JP5163498B2 - Camera system - Google Patents

Description

  The present invention relates to a camera system.

  There is known a technique of performing preliminary light emission prior to main light emission at the time of photographing using a flash device, and determining the light amount at the time of main light emission based on the amount of light reflected from the subject at the time of preliminary light emission (Patent Literature). 1). Further, a technique for controlling the color temperature of illumination light emitted from a flash device in accordance with the color temperature of external light is known (see Patent Document 2).

JP 2005-173254 A JP 2003-15179 A

  The light reflectance of a subject and the light receiving sensitivity of a sensor that detects the amount of light reflected from the subject have different wavelength dependencies depending on the wavelength of light. For this reason, when the color temperature at the time of preliminary light emission is different from the color temperature at the time of main light emission, it is difficult to correctly obtain the light amount at the time of main light emission based on the amount of light reflected from the subject at the time of preliminary light emission.

(1) In the camera system according to the first aspect of the present invention, the main light emission that illuminates the subject with light having the first color temperature at the time of photographing, and the second that is different from the first color temperature before photographing. Illuminating means for performing preliminary light emission that illuminates with light having a color temperature, an imaging element that captures a subject image and outputting an imaging signal, and an imaging signal that is output from the imaging element when the illumination means performs preliminary light emission Based on the color temperature difference between the main light emission and the preliminary light emission, and the sensitivity difference of the image sensor due to the color temperature difference and the color temperature difference based on the color temperature difference between the main light emission and the preliminary light emission. Based on at least one of the differences in the reflectance of the subject caused by the correction means, the correction means that corrects the light emission amount calculated by the calculation means, and the illumination means so that the main light emission is performed with the light emission amount corrected by the correction means And an illumination control means for .
(2) In the camera system according to claim 1, the illumination unit includes a color temperature variable light source, and the illumination control unit further controls the illumination unit so that the color temperature of the main light emission matches the color temperature of the external light. Also good. The correction means in this case is based on the color temperature difference between the external light and the preliminary light emission, the sensitivity difference of the image sensor due to the color temperature difference, the difference in the reflectance of the subject due to the color temperature difference, The light emission amount calculated by the calculation means can be corrected based on at least one of the changes in the light emission amount caused by the difference in the light emission efficiency of the illumination means due to the color temperature difference.
(3) In the camera system according to claim 2, the illumination control unit includes an imaging signal output from the image sensor when the illumination unit performs preliminary light emission and an image output from the image sensor when the illumination unit does not emit light. The color temperature of external light can also be calculated based on the signal.
(4) In the camera system according to claim 2 or 3, the illumination control means may further control the illumination means so that the color temperature of the preliminary light emission matches the color temperature of the white light. The correction means in this case is based on the color temperature difference between the external light and the white light, the sensitivity difference of the image sensor due to the color temperature difference, the difference in the reflectance of the subject due to the color temperature difference, The light emission amount calculated by the calculation means can be corrected based on at least one of the changes in the light emission amount caused by the difference in the light emission efficiency of the illumination means due to the color temperature difference.
(5) In the camera system according to claim 2 or 3, the illumination unit further includes a white light source that emits white light, and the illumination control unit further controls the illumination unit to emit the white light source during preliminary light emission. Also good. The correction means in this case is based on the color temperature difference between the external light and the light from the white light source, and the sensitivity difference of the image sensor due to the color temperature difference and the reflectance of the subject due to the color temperature difference. The light emission amount calculated by the calculating means can be corrected based on at least one of the difference and the change in the light emission amount due to the difference in the light emission efficiency of the illumination means due to the color temperature difference.
(6) In the camera system according to the first aspect, the imaging device may include a photographic imaging device and a photometric imaging device different from the photographic imaging device. The correction means in this case is based on the color temperature difference between the main light emission and the preliminary light emission, the sensitivity difference of the image sensor for photographing caused by the color temperature difference, and the photometric image sensor caused by the color temperature difference. The light emission amount calculated by the calculation means can be corrected based on at least one of the difference in sensitivity and the difference in reflectance of the subject caused by the color temperature difference.
(7) The camera system according to (6) further includes color adjustment for performing color temperature adjustment on a photographic image signal output from the photographic image sensor with a color temperature adjustment coefficient corresponding to the color temperature of the main light emission. Means may be provided.
(8) In the camera system according to any one of claims 1 to 7, the correction unit captures an image signal output from the image sensor when the illumination unit performs preliminary light emission and an image when the illumination unit does not emit light. The reflectance of the subject can also be calculated based on the imaging signal output from the element.

