JP2013003249A - Imaging apparatus and method for controlling the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform exposure calculation by using a photometric value to which the brightness of an object is reflected, even when the photometric value is estimated.SOLUTION: An estimated photometric value is calculated based on a first photometric value based on the output of photometric means when a first time is elapsed from when reset operation is performed so that the output value of the photometric means becomes a predetermined value and a second photometric value based on the output of the photometric means when a second time longer than the first time is elapsed from when the reset operation is performed. When a third photometric value based on the output of the photometric means is obtained when a third time longer than the second time is elapsed from when the reset operation is performed, it is decided whether or not the estimated photometric value is used for the exposure calculation, based on the third photometric value.

Description

  The present invention relates to an imaging apparatus that predicts a photometric value.

  In photometric devices such as single-lens reflex cameras, photometric sensors that measure the luminance of a subject and the photocurrent of a photodiode with a LOG characteristic of a diode or the like are widely used.

  In a photometric circuit using such LOG characteristics, a long waiting time is required to obtain an accurate photometric output after receiving the subject light when the power is turned on, particularly under a low luminance with a small photocurrent. It was. Also, especially in a system where the mirror is retracted during shooting and the light to the photodiode is shielded, such as in a single-lens reflex camera, the decrease in photometric performance under low brightness due to light response causes an increase in the release time lag. This is a very big problem such as a decrease in the continuous shooting speed.

  Furthermore, in recent digital cameras, high-sensitivity cameras with ISO sensitivity of several tens of thousands have appeared due to improved sensitivity of image sensors and advanced image processing. It is necessary to improve the photometric performance at

  In order to solve such a problem, for example, in Patent Document 1, when photometry is performed a plurality of times and changes in the plurality of photometry outputs Vo are linear, it is determined that the photometry output is not stabilized. A photometric circuit for obtaining the photometric output Vout by calculation is described.

JP 62-43526 A

  However, in the photometric circuit described in Patent Document 1, when the plurality of photometric outputs Vo are not linear, the final photometric output Vo is regarded as the photometric output Vout because the photometric output Vo is stabilized. Therefore, for example, if the photometric output Vo is not linear, even if the photometric output Vo is not stabilized, the last photometric output Vo is set as the photometric output Vout, and an appropriate photometric output Vout cannot be obtained. There is.

  The present invention has been made in view of the above problems, and it is an object of the present invention to be able to perform exposure calculation using a photometric value reflecting the luminance of a subject even when predicting the photometric value. And

  In order to achieve the above object, an imaging apparatus according to the present invention includes a photometric unit that performs photometry on a subject, a reset unit that resets the photometric unit so that an output value of the photometric unit becomes a predetermined value, and the reset. The first photometric value based on the output of the photometric means when the first time has elapsed since the first time, and the second photometric time when the second time longer than the first time has elapsed since the resetting. A calculating means for calculating a predicted photometric value based on a second photometric value based on an output of the photometric means, and the photometry when a third time longer than the second time has elapsed since the reset. Determining means for determining whether or not to use the predicted photometric value for the exposure calculation based on the third photometric value when the third photometric value based on the output of the means is acquired. .

  In order to achieve the above object, a method for controlling an imaging apparatus according to the present invention includes a photometric unit that performs photometry on a subject, and a reset unit that resets the photometric unit so that an output value of the photometric unit becomes a predetermined value. And a first photometric value based on an output of the photometric means when a first time has elapsed since the resetting, and the first photometric value after the resetting. A calculation step of calculating a predicted photometric value based on a second photometric value based on an output of the photometric means when a second time longer than the first time has elapsed, and the second step after performing the reset. If the third photometric value based on the output of the photometric means is acquired when a third time longer than the time elapses, whether the predicted photometric value is used for the exposure calculation based on the third photometric value? Decide whether or not A determining step, and having a.

  According to the present invention, even when the photometric value is predicted, the exposure calculation can be performed using the photometric value reflecting the luminance of the subject.

