JPH09203927A - Camera - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the error in exposure control based on the error in the detection of a brightness value in the case where an AF sensor is used commonly as an AE sensor for spot photometry. SOLUTION: The distance measuring sensor of a distance measuring section 5 is commonly used as the photometric sensor for the spot photometry at the center of a screen. The image data obtd. by this distance measuring sensor having spectral sensitivity in an IR region is stored into the basis part/reference part data areas 125a, 125b of a memory 125. The spot photometric data is calculated by using the image data of the basis part data area 125a by a photometric arithmetic section 122. A photometric section 4 has a photometric sensor having spectral sensitivity in a visible region. The photometric data for the entire part of the photographic screen is detected from the output of the photometric sensor. The exposure control is executed by the photometric data alone when the photometric data is smaller than the prescribed value estimated to be an artificial light source. The exposure control is executed by the photometric data and the spot photometric data when the data is above the prescribed value. The error in the exposure control is prevented by not using the spot photometric data under the artificial light source of the low reliability of the photometric value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to automatic focusing (A
The present invention relates to a camera that also functions as a distance measuring device for detecting distance measuring information for F) as a photometric device that spot-lights the center of a shooting screen.

[0002]

2. Description of the Related Art Conventionally, in a camera provided with a distance measuring device for AF and a photometric device for automatic exposure adjustment (AE), the sensor output of the distance measuring device is used to spotwise measure the center of the photographic screen. A camera has been proposed in which exposure control is performed based on the spot photometric data and the photometric data for the entire photographic screen obtained by the photometric device.

For example, Japanese Unexamined Patent Publication (Kokai) No. 3-253829 discloses a camera which determines whether or not a shooting scene is backlit based on photometric data from a photometric device and spot photometric data from a distance measuring device. ing. Also, Japanese Patent Application Laid-Open
In Japanese Patent Publication No. 129732, it is determined whether or not the shooting scene is backlit based on the photometric data from the photometric device and the spot photometric data from the distance measuring device, and based on the distance measuring data from the distance measuring device. To determine whether the subject distance is within the flash range,
In addition, a camera that automatically emits a flash to perform daytime synchronized photography is shown if the subject distance is a distance that allows flash photography.

[0004]

By the way, since a sensor of a distance measuring device (hereinafter referred to as an AF sensor) generally has a spectral sensitivity characteristic biased to an infrared region, spot photometry is performed using the AF sensor. When the data is calculated, the spot photometric data has a level difference with the photometric data obtained by using the output of the sensor (hereinafter referred to as AE sensor) of the photometric device having the spectral sensitivity characteristic in the visible region. For this reason, if the photometric data for AE control is set based on both photometric data, exposure control may be inappropriate.

In particular, when backlight determination is performed from the brightness difference between the photometric data obtained by the AE sensor and the spot photometric data, if the light source of the subject is an artificial light such as a fluorescent lamp or an incandescent lamp,
Since the reliability of the spot photometric data is low, the reliability of the determination result is low. For example, 700 nm for fluorescent lamps
Since there are almost no long-wavelength components above, spot photometric data has a value on the under side, and incandescent light bulbs have many long-wavelength components in the infrared region, spot photometric data has a value on the over side, and with an AE sensor using an artificial light source The variation in the brightness difference between the obtained photometric data and the spot photometric data becomes large. Therefore, it is difficult to accurately determine the backlight under the artificial light source, and when the exposure control is performed based on the backlight determination, there is a high possibility that the control will be inappropriate.

In the above-mentioned JP-A-3-253829 and JP-A-60-129732, the exposure control considering the reliability of the photometric data due to the difference in the light source when the AF sensor is also used as the AE sensor is not possible. This is not done, and it is difficult to properly control exposure under artificial light sources.

The present invention has been made in view of the above problems, and provides a camera capable of suitable exposure control even when the AF sensor is used as an AE sensor for spot photometry.

