JP2013113967A - Imaging apparatus, control method thereof, and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an imaging apparatus that can be controlled so as to obtain a proper exposure even if there exists a photometric area having a subject luminance equal to or less than a low luminance limit, a control method thereof, and a program.SOLUTION: An imaging apparatus 1 sets a weighting coefficient for a photometric value which is not subjected to correction according to a luminance limit value to be higher than a weighting coefficient for a photometric value which is subjected to correction according to the luminance limit value, and performs weighting operation for the plural photometric values obtained by photometry, and determines an exposure value on the basis of the operational results.

Description

  The present invention relates to an imaging apparatus, a control method thereof, and a program.

  Conventionally, it has a photometric sensor that divides the object scene into multiple photometric areas and measures the brightness of each photometric area, and automatically exposes the appropriate exposure for imaging from the photometric value of each divided photometric area Imaging devices that perform control are widely used.

  For example, in an imaging apparatus having a plurality of focus detection areas, means for obtaining an appropriate exposure for imaging by changing the weighting of each photometric area for each focus detection area is disclosed (for example, Patent Document 1).

  In addition, in an imaging apparatus, it is known that a photometric value in a peripheral photometric area becomes dark even when photometry is performed on a uniform luminance surface due to the influence of an optical system such as a lens. Therefore, a method for correcting a photometric value so that the same photometric value is obtained when photometry is performed on a uniform luminance surface is well known.

  In recent years, high sensitivity digital cameras with ISO sensitivity of tens of thousands have appeared due to improved sensitivity of image sensors and advanced image processing, and imaging that provides proper exposure even when shooting low-luminance subjects. An apparatus is desired.

  On the other hand, in an imaging apparatus such as a single-lens reflex camera, a photometric sensor that measures the luminance of a subject and the photocurrent of a photodiode using a LOG characteristic such as a diode to measure the luminance of the subject with a wide dynamic range is widely used. (For example, refer to Patent Document 2).

Japanese Patent Laid-Open No. 3-223825 Japanese Patent Laying-Open No. 2005-077938

  However, in the photometric circuit using the photocurrent of the photodiode as described in Patent Document 2, the low luminance at which accurate photometry cannot be performed when the ratio of the leakage current of the photodiode to the photocurrent is low. There is a limit.

  FIG. 9 is a diagram showing the relationship between subject brightness and photometric value. In FIG. 9, a solid line 901 indicates the relationship between the subject luminance and the photometric value of a certain photometry circuit, a broken line 902 indicates an ideal relationship between the subject luminance and the photometric value, and a broken line 902 indicates a linear relationship between the subject luminance and the photometric value. Show.

  In FIG. 9, a photometric value 903 indicating a boundary where the linearity of the solid line 901 is not maintained is a low luminance limit value. The low luminance limit value varies from one individual to another due to manufacturing variations, and also varies from one photometric area to another, and when the subject luminance below the low luminance limit is measured, the photometric value becomes brighter than appropriate.

  When the conventional technique disclosed in Patent Document 1 is used, if the photometry area corresponding to the selected focus detection area is subject luminance below the low brightness limit, the photometry area corresponding to the selected focus detection area is weighted. If it is increased, it will be darker than the proper exposure.

  An object of the present invention is to provide an imaging apparatus that can be controlled so that proper exposure can be achieved even when a photometric area having subject luminance below the low luminance limit exists, a control method therefor, and a program.

  In order to achieve the above object, an imaging apparatus according to claim 1 includes a photometric unit that performs photometry for each of a plurality of photometric areas obtained by dividing a photographing screen, and a plurality of photometric values obtained by photometry by the photometric unit. Correction means for correcting the photometric value for each of the plurality of photometric areas, and a weighting coefficient for a photometric value that is corrected by the correcting means for a photometric value that is not corrected by the correcting means. And determining means for performing weighting calculation of a plurality of photometric values obtained by photometry by the photometry means and determining an exposure value based on the calculation result.

  According to the present invention, it is possible to provide an imaging apparatus that can be controlled so that proper exposure can be achieved even when a photometric area having subject luminance below the low luminance limit exists, a control method therefor, and a program.

