pulse Vφ, and a sub pulse φSUV when the shutter button is half-pressed in a conventional digital still camera.
As shown in the figure, in order to set a frame rate of 120 fps, a vertical synchronization pulse VD having a period of 1/120 second is generated, and within this period, charge is swept away by the sub-pulse φSUB and subsequent exposure is performed. .
Further, in order to complete the transfer of all the horizontal lines constituting one frame within a period of 1/120 seconds, a normal period is used for a plurality of horizontal lines B at the center of the imaging surface to be used for autofocus processing. Is generated and normal transfer is performed, and the vertical transfer pulses Vφ having a cycle shorter than the normal cycle are generated for the upper and lower horizontal lines A to perform high-speed transfer. .
JP 2003-333409 A [H04N5 / 232]

However, in the conventional digital camera, when the shutter button is pressed, a constant frame rate (120 fps) is set regardless of the brightness of the object to be photographed, that is, regardless of the length of the exposure time. Even when the time is sufficiently shorter than 1/120 second, the charge sweep-out process and the exposure process are executed at a period of 1/120 second, and the processing time is not shortened.
Further, as shown in FIG. 7B, when the exposure time is longer than 1/120 second, the charge sweeping process and the exposure process cannot be executed in a period of 1/120 second. The charge sweep-out process and the exposure process must be executed in a period of 2 frames, that is, a period of 1/60 seconds. In this case, it is not necessary to perform the normal transfer for the horizontal line B and the high-speed transfer for the horizontal line A with a period of 1/120 seconds as shown in FIG. 7B, and all the horizontal lines as shown in FIG. 7C. It is only necessary to perform normal transfer with a period of 1/60 seconds for the line. In any case, the charge sweep-out process and the exposure process are executed at a period of 1/60 seconds, and the processing time is not shortened.

  Accordingly, an object of the present invention is to provide a photographing apparatus capable of shortening the time until focusing is achieved by shortening the execution cycle of the charge sweep-out process and the exposure process in the autofocus operation according to the shutter operation compared to the conventional one. Is to provide.

  An image pickup apparatus according to the present invention supplies a vertical transfer pulse and a horizontal transfer pulse to an image pickup device having an image pickup surface including an array of a plurality of pixels to drive the image pickup device, and supplies a sub-pulse to the image pickup device. The process of exposing the imaging surface after sweeping out the electric charge accumulated in each pixel to the outside is repeatedly executed, and the frame rate when driving the imaging device according to the shutter operation corresponds to the exposure time. By variably setting a value, among a plurality of pixels constituting one frame, a plurality of pixels that are not used for autofocus processing are transferred at a higher speed than a transfer speed for a plurality of pixels used for autofocus processing. .

  According to the imaging apparatus of the present invention, in the autofocus operation according to the shutter operation, among the plurality of pixels constituting the frame, the plurality of pixels not used for the autofocus process is a plurality of pixels used for the autofocus process. By performing transfer at a speed higher than the transfer speed for the pixels, it becomes possible to variably set the frame rate for driving the image sensor to a value corresponding to the exposure time. The execution cycle of processing can be shortened compared to the conventional method.

Specifically, the imaging device according to the present invention is:
Means for determining an exposure time required for shooting according to a shutter operation;
Means for variably setting a frame rate when driving the imaging device based on the determined exposure time;
Means for calculating the number of horizontal lines to be used for autofocus processing among a plurality of horizontal lines constituting one frame image at a period according to the set frame rate;
In a cycle according to the set frame rate, normal transfer is performed at normal speed for a plurality of horizontal lines to be used for autofocus processing, and high-speed transfer at higher speed than normal speed is performed for the other horizontal lines. Means to perform,
Means for executing a focusing operation based on the plurality of normally transferred horizontal lines.

In the photographing apparatus, first, an exposure time required for photographing is determined according to a shutter operation, and a frame rate for driving the image sensor is variably set based on the exposure time. As a result, when the exposure time is short, a high frame rate is set, and when the exposure time is long, a low frame rate is set.
Then, the number of horizontal lines to be used for the autofocus process is calculated from a plurality of horizontal lines constituting one frame image at a cycle according to the set frame rate. That is, when the frame rate is high so that the time required for high-speed transfer and normal transfer for a horizontal line for one frame is within one cycle according to the set frame rate, the horizontal line to be used for autofocus processing The number is reduced and the number of other horizontal lines is increased. Conversely, when the frame rate is low, the number of horizontal lines to be used for autofocus processing is increased, and the number of other horizontal lines is decreased.