[0008]

According to the present invention, a light receiving unit having a spectral sensitivity characteristic in the visible region receives light in a photographic screen and detects the first luminance information for the entire photographic screen based on the amount of received light. A first photometric means, and a distance measuring means for picking up an image of a partial area in a shooting screen by an image pickup means having a spectral sensitivity characteristic in an area deviated from the visible area, and detecting distance information of a subject based on the picked-up image. A camera including second photometric means for detecting second brightness information for a subject in a distance measurement area based on the amount of light received by the imaging means, and exposure control being performed based on the first and second brightness information; Determination means for determining whether or not the first brightness information is equal to or higher than a predetermined threshold value, and when the first brightness information is equal to or higher than the threshold value, exposure control based on the first and second brightness information is performed. Control brightness value for Constant and, when the first luminance information is smaller than the threshold, in which a control luminance value setting means for setting the control luminance value based on the first luminance information (claim 1).

According to the above construction, the first photometric distance means detects the first luminance information for the entire photographic screen based on the amount of light received by the photometric light receiving means, and the second photometric means measures the distance. The second brightness information for the subject in the distance measurement area within the shooting screen is detected based on the captured image captured by the dedicated image capturing means. It is determined whether or not the first brightness information is equal to or higher than a predetermined threshold value, and when the first brightness information is equal to or higher than the threshold value, a control brightness value is set based on the first and second brightness information. When the first brightness information is smaller than the threshold value, the control brightness value is set based on the first brightness information. Then, the exposure control is performed based on the control brightness value.

Further, according to the present invention, in the above camera, there is provided a flash light generation means and a light emission control means for causing the flash light generation means to emit light when the first luminance information is smaller than the threshold value. Item 2).

According to the above arrangement, when the brightness information for the entire photographic screen is smaller than the predetermined threshold value, a flash light is emitted to control the exposure.

Further, according to the present invention, in the above camera, correction data setting means for setting predetermined correction data based on a brightness difference between the first brightness information and the second brightness information, and the control by the correction data. And a correction means for correcting the brightness value (claim 3).

According to the above configuration, the predetermined correction data is set based on the brightness difference between the brightness information for the entire shooting screen and the brightness information for the subject in the distance measurement area within the shooting screen.
The control brightness value is corrected with this correction data.

The correction data may be proportional to the brightness difference (claim 4). According to this configuration, the control brightness value is corrected with the correction data proportional to the brightness difference.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION The AE function of a camera according to the present invention will be described with reference to the drawings. FIG. 1 is a front view showing the external appearance of a camera according to the present invention. The camera 1 according to the present invention has an average photometry unit for average photometry of the entire photographic screen and a spot photometry unit for spot photometry of the center of the photographic screen.
The exposure control value for taking a photograph is automatically set based on the average photometric information and the spot photometric information. Moreover, the photometric sensor of the spot photometric unit automatically adjusts the focus (A
The distance measuring sensor for F) is also used.

The camera 1 has a taking lens 3 which is a zoom lens in the center of the front of a camera body 2, and a photometric unit 4 is provided in the diagonally upper left part. The lens system of the photographing lens 3 is provided with a lens shutter formed by combining a plurality of shutter blades. Further, a distance measuring unit 5 is provided above the photographing lens 3, and a finder objective window 6 is provided on the right side thereof. Further, a pop-up type built-in flash 7 is provided on the upper right end of the camera body 2.

As shown in FIG. 2, the photometric section 4 includes a first light receiving section for photometrically measuring the peripheral portion 83 in the photographing screen 8 and the photographing screen 8.
A second light receiving portion for photometry of the central portion 82 in the
An unillustrated light receiving element (hereinafter referred to as an AE sensor) composed of a PC (Silicon Photo Cell) or the like is provided, and the photographing screen 8 is based on the photometric information obtained for each of the photometric regions 82 and 83 from the light receiving signals of both light receiving portions. The photometric data (luminance data of the subject) for the whole is calculated. In addition,
The AE sensor has an IR cut filter on the image pickup surface, and its spectral sensitivity is adjusted to be in the visible region.