It is a figure which shows the mechanical structure of the digital camera which concerns on embodiment of this invention. It is a figure which shows the electrical constitution of the digital camera in FIG. It is a figure which shows the photometric value example and a correction value. It is a figure which shows the correspondence of a photometry area | region and a to-be-photographed object, a photometry value, and a correction value. It is a figure which shows the relationship between each photometry area | region and the weighting example for photometry value calculation. It is a flowchart which shows the procedure of the imaging process performed by the camera control part in FIG. It is a figure for demonstrating the weighting using ranging point information. It is a flowchart which shows the procedure of the imaging process performed by the camera control part in FIG. It is the figure which showed the relationship between a subject brightness | luminance and a photometric value.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[First Embodiment]
FIG. 1 is a diagram showing a mechanical configuration of a digital camera (imaging device) 1 according to an embodiment of the present invention.

  In FIG. 1, a lens unit 150 is detachably attached to the digital camera 1 via a mount mechanism (not shown). The mount portion has an electrical contact portion (not shown), and control signals, status signals, and data signals can be communicated and supplied between the digital camera 1 and the lens unit 150.

  Next, the imaging light flux from the subject image will be described. This imaging light flux is guided to the quick return mirror 110 via the imaging lens 152 and the diaphragm 153. The central portion of the quick return mirror 110 is a half mirror, and a part of the light beam is transmitted when the quick return mirror 110 is lowered.

  The transmitted light beam is guided to a known phase difference type focus detection unit including a field lens 112, a secondary imaging lens 113, and an autofocus sensor 114 by a sub-mirror 111 installed on the quick return mirror 110. The autofocus sensor 114 has a plurality of focus detection positions.

  On the other hand, the imaging light flux reflected by the quick return mirror 110 reaches the eyes of the photographer via a focus detection plate (hereinafter referred to as “focus plate”) 115, a pentaprism 116, and an eyepiece lens 117.

  The focus plate 115 is disposed on an image plane equivalent to the image plane of the image sensor 118 typified by a CMOS or the like, and the subject image reflected by the quick return mirror 110 is primarily imaged by the focus plate 115.

  The photometric circuit 119 disposed in the vicinity of the eyepiece lens 117 subjects the subject image formed on the focusing plate 115 by the photometric prism 120 and the photometric lens 121 to a secondary image on the chip of the photometric circuit 119, thereby subjecting the subject. The brightness of the image is detected.

  The photometric circuit thermometer 122 measures the temperature of the photometric circuit. The photometric value or the low luminance limit value of the photometric value is corrected according to the measured temperature. That is, the luminance limit value may be determined according to the temperature measured by the photometric circuit thermometer 122.

  Further, when the photographer presses a release button (not shown), the quick return mirror 110 is retracted out of the optical path of the imaging lens 152.

  On the other hand, the amount of light of the imaging light beam collected by the imaging lens 152 is controlled by the focal plane shutter 123, subjected to photoelectric conversion processing as a subject image by the imaging device 118, and then recorded as a captured image on a recording medium (not shown). Is done. The display device 124 is a liquid crystal device or the like, and displays captured images, various types of imaging information, setting information, and the like.

  Further, in FIG. 1, the camera control unit 100 performs overall control of the digital camera 1, and the lens control unit 151 performs overall control of the lens unit 150.

  An attitude detection unit 125 is connected to the camera control unit 100 and detects the attitude of the digital camera 1 (whether the optical finder is positioned above the photographic optical axis or next to the photographic optical axis). .

  Further, an operation member 126 is connected to the camera control unit 100, and is used to select a focus detection position to be used from a plurality of focus detection positions of the imaging mode and setting information or the above-described autofocus sensor 114.

  In addition, an imaging lens drive control unit 154 is connected to the lens control unit 151. The imaging lens drive control unit 154 performs control related to driving of the imaging lens 152.

  FIG. 2 is a diagram showing an electrical configuration of the digital camera 1 in FIG.

  2, the digital camera 1 includes a camera control unit 100, a photometry circuit 119, a photometry circuit thermometer 122, an attitude detection unit 125, an autofocus sensor 114, a quick turn mirror 110, and a focal plane shutter 123.