1 is a schematic configuration diagram of an imaging apparatus according to a first embodiment of the present invention. 1 is a block diagram of an imaging apparatus according to a first embodiment of the present invention. The figure which showed an example of the circuit diagram of the photometry circuit in the 1st Embodiment of this invention. The figure which showed the time transition of the photometry output with respect to different brightness | luminance. The figure which showed the relationship between the photometric value and elapsed time in the 1st Embodiment of this invention. The figure which showed the flowchart of the exposure calculation operation | movement in the 1st Embodiment of this invention. The figure which showed the relationship between the photometric value and elapsed time in the 2nd Embodiment of this invention. The figure which showed the flowchart of the exposure calculation operation | movement in the 2nd Embodiment of this invention. The figure which showed the example of the prediction function which estimates the time characteristic of photometry output.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. In the drawings used for the following description, the same component parts are denoted by the same reference numerals.

(First embodiment)
FIG. 1 is a schematic configuration diagram of an imaging apparatus according to the first embodiment of the present invention. In the figure, reference numeral 101 denotes a CPU (central processing unit), and the operation of each part of the imaging apparatus is controlled by the CPU 101.

  A light beam from a subject image (not shown) is guided to the quick return mirror 110 via the photographing lens 115 and the diaphragm 112 in the lens unit. The central portion of the quick return mirror 110 is a half mirror, and a part of the light beam is transmitted. The transmitted light beam is guided to a known phase difference type focus detection unit consisting of 117, 118, and 119 by a sub mirror 116 installed on the quick return mirror 110. Here, 117 is a field lens, 118 is a secondary imaging lens, and 119 is an AF sensor. Based on the output of the AF sensor 119, the CPU 101 sends a driving pulse for driving the photographing lens 115 to the photographing lens drive control unit 125. The photographic lens drive control unit 125 drives the pulse motor in accordance with the received drive pulse and drives the photographic lens 115 to the in-focus position to perform automatic focus adjustment.

  On the other hand, the light beam reflected by the quick return mirror 110 is guided to the eyepiece 122 via a focus detection plate (hereinafter referred to as “focus plate”) 120 and a pentaprism 121. The focus plate 120 is disposed on an image plane equivalent to the imaging element image plane of the photographic lens 115, and the subject image reflected by the quick return mirror 110 is primarily imaged by the focus plate 120.

  The photometric circuit 100 arranged in the vicinity of the eyepiece lens 122 subjects the subject image formed on the focus plate 120 by the photometric prism 123 and the photometric lens 124 to a secondary image on the chip of the photometric circuit 100, thereby forming a subject image. Perform photometry.

  When the photographer presses a release button (not shown), the quick return mirror 110 is retracted out of the optical path to the image sensor 113. On the other hand, the amount of light collected by the photographing lens 115 is controlled by a focal plane shutter 111 (hereinafter referred to as a shutter), subjected to photoelectric conversion processing by an image sensor 113 such as a CMOS, and is not shown as a photographed image. Recorded on recording media.

  FIG. 2 is a block diagram of the imaging apparatus of the present embodiment. The photometric circuit 100 divides the object scene into a plurality of areas and performs photometry, and sequentially outputs photometric data of each area. Photometric data output from the photometric circuit 100 is stored in the storage unit 102. The photometric data stored in the storage unit 102 is output to the photometric value determination unit 103, the photometric control unit 104, the predicted photometric value calculation unit 106, and the exposure calculation unit 107. The photometric value determination unit 103 determines whether the photometric data output from the photometric circuit 100 is photometric data output when the photometric circuit 100 is stable, the timing at which the photometric data is output, and the threshold value stored in the storage unit 102. Judgment based on the comparison. The photometric value determining unit 103 also compares the photometric data output from the photometric circuit 100 to determine whether or not the luminance of the subject has changed.