The distance measuring section 5 has a distance measuring area 81 in a substantially central portion of the photographing screen 7, and from the image information obtained by receiving the reflected light from the object contained in the distance measuring area 81 to the object. A distance (hereinafter referred to as a subject distance) D (m) is detected. As shown in FIG. 3, the distance measuring unit 5 mainly includes an AF including a pair of line image sensors 91 and 92.
The sensor 9 and the pair of microlens arrays 1 arranged in front of the line image sensors 91 and 92, respectively.
The lens system 10 is composed of 01 and 102. The line image sensors 91 and 92 are arranged on the same line with a predetermined interval. Line image sensor 91,
Reference numeral 92 denotes, for example, a CCD line sensor in which a large number of charge-coupled devices (hereinafter, referred to as pixels) are linearly arranged, and the distance measuring unit 5 causes the line image sensors 91 and 92 to partially detect an object image. An image is taken, and the object distance D (m) is detected by using the data (data output from each pixel. Hereinafter, referred to as pixel data) forming both the picked-up images.

The object distance D is determined by the line image sensor 9
Of the reference numerals 1, 92, the image pickup section of the line image sensor 91 on the side closer to the optical axis L of the finder optical system 11 is the reference section, and the image pickup section of the line image sensor 92 on the side farther from the optical axis L is the reference section. It is calculated from the amount of positional shift between the two images by comparing the linear image of No. 2 and the linear image of the reference portion.

The line image sensor 9 of the distance measuring unit 5
1 is also used as a photometric element for spot-photometrically measuring the center of the photographic screen, and as will be described later, spot photometric data at the center of the photographic screen is calculated using pixel data forming a linear image of the reference portion. The line image sensor 92
Can also be used as a photometric element, but in order to reduce the parallax between the visual field range of the finder optical system 8 and the photometric range of the AF sensor 9 as much as possible, in the present embodiment, the finder optical system 11 The line image sensor 91 on the side close to the optical axis L is used as a spot photometric element.

FIG. 4 is a block diagram showing a photometry and distance measurement control system of the camera. In the figure, the CPU 12
It is a microcomputer that centrally controls a series of shooting operations of cameras such as AF, AE, and release. CPU 12
Is a distance calculation unit 121 for AF control, a photometry calculation unit 122 for calculating spot photometric data, a light source correction unit 123, an exposure calculation unit 124 for calculating photometry information for exposure control, and the above calculation process. Memory 125 for
have.

The memory 125 is a reference part data area 125.
a, reference data area 125b, AF data area 1
25c, an SAE data area 124d and a correction data area 125e, and pixel data forming a linear image of a subject imaged by the line image sensor 91 of the AF sensor 9 in the standard part data area 125a and the reference part data area 125b. (Hereinafter referred to as reference part data) and pixel data forming a linear image of the subject imaged by the line image sensor 92 (hereinafter referred to as reference part data).
Are stored respectively in the AF data area 125c, data relating to the subject distance calculated using the standard part data and the reference part data (hereinafter referred to as AF data) are stored in the AF data area 125c, and the standard part data is stored in the SAE data area 124d. The data relating to the subject brightness in the spot photometric area (hereinafter referred to as SAE data) calculated by using the above and the average photometric data calculated by the photometric unit 4 are stored. Further, the correction data area 125e stores preset correction data relating to the light source of the subject.

