JP6541312B2 - Image pickup apparatus and control method thereof - Google Patents

Description

  The present invention relates to an imaging device such as a digital camera, for example, and more particularly to a technique for improving exposure unevenness due to flicker (change in external light generated at the time of shooting).

  In an imaging apparatus such as a digital camera, with the recent increase in ISO, high-speed shutters are released even under an artificial light source that generates flicker. While high-speed shutter shooting has the advantage of being able to shoot blur-free photos when shooting indoor sports, etc., under the flicker light source, the effects of flicker cause uneven image exposure and color within each frame or within one frame. It may occur.

  As a solution to this problem, there is a method of reducing the influence of flicker by detecting flicker and performing exposure at the flicker peak position with the least change in brightness. For example, a technique has been proposed in which the output of the photometry unit is acquired at intervals of 1 ms, the flicker period and phase are determined from the luminance information, and exposure is performed at peak timing (Japanese Patent Application Laid-Open No. 2008-101501).

  On the other hand, in digital single-lens reflex cameras and the like, those having an AE sensor for photometry separately from an image sensor for acquiring a photographed image are mainstream. AE sensors in recent years are equipped with a relatively high resolution image sensor with several thousand to hundreds of thousands of pixels, perform photometry and scene analysis etc. from the high resolution acquired image, and various subjects There is also one that acquires information and uses the information for various photographing control. An example of scene analysis is face detection, etc. If the resolution is higher, a smaller face can be detected, which is very useful information at the time of shooting control.

JP, 2010-74484, A

  In the patent document 1, the output of the photometry unit is acquired at an interval of 1 ms. In this case, in the case where a high resolution image sensor is mounted as the AE sensor, it is sufficient if high resolution AE sensor images can be acquired at intervals of 1 ms. However, in view of the driving speed of a general image sensor in recent years, in order to realize imaging at an interval of 1 ms, processing for reducing resolution such as thinning and addition is practically required.

  That is, in order to detect a flicker cycle and a phase from an image obtained by the AE sensor, only low-resolution images can be obtained if imaging is performed at relatively high speed intervals (for example, 1 ms). Therefore, when a high resolution image necessary for scene recognition or the like is desired, it is necessary to perform accumulation and readout operations of high resolution pixels again separately from the image for flicker detection. In this case, as a result, the shooting sequence is extended, which leads to a reduction in the speed of the frame, particularly at the time of continuous shooting.

  Therefore, it is an object of the present invention to provide a mechanism that makes it possible to detect flicker with high accuracy while suppressing the time required for detection.

In order to achieve the above object, an image pickup apparatus according to the present invention comprises a plurality of photometry results obtained by performing a plurality of first photometry operations by an image pickup means, a photometry means provided with a photometric element, and the photometry means. Calculating a predetermined timing based on the light amount of light from the subject satisfying a predetermined condition, and a plurality of photometry results obtained by performing the second photometry a plurality of times by the photometry means On the basis of the second calculation means for calculating the light quantity change period of the light from the subject, and the exposure timing using the imaging means on the basis of the predetermined timing calculated by the first calculation means. The determination means to be determined, and the control means for controlling the number of times of photometry for performing the first photometry and the photometry interval are provided, and the first photometry is a signal read from the photometry element rather than the second photometry. There are a lot of The time required to read out the signal from the photometric element is long, and the second calculating means obtains the second photometry a plurality of times by the photometric means before starting continuous shooting using the imaging means. The light quantity change period of the light from the subject is calculated based on the plurality of photometry results, and the first calculation means determines the light quantity change period before starting the continuous shooting by the second calculation means. The predetermined timing is calculated based on a plurality of photometry results obtained by performing the plurality of first photometry operations by the photometry unit during the continuous shooting after the image is calculated, and the control unit is configured to The signal is read out from the photometric element by the first photometry in the case where the light amount change cycle of the light from the subject is a first cycle and the case where the light cycle is a second cycle different from the first cycle . the even time identical required, the And controlling so as to vary the metering times and metering interval for the first metering.