  The camera control unit 100 includes a photometry control unit 201, a memory 202, a low luminance limit determination unit 203, an exposure calculation unit 204, an exposure control unit 206, and a focus detection control unit 205.

  In this configuration, during imaging, the camera control unit 100 transmits the driving amount of the imaging lens 152 to the lens control unit 151 based on the output of the autofocus sensor 114.

  The lens control unit 151 sends a drive amount pulse for driving the imaging lens to the imaging lens drive control unit 154. The imaging lens drive control unit 154 drives the pulse motor in accordance with the transmitted pulse and drives the imaging lens 152 to the in-focus position to perform automatic focus adjustment.

  When an imaging preparation operation such as half-pressing the release button is performed by the photographer, the photometry control unit 201 outputs a drive signal to the photometry circuit 119.

  The photometry circuit 119 divides the photographing screen into a plurality of photometry areas, performs photometry for each photometry area, and outputs each photometry data.

  Photometry data output from the photometry circuit 119 is stored in the memory 202. The photometric data stored in the memory 202 is output to the photometric control unit 201, the low luminance limit determination unit 203, and the exposure calculation unit 204.

  The low brightness limit determination unit 203 determines whether the photometry data for each photometry area read from the photometry circuit 119 is equal to or lower than the low brightness limit value based on the threshold value stored in the memory 202.

  The photometric control unit 201 also has a function of controlling the timing for storing and reading out the photometric circuit when predicting the photometric value from the transient photometric data.

  The photometry circuit thermometer 122 is connected to the low brightness limit determination unit 203 and the exposure calculation unit 204, and corrects the low brightness limit value and the photometry data of each photometry area stored in the memory 202 according to the output result. Do.

  A lens control unit 151 is connected to the exposure calculation unit 204 and acquires lens information necessary for exposure calculation such as a focal length, an open aperture value, an exit pupil position, and vignetting information of the imaging lens of the lens unit 150.

  In addition, a posture detection unit 125 is connected to the exposure calculation unit 204, and the exposure calculation unit 204 performs an exposure calculation according to the posture detection result detected by the posture detection unit 125. For example, the weighting of the photometry area above the object field area is made smaller than the weighting of the photometry area below the object field area according to the detected posture.

  The focus detection control unit 205 is connected to an autofocus sensor 114 and a lens control unit 151, and transmits a lens driving amount to the lens control unit 151 in accordance with an output at a focus detection position selected by the autofocus sensor 114. .

  In addition, the focus detection control unit 205 outputs the selected focus detection position, defocus information of each focus detection position, and the like to the exposure calculation unit 204. The focus detection control unit 205 can also detect that the subject image within the range included in the photometry area is in focus.

  The exposure calculation unit 204 calculates an optimum exposure from information obtained from each unit. When the release button is pressed, the exposure control unit 206 controls the diaphragm 153 through the quick return mirror 110, the focal plane shutter 123, and the lens control unit 151 based on an appropriate exposure value calculated by the exposure calculation unit 204. Control exposure.

  FIG. 3 is a diagram showing an example of photometric values and correction values. FIG. 3A shows an example of photometric values in each photometric area when a predetermined lens is attached and a uniform luminance surface is metered. b) shows the correction value in each photometric area.

  In FIG. 3, a layout diagram of each photometric area in the photometric sensor included in the photometric circuit 119 is used. And, according to this layout diagram, the case where the object scene is divided into 63 parts of 7 vertical parts and 9 horizontal parts is shown as an example, but the present invention is not limited to this.

  In the layout diagram, the field area 301 is vertically divided into seven parts from A to G, and nine parts from a to i. Note that the photometric values in FIG. 3A indicate that the larger the numerical value, the brighter the value. In addition, the photometric value acquisition method may be obtained by acquiring a photometric output a plurality of times within a predetermined time, and calculating a photometric value that is considered appropriate by using a change amount of the photometric value obtained a plurality of times. In other words, the photometric value to be corrected may be a photometric value determined from the amount of change in a plurality of photometric values obtained by performing photometry a plurality of times. In this case, among the plurality of photometry areas, the photometry value determined from the amount of change of the plurality of photometry values obtained by performing the photometry a plurality of times is corrected for the photometry value of the photometry area having the low luminance limit value or less. It will be.