In this correction, the light source of the subject is the AF sensor 9
The error of the AE control data that occurs when the light source is different from the adjusted light source is corrected according to the light source of the subject. That is, the spot photometric value by the AF sensor 9 and the A of the photometric unit 5
The output characteristic of the AF sensor 9 is adjusted with respect to the standard light source A in the same manner as the output characteristic of the AE sensor of the photometric unit 5 in order to adjust the level with the average photometric value by the E sensor. If you take a photo with sunlight as a light source,
Light source with adjusted output characteristics of AF sensor 9 (standard light source A)
And the actual light source (light sources close to the standard light sources B and C) are different, the AE data obtained from the output of the AF sensor 9 is
It becomes smaller than the actual brightness value. The above correction is to correct the output level from the AF sensor 9 due to the difference in the subject light source. For example, the output of the AF sensor 9 when the standard light source A is received and the standard light source B are received in the correction data area 125e. Correction data ΔB _B (≈1.21 EV) for correcting the difference between the output of the AF sensor 9 and the output of the AF sensor 9 when the standard light source A is received and the standard light source C
The correction data ΔB _C (≈1.51 EV) for correcting the difference from the output of the AF sensor 9 when the light is received is previously calculated and stored.

The AF data is obtained by dividing the image pickup area of the reference portion into a plurality of AF areas and calculating each AF area.
The calculation result is stored in the AF data area 125c corresponding to each AF area, the SAE data is calculated for each AE area by dividing the imaging area of the reference portion into a plurality of AE areas, and the calculation result is calculated for each AE area. SA corresponding to the area
It is stored in the E data area 124d.

FIG. 5 is a diagram showing an example of the AF area and AE area set in the image pickup area of the line image sensor 91.

In the image pickup area of the line image sensor 91, 6 AE areas and 6 AF areas are set. The AE areas AE1 to AE6 are configured by equally dividing the image pickup area of the line image sensor 91 into six.
Further, the AE areas AF1 to AF6 are divided areas AR1 to AR6, which are obtained by equally dividing the image pickup area of the line image sensor 91 into six areas, where AF1 = AR1 + AR2, AF2 =
AR2 + AR3, AF3 = AR3 + AR4, AF4 = A
R4 + AR5, AF5 = AR5 + AR6, AF6 = AR
1 + AR2 + AR3 + AR4 + AR5 + AR6.

In this embodiment, the AE areas AE1 to AE
Since each area of E6 corresponds to each of the divided areas AR1 to AR6, each of the AF areas AF1 to AF1
The AF6 is configured by combining the AE areas AE1 to AE6. This is AF area AF1-A
This is because when any one of F6 is selected and AF control is performed, SAE data for a subject in the selected AF area can be detected, and exposure control can be performed based on this SAE data.

Therefore, the AF area and the AE area are set such that the minimum size AE area has a size substantially equal to or smaller than the minimum size AF area, and
If each AF area is configured so as to include at least one AE area, the imaging area of the line image sensor 91 is divided by another method.
You may make it comprise an F area. It should be noted that when at least one AE area is included in each AF area, the SAE data in the AE area corresponding to the AF area is a portion protruding from the AF area even if the AE area is slightly larger than the AF area. If it does not affect, since the size of the AE area can be equivalently treated as the size of the AF area as SAE data,
In such a case, it is not necessary to have a strict size relationship between the AE area and the AF area.

Returning to FIG. 4, the distance calculation unit 121 uses each of the AF area AF1 to AF1 by using the reference portion data and the reference portion data.
The AF data is calculated for each AF 6, and the calculation result is stored in the addresses corresponding to the distance measuring areas AF1 to AF6 of the memory 125. Further, the photometric calculation unit 122
The SAE data is calculated for each of the AE areas AE1 to AE6 using the reference portion data, and the spot photometric area (imaging area of the reference portion) is controlled using the SAE data corresponding to the AF area selected for AF control. A brightness value (hereinafter referred to as SAE control data) is calculated, and the calculation result is stored in an address corresponding to each distance measuring area AE1 to AE6 of the memory 125.