  The photometry control unit 104 controls the timing of accumulating the charges of the photometry circuit 100 and reading the accumulated charges based on the photometry data stored in the storage unit 102 and the determination result of the photometric value determination unit 103. Details of the operation of the photometric circuit 100 will be described later.

  The exposure calculation unit 107 is based on the photometric data stored in the storage unit 102 and the lens data such as the focal length of the lens unit, the maximum aperture value, the exit pupil position, and the vignetting information stored in the lens data 108. To calculate the exposure value.

  When a release button (not shown) is pressed, the exposure control unit 109 performs exposure by controlling the quick return mirror 110, the shutter 111, the aperture 112, and the like based on the exposure value calculated by the exposure calculation unit 107. The storage unit 102, the photometric value determination unit 103, the photometric control unit 104, the predicted photometric value calculation unit 106, the exposure calculation unit 107, and the exposure control unit 109 are all realized by the CPU 101, but some of the functions or It is also possible to realize all by other electric circuits.

  FIG. 3 is an example of a circuit diagram showing a detailed configuration of the photometric circuit 100 of the present embodiment. In FIG. 3, Q1 is an NPN phototransistor having a photoelectric conversion region that generates a charge in response to incident light, MP1 is a PMOS for fixing the base potential of Q1, and I is a current source that is a load of MP1. is there. MP2 is a PMOS for feeding back the gate potential of MP1 to the drain of MP1, and MP3 is a PMOS for pixel reset (hereinafter also referred to as reset operation) for forcibly injecting carriers into Q1. Reference numeral 206 denotes a logarithmic compression unit for logarithmically compressing the emitter current of Q1.

  Note that the configuration of the photometric circuit 100 is not limited to the circuit configuration illustrated in FIG. 3, and may be any circuit configuration that can reset the base potential (photoelectric conversion region) of the phototransistor. For example, the photometric circuit 100 is used as a configuration capable of resetting the base potential of a phototransistor of a circuit described in Japanese Patent Application Laid-Open Nos. 2000-77644, 2010-45293, 2010-45294, and the like. be able to.

  Since the gate voltage of MP1 through which the constant current has flowed has a constant potential difference Vth with respect to the voltage VCC, the base potential of Q1 also becomes a constant potential regardless of the light intensity incident on Q1. In addition, the base potential of Q1 is further stabilized by forming feedback using MP2. This eliminates the need to charge and discharge the large base capacitance Ccb. Therefore, the responsiveness of the photometry circuit shown in FIG. 3 is determined by the drain capacitance of the emitter capacitance Ceb and MP2 and the photocurrent, which are smaller than the collector capacitance. Therefore, under low brightness where the influence of responsiveness begins to appear, the photometric value will be higher than the value corresponding to the actual brightness, so the exposure control is based on the photometric value higher than the value corresponding to the actual brightness. If you shoot after shooting, the image will be underexposed.

  FIG. 4 is a diagram showing how the photometric output of the photometric circuit 100 stabilizes with time. The vertical axis represents the result of AD conversion of the photometric output (hereinafter also referred to as photometric value) of the photometric circuit 100, and the horizontal axis represents the elapsed time after the reset operation. Each series of graphs is an example of a difference depending on luminance, and represents a change in photometric output when luminance = BV2, BV0, BV-2, and BV-4. In each series, the results read when the elapsed time after the reset operation is 10 ms, 20 ms, 50 ms, 150 ms, and 250 ms are plotted. Since the characteristics until the stable state is reached after the reset operation is different for each luminance, the photometric output is read out a plurality of times during the period (transient state) until the stable state is reached, and the predicted photometric value calculating unit 106 Predict the photometric output when it reaches a stable state.