  According to the present invention, it is possible to appropriately determine the main light emission amount even when the color temperature is different between the preliminary light illumination light and the main light illumination light.

It is a figure explaining the single-lens reflex camera system by one embodiment of this invention. It is a figure which illustrates the composition of a color filter. It is a functional block diagram of a camera system. It is a flowchart explaining the flow of the imaging | photography process which a microcomputer performs. It is a figure which illustrates the structure which controls the color of a color variable filter electrically. It is a figure which illustrates other composition of an illuminating device.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. FIG. 1 is a diagram for explaining a main configuration of a single-lens reflex camera system according to an embodiment of the present invention. In FIG. 1, an illumination device 17 and an interchangeable lens 2 that are detachable from the camera body 1 are mounted.

  Light from the subject incident on the interchangeable lens 2 is incident on the camera body 1 via the lens group 3 and a diaphragm (not shown). The subject light incident on the camera body 1 is guided to the upper finder by a quick return mirror (hereinafter referred to as a main mirror) 5 positioned as indicated by a solid line before being released, and forms an image on the diffusion screen 11. Further, part of the subject light incident on the camera body 1 is reflected downward by the sub mirror 6 and also enters the focus detection unit 7. The focus detection unit 7 includes a known phase difference detection type AF sensor, and is used at the time of focus detection for detecting a focus adjustment state by the interchangeable lens 2.

  The subject light imaged on the diffusing screen 11 further enters the pentaprism 13 through the condenser lens 12. The pentaprism 13 guides the incident subject light to the eyepiece lens 14 and also guides a part thereof to the re-imaging lens 15. The re-imaging lens 15 forms a subject image on the photometric sensor 16. The photometric sensor 16 outputs an image signal for photometric processing corresponding to the brightness of the subject image. The photometric sensor 16 is constituted by, for example, a CCD image sensor that receives incident light through a color filter. From the image signal obtained by the photometric sensor 16, color information (color information of ambient light) can be acquired in addition to the luminance information.

  After the release, the main mirror 5 rotates to the position indicated by the broken line, and the subject light is guided to the image sensor 9 via the focal plane shutter 8 to form a subject image on the imaging surface. The image sensor 9 includes a CCD image sensor provided with a plurality of photoelectric conversion elements corresponding to pixels. The imaging sensor 9 captures a subject image formed on the imaging surface and outputs an image signal for photographing according to the brightness of the subject image. The image signal is subjected to predetermined image processing in an image generation unit 109 (FIG. 2) described later, and then recorded on a recording medium by a recording unit 110 (FIG. 2) described later.

  A microcomputer (hereinafter referred to as a microcomputer) 10 performs a predetermined exposure calculation using an image signal from the photometric sensor 16. The microcomputer 10 controls the focal plane shutter 8 and the diaphragm (not shown) provided in the interchangeable lens 2 based on the exposure calculation result during the release operation, and also controls the imaging operation by the imaging sensor 9. The microcomputer 10 further includes a communication circuit that performs communication with the lighting device 17. The microcomputer 10 determines the color temperature of the necessary illumination light based on the color information of the ambient light acquired by the photometric sensor 16, and sends an emission color control signal to the illumination device 17 so as to emit the illumination light of the determined color temperature. Send.

  In this embodiment, the emission color control signal is transmitted from the camera body 1 side to the illumination device 17 side. However, the illumination in the illumination device 17 that has received the color temperature information of the ambient light from the camera body 1 side. The control circuit 18 may determine the color temperature of the illumination light.

  The microcomputer 10 further sends a control signal to the lens drive motor 4 in accordance with the focus adjustment state detected by the focus detection unit 7 to move the focus adjustment lens included in the lens group 3 forward and backward in the optical axis direction. The rotation direction and the rotation amount of the drive motor 4 (the movement direction and movement amount of the focus adjustment lens) are determined based on the detection signal from the focus detection unit 7. Thereby, the focus adjustment for the main subject is automatically performed (AF processing).