The calculation and storage of SAE data is performed by A
This is performed before the calculation of the AF data so as not to be affected by the calculation of the F data, so that even when the AF sensor 9 is also used as the AE sensor for spot photometry, the storage area of the data for both calculations in the memory 125. Is trying not to increase as much as possible. That is, as will be described later, the AF data is calculated by converting the standard part data and the reference part data into difference data, centroid data, etc., respectively, and then calculating the correlation value between the standard part data and the reference part data. Therefore, if the AF data calculation is performed independently of the SAE data calculation, it is necessary to store the standard part data and the reference part data separately for the SAE data calculation. However, in the present embodiment, the AF data is calculated. By calculating the SAE data before the calculation, the standard part data and the reference part data are not saved unnecessarily, and the increase in the memory capacity is reduced accordingly. Further, since one SAE data is calculated for each AE area AE1 to AE6, the number of SAE data for calculating the SAE control data is only 6 and the memory for storing the SAE data and the SAE control data is required. Is reduced as much as possible.

The light source correction unit 123 corrects the calculation error of the SAE control data based on the object light source, and adds and corrects the correction data to the calculated SAE control data. The exposure calculation unit 124 calculates photometric information for exposure control based on the photometric data for the entire screen by the photometric unit 4 and the SAE control data. The AF controller 13 controls the drive of the taking lens 3 and adjusts the focus of the taking lens 3. Also, the focal length detection unit 1
Reference numeral 4 is for detecting the focal length of the taking lens 3.

Next, the calculation of the AF data and SAE control data using the image picked up by the AF sensor 9 will be described.

FIG. 6 is a main flow of arithmetic control of AF data and SAE data using an image picked up by the AF sensor 9. This flow is executed in the shooting preparation process performed by pressing the release button halfway.

First, the AF sensor 9 is driven for a predetermined time set in advance, and charges corresponding to the amount of received light are accumulated in each pixel of the line image sensors 91 and 92 (# 1). All pixel data of the line image sensors 91, 92 is CPU
12 and the pixel data of the reference portion is stored in the memory 125.
Stored in the standard portion data area 125 a of the reference portion, and the pixel data of the reference portion is stored in the reference portion data area 125
It is stored in b (# 2).

Subsequently, the reference portion data is read from the reference portion data area 125a of the memory 125 for each AE area _AE1 to AE6, and the SAE data D _{AE1 to} D _AE6 corresponding to each AE area _{AE1 to AE6} is calculated. ((
3). For the calculation of the SAE data D _{AE1 to} D _AE6 , for example, various methods shown in Table 1 below can be adopted.
Each data content in Table 1 is calculated by the calculation formula shown in the table.

[0036]

[Table 1]

In Table 1, the method of "average value 1" is AE
The arithmetic average value of all pixel data in the area is used as SAE data of the AE area. Since the method of "average value 1" averages the entire brightness in the area, proper exposure control can be performed when the brightness balance in the area is within a certain range. The method of “average value 2” is to calculate the arithmetic average value of all the remaining pixel data excluding the pixel data having the maximum brightness and the minimum brightness in the pixel data in the AE area.
This is the SAE data for the area. "Average value 2"
This method eliminates the effects of abnormally bright and dark areas when the brightness balance in the area exceeds a certain range, so that proper exposure control can be obtained even when the brightness balance in the area exceeds a certain range. This is an improved method of the “average value 1”.

Further, the method of "average value 3, 4" is based on only the pixel data in the AE area which has a luminance value below or above a predetermined threshold value set according to the average photometric value. The arithmetic mean value is used as the SAE data of the AE area, which is a method capable of simplifying the arithmetic processing for AE control. That is, in the method of “average value 3, 4”, since the bright portion or the dark portion is extracted with the threshold value based on the average photometric value as a reference, it is not necessary to separately determine the backlight of the shooting scene after calculating the SAE data. It is possible to simplify the calculation processing when calculating the SAE control data using the SAE data.

In the “minimum value” method, the pixel data having the minimum luminance among the pixel data in the AE area is set as the SAE data of the AE area, and the “maximum value” method is the pixel in the AE area. Among the data, the pixel data having the maximum brightness is used as the SAE data of the AE area. The method of "minimum value" is suitable for overexposure control, and the method of "maximum value" is suitable for underexposure control.