After that, normal transfer is executed at normal speed for multiple horizontal lines that should be used for autofocus processing at a cycle according to the frame rate, and high-speed transfer at higher speed than normal speed is executed for the other horizontal lines. The Here, since the ratio of the number of horizontal lines to be used for autofocus processing and the number of other horizontal lines is adjusted according to the frame rate, all of the images constituting one frame image are controlled regardless of the frame rate. The transfer of the horizontal line is completed within one cycle corresponding to the frame rate.
Then, the focusing operation is performed based on the plurality of normally transferred horizontal lines.

Specifically, there is provided means for determining an area in the vertical direction on the imaging surface composed of a plurality of horizontal lines to be used for autofocus processing.
In the determination, first, an autofocus evaluation value is calculated for the entire frame, and a preliminary focusing operation is executed based on the result. Thereafter, in the image of one frame obtained by the focusing operation, for example, a portion with the highest frequency of the luminance signal is detected, and the next focusing operation is performed based on the image signal of the vertical region including the portion. Execute. As a result, a more accurate focusing operation is realized.

  According to the photographing apparatus of the present invention, since the frame rate when driving the image sensor in the autofocus operation according to the shutter operation is variably set to a value corresponding to the exposure time, the charge sweep-out process and the exposure process The execution cycle can be shortened as compared with the prior art, and as a result, the time until focusing can be shortened.

Hereinafter, the embodiment in which the present invention is implemented in a digital still camera provided with a solid-state imaging device made of a CCD will be described in detail.
The digital still camera according to the present invention includes a solid-state imaging device (1) shown in FIG. 2, and the solid-state imaging device (1) has an input terminal 8 for a first vertical transfer pulse Vφ1 having a first phase. , An input terminal 7 of a second vertical transfer pulse Vφ2 having a second phase, a pair of third vertical transfer pulses Vφ3A and Vφ3B having a third phase, input terminals 6 and 5, a fourth vertical having a fourth phase. There are provided an input terminal 4 for the transfer pulse Vφ4, a pair of fifth vertical transfer pulses Vφ5A and Vφ5B having the fifth phase 3, 2 and an input terminal 1 for the sixth vertical transfer pulse Vφ6 having the sixth phase. It has been.
The solid-state imaging device (1) includes a pair of first horizontal transfer pulses Hφ1A and Hφ1B input terminals 21 and 16 and a pair of second horizontal transfer pulses Hφ2A and Hφ2B formed by inverting the first horizontal transfer pulse. Input terminals 22 and 17 are provided.
Further, the solid-state imaging device (1) is provided with an input terminal 19 for a sub pulse φSUB for executing an electronic shutter operation.

  FIG. 1 shows the configuration of a digital still camera according to the present invention. A vertical transfer drive circuit (2) and a horizontal transfer drive circuit (3) are connected to the solid-state imaging device (1), and the first vertical transfer pulse Vφ1 and the second transfer pulse from the vertical transfer drive circuit (2). A vertical transfer pulse Vφ2, a pair of third vertical transfer pulses Vφ3A, Vφ3B, a fourth vertical transfer pulse Vφ4, a pair of fifth vertical transfer pulses Vφ5A, Vφ5B, a sixth vertical transfer pulse Vφ6, and a sub-pulse φSUB are supplied. A pair of first horizontal transfer pulses Hφ1A and Hφ1B and a pair of second horizontal transfer pulses Hφ2A and Hφ2B are supplied from the transfer drive circuit (3).

A timing generator (TG) (4) is connected to the vertical transfer drive circuit (2) and the horizontal transfer drive circuit (3). In the timing generator (4), a first vertical timing pulse, a second vertical timing pulse, a pair of third vertical timing pulses, a fourth vertical timing pulse, a pair of fifth vertical timing pulses, a sixth vertical timing pulse, a charge readout pulse And sub-timing pulses are generated, and these pulses are supplied to the vertical transfer driving circuit (2). Also, a pair of first horizontal timing pulses and a pair of second horizontal timing pulses are generated, and these pulses are supplied to the horizontal transfer drive circuit (3).
In the vertical transfer driving circuit (2), the first to sixth vertical transfer pulses Vφ1, Vφ2, Vφ3A, Vφ3B, Vφ4, Vφ5A from the charge readout pulse obtained from the timing generator (4) and the first to sixth vertical timing pulses, Vφ5B and Vφ6 are created, and the sub-pulse φSUB is created by amplifying the sub-timing pulse, and the created pulse is supplied to the solid-state imaging device (1). On the other hand, the horizontal transfer driving circuit (3) amplifies the pair of first horizontal timing pulses and the pair of second horizontal timing pulses obtained from the timing generator (4) to thereby generate a pair of first horizontal transfer pulses Hφ1A, Hφ1B and A pair of second horizontal transfer pulses Hφ2A and Hφ2B are generated, and these pulses are supplied to the solid-state imaging device (1).