  According to the present invention, it is possible to accurately detect flicker while suppressing the time required for detection.

FIG. 1 is a schematic view showing a system configuration example of a digital single-lens reflex camera having a continuous shooting function, which is an example of an embodiment of an imaging device of the present invention. FIG. 7 is a flowchart illustrating an operation in the case of performing continuous shooting while calculating a cycle of light quantity change of light from a subject and a timing at which the light quantity change satisfies a predetermined condition. It is a graph which shows the output of AE sensor. It is a graph which shows the output of AE sensor. FIG. 7 is a timing chart diagram showing a sequence of camera operations during continuous shooting. It is a graph explaining the example of the method of computing the peak timing of a flicker. It is a graph which shows the condition which can detect the flicker of power supply frequency 50Hz by the light measurement space | interval Xms and 6 times of light measurement frequency | count. It is a figure which shows the frequency | count of a light detection which can be peak detected when changing a light measurement space | interval for every frequency of a flicker.

  Hereinafter, an example of an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic view showing an example of the system configuration of a digital single-lens reflex camera having a continuous shooting function, which is an example of an embodiment of the imaging apparatus of the present invention.

  In the digital single-lens reflex camera according to the present embodiment, as shown in FIG. 1, a lens barrel 200 for replacement is detachably mounted to a camera body 100.

  The camera body 100 has a camera CPU 101 that controls the entire camera, and a memory 102 such as a RAM or a ROM is connected to the camera CPU 101. At the time of finder observation, the main mirror 105 and the sub mirror 111 guide the subject light flux which has entered the shooting optical path and passed through the lens barrel 200 to the focusing plate 106, and withdraw from the shooting optical path when shooting. Lead. The main mirror 105 is a half mirror, and the sub mirror 111 reflects a part of the subject light flux transmitted through the main mirror 105 and guides it to the AF unit.

  The penta roof prism 109 converts the subject light flux formed on the focusing plate 106 into a subject image of an erecting right image, and the converted subject image is guided to the AE sensor 108 and observed through an optical finder. The display element 107 displays an AF distance measurement frame such as PN liquid crystal and indicates at which position the user is focused when looking through the optical finder.

  The imaging element 103 is configured of a CCD sensor, a CMOS sensor, and the like, and includes an infrared cut filter, a low pass filter, and the like. The imaging element 103 photoelectrically converts an object image formed by passing through the lens barrel 200 at the time of photographing and outputs an image signal. The shutter 104 shields the image sensor 103 from light when not photographing, and opens it to guide subject light to the image sensor 103 during photographing.

  The AE sensor 108 corresponds to an example of the photometric element of the present invention, and performs not only photometry but also scene recognition such as face detection and flicker detection by using an imaging element such as a CCD sensor or a COMS sensor. In the present embodiment, a CMOS sensor having a resolution of QVGA is used as the AE sensor 108. This CMOS sensor has a pixel addition mode for reading out with a resolution obtained by adding two pixels of the same color vertical in addition to an all pixel mode for reading out all pixels of QVGA. Then, it takes 2 ms to read out in the all pixel mode, and 1 ms to read out in the pixel addition mode. The time shown here is merely an example, and it is intended to show that the time required for reading is shorter in the pixel addition mode than in the all pixel mode.

  The ICPU 112 is a CPU for driving control of the AE sensor 108 and image processing / calculation. The ICPU 112 calculates the timing at which the cycle of the light amount change of light from the subject described later and the light amount change satisfy the predetermined condition (for example, the light amount becomes maximum, in addition to the face detection operation, tracking operation, photometric operation, etc. It also calculates the light quantity change characteristics such as the timing and the timing at which it becomes minimum. The light quantity change characteristic of light from the subject calculated by the ICPU 112 corresponds to the light quantity change characteristic of a light source (flicker light source) whose light quantity changes periodically according to the frequency of the commercial power source. The periodic light quantity change of the light of is also called flicker. A memory 113 such as a RAM or a ROM is connected to the ICPU 112. In the present embodiment, the dedicated ICPU 112 of the AE sensor 108 is used, but all processing of the ICPU 112 may be performed by the camera CPU 101. The LPU 201 is a CPU in the lens barrel 200, and sends information on a distance to an object and the like to the camera CPU 101.