Subsequently, after the calculated SAE data is stored in the SAE data area 124d of the memory 125 (# 4), the AF control AF is performed using the standard part data and the reference part data stored in the memory 125. An area (AF area used for AF control; hereinafter referred to as AF control area) and a subject distance D with respect to a subject in this AF control area are calculated, and the calculation result is stored in the AF data area 125c of the memory 125. Is done (# 5). Note that the subject distance D is the data of the reference portion for each AF area after data conversion of the reference portion data of the reference portion data area 125a and the reference portion data of the reference portion data area 125b into, for example, difference data or luminance centroid data. Is calculated from the correlation value obtained by comparing the data in the reference section with the data in the reference section.
Then, of the AF areas AF1 to AF6, for example, the AF area with the smallest subject distance D is selected as the AF control area.

Next, the AF control area and the subject distance D
The spot metering area is set on the basis of (# 6).

FIG. 7 shows the AF control area and the subject distance D.
It is an example of a chart diagram for selecting the AE control area based on. In the figure, "1" in the "AE area" column,
“2”, ..., “6” indicates AE1, AE2, ..., AE6, and “1”, “2”, ..., “6” in the “AF area” column
Indicates AF1, AF2, ..., AF6. “All low contrast” is a case where the focus positions of all the AF areas AF1 to AF6 cannot be detected due to low contrast. Also, "●" indicates the selected AE area,
"-" Indicates an AE area that was not selected.

In the AE area selection method shown in the figure, the object distance D is divided into three stages of "short distance", "medium distance" and "long distance", and the same AF area is selected as the AF control area. Even in such a case, the selection range of the AE control area is gradually widened as the subject distance D approaches the “short distance” side. For example, when the AF area AF3 is selected as the AF control area, the AE area AE included in the AF area AF3 when the subject distance D is “long distance”.
3 and AE4 are selected as AE control areas, but when the subject distance D is "medium distance", AE areas AE2 and AE5 outside the AF area AF3 are added as AE control areas,
Furthermore, when the subject distance D becomes "short distance", all AE areas A
E1 to AE6 are selected as the AE control area.

It is desirable that the range of the AE control area is as wide as possible, but the size of the subject image with respect to the photographic screen is small for a distant subject (see FIG. 8), and the AE area outside the AF control area is AE. When included in the control area, the subject and the background are included in the AE control area, and the SAE control data calculated based on the SAE data in the AE control area may be affected by the background brightness.
While the AE area in the AF control area is selected as the AE control area, the size of the subject image with respect to the shooting screen gradually increases for medium or short distance subjects.
Even if an AE area outside the AF control area is included in the AE control area, the background is unlikely to be included in the AE control area, and it is considered that the AE control data is less likely to be affected by the background brightness. The AE area outside the area is also selected as the AE control area.

Further, in the case of the present embodiment, the control is made so that photographing is possible even in the low contrast mode. Therefore, even if "all low contrast" or AF area AF6 close to "all low contrast" is selected, the AE areas AE1 to AE6 are selected. SAE control data is calculated as the AE control area.

When the position of spot metering of the subject is fixed, the size of the subject image in the photographing screen becomes smaller as the subject distance D becomes longer. Therefore, in order to obtain accurate AE control data, the subject image can be obtained. It is necessary to change the maximum size of the AE control area according to the spot photometric position (that is, the subject distance D).

For example, when a human of a standard size is assumed as a subject and a human face is set as the position of spot photometry, the relationship between the subject distance D and the maximum number of pixel data in the suitable AE control area is shown in FIG. As shown by the dotted line in FIG. 9, when the human torso is set as the position of spot photometry, the relationship between the subject distance D and the maximum number of pixel data in the preferable AE control area is shown by the dashed line in FIG. Like Therefore, when a human face is assumed as the position of spot photometry and the maximum size of the control AE area is set according to the subject distance D, the size of the AE control area becomes extremely small for a subject at a long distance.