  In FIG. 3A, for example, the photometric value S (D, h) of the photometric area (D, h) = 10. Further, the photometric values in the peripheral part are darkened concentrically from the photometric value S (D, e) at the center (D, e) of the object scene. This is an influence of the optical system, and even a lens to be mounted or the same lens changes depending on a difference in focal length.

  When photometry is performed on a uniform luminance surface, if there is a difference in the photometric value of each photometric area, proper exposure calculation cannot be performed. Accordingly, the exposure calculation unit 204 corrects the difference between the reference luminance metering value when the reference luminance is measured and the metering value of each metering region in which the reference luminance is measured, thereby causing variations in the optical system and individual variations in the metering circuit. Proper metering is possible even if it exists.

For example, assuming that the subject luminance in FIG. 3A is the reference luminance Sref, the photometric value in the photometric area (D, h) is corrected by the following formula 1 when the correction value S ′ (D, h) is set. The
S ′ (D, h) = Sref−S (D, h) (Formula 1)
In the following description, Sref = 30. Using this correction value S ′ (D, h), (S ′ + photometry value) is set as a corrected photometry value (corrected photometry value).

  FIG. 3B is a correction value based on the reference luminance Sref in the optical system of FIG. 3A and is a diagram showing the low luminance limit value of each photometric area.

  Specifically, the luminance at which the photometric value obtained by the photometric sensor is 0 is shown. For example, in the photometric area (A, a), the luminance value 30 indicates that the photometric value is 0. That is, the photometric value is 0 for luminance values of luminance value 30 or less.

  By adding this low luminance limit value to the photometric value obtained by the photometric sensor, a corrected photometric value is obtained, so the low luminance limit value is also a correction value.

  Therefore, in FIG. 3B, for example, the low luminance limit value S (D, h) min = 20 of the photometric area (D, h). In this case, when a subject having a luminance value less than 20 is measured, an appropriate photometric value cannot be obtained.

  For example, when the subject brightness is ideally the photometric value S (D, h) = 10, 10 is less than 20, and thus the photometric value obtained by the photometric sensor becomes zero. Therefore, by adding the correction value 20 shown in FIG. 3B, the corrected photometric value becomes 20, which is a brighter photometric value than 10 which is an appropriate photometric value.

  That is, the low luminance limit value Smin is a luminance threshold value at which an appropriate photometric value cannot be obtained when the luminance below that is measured.

  Therefore, in FIG. 3B, proper photometry cannot be performed even when the photometric value S (D, h) of the photometric area (D, h) is brighter than the photometric value S (D, e) of the central portion. It means that.

  In this embodiment, for the sake of simplification, description is made only with variations in the optical system. However, actually, the low luminance limit values of the photometric areas of the photometric sensors of the same photometric circuit 119 are different.

  FIG. 4 is a diagram showing the correspondence between the photometric area and the subject, the photometric value, and the correction value. Specifically, FIG. 4A shows the correspondence between the photometry area and the subject. FIG. 4B shows the corrected photometric value of each photometric area in FIG. FIG. 4C shows ideal photometric values in the respective photometric areas when there is no low luminance limit by the photometric circuit of FIG.

  In FIG. 4B, by comparing with the photometric value of each photometric area in FIG. 4C, the photometric areas other than the photometric area 401 are the photometric values below the low luminance limit, and appropriate photometric values are obtained. Absent. The photometric area 401 includes ((C, d), (C, e), (C, f), (D, d), (D, e), (D, f), (E, d), (E, e), (E, f), (F, d), (F, e), (F, f)).

  For example, the photometric value S (C, d) in the photometric area (C, d) = 5 matches the ideal value, but the photometric value S (A, a) in the photometric area (A, a) = 30. It does not match the ideal value “2”, and an appropriate photometric value is not obtained.

  FIG. 5 is a diagram illustrating a relationship between each photometric area and a weighting example for calculating a photometric value.