  The light emitter 19 of the illumination device 17 is constituted by, for example, a xenon tube. The illumination control circuit 18 includes a charging circuit and charges a capacitor (not shown). The illumination control circuit 18 discharges the charged charges in accordance with the light emission instruction and the light emission control signal transmitted from the camera body 1, and discharges the xenon tube 19 to emit light. The light emission control signal includes a signal that indicates the light emission amount of the xenon tube 19. The light emitted from the xenon tube 19 is emitted to the left in the figure through the color filter 21.

  FIG. 2 is a diagram illustrating details of the color filter 21. In FIG. 2, the color filter 21 is formed by integrally forming color filters 21a to 21c having a plurality of different transmission wavelength ranges in a roll shape. The color filter disposed in front of the xenon tube 19 is selectively switched by the same structure (two spool structures of winding and rewinding) as the film take-up spool of the film camera.

  The drive mechanism 22 performs winding and rewinding driving of the spool in response to an instruction from the illumination control circuit 18. The illumination control circuit 18 controls the drive amount of the drive mechanism 22 in accordance with the light emission control signal transmitted from the camera body 1 to place the color filter 21 of a predetermined color in front of the xenon tube 19. The light emission control signal includes a signal indicating the color temperature of light to be emitted through the color filter 21.

  FIG. 3 is a functional block diagram of the above-described camera system. In FIG. 3, the second image sensor 102 corresponds to the photometric sensor 16 (FIG. 1). The first image sensor 108 corresponds to the image sensor 9 (FIG. 1). The lighting unit 105 corresponds to the lighting device 17 (FIG. 1). The second imaging sensor control unit 101, the color temperature calculation unit 103, the illumination control unit 104, the exposure calculation unit 106, the imaging control unit 107, and the image generation unit 109 correspond to the microcomputer 10 (FIG. 1), respectively. The recording unit 110 is not shown in FIG.

  The camera system according to the present embodiment has a feature in photographing in which preliminary light emission is performed before the illumination device 17 performs main light emission as photographing auxiliary light, and this photographing process will be mainly described. In the preliminary light emission, the illumination device 17 is caused to emit light with a small light amount before photographing in order to determine the illumination light amount (main light emission amount) necessary for photographing. The camera system determines the main light emission amount necessary for photographing based on the amount of light reflected from the subject during preliminary light emission.

<Shooting process>
A flow of photographing processing performed by the microcomputer 10 will be described with reference to a flowchart of FIG. When a half-press operation signal indicating that a release button (not shown) is half-pressed is input, the microcomputer 10 activates a program that performs the processing shown in FIG. Although not shown, AF processing is performed based on the output detected by the focus detection unit 7 when the program is started.

  In step S201 of FIG. 4, the microcomputer 10 (second imaging sensor control unit 101) causes the second imaging sensor 102 to acquire (image) the image data of the object scene, and the process proceeds to step S202. In step S202, the microcomputer 10 (exposure calculation unit 106) calculates the exposure amount of the first image sensor 108 necessary for shooting based on the image data acquired in step S201, and proceeds to step S203. Specifically, the luminance information of the object scene is calculated using the image data, and the shutter time, the aperture value, and the ISO sensitivity are determined so that an appropriate exposure can be obtained based on the luminance information.

  In step S203, the microcomputer 10 determines whether or not a release operation (that is, a release button full-press operation) has been performed. When a full-press operation signal indicating that a release button (not shown) is fully pressed is input, the microcomputer 10 makes an affirmative determination in step S203 and proceeds to step S204. The full-press operation refers to an operation mode in which the release button is pressed deeper than the half-press operation. On the other hand, when the full-press operation signal is not input, the microcomputer 10 makes a negative determination in step S203 and returns to step S201. When returning to step S201, the processing of steps S201 to S203 is repeated.

  In step S <b> 204, the microcomputer 10 (exposure calculation unit 106) determines whether or not the lighting unit 105 needs to emit light. The microcomputer 10 (exposure calculation unit 106) makes an affirmative determination in step S204 when it is determined that the light emission is necessary because the lighting unit 105 is permitted to emit light and the luminance information calculated in step S202 is equal to or lower than the predetermined luminance. Then, the process proceeds to step S206. The microcomputer 10 (exposure calculation unit 106) does not need to emit light when the lighting unit 105 is prohibited from emitting light or the luminance information calculated in step S202 exceeds the predetermined value although the lighting unit 105 is allowed to emit light. If determined to be negative, a negative determination is made in step S204 to proceed to step S205. Here, the determination target is whether or not light emission is necessary for the main light emission.