However, when the subject is a human, the framing of the subject by the photographer is generally carried out so that the face of the subject K enters the center of the photographing screen 7 at a short distance as shown in FIG. 8, but at a long distance. Since the entire subject K is placed as much as possible within the photographing screen 7 and the position of spot metering of the subject changes depending on the subject distance D, a certain distance D
It is necessary to perform spot metering on the face of the subject K for a subject K at a short distance of 1 or less, but spot metering for the body of the subject K for a subject K farther than a certain distance D1. It can be performed.

Therefore, a suitable AE according to the subject distance D
In FIG. 9, the number of pixel data in the control area can be switched from a certain distance D1 to a larger number of pixel data having the relation shown by in a longer distance than the certain distance D1.
In the setting of the range of the AE control area in FIG. 7, in consideration of the above, two AE areas included in the AF control area are selected as the AE control area even when the subject is a long distance, and the AE control is performed as much as possible. Suitable SAE with wide area
Control data is available.

Note that, in FIG. 9, the relation (concatenation of the relation for switching from to at the distance D1) gives the maximum number of pixel data in the AE control area, and is less than or equal to this number of pixel data. The range indicates the range of the AE control area that is less affected by the background. In the present embodiment, since spotlighting is also performed by using the outside light type distance measuring unit 5 as well, A according to the subject distance D
Although the E control area is set, when the distance measuring unit 5 is configured by the TTL (Through The Lens) method, the AE control area is set according to the image magnification β instead of the object distance D. It is good to do so.

10 and 11 show "AE control area selection based on AF control area and subject distance D".
8 shows an execution procedure of the AE control area selection method shown in FIG. 7 in the "area selection" subroutine.

First, it is sequentially determined whether or not all the AF areas are low contrast or whether the AF area AF6 is set as the AF control area (# 11, # 1).
2) If all low contrast or AF area AF6 is set as the AF control area (YE in # 11 and # 12)
S), AE areas AE1 to AE6 are set as AE control areas (# 24), and the process returns.

All are not low contrast, and the AF area AF6 is not set as the AF control area (# 11, # 1
If NO in 2), the distance range of the subject is determined from the subject distance D (# 13, # 14). Subject distance is "short distance"
If (b> D) (YES in # 13), AE area A
E1 to AE6 are set as AE control areas (# 2
4) Return and subject distance is "long distance" (D ≧ a)
If so (NO in # 14), it is sequentially determined whether or not each of the AF areas AF1 to AF4 has been selected as an AF control area (# 15, # 1).
7, # 19, # 21).

When the AF area AF1 is set as the AF control area (YES in # 15), the AE areas AE1 and AE2 are set as the AE control areas (# 1).
6) If the AF area AF2 is set as the AF control area (YES in # 17), the AE areas AE2, AE3
Is set as the AE control area (# 18), and the AF area AF3 is set as the AF control area (# 19).
YES), AE areas AE3 and AE4 are set as AE control areas (# 20), and AF area AF4 is set to AF.
If it is set in the control area (YES in # 21), A
The E areas AE4 and AE5 are set as the AE control areas (# 22), the process returns, and the AF areas AF1 to AF
If none of 4 is selected, that is, if the AF area AF5 is set as the AF control area (NO in # 21), the AE areas AE5 and AE6 are set as the AE control area (# 23), and the return is executed. To do.

If the subject distance is "medium distance"(a> D≥b) (YES in # 14), AF area AF1 or AF
2 is set in the AF control area (# 25), and if the AF area AF1 or AF2 is set in the AF control area (YES in # 25), the AE areas AE1 to AE4 are AE controlled. The area is set (# 26) and the process returns. In addition, the AF area AF1,
If AF2 is not set in the AF control area (# 2
5 is NO), and then it is determined whether or not the AF area AF3 is set as the AF control area (# 27).
If area AF3 is set as the AF control area (#
(YES in 27), the AE areas AE2 to AE5 are set as the AE control areas (# 28), and the AF area AF3 is not set as the AF control area (N in # 27).
O), AE areas AE3 to AE6 are set as AE control areas (# 29), and the process returns.

Returning to the flowchart of FIG