  Further, in the camera according to the present embodiment, when the release button (not shown) is pressed halfway, the release switch SW1 is turned on to perform shooting preparation operations such as AF and AE, and the release button is fully pressed. The release switch SW2 is turned on to perform the photographing operation.

  Next, an operation example of the digital single-lens reflex camera will be described with reference to FIGS. FIG. 2 is a flowchart for explaining the operation in the case of performing continuous shooting while calculating the cycle of the light amount change of light from the subject and the timing at which the light amount change satisfies the predetermined condition. Note that each process in FIG. 2 is executed by the ICPU 112 after the program stored in the ROM or the like of the memory 113 is expanded in the RAM under the control of the camera CPU 101.

  In FIG. 2, in step S101, when the release switch SW1 is turned on to start continuous shooting, the ICPU 112 determines whether or not flicker exists, and if it exists, the light amount change period (frequency) of the flicker is Determine how many.

  In the present embodiment, as shown in FIG. 3, accumulation and readout of the pixels of the AE sensor 108 are performed twelve times in succession at a cycle of about 1.667 ms as shown in FIG. 3 in order to detect flickers. Generally, the frequency at which the light and dark of the flicker light source changes is twice the frequency of the commercial power supply. Therefore, in a power supply area where the power supply frequency is 50 Hz, the frequency is 100 Hz and the light amount change period is 10 ms. Similarly, in a region where the power supply frequency is 60 Hz, the frequency is 120 Hz, and the light amount change period is 8.33 ms.

  FIG. 3A is a graph showing the output of the AE sensor 108 when pixels are accumulated at intervals of 1.667 ms when there is a flicker light source with a power supply frequency of 50 Hz. In FIG. 3A, the nth accumulation of the pixel is "accumulation n", the readout of the accumulation n is "readout n", and the photometric value obtained from the result of the readout n is "AE (n)". Regarding the acquisition time of each photometric value in FIG. 3A, accumulation is performed in a finite time, and therefore, is represented by the median value during the accumulation period.

  Since the light intensity change period of the flicker at the commercial power supply 50 Hz is 10 ms and 10 ÷ 1.667 ≒ 6 as described above, as shown in FIG. Equal photometric values are obtained. That is, the relationship of AE (n) = AE (n + 6) is established.

  Similarly, since the light intensity change period of the flicker at the commercial power supply 60 Hz is 8.33 ms and 8.338.31.67 よ う 5 as described above, as shown in FIG. Approximately equal photometric values are obtained, and the relationship of AE (n) = AE (n + 5) is obtained.

  On the other hand, under the environment where there is no flicker, AE (n) is constant regardless of n. From the above, evaluation value F50 and evaluation value F60 are defined by the following equations (1) and (2), respectively, and by using threshold value F_th, whether or not flicker exists, and if it exists, the light amount of the flicker It can be determined what change period (frequency) is.

  That is, when F50 <F_th and F60 <F_th are satisfied, it can be determined that there is no flicker. When F50 <F_th and F60 ≧ F_th are satisfied, it can be determined that the light quantity change period T = 10 ms (power supply frequency 50 Hz) under the flicker environment. Furthermore, when F50 ≧ F_th and F60 <F_th are satisfied, it can be determined that the light quantity change period T = 8.33 ms (power supply frequency 60 Hz) is under flicker environment.

  In addition, it is conceivable that both F50 and F60 exceed F_th due to panning and the subject moving. In this case, the magnitudes of F50 and F60 are compared, and if F50 is smaller, it is determined that the light quantity change cycle T = 10 ms (power supply frequency 50 Hz) flicker environment, and if F60 is smaller, the light quantity change It is determined that the flicker environment has a cycle T = 8.33 ms (power supply frequency 60 Hz).