  The CCD output obtained from the solid-state imaging device (1) is a predetermined image processing such as a CDS / AGC circuit (5) comprising a sampling unit CDS and a gain control unit AGC, an A / D converter (6), and compression processing. After passing through the image processing circuit (7) for performing the above, it is output to the subsequent circuit. Sampling signals SHP and SHD for sampling the CCD output are supplied from the timing generator (4) to the CDS / AGC circuit (5), and from the timing generator (4) to the A / D converter (6). A sampling signal ADCK for A / D conversion is supplied.

A control circuit (8) is connected to the timing generator (4) and the image processing circuit (7), and a shutter button (9) is connected to the control circuit (8). The control circuit (8) controls the output operation of the vertical timing pulse to the vertical transfer driving circuit (2) of the timing generator (4) and the output operation of the horizontal timing pulse to the horizontal transfer driving circuit (3).
The control circuit (8) acquires the image signal (luminance signal) of the effective area of the solid-state imaging device (1) from the image processing circuit (7), detects the signal level of the image signal, and outputs the detection result. Based on this, an exposure time and an autofocus evaluation value are calculated. In accordance with the calculation result, the sub-timing pulse output operation to the vertical transfer driving circuit (2) of the timing generator (4) is controlled, and the operation of the lens driving circuit (not shown) is controlled.

In the digital camera according to the present invention, it is possible to set a monitor mode for displaying a moving image shot by the solid-state imaging device (1) on the display as a through image. In the monitor mode, the entire obtained screen is targeted. Thus, a state close to the in-focus state is obtained.
In this state, when the shutter button (9) is pressed halfway, a highly accurate focusing operation for a part of the screen is executed, and then the shutter button (9) is fully pressed to achieve the focus. The image will be taken into memory.

FIG. 4 shows a vertical synchronization pulse VD, a vertical transfer pulse Vφ, and a sub-pulse φSUV that are generated before and after the shutter button is half-pressed.
As shown in the figure, before half-pressing the shutter button, a frame rate of 60 fps is set in the monitor mode described above, and exposure processing, autofocus evaluation value acquisition, and focusing operation (lens motor drive) are 1 / It is repeatedly executed with a period of 60 seconds.
As a result, a state close to the in-focus state is obtained, and a through image is displayed on the display.

  When the shutter button is pressed halfway, the optimum exposure time is determined according to the brightness of the subject at that time, and the frame rate is set to a value of 120 fps or less or 120 fps or more according to the exposure time. At a period T, a vertical transfer pulse Vφ for performing vertical transfer for a plurality of horizontal lines constituting one frame is generated, and generation of the subpal φSUB and exposure processing are repeated. Further, following the exposure processing in each cycle, the acquisition of the autofocus evaluation value and the focusing operation are repeated in the cycle T.

In the generation of the vertical transfer pulse Vφ, in order to complete the transfer of all the horizontal lines constituting one frame within the period T, the plurality of horizontal lines B at the center of the imaging surface to be used for the autofocus process A vertical transfer pulse Vφ having a normal cycle is generated, and a vertical transfer pulse Vφ having a cycle shorter than the normal cycle is generated for a plurality of horizontal lines A above and below the vertical transfer pulse Vφ.
As a result, normal transfer is performed at a normal speed for a plurality of horizontal lines B to be used for autofocus processing, while high-speed higher than the normal speed is performed for a plurality of horizontal lines A above and below them. Transfer will be performed.

FIG. 5 shows the vertical synchronization pulse VD, the vertical transfer pulse Vφ, and the sub-pulse φSUV when the exposure time is short because the subject is bright and the frame rate is greater than 120 fps, that is, when the period T is 1/120 seconds or less. Yes.
In this case, in order to complete the transfer of all the horizontal lines constituting one frame within the period T, the number of the plurality of horizontal lines B at the center of the imaging surface to be used for the autofocus process is reduced, The number of other horizontal lines A is increased. As a result, the transfer time for all horizontal lines in one frame coincides with the period T. As a result, image data for a plurality of horizontal lines B to be used for the autofocus process is acquired at the period T. A focusing operation is executed based on the image data.

FIG. 6 shows the vertical synchronization pulse VD, the vertical transfer pulse Vφ, and the sub-pulse φSUV when the subject is dark and the exposure time is long and the frame rate is smaller than 120 fps, that is, when the period T is 1/120 second or more. Yes.
In this case, in order to complete the transfer of all the horizontal lines constituting one frame within the period T, the number of the plurality of horizontal lines B at the center of the imaging surface to be used for the autofocus process is increased, The number of other horizontal lines A is reduced. As a result, the transfer time for all horizontal lines in one frame coincides with the period T, and as a result, image data for a plurality of horizontal lines B to be used for autofocus processing is acquired, and based on these image data Thus, the focusing operation is performed.