  In step S206, the microcomputer 10 (illumination control unit 104) performs processing by the main light emission parameter calculation subroutine, and proceeds to step S207. Details of the light emission parameter calculation subroutine will be described later. In step S207, the microcomputer 10 (imaging control unit 107) instructs the main mirror 5 to rotate, causes the first imaging sensor 108 to start obtaining (imaging) image data of the object scene, and then proceeds to step S208. In this case, the imaging control unit 107 controls imaging by the first imaging sensor 108 so that the exposure amount calculated in step S202 is obtained.

  In step S208, the microcomputer 10 (illumination control unit 104) controls the illumination unit 105 to emit photographing auxiliary light under the light emission condition based on the main light emission parameter calculated in step S206, and proceeds to step S209. Thereby, the illumination unit 105 emits light with a predetermined light amount and a predetermined color temperature during imaging by the first imaging sensor 108.

  In step S209, the microcomputer 10 (image generation unit 109) performs white balance adjustment processing on the image data acquired by the first imaging sensor 108 based on the color temperature information calculated in step S206, and then step S210. Proceed to In step S210, the microcomputer 10 sends an instruction to the recording unit 110 (FIG. 3), causes the image data after the white balance adjustment processing to be recorded on the recording medium, and ends the processing in FIG.

  In step S205, which proceeds after making a negative determination in step S204 described above, the microcomputer 10 (exposure calculation unit 106) instructs the main mirror 5 to rotate, and acquires image data of the object scene from the first image sensor 108 (imaging). Then, the process proceeds to step S209. The imaging control unit 107 controls imaging by the first imaging sensor 108 so that the exposure amount calculated in step S202 immediately before the release operation is obtained. In this case, imaging is performed without causing the illumination unit 105 to emit light.

<Light emission parameter calculation subroutine>
The flow of the main light emission parameter calculation process performed by the microcomputer 10 will be described with reference to the flowchart of FIG. In this subroutine, the light emission condition of the photographing auxiliary light, that is, the main light emission amount and its color temperature are calculated. In step S301 in FIG. 5, the microcomputer 10 (second imaging sensor control unit 101) causes the second imaging sensor 102 to start acquiring (imaging) image data of the object scene, and then proceeds to step S302.

  In step S302, the microcomputer 10 (illumination control unit 104) controls the illumination unit 105 to perform preliminary light emission at a color temperature (K1) corresponding to white light, for example, and proceeds to step S303. Specifically, the lighting control circuit 18 is instructed to drive the spool to wind or rewind so that the light having the color temperature K1 is emitted through the color filter. Thereby, the illumination unit 105 is white light and preliminarily emits light with a light amount smaller than that during main light emission.

  In step S303, the microcomputer 10 (exposure calculation unit 106) calculates the main light emission amount GN (K1) and proceeds to step S304. Specifically, the luminance information of the object scene is calculated based on the image data in the case of the preliminary light emission, and the luminance information at the time of non-preliminary light emission calculated in step S202 immediately before the release operation is subtracted from the luminance information, Reflected light amount data (reflective data Rf1 to be described later) in which the pre-emitted light is reflected by the subject is obtained. Based on the reflected light amount data at the time of preliminary light emission, the main light emission amount of the illumination unit 105 required at the time of photographing is calculated.

  An area where the difference between the image data at the time of preliminary light emission and the image data at the time of non-preliminary light emission is large corresponds to a subject area (foreground area) that exists in the vicinity of the camera system and reflects light from the illumination unit 105. The microcomputer 10 (exposure calculation unit 106) calculates the main light emission amount so that proper exposure is obtained in this region.

  In step S304, the microcomputer 10 (color temperature calculation unit 103) calculates the color temperature of the main light emission and proceeds to step S305. Specifically, the luminance information at the time of preliminary light emission is subtracted from the luminance information at the time of non-preliminary light emission to extract a region (distant view region) that does not reflect light from the illumination unit 105.