  That is, when F50 ≧ F_th and F60 ≧ F_th hold, it is determined that the light quantity change cycle T = 10 ms (power supply frequency 50 Hz) flicker condition in F50 ≦ F60, and the light quantity change cycle T = 8.33 ms in F50> F60 It is determined that the flicker environment is (power supply frequency 60 Hz).

  Alternatively, in such a case, the flicker detection may be re-performed as the reliability of the flicker detection result is low. As described above, by calculating evaluation values such as F50 and F60, there is flicker in the shooting environment, and if it exists, which of the power supply frequencies is 50/60 Hz and the light intensity change period at that time T can be calculated.

  Since the flicker frequency is determined by the power supply frequency, it is considered extremely unlikely that the flicker frequency changes during continuous shooting. Therefore, it is assumed that the flicker frequency determined in step S101 of FIG. 2 is fixed until the end of a series of continuous shooting.

  Then, in step S101, when it is determined that there is no flicker, the ICPU 112 proceeds to step S102. If the ICPU 112 determines that the power supply frequency is 50 Hz, it switches to the processes of steps S103 and S106. If the ICPU 112 determines that the power supply frequency is 60 Hz, it switches to the processes of step S104 and S107. .

  In step S102, while the release switch SW2 is turned on, the ICPU 112 performs an imaging operation once in the normal sequence of step S105, and continuous shooting is realized by repeating this.

  In the normal sequence, as shown in FIG. 4A, first, the pixels of the AE sensor 108 are accumulated in the all pixel mode and read out. The hatched portion in the figure indicates the readout of the pixel, and as described above, the readout time of the all-pixel mode of the AE sensor 108 is 2 ms. After that, the mirrors 105 and 111 are retracted from the photographing optical path (mirror up), and the photographing operation (exposure time and trailing movement of the shutter 104) is performed, and then the mirrors 105 and 111 enter the photographing optical path again (mirror down). . Here, for example, assuming that the accumulation time of the AE sensor 108 is 9 ms, the AE time including the readout is 11 ms.

  Although illustration is omitted, the accumulation in the AF unit 110 is also performed in parallel during this AE time, and the AF / AE operation is performed. In the AF / AE operation, the scene analysis result is fed back from the high resolution image acquired by the AE sensor 108. Thereafter, it is assumed that the mirror up and the mirror down are each 30 ms, and the exposure is 1 ms, and the trailing curtain traveling time of the shutter 104 is 3 ms. In this case, the cycle time required to capture one image is 75 ms, and the frame speed is 13.3. The time required for each process shown in FIG. 4 is merely an example, and is for comparing the total processing time due to the difference in the process executed in FIGS. 4 (a) to 4 (d). Therefore, in FIGS. 4A to 4D, the time required for the same processing may be the same, and the different processing may be different for the time required for the processing in accordance with each feature.

  Next, step S103 is a case where the flicker of 50 Hz of power supply frequency is detected in step S101. While the release switch SW2 is turned on, the ICPU 112 performs an imaging operation once in the 50 Hz peak detection sequence of step S106, and continuous shooting is realized by repeating this. In the image pickup operation according to the 50 Hz peak detection sequence, the camera CPU 101 controls the image pickup element 103 so that the exposure timing of the image pickup element 103 matches the peak timing of the flicker of the power supply frequency 50 Hz.

  In step S106, since flicker is detected in step S101, it is necessary to detect the peak timing of the flicker. The peak timing of the flicker can be calculated based on the 12 photometry results acquired in step S101. In this case, the peak timing of the flicker is detected only once at the start of continuous shooting, and then the camera operates assuming that there is a peak at each flicker cycle Tms.

  However, the influence of the clock error that actually measures time inside the camera and the frequency of the power supply supplied to the flicker light source are not limited to 50 or 60 Hz strictly, such as 50 ± 0.2 Hz, to some extent Have an error. For this reason, as the number of continuous shots increases, the difference between the calculated peak timing of flicker and the actual peak timing can not be ignored.