For example, the prediction function shown in the following formula (1) and FIG.
V = (VR−VT) exp (−kt) + VT (1)
In equation (1), a stable photometric output is predicted by determining the parameters of the above equation from the three photometric outputs. That is, after the reset operation, photometry is performed twice to calculate an expected photometric value that is an expected stable photometric value. Here, V is a photometric output value when the time t has elapsed after the reset operation, and VR, VT, and k are parameters that determine time characteristics of the photometric output. That is, this equation indicates that the value of V becomes a stable photometric output when t = ∞. Since t = 0 and V = VR, VR is a parameter related to the reset potential. From t → ∞, V = VT, and converges to VT, which is a stable metering output. k is a parameter that defines the curvature of the time characteristic curve of the photometric output, and depends on the parasitic capacitance, hFE, photocurrent, and the like. In the present embodiment, it is assumed that the output value of the photometry circuit 100 immediately after the reset operation is a predetermined value determined in advance. In addition, the method for predicting the photometric output in the stable state is not limited to the method using the above formula (1), and any method may be used as long as it uses the photometric output obtained in the transient state.

  FIG. 5 shows a photometric value obtained by a plurality of photometry performed after the reset operation. The photometric value obtained when the elapsed time after the reset operation is T1 is AE1, and the photometric value obtained when the elapsed time is T2 is AE2. The predicted photometric value calculated based on these two photometric timings and photometric values and the above equation (1) is defined as AEp.

  The photometric values obtained when the elapsed time after the reset operation is T3 are shown in three cases. The case shown in (1) shows a case where the third photometric value is larger than the second photometric value AE2. In this case, since it is assumed that the luminance of the subject has changed to the high luminance side between the second metering and the third metering, the metering value based on the third metering output is more subject than the predicted metering value AEp. It can be said that the brightness of is accurately reflected.

  The case shown in (2) shows a case where the third photometric value is between the second photometric value AE2 and the predicted photometric value AEp. In this case, there is no change in the brightness of the subject between the second and third metering and the metering output changes according to the prediction function, or the subject between the second and third metering. It is assumed that there is a small change in brightness. However, the prediction function shown in the above equation (1) is for predicting the photometric output, and does not always change so that the photometric output in the transient state matches the prediction function. Therefore, it is determined from the third photometric output whether the change between the second photometric output and the third photometric output is a change caused by a transient state or a change caused by the luminance change of the subject. It is difficult.

  In the case shown in (3), the third photometric value is smaller than the predicted photometric value AEp. In this case, since it is assumed that the brightness of the subject has changed to the lower brightness side between the second and third metering, the third metering value is more accurate than the predicted metering value AEp. It can be said that it is reflected in.

  As described above, when the metering is performed after calculating the predicted metering value, the predicted metering value more accurately reflects the luminance of the subject among the metering values based on the predicted metering value and the latest metering output. Any of the cases where the latest photometric value is more accurately reflected can be considered.

  Therefore, whether or not the predicted photometric value is used for the exposure calculation when the photometric value is calculated after calculating the predicted photometric value will be described with reference to the flowchart of FIG.

  FIG. 6 is a flowchart showing the exposure calculation operation in the present embodiment.

  In step S601, the photometry control unit 104 operates the photometry circuit 100 to perform a reset operation. After performing the reset operation, the process waits in step S602 until the time T1 (first time) elapses according to a timer (not shown). Thereafter, the CPU 101 reads out the output of the photometric circuit 100 in step S603, and stores the photometric value AE1 (first photometric value) obtained by the reading in the storage unit 102.

  Subsequently, in step S604, the CPU 101 waits until the time T2 (second time) elapses from the reset operation, and then in step S605, the output of the photometric circuit 100 is read, and the photometric value AE2 (first) obtained by reading is read out. 2) is stored in the storage unit 102.

  The times T1 and T2 are set to 10 ms and 20 ms, for example, as shown in FIG.

  In step S606, the predicted photometric value calculation unit 106 calculates the predicted photometric value AEp based on the photometric values AE1 and AE2.

  Next, in step S607, the CPU 101 determines whether or not there is time to perform photometry. If there is no time to perform photometry, for example, the next frame must be exposed, the process proceeds to step S608. In step S608, the exposure calculation unit 107 determines the predicted photometric value AEp as the photometric value used for the exposure calculation and performs the exposure calculation.