  An area different from the foreground area described above corresponds to a distant view area that exists far away from the camera system and hardly reflects light from the illumination unit 105 (light from the illumination unit 105 does not reach). The microcomputer 10 (color temperature calculation unit 103) calculates average values Rm, Gm, and Bm for each color of the RGB color data constituting the image data of this area, and the ambient light based on the ratio of these Rm, Gm, and Bm. The color temperature (external light) (K2) is calculated. Here, information indicating the relationship between the ratio of Rm, Gm, and Bm and the color temperature is stored in advance in a nonvolatile memory (not shown) in the microcomputer 10 as table data. The microcomputer 10 (illumination controller 104) instructs the illumination control circuit 18 to wind or rewind the spool so as to emit light having the color temperature K2 through the color filter.

  The microcomputer 10 (color temperature calculation unit 103) further determines an adjustment coefficient used for white balance adjustment processing. Specifically, an adjustment coefficient suitable for the ambient light having the color temperature K2 is set.

  In step S305, the microcomputer 10 (exposure calculation unit 106) corrects the main light emission amount GN (K1) calculated in step S303 according to the color temperature information. The microcomputer 10 (illumination control unit 104) instructs the corrected main light emission amount GN (K2) to the illumination control circuit 18 and ends the processing in FIG.

The details of correction performed in step S306 will be described below.
[1] Correction according to the luminous efficiency of the illumination unit 105 The microcomputer 10 (exposure calculation unit 106) determines that the light intensity emitted from the illumination unit 105 is different between the color temperature K1 and the color temperature K2. Correction is performed using the correction amount H1 according to the equation (1).
H1 = Log2 {I (K1) / I (K2)} (1)
However, I (K2) is the emission intensity at the color temperature K2, and I (K1) is the emission intensity at the color temperature K1. Here, information indicating the relationship between the emission intensity and the color temperature is stored in advance in a non-volatile memory (not shown) in the illumination control circuit 18 as table data. This information is sent from the illumination control circuit 18 to the microcomputer 10 (exposure calculation unit 106).

[2] Correction according to sensitivity characteristics of first image sensor 108 When microcomputer 10 (exposure calculation unit 106) has different light reception sensitivity (photoelectric conversion efficiency) of first image sensor 108 between color temperature K1 and color temperature K2. Is corrected using a correction amount H2 according to the following equation (2).
H2 = Log2 {S1 (K1) / S1 (K2)} (2)
However, S1 (K2) is the light receiving sensitivity of the first image sensor 108 at the color temperature K2, and S1 (K1) is the light receiving sensitivity of the first image sensor 108 at the color temperature K1. Here, information indicating the relationship between the light receiving sensitivity of the first image sensor 108 and the color temperature is stored in advance in a nonvolatile memory (not shown) in the microcomputer 10 as table data.

[3] Correction According to Sensitivity Characteristics of Second Image Sensor 102 When microcomputer 10 (exposure calculation unit 106) has different light reception sensitivity (photoelectric conversion efficiency) between second image sensor 102 between color temperature K1 and color temperature K2. Is corrected using a correction amount H3 according to the following equation (3).
H3 = −Log2 {S2 (K1) / S2 (K2)} (3)
However, S2 (K2) is the light receiving sensitivity of the second image sensor 102 at the color temperature K2, and S2 (K1) is the light receiving sensitivity of the second image sensor 102 at the color temperature K1. Here, information indicating the relationship between the light receiving sensitivity of the second image sensor 102 and the color temperature is stored in advance in a nonvolatile memory (not shown) in the microcomputer 10 as table data.

[4] Correction according to subject reflectance When the intensity of light reflected by the subject differs between the color temperature K1 and the color temperature K2, the microcomputer 10 (exposure calculation unit 106) ) Is used for correction.
H4 = Log2 (Rf1 / Rf2) (4)
However, Rf2 is foreground reflection data that is assumed when the illumination unit 105 emits light at the color temperature K2 during main light emission and the same light emission amount as during preliminary light emission. Rf1 is the reflection data calculated in step S304, and is reflection data based on the foreground when preliminary light emission is performed at the color temperature K1. The reflection data Rf2 is expressed by the following equation (5).