  In FIG. 5, the photometric value of each photometric area of FIG. 4B is compared with the low luminance limit value of FIG. 3B, and the weighting coefficient W (x, y) of the photometric area corresponding to the low luminance limit value or less. Is set to 1. Further, the weighting coefficient W (x, y) of the photometric area 401 in which an appropriate photometric value not lower than the low luminance limit value is obtained is 10.

The exposure calculation unit 204 multiplies the correction value S ′ (x, y) and the weighting coefficient W (x, y) for each photometric area and divides by the sum of the weighting coefficients as shown in the following equation 2. The exposure value X is calculated.
X = Σ (S ′ (x, y) × W (x, y)) / ΣW (x, y) (Expression 2)
(Σ is the sum of x = A, B ... G, y = a, b ... i)
Based on the exposure value X calculated from Equation 2, the exposure control unit 206 performs exposure control. Thus, an appropriate exposure value can be obtained by increasing the weighting of the photometric area that is not lower than the low luminance limit. Note that if the weighted average is simply taken without increasing the weight, in the case of FIG. 4, it is pulled to the corrected value in the vicinity such as (A, a), though it is originally intended to match the brightness to the center subject. The exposure value is higher than the weighted average obtained by increasing the weight of the photometry area that is not lower than the low luminance limit.

  FIG. 6 is a flowchart illustrating a procedure of imaging processing executed by the camera control unit 100 in FIG.

  In FIG. 6, the photometry control unit 201 controls the photometry circuit 119 according to the imaging instruction, and acquires the photometry value S of each photometry area (step S601).

  Next, the low luminance limit determination unit 203 reads the acquired photometric value S and the low luminance limit value from the memory 202, and compares the photometric value of each photometric area with the low luminance limit value (step S602). It is determined whether or not it is below the low luminance limit, and the determination result is output to the exposure calculation unit 204.

  The exposure calculation unit 204 calculates a weighting coefficient W (x, y) of each photometric area for the exposure calculation from the photometric value of each photometric area and the low luminance limit discrimination result (step S603). This step S603 corresponds to a process of performing a weighting calculation of a plurality of photometric values by making the weighting factor for the photometric value not corrected larger than the weighting factor for the photometric value corrected.

  Then, the exposure calculation unit 204 corrects the obtained photometric value S (x, y) of each photometric area (step S604) to obtain a corrected value S ′ (x, y). This step S604 corresponds to processing for correcting a plurality of photometric values obtained by photometry according to the luminance limit values that can be measured for each of the plurality of photometric areas.

  Next, the exposure calculation unit 204 calculates an exposure value X by Equation 2 from the calculated photometric value S ′ (x, y) of each photometric area and the weighting coefficient W (step S605). This step S605 corresponds to the process of determining the exposure value based on the calculation result of the weighting calculation. Then, the exposure control unit 206 performs exposure control based on the calculated exposure value X, performs imaging by driving the shutter and the lens (step S606), and ends this process.

  By this imaging processing, the weighting of the photometric value in the photometric area where the subject luminance is not lower than the low luminance limit becomes larger than that in the photometric area where the subject luminance is lower than the low luminance limit, so that appropriate exposure calculation is possible.

  In this embodiment, the weighting coefficient is 1 or 10, but the present invention is not limited to this. The ratio of the coefficients may be changed or may be changed for each photometric area. You may make it exclude the photometry area | region below a low-luminance limit from a calculation.

  Further, it is not necessary to use only the low luminance limit value for calculating the weighting coefficient. The weighting may be determined using the distribution of the photometric value together with the information on the low luminance limit value, or the weighting may be determined using the position of the photometric area with respect to the object scene and the attitude of the digital camera 1. .

  Furthermore, the correction of the photometric value in each photometric area is limited only to the correction of the optical system, but is not limited to this. The correction may be made according to the temperature, or may be changed according to the lens information instead of being fixed.