  If it is determined in step S607 that there is a time for further photometry, the process proceeds to step S609, where the CPU 101 reads the output of the photometry circuit 100 and obtains the photometric value AE3 (third photometric value) obtained by reading. . In step S610, the CPU 101 stores in the storage unit the time T3 (third time) that has elapsed since the reset operation when the photometric value AE3 was acquired.

  In step S611, the photometric value determination unit 103 determines whether or not the time T3 is less than the threshold value Tth (less than the first threshold value). If the time T3 is equal to or greater than the threshold value Tth (greater than the first threshold value), the photometric value AE3 is acquired. It is determined that the time is in a stable state, and the process proceeds to step S612. In step S612, the exposure calculation unit 107 performs exposure calculation by determining the photometric value AE3 as a photometric value used for the exposure calculation.

  Here, the threshold value Tth is set to a time required for the photometric output of the photometric circuit 100 to become stable, for example, 120 ms, when the luminance of the subject does not change after the reset operation. Note that the threshold value Tth only needs to be set based on the time required for the photometric output of the photometric circuit 100 to become stable, so the value of the threshold value Tth may be changed according to the luminance of the subject. For example, the threshold value Tth may be changed by determining the luminance of the subject from the magnitude of the predicted photometric value AEp.

  If the time T3 is less than the threshold Tth, the photometric value determination unit 103 determines that the photometric value AE3 is in a transient state when the photometric value AE3 is acquired, and the process proceeds to step S613. In step S613, the photometric value determination unit 103 compares the photometric value AE3 with the photometric value AE2 and the predicted photometric value AEp.

  In the case of (1) or (3) shown in FIG. 5 when the photometric value AE3 does not satisfy AEp ≦ AE3 <AE2 (the third photometric value is smaller than the predicted photometric value or greater than the second photometric value) It is assumed that the luminance of the subject has changed greatly between the second and third photometry. Therefore, the process proceeds to step S614, and the exposure calculation unit 107 performs exposure calculation by determining the photometric value AE3 as a photometric value used for the exposure calculation.

On the other hand, when AEp ≦ AE3 <AE2 is satisfied (the third photometric value is equal to or larger than the predicted photometric value and smaller than the second photometric value), this corresponds to the case (2) shown in FIG. That is, it cannot be determined whether the difference between the photometric value AE2 and the photometric value AE3 is due to a transient state or a change in the luminance of the subject. Therefore, the process proceeds to step S615, and the exposure calculation unit 107 calculates the photometric value AE ′ used for the exposure calculation by the weighted average of the photometric value AE3 and the predicted photometric value AEp using the following formula (2).
AE ′ = (T3 × AE3 + (Tth−T3) × AEp) / Tth (2)
As shown in Expression (2), the photometric value AE ′ is calculated such that the weighting of AE3 increases as the time T3 approaches the threshold Tth. This is because, as the elapsed time after performing the reset operation is closer to the threshold value Tth, the photometric value in the transient state is closer to the predicted photometric value AEp. For example, when there is no change in the luminance of the subject, the difference between the photometric value AE3 and the predicted photometric value AEp becomes smaller as the time T3 is closer to the threshold value Tth. Therefore, if the time T3 is close to the threshold value Tth, even if the photometric value AE3 is calculated by increasing the weighting of the photometric value AE3, the difference between the calculation result and the predicted photometric value AEp is small, and an erroneous photometric value is unlikely. Further, even when there is a change in the luminance of the subject, by increasing the weighting of the photometric value AE3, the contribution ratio of the predicted photometric value AEp is reduced, and the photometric value reflecting the change in the luminance of the subject can be calculated. it can.

  As described above, when photometry is performed after predicting the photometric value, exposure is performed using the photometric value that reflects the brightness of the subject by determining the photometric value used for the exposure calculation based on the latest photometric value. Arithmetic can be performed.