Rf2 = PF (K2) × OC (5)
However, PF (K2) is spectral distribution data of light emitted from the illumination unit 105 set to the color temperature K2 at the time of main light emission. Spectral distribution data from the illumination unit 105 is stored in advance in a nonvolatile memory (not shown) in the microcomputer 10 as table data. Among these, the data for the color temperature K2 is sent from the illumination control circuit 18 to the microcomputer 10 (exposure calculation unit 106).

OC is spectral distribution data of the reflectance of the subject, and is calculated by the following equation (6).
OC = Rf1 / (PF (K1)) (6)
However, Rf1 is the reflection data calculated in step S304. PF (K1) is spectral distribution data of light emitted from the illumination unit 105 set to the color temperature K1. Of the table data stored in the non-volatile memory (not shown) in the microcomputer 10, the data for the color temperature K1 is sent from the illumination control circuit 18 to the microcomputer 10 (exposure calculation unit 106).

The microcomputer 10 (exposure calculation unit 106) corrects the main light emission amount GN (K1) before correction using the correction amounts H1 to H4 as shown in the following equation (7), and corrects the main light emission amount GN (K2). Get.
GN (K2) = GN (K1) × {(√2) ^ (H1 + H2 + H3 + H4)} (7)

According to the embodiment described above, the following operational effects can be obtained.
(1) In so-called auxiliary light imaging in which illumination light from the illumination device 17 is used as auxiliary light with respect to outside light (environmental light), the color temperatures of preliminary light emission and main light emission for determining the main light emission amount required at the time of photographing The difference in light receiving sensitivity (photoelectric conversion efficiency) of the photometric sensor 16 (second imaging sensor 102) caused by the difference is corrected as the correction amount H3. As a result, an appropriate amount of main light emission can be obtained, so that the possibility that a light amount over or under light amount will occur in the captured image can be reduced.

(2) In addition to the above (1), the difference in light receiving sensitivity (photoelectric conversion efficiency) of the image sensor 9 (first image sensor 108) due to the color temperature difference between the preliminary light emission and the main light emission is corrected as the correction amount H2. I tried to do it. Thereby, an appropriate amount of main light emission can be obtained.

(3) Further, the difference in reflectance due to the subject due to the color temperature difference between the preliminary light emission and the main light emission is corrected as the correction amount H4. Thereby, an appropriate amount of main light emission can be obtained.

(4) Furthermore, the difference in luminous efficiency of the lighting device 17 between the color temperature during preliminary light emission and the color temperature during main light emission is corrected as the correction amount H1. Thereby, an appropriate amount of main light emission can be obtained.

(5) The color temperature of preliminary light emission is adjusted to the color temperature of white light. For example, when the color temperature information cannot be acquired correctly from a distant view area in a dark environment where external light is insufficient, it is necessary to acquire the color temperature information based on the reflected light from the subject in the foreground area. By adjusting the preliminary light emission to the color temperature of white light, it is possible to correctly acquire various color information of the subject as compared with the case of illuminating with light having a reddish color temperature or a bluish color temperature.

(6) Since the subject area (foreground area) and the distant view area are discriminated based on the difference between the image data at the time of preliminary light emission and the image data at the time of non-preliminary light emission, it can be discriminated without using distance measurement information.

(7) The color temperature of the main light emission is adjusted to the color temperature of the external light. Thereby, compared with the case where it illuminates with the light of color temperature different from external light, the discomfort which a photographer feels from a picked-up image can be suppressed.

(8) Since the white balance adjustment coefficient is set in correspondence with the color temperature of the main light emission, the photographer is compared with the case of adjusting the white balance (color temperature adjustment) in correspondence with the color temperature different from the main light emission. Can suppress a sense of incongruity felt from a photographed image.

(Modification 1)
Although the example in which the preliminary light emission and the main light emission are performed by the illumination device 17 has been described, the preliminary light emission may be performed by the LED light source and the main light emission may be performed by the illumination device 17. In this case, the LED light source is configured to emit white light. Further, the LED light source may be used exclusively for preliminary light emission, or may be configured to also serve as an AF auxiliary light source or a self-timer operation indicator lamp.

(Modification 2)
In the above description, for the sake of convenience, the color temperature has been described with K1 and K2, but the actual illumination light is not monochromatic but has a range in color temperature. For this reason, in each of the above-described expressions, the color temperature may be integrated, or a value included in the color temperature width may be used as a representative value.