  Therefore, in the present embodiment, the flicker frequency is detected before the start of continuous shooting, and the detection of the flicker peak timing is a sequence performed before the imaging operation of each frame during continuous shooting.

  Here, an algorithm for detecting a flicker peak timing will be described with reference to FIG. FIG. 5 is a graph for explaining an example of a method of calculating the peak timing of flicker.

  In an environment with flicker, photometry by the AE sensor 108 is continuously performed a plurality of times at predetermined time intervals, and the result is referred to as AE (n). The point at which the maximum output is obtained among these multiple photometric results AE (n) is P2 (t (m), AE (m)), and the point of the photometric result immediately before that is P1 (t (m (t) -1) and AE (m-1)), and the point of the photometric result one after is P3 (t (m + 1), AE (m + 1)).

  First, a straight line passing two points of AE (m-1) and AE (m + 1) (P3 in the example of FIG. 5) and point P2 is determined as L1 = at + b. Further, a straight line with a slope of -a is obtained as L2 through a point (P1 in the example of FIG. 5) which takes the larger of AE (m-1) and AE (m + 1). By calculating the intersection of L1 and L2 thus determined, it is possible to calculate the peak timing t_peak of the flicker and the photometric value AE_peak at the peak.

  This algorithm approximates the peak timing by a simple calculation from the maximum value AE (m) measured at the timing near the peak and the photometry result one time before and after it among a plurality of photometry results AE (n) Ask for Taking the above into consideration, the minimum number of times necessary for performing flicker peak timing detection and the time interval of photometry will be considered for multiple photometry results AE (n).

  FIG. 6 is a graph showing a situation where flickers with a power supply frequency of 50 Hz, for example, can be detected at a photometric interval Xms and six photometric times. As shown in FIG. 6, among the photometric values AE (1) to AE (6) acquired six times, it was the timing when AE (1) and AE (6) at both ends of the figure become the photometric values of the flicker peak. In the case, the algorithm of FIG. 5 using the peak and one photometric value before and after that does not hold.

  That is, if the photometric interval X is slightly shorter than the situation shown in FIG. 6, AE (1) or AE (6) will be the maximum photometric value, and flicker peak timing can not be calculated. Since the condition of FIG. 6 is established when 4 × = 10 ms is established according to the diagram, X = 2.5 ms.

  At this time, AE (1) = AE (2) = AE (5) = AE (6), and theoretically, it is possible to detect the peak of the flicker by the algorithm described in FIG. However, since there is a certain degree of variation in the frequency of the flicker light source, it is considered that X> 2.5 ms, not X 検 出 2.5 ms, that the flicker peak can be detected by six photometry.

  Up to this point, we have considered the situation where the peak frequency of 50 Hz of the power supply frequency can be detected by photometry six times, but with the same conception, the metering interval X where peak detection can be performed N times The period T can be used to calculate by the following equation (3).

X = T / (N-2) (3)
FIG. 7 is a table in which the number of peak-detectable photometric times when the photometric interval is changed in 0.1 ms steps for each flicker frequency using the above equation (3) is summarized as a table. The table of FIG. 7 is stored in the memory 113. Thus, using the above equation (3) or the table of FIG. 7, the ICPU 112 can determine the photometry interval and the number of photometry times necessary for detecting the peak of the flicker.

  If it is determined that flicker peak detection should be performed by photometry at 1 ms intervals, it can be seen from FIG. 7 that 13 photometry operations are required to perform flicker peak detection at a power supply frequency of 50 Hz. The sequence of the camera operation at this time is shown in FIG.

  In the present embodiment, the AE sensor 108 requires a readout time of 2 ms in the all pixel mode. For this reason, it is necessary to read out in pixel addition mode in order to measure light at intervals of 1 ms at peak detection, but the resolution is too low for scene analysis in pixel addition mode. An additional image of all pixel mode is acquired for scene analysis. Since flicker exists in the image at this time, the influence is reduced by setting the accumulation time of one cycle of the flicker for the image for scene analysis.