  Also, by determining the photometric value used for the exposure calculation based on the timing for obtaining the latest photometric value, the exposure calculation can be performed using the photometric value reflecting the luminance of the subject.

(Second Embodiment)
In the first embodiment, the case where the photometric value used for the exposure calculation is determined based on the photometric value obtained by performing photometry after the calculation of the predicted photometric value has been described, but in the present embodiment, the calculation of the predicted photometric value is calculated. A case will be described where even if photometry is performed later, it does not contribute to the determination of the photometric value used for the exposure calculation. Note that the configuration of the imaging apparatus according to the present embodiment is the same as that of the first embodiment, and a description thereof will be omitted.

  FIG. 7 is a diagram in which a plot of photometric values when photometry is possible between the second photometry and the third photometry in FIG. 5 is added to FIG.

  Even if the third metering is possible after the second metering required to predict the metered value, if the third metering is too close to the second metering, the brightness of the subject will change and the metering value It is difficult to determine that the brightness has changed, and it is difficult to determine a photometric value that accurately reflects the brightness of the subject.

  Therefore, in the present embodiment, when the photometry is performed after the calculation of the predicted photometry value, it is determined whether to contribute to the determination of the photometry value used for the exposure calculation according to the timing of performing the photometry.

  FIG. 8 is a flowchart for explaining the exposure calculation operation in this embodiment. Steps S801 to S807 perform the same processing as steps S601 to S607 in FIG.

  In step S807, the CPU 101 determines whether or not there is a time for performing photometry. If there is no time to perform photometry, for example, the next frame must be exposed, the process advances to step S808. In step S808, the exposure calculation unit 107 determines the predicted photometric value AEp as the photometric value used for the exposure calculation, and performs the exposure calculation.

  If it is determined in step S807 that there is time for further photometry, the process proceeds to step S809, where the CPU 101 reads the output of the photometry circuit 100, and obtains the photometric value AEn (initial value of n = 3) obtained by the readout. To do. In step S810, the CPU 101 stores in the storage unit the time Tn that has elapsed since the reset operation when the photometric value AEn was acquired.

  In step S811, the photometric value determination unit 103 compares the photometric value AEn-1 and the photometric value AEn, and if AEn-1 <AEn, determines that the luminance of the subject has changed to the high luminance side, and proceeds to step S812. In step S812, the exposure calculation unit 107 determines the photometric value AEn as the photometric value used for the exposure calculation and performs the exposure calculation.

  If AEn-1 ≧ AEn, the process advances to step S813, and the CPU 101 compares the time Tn with the time Ta (second threshold). The time Ta is set to a time slightly longer than the time T2 when the photometric value AE2 is acquired, for example, 40 ms.

  If Tn <Ta (time Tn is less than the second threshold value), the CPU 101 determines that the nth photometric output has been read immediately after calculating the predicted photometric value, increments n in step S814, and proceeds to step S807. Then, it is determined whether or not there is a time to perform photometry again.

  If Tn ≧ Ta (time Tn is greater than or equal to the second threshold), the process proceeds to step S815. In step S815, the photometric value determination unit 103 compares the time Tn with the threshold value Tth. If Tn ≧ Tth, the photometric value AEn is determined to be in a stable state, and the process proceeds to step S816. In step S816, the exposure calculation unit 107 determines the photometric value AEn as the photometric value used for the exposure calculation and performs the exposure calculation.

  If Tn <Tth, the photometric value determination unit 103 determines that the photometric value AEn is in a transient state when acquiring the photometric value AEn, and compares the photometric value AEn with the predicted photometric value AEp in step S817. When AEp ≦ AEn is not satisfied, it is assumed that the luminance of the subject has changed greatly between the (n−1) th photometry and the nth photometry. Therefore, the process proceeds to step S816, and the exposure calculation unit 107 performs exposure calculation by determining the photometric value AEn as a photometric value used for the exposure calculation.