  According to the imaging process of FIG. 6, the weighting factor for calculating the weighted average of the photometric values in each photometric region is set so that the weighting factor for the uncorrected photometric value is larger than the weighting factor for the corrected photometric value. calculate. Since the exposure is controlled using a weighted average using the calculated weighting coefficient, it is possible to control the exposure so that the exposure is appropriate even when there is a photometric area having subject luminance below the low luminance limit.

[Second Embodiment]
In the following, as a second embodiment of the present invention, an embodiment using distance measuring point information will be described. The mechanical and electrical configuration of the digital camera in the present embodiment is the same as that in the first embodiment.

  FIG. 7 is a diagram for explaining weighting using distance measuring point information. FIG. 7A is a diagram showing the positional relationship between the focus detection position of the autofocus sensor 114 and each photometric area. ) Is a diagram illustrating an example of a weighting coefficient.

  In FIG. 7A, distance measuring points 701, 702, 703, and 704 are distance measuring points that can be independently detected by the autofocus sensor 114, respectively. The photographer can arbitrarily select one of the distance measuring points 701, 702, 703, and 704 for these distance measuring points, or the digital camera 1 can automatically select them. These distance measuring points detect that the subject image within the range included in the photometric area is in focus.

  Since the focus detection method is not directly related to the present embodiment, a specific method is not described, but the focus detection method and focus detection information are not limited.

  FIG. 7B shows an example of the weighting coefficient of the photometric area when the focus detection control unit 205 determines that the distance measuring points 703 and 705 are in focus. The weighting coefficient W ′ of the photometry area corresponding to the focused distance measuring point is set to 10, and the weighting coefficient of the adjacent photometry area is set to 5.

  For example, in FIG. 7B, the weighting coefficient W ′ (D, e) of the photometric area (D, e) corresponding to the distance measuring point 703 is 10. Further, the weighting coefficient W ′ of the adjacent photometric areas (C, e), (D, d), (D, f), (E, e) is 5. In addition, the weighting coefficient W ′ corresponding to the photometric area not including the distance measuring point is set to 1. In this way, the weighting coefficient for the photometric value corresponding to the photometric area including the subject image detected to be in focus and the photometric area around the photometric area is compared with the case where it is not in focus. Calculate to increase.

As shown in Expression 3, the exposure calculation unit 204 multiplies the correction value S ′ of each photometric area by the weighting coefficient W from the discrimination result of the low luminance limit and the weighting coefficient W ′ from the focus detection result to obtain a weighting coefficient. The exposure value X is calculated by dividing by the sum of those multiplied.
X = Σ (S ′ (x, y) × W (x, y) × W ′ (x, y)) / Σ (W (x, y) × W ′ (x, y)) (Formula 3)
(Σ is the sum of x = A, B ... G, y = a, b ... i)
FIG. 8 is a flowchart illustrating a procedure of imaging processing executed by the camera control unit 100 in FIG.

  In FIG. 8, in response to the imaging instruction, the focus detection control unit 205 acquires distance measurement information from each focus detection of the autofocus sensor 114 (step S801), and the information on the selected distance measurement points necessary for the exposure calculation is displayed in the exposure calculation unit. To 204.

  Next, the exposure calculation unit 204 calculates a weighting coefficient W ′ for each photometric area for exposure calculation based on the acquired distance measuring point information using Equation 3 (step S802).

  The photometric control unit 201 controls the photometric circuit 119 to acquire the photometric value S of each photometric area (step S803). Next, the low luminance limit determination unit 203 reads the acquired photometric value S and the low luminance limit value from the memory 202, and compares the photometric value of each photometric area with the low luminance limit value (step S804). It is determined whether or not it is below the low luminance limit, and the determination result is output to the exposure calculation unit 204.

  The exposure calculation unit 204 calculates a weighting coefficient W (x, y) of each photometric area for exposure calculation from the photometric value of each photometric area and the low luminance limit discrimination result (step S805). Then, the exposure calculation unit 204 corrects the obtained photometric value S (x, y) of each photometric area (step S806) to obtain a corrected value S ′ (x, y).

  Next, the exposure calculation unit 204 calculates an exposure value X by Equation 2 from the calculated photometric value S ′ (x, y) of each photometric area and the weighting coefficient W and W ′ (step S807). Then, the exposure control unit 206 performs exposure control based on the calculated exposure value X, performs imaging by performing shutter and lens driving (step S808), and ends this processing.