(Modification 3)
In the above description, all of the correction amounts H1, H2, H3, and H4 are added to the correction term. However, correction may be performed using at least one of the correction terms.

(Modification 4)
In the above description, the illumination device 17 of the type that is attached to the accessory shoe or the like of the camera body 1 has been described as an example, but the illumination unit may be configured to be built in the camera (that is, the illumination device built in the camera). It does not matter if you apply).

(Modification 5)
As an example of the camera body 1, an electronic camera that performs imaging with the first imaging sensor 108 (imaging sensor 9) has been described. Instead, the present invention may be applied to a silver salt camera that performs imaging with a photosensitive member such as a film. In the case of a silver salt camera, exposure to the photosensitive member is started in step S207. In this case, the processing in steps S209 to S210 is not necessary.

(Modification 6)
The present invention may be applied to an electronic camera that is not a single-lens reflex camera type, or may be applied to a camera (a lens-integrated camera) in which a photographing lens cannot be replaced. In this case, the imaging sensor 9 for photographing is also used as a photometric sensor. That is, luminance information and color temperature information of the object scene are calculated based on the image data acquired by the imaging sensor 9 (steps S202 and S206). In particular, the camera is in a live view mode in which an image captured by the image sensor 9 is displayed in real time on a display unit (not shown) (LCD or the like) provided on the back of the camera body 1 (on the right side of the camera body 1 in FIG. 1). When set, it is desirable to calculate the color temperature information based on a signal imaged by the imaging sensor 9 during live view. In this case, since the sensor for obtaining the color temperature is the same as the sensor used for actual imaging, there is an advantage that it is not necessary to consider the influence of the difference in the light receiving sensitivity between the sensors.

(Modification 7)
As a configuration example of the color filter 21 of the illuminating device 17, a method of winding a roll-shaped one with a spool structure has been described. Instead, as illustrated in FIG. 6, an electrically color-variable filter 25 composed of a liquid crystal panel or the like is provided in front of the xenon tube 19 so that the color of the color-variable filter 25 is electrically controlled. May be.

(Modification 8)
In the above embodiment, the xenon tube is used as the light emitter of the illumination device 17, but another light source may be used. For example, the light emitter is composed of a red LED 19a, a green LED 19b, and a blue LED 19c. In this case, the illumination control circuit 18 supplies current to the LEDs 19a, 19b, and 19c in accordance with the light emission instruction and the light emission control signal transmitted from the camera body 1, and causes each LED to emit light. The light emission control signal is a light emission color control signal that indicates the light emission intensity ratio of the LEDs 19a, 19b, and 19c (that is, the color temperature of the illumination light by the illumination device 17), and the light emission amount control signal that indicates the light emission amount by the LEDs 19a, 19b, and 19c including. The light emission amounts of the LEDs 19a, 19b, and 19c are changed by increasing or decreasing the current supplied to each LED. The light emission intensity ratio of the LEDs 19a, 19b, and 19c is changed by changing the current ratio supplied to each LED.

(Modification 9)
The color temperature of the preliminary light emission itself may be variable to an arbitrary color temperature. For example, the color temperature at the time of preliminary light emission may be made variable based on the color temperature of the shooting scene (color temperature of external light). As a specific example, the color temperature of the preliminary light emission is basically set to white. However, for example, when the shooting scene is a shooting scene that is reddish due to the influence of red external light (for example, a sunset scene) The preliminary light emission is performed after the color temperature of the preliminary light emission is set to be slightly reddish white.

  In performing such control, the color temperature of external light may be acquired using the photometric sensor 16 as described in the above embodiment. Note that the color temperature of the main light emission in the case of this shooting scene is set to match the color temperature of the red external light. As described above, the color temperatures of the preliminary light emission and the main light emission can be individually controlled, and even if the color temperatures of the main light emission and the preliminary light emission are different due to the control, the correction calculation of the main light emission amount as described above is performed. Thus, an appropriate main light emission amount can be calculated.