When AEP ≦ AEn is satisfied, it cannot be determined whether the difference between the photometric value AEn-1 and the photometric value AEn is due to a transient state or due to a change in the luminance of the subject. Therefore, the exposure calculation unit 107 calculates the photometric value AE ″ used for the exposure calculation by the weighted average of the photometric value AEn and the predicted photometric value AEp using the following equation (3).
AE ″ = (Tn × AEn + (Tth−Tn) × AEp) / Tth (3)
The expression (3) is also based on the same concept as the expression (2) described above, and the weighting of AEn is increased as the time Tn is closer to the threshold value Tth.

  When the photometric value AE ″ is calculated as described above, the exposure calculation unit 107 performs the exposure calculation by determining the calculated photometric value AE ″ as a photometric value used for the exposure calculation.

  As described above, when the photometric value is predicted after the photometric value is predicted, the photometric value obtained within a predetermined time after the calculation of the predicted photometric value is prevented from contributing to the determination of the photometric value used for the exposure calculation. Thus, a photometric value that more accurately reflects the luminance of the subject can be used for the exposure calculation.

  In addition, although preferable embodiment of this invention was described, this invention is not limited to these embodiment, A various deformation | transformation and change are possible within the range of the summary.

100 photometric circuit 101 CPU
DESCRIPTION OF SYMBOLS 102 Memory | storage part 103 Photometry value determination part 104 Photometry control part 106 Predictive photometry value calculation part 107 Exposure calculation part 109 Exposure control part 111 Shutter 112 Aperture 113 Image sensor

Claims (8)

A metering means for metering the subject;
Reset means for resetting the photometric means so that the output value of the photometric means becomes a predetermined value;
The first photometric value based on the output of the photometric means when the first time has elapsed since the reset and the second time longer than the first time after the reset Calculating means for calculating a predicted photometric value based on the second photometric value based on the output of the photometric means at the time;
When a third photometric value based on the output of the photometric means is acquired when a third time longer than the second time has elapsed since the resetting, exposure is performed based on the third photometric value. And an deciding means for deciding whether or not to use the predicted photometric value for the calculation.   The determining means uses the third photometric value for the exposure calculation without using the predicted photometric value when the third photometric value is equal to or greater than the second photometric value. The imaging device according to claim 1.   The determination means uses the third photometric value for the exposure calculation without using the predicted photometric value when the third photometric value is smaller than the predicted photometric value. Item 3. The imaging device according to Item 1 or 2.   The determining means calculates the weighted average of the third photometric value and the predicted photometric value when the third photometric value is smaller than the second photometric value and greater than or equal to the predicted photometric value. The imaging apparatus according to claim 1, wherein the measured photometric value is used for the exposure calculation.   When the third time is less than the first threshold, the determining means increases the weight of the third photometric value and calculates the weighted average as the third time is closer to the first threshold. 5. The image pickup apparatus according to claim 4, wherein the photometric value calculated in the above is used for the exposure calculation.   The determination means uses the third photometric value for the exposure calculation without using the predicted photometric value when the third time is equal to or greater than the first threshold. 5. The imaging device according to 5. The determining means, when the third time is less than a second threshold smaller than the first threshold,
The imaging apparatus according to claim 6, wherein a photometric value used for an exposure calculation is determined based on a photometric value of the photometric unit when a time equal to or greater than the second threshold has elapsed. A method for controlling an imaging apparatus, comprising: a photometric unit that performs photometry on a subject; and a reset unit that resets the photometric unit so that an output value of the photometric unit becomes a predetermined value.
The first photometric value based on the output of the photometric means when the first time has elapsed since the reset and the second time longer than the first time after the reset A calculation step of calculating a predicted photometric value based on a second photometric value based on the output of the photometric means when
When a third photometric value based on the output of the photometric means is acquired when a third time longer than the second time has elapsed since the resetting, exposure is performed based on the third photometric value. And a determination step for determining whether or not to use the predicted photometric value for the calculation.

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