  This imaging process increases the weighting of the photometry area corresponding to the distance measuring point, and the weighting of the photometry value in the photometry area where the subject brightness is not lower than the low brightness limit is larger than the photometry area below the low brightness limit. Therefore, proper exposure calculation can be performed.

  In the present embodiment, the focus detection control unit 205 is configured to be able to select five independent ranging points, but is not limited thereto. The number may be single or other distance measuring points.

  Further, the weighting coefficient is set as an example for explanation only, and the present invention is not limited to this. The weighting calculation method is not limited to the calculation method shown in the present embodiment.

  Furthermore, although the weighting coefficient is changed according to the selected distance measuring point information, the present invention is not limited to this, and unselected distance measuring point information such as defocus information of each distance measuring point may be used. .

  As mentioned above, although two 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.

  For example, the weight may be calculated based on the photometric mode, the imaging mode, and the posture information instead of the information on the focus detection unit, or a plurality of weights may be combined.

(Other embodiments)
The present invention is also realized by executing the following processing. That is, software (program) that realizes 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, etc.) of the system or apparatus reads the program code. It is a process to be executed. In this case, the program and the storage medium storing the program constitute the present invention.

DESCRIPTION OF SYMBOLS 1 Digital camera 100 Camera control part 114 Auto focus sensor 118 Image sensor 119 Photometry circuit 122 Photometry circuit thermometer 125 Attitude detection part 150 Lens unit 201 Photometry control part 202 Memory 203 Low-luminance limit discrimination part 204 Exposure calculation part 205 Focus detection control part 206 Exposure control unit

Claims (6)

A metering means for performing metering for each of a plurality of metering areas obtained by dividing the shooting screen;
Correction means for correcting a plurality of photometric values obtained by photometry by the photometry means in accordance with luminance limit values that can be measured for each of the plurality of photometric areas,
Weighting of a plurality of photometric values obtained by photometry by the photometry means by making a weighting coefficient for photometry values not corrected by the correction means larger than a weighting coefficient for photometry values corrected by the correction means An imaging apparatus comprising: a determination unit that performs an operation and determines an exposure value based on the operation result.   2. The imaging according to claim 1, wherein the photometric value corrected by the correcting unit is a photometric value determined from a change amount of a plurality of photometric values obtained by performing photometry a plurality of times by the photometric unit. apparatus.   The correction means is a photometric measurement of a photometric area in which a photometric value determined from the amount of change of a plurality of photometric values obtained by performing photometry a plurality of times by the photometric means among the plurality of photometric areas is equal to or less than the luminance limit value. The imaging apparatus according to claim 2, wherein the value is corrected. A temperature measuring means for measuring the temperature of the photometric means;
The imaging apparatus according to claim 1, wherein the luminance limit value is determined according to a temperature measured by the temperature measuring unit. A method for controlling an imaging apparatus including a photometric means for performing photometry for each of a plurality of photometric areas obtained by dividing a photographing screen,
A correction step of correcting a plurality of photometric values obtained by photometry by the photometric means according to a luminance limit value that can be measured for each of the plurality of photometric areas,
Weighting of a plurality of photometric values obtained by photometry by the photometric means by making a weighting factor for photometric values not corrected by the correcting step larger than a weighting factor for photometric values corrected by the correcting step A control method comprising: a determination step of performing an operation and determining an exposure value based on the operation result. A program for causing a computer to execute a control method of an imaging apparatus including a photometric unit that performs photometry for each of a plurality of photometric areas obtained by dividing a photographing screen
The control method is:
A correction step of correcting a plurality of photometric values obtained by photometry by the photometric means according to a luminance limit value that can be measured for each of the plurality of photometric areas,
Weighting of a plurality of photometric values obtained by photometry by the photometric means by making a weighting factor for photometric values not corrected by the correcting step larger than a weighting factor for photometric values corrected by the correcting step A program comprising: a determination step for performing an operation and determining an exposure value based on the operation result.

Images