  Since the light quantity change period of the power supply frequency of 50 Hz is 10 ms and the light emission cycle of the power supply frequency of 60 Hz is 8.33 ms, by accumulating approximately 9 ms between them, it does not depend on the flicker frequency. It is possible to acquire an image for stable scene analysis. After acquiring an image for scene analysis, a mirror-up operation is performed, and then peak timing of flicker is waited, and the shutter 104 is made to travel in synchronization with the peak timing.

  The peak timing is calculated by the algorithm shown in FIG. 5 from the 13 photometric results for flicker by the AE sensor 108. Then, assuming that the peak timing calculation result is t_peak, there is a flicker peak for every t_peak + m × T (m is an arbitrary natural number) using the light amount change cycle T of the flicker. Therefore, exposure control synchronized with the peak timing can be realized by matching the exposure timing of the image sensor 103 with the peak timing of the flicker (matching the traveling of the shutter 104).

  In the case of a flicker light source with a power supply frequency of 50 Hz, since the light quantity change period of the flicker is 10 ms, waiting for the peak timing is also 0 to 10 ms. Thereafter, when the photographing operation and the mirror down are performed, the time required for one continuous shooting becomes 89 to 99 ms, and the frame speed at this time becomes 10.1 to 11.2.

  In the sequence of FIG. 4D, photometry is performed separately for the flicker AE and the scene analysis AE, so a relatively long time is required. Therefore, the sequence of FIG. 4B in which the time is shortened by sharing the two types of photometry can be considered.

  In the sequence of FIG. 4B, it is first considered to use only the all-pixel mode in order to use both the image for flicker and the image for scene analysis. Since the readout time in the all pixel mode is 2 ms, the photometry interval of the multiple photometry for flicker peak detection can be performed only in 2 ms or more.

  Therefore, referring to FIG. 7, the photometry interval is 2.1 ms at which the time taken for accumulation is the shortest when the photometry interval is 2 ms or more, and the number of photometry required is seven times. Therefore, if the mirror up, imaging operation, and mirror down are performed after 7 times of accumulation at 2.1 ms intervals in the all pixel mode, the time required for one continuous shooting is 80.7 to 90.7 ms, and The speed is 11.0 to 12.4. For this reason, time can be shortened compared with coma speed 10.1-11.2 of FIG.4 (d). Therefore, in the present embodiment, the sequence of FIG. 4B is performed as the 50 Hz peak detection sequence of step S106.

  Next, step S104 is the case where flicker of the power supply frequency 60 Hz is detected in step S101. While the release switch SW2 is on, the ICPU 112 performs an imaging operation once in the 60 Hz peak detection sequence of step S107, and continuous shooting is realized by repeating this. In the image pickup operation according to the 60 Hz peak detection sequence, the camera CPU 101 controls the image pickup element 103 so that the exposure timing of the image pickup element 103 matches the peak timing of the flicker at the power supply frequency of 60 Hz.

  Also in this case, with reference to FIG. 7, the photometry interval is 2.1 ms, and the required number of times of photometry is six, that the time required for the accumulation becomes shortest at the accumulation interval of 2 ms or more. Thus, the required number of photometry changes when the power supply frequency is 50 Hz and 60 Hz. The 60 Hz peak detection sequence in step S107 is the sequence of FIG. 4C from the same concept as the case of the 50 Hz peak detection sequence in step S106. The optimum photometric interval and the number of photometric times of the AE sensor 108 are influenced by the readout time of the all pixel mode, so the optimal photometric interval and the number of photometric times are also described above if the readout time of the all pixel mode is less than 2 ms. It goes without saying that it is different from the combination.

  As described above, in the present embodiment, the photometry interval and the number of photometry times of the AE sensor 108 necessary for detecting the peak timing of the flicker are optimized, and the flicker is detected at the time of continuous shooting. It is possible to suppress the decline.

  The present invention is not limited to the ones exemplified in the above embodiments, and can be appropriately modified without departing from the scope of the present invention. For example, the light amount change period of the flicker may not be calculated by the method described above, but may be set by the user operating a setting button (not shown) provided on the camera body 100. Alternatively, it may be calculated based on the image signal output from the imaging element 103 using an accumulation time different from the light amount change period of the flicker.