  In the above modification, the white light is used as a base, and the color temperature of the preliminary light emission is set by adding the color temperature component of external light to the white. However, the color temperature of preliminary light emission may be controlled to match the color temperature of external light. For example, the color temperature of the preliminary light emission is set based on the photometry result of the external light (the output of the photometric sensor 16) under the condition where the illumination device does not emit light as described above. If the system is set based on the color temperature of the shooting scene obtained during the light emission, the color temperature set for the preliminary light emission and the main light emission may be different. Even in such a case, the present invention can calculate an appropriate main light emission amount by performing the correction calculation of the main light emission amount as described above.

  The above description is merely an example, and is not limited to the configuration of the above embodiment.

DESCRIPTION OF SYMBOLS 1 ... Camera body 9 ... Imaging sensor 10 ... Microcomputer 16 ... Photometric sensor 17 ... Illuminating device 18 ... Illumination control circuit 19 ... Xenon tube

Claims (8)

Main light emission for illuminating a subject with light having a first color temperature during photographing, and preliminary light emission for illuminating the subject with light having a second color temperature different from the first color temperature before photographing. Lighting means for performing,
An image sensor that captures a subject image and outputs an image signal;
Calculation means for calculating a light emission amount during the main light emission based on an image pickup signal output from the image pickup device when the illumination means performs the preliminary light emission;
Based on the color temperature difference between the main light emission and the preliminary light emission, at least of the difference in sensitivity of the image sensor due to the color temperature difference and the difference in reflectance of the subject due to the color temperature difference Correction means for correcting the light emission amount calculated by the calculation means based on one of the following:
An illumination control means for controlling the illumination means so that the main light emission is performed with the light emission amount corrected by the correction means. The camera system according to claim 1,
The illumination means includes a color temperature variable light source,
The illumination control means further controls the illumination means to match the color temperature of the main light emission with the color temperature of external light,
The correction unit is configured to determine a difference in sensitivity of the image sensor due to the color temperature difference and a reflectance of the subject due to the color temperature difference based on a color temperature difference between the external light and the preliminary light emission. The light emission amount calculated by the calculating means is corrected based on at least one of a difference and a change in light emission amount caused by a difference in light emission efficiency of the illumination means due to the difference in color temperature. Camera system. The camera system according to claim 2,
The illumination control means is based on an imaging signal output from the imaging element when the illumination means emits the preliminary light and an imaging signal output from the imaging element when the illumination means does not emit light. A camera system for calculating a color temperature of outside light. The camera system according to claim 2 or 3,
The illumination control means further controls the illumination means to match the color temperature of the preliminary light emission with the color temperature of white light,
The correction unit is configured to determine a difference in sensitivity of the image sensor due to the color temperature difference and a reflectance of the subject due to the color temperature difference based on a color temperature difference between the external light and the white light. The light emission amount calculated by the calculating means is corrected based on at least one of a difference and a change in light emission amount caused by a difference in light emission efficiency of the illumination means due to the difference in color temperature. Camera system. The camera system according to claim 2 or 3,
The illumination means further includes a white light source that emits white light,
The illumination control means further controls the illumination means to emit the white light source during the preliminary light emission,
The correction means is based on the color temperature difference between the external light and the light from the white light source, and the sensitivity difference of the image sensor due to the color temperature difference, the reflection of the subject due to the color temperature difference. Correcting the light emission amount calculated by the calculation means based on at least one of the change in the light emission amount caused by the difference in rate and the light emission efficiency of the illumination means due to the difference in color temperature. A featured camera system. The camera system according to claim 1,
The imaging device includes a photographic imaging device and a photometric imaging device different from the photographic imaging device,
The correction means is based on a color temperature difference between the main light emission and the preliminary light emission, and a sensitivity difference of the imaging imaging element due to the color temperature difference, and the photometry imaging due to the color temperature difference. A camera system, wherein the light emission amount calculated by the calculating means is corrected based on at least one of a difference in sensitivity between elements and a difference in reflectance of the subject due to the color temperature difference. The camera system according to claim 6,
A camera system, further comprising: a color adjustment unit configured to adjust a color temperature with a color temperature adjustment coefficient corresponding to the color temperature of the main light emission with respect to a shooting image signal output from the shooting imaging element. In the camera system according to any one of claims 1 to 7,
The correction unit is configured to detect the subject based on an imaging signal output from the imaging device when the illumination unit performs the preliminary light emission and an imaging signal output from the imaging device when the illumination unit does not emit light. The camera system characterized by calculating the reflectance.

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