FIG. 3 shows the flow of autofocus processing in the digital camera according to the present invention.
Steps S1 to S4 are processes in the monitor mode. After performing exposure calculation in step S1, an autofocus evaluation value is acquired in step S2, and the focusing operation in step S3 is executed based on the result. To do. Thereafter, in step S4, it is determined whether or not the shutter is half-pressed. If it is determined no, the process returns to step S1 and the same processing is repeated.

  When the shutter button is half-pressed and it is determined as YES in step S4, the process proceeds to step S5, and it is determined whether or not the exposure time is 1/60 second or more. Here, when it is determined that the exposure time is 1/60 second or more, since there is no need for high-speed transfer, the process proceeds to step S6 and normal transfer is performed. On the other hand, when it is determined that the exposure time is less than 1/60 seconds, the process proceeds to step S7, and the reading position of the vertical screen area to be subjected to autofocus processing is acquired. Note that the vertical screen area to be subjected to the autofocus process is determined based on the result of the evaluation value acquisition process in step S2.

  Subsequently, in step S8, as described with reference to FIGS. 5 and 6, the number of horizontal lines to be used for autofocus processing is calculated based on the frame rate. In step S9, normal transfer is performed for a plurality of horizontal lines to be used for autofocus processing, and high-speed transfer is performed for other horizontal lines.

Thereafter, in step S10, an autofocus evaluation value is acquired based on image data of a plurality of horizontal lines to be used for autofocus processing, and in step S11, a focusing operation is executed based on the result.
Finally, in step S12, it is determined whether or not an in-focus state has been obtained. If NO is determined, the process returns to step S10 to repeat the acquisition of the autofocus evaluation value and the focusing operation. As a result, when the in-focus state is obtained and it is determined as YES in step S12, the autofocus process is terminated, and the process proceeds to the image data capturing process corresponding to the full press of the shutter button.

  According to the above digital camera, in the autofocus operation according to the shutter operation, the frame rate is variably set according to the exposure time, and a plurality of horizontal lines constituting one frame are not used for the autofocus process. For horizontal lines, transfer is performed faster than the transfer speed for multiple horizontal lines used for autofocus processing. It is possible to shorten the time to reach.

It is a block diagram which shows the structure of the digital camera which concerns on this invention. It is a block diagram showing the structure of a solid-state image sensor. 4 is a flowchart showing autofocus processing of the digital camera according to the present invention. 6 is a time chart showing an autofocus operation of the digital camera according to the present invention. It is a time chart showing the autofocus operation after half-pressing the shutter button when the exposure time is short. It is a time chart showing the autofocus operation after half-pressing the shutter button when the exposure time is short. It is a time chart showing the autofocus operation after half-pressing the shutter button of a conventional digital camera. It is a time chart showing operation | movement of the conventional digital camera.

Explanation of symbols

(1) Solid-state image sensor
(2) Vertical transfer drive circuit
(3) Horizontal transfer drive circuit
(4) Timing generator
(5) CDS / ADC circuit
(6) A / D converter
(7) Image processing circuit
(8) Control circuit
(9) Shutter button

Claims (4)

A vertical transfer pulse and a horizontal transfer pulse are supplied to an image pickup device having an image pickup surface composed of an array of a plurality of pixels to drive the image pickup device, and a sub-pulse is supplied to the image pickup device to store charges accumulated in each pixel. In an imaging device that repeatedly executes a process of exposing the imaging surface after sweeping outside,
Depending on the shutter operation, the frame rate when driving the image sensor is variably set to a value corresponding to the exposure time, and among the plurality of pixels constituting one frame, the plurality of pixels that are not used for the autofocus process, An image pickup apparatus that performs transfer at a speed higher than a transfer speed for a plurality of pixels used for autofocus processing. Means for determining an exposure time required for shooting according to a shutter operation;
Means for variably setting a frame rate when driving the imaging device based on the determined exposure time;
Means for calculating the number of horizontal lines to be used for autofocus processing among a plurality of horizontal lines constituting one frame image at a period according to the set frame rate;
In a cycle according to the set frame rate, normal transfer is performed at normal speed for a plurality of horizontal lines to be used for autofocus processing, and high-speed transfer at higher speed than normal speed is performed for the other horizontal lines. Means to perform,
The photographing apparatus according to claim 1, further comprising means for performing a focusing operation based on the plurality of normally transferred horizontal lines.   The means for calculating the number of horizontal lines to be used for the autofocus process is such that the time required for high-speed transfer and normal transfer for a horizontal line for one frame is within a period corresponding to the set frame rate. The photographing apparatus according to claim 2, wherein the ratio of the number of horizontal lines to be used for autofocus processing and the number of other horizontal lines is changed.   4. The photographing apparatus according to claim 2, further comprising means for determining a vertical region on the imaging surface composed of a plurality of horizontal lines to be used for autofocus processing.

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