  The present invention is also realized by executing the following processing. That is, software (program) for realizing the functions of the above-described embodiments is supplied to a system or apparatus via a network or various storage media, and a computer (or CPU, MPU or the like) of the system or apparatus reads the program. It is a process to execute. It can also be realized by executing software (program) acquired via a network or various storage media on a personal computer (CPU, processor).

103 image sensor 104 shutter 108 AE sensor 112 ICPU

Claims (4)

Imaging means,
Photometric means provided with a photometric element ;
First calculation means for calculating a predetermined timing at which the light quantity of light from the subject satisfies a predetermined condition based on a plurality of photometry results obtained by performing the first photometry a plurality of times by the photometry means;
Second calculation means for calculating a light amount change cycle of light from the subject based on a plurality of photometry results obtained by performing the second photometry a plurality of times by the photometry means;
A determination unit that determines an exposure timing using the imaging unit based on the predetermined timing calculated by the first calculation unit;
Control means for controlling the number of times of photometry for performing the first photometry and the photometry interval ;
In the first photometry, the number of signals read out from the photometry element is larger than in the second photometry, and the time required to read out the signal from the photometry element is longer,
The second calculation unit is configured to obtain the subject from the subject based on a plurality of photometry results obtained by performing the second photometry a plurality of times by the photometry unit before starting continuous shooting using the imaging unit. Calculate the light intensity change cycle of the
The first calculation means is configured to perform the first photometry of the plurality of times by the photometry means during the continuous shooting after the light amount change period is calculated before the second calculation means starts the continuous shooting. Calculating the predetermined timing based on a plurality of photometric results obtained by performing
The control means is configured to perform the first photometry by the first photometry in a case where a light amount change cycle of light from the subject is a first cycle and a case where the light cycle is a second cycle different from the first cycle. An imaging apparatus characterized in that control is performed so that the number of times of photometry for performing the first photometry and the photometry interval are made different even if the time required to read out the signal from the same is the same . Before SL control means, in any case the light amount change period is the first period and the second period as if it is also the first photometry by the photometric intervals as photometric count is minimum The imaging apparatus according to claim 1 , wherein the imaging apparatus is executed a plurality of times. 3. The image pickup apparatus according to claim 2 , wherein the photometry result of the first photometry is used for a predetermined process other than the calculation of the predetermined timing. A control method of an image pickup apparatus, comprising: an image pickup means; and a photometric means provided with a photometric element , wherein
A first calculation step of calculating a predetermined timing at which the light quantity of light from the subject satisfies a predetermined condition based on a plurality of photometry results obtained by performing the first photometry a plurality of times by the photometry means;
A second calculation step of calculating a light amount change cycle of light from the subject based on a plurality of photometry results obtained by performing a plurality of second photometry in the photometry step;
A determination step of determining an exposure timing using the imaging unit based on the predetermined timing calculated in the first calculation step;
A control step of controlling the number of times of photometry for performing the first photometry and the photometry interval ;
In the first photometry, the number of signals read out from the photometry element is larger than in the second photometry, and the time required to read out the signal from the photometry element is longer,
In the second calculation step, based on a plurality of photometry results obtained by performing the plurality of second photometry steps in the photometry step before starting continuous shooting using the imaging unit Calculate the light intensity change cycle of the
In the first calculation step, the plurality of first photometry operations are performed in the photometry step during the continuous shooting after the light amount change period is calculated before the continuous shooting is started in the second calculation step. Calculating the predetermined timing based on a plurality of photometric results obtained by performing
The control means is configured to perform the first photometry by the first photometry in a case where a light amount change cycle of light from the subject is a first cycle and a case where the light cycle is a second cycle different from the first cycle. A control method of an image pickup apparatus, wherein control is performed so that the number of times of photometry for performing the first photometry and the photometry interval are made different even if the time required to read out the signal from the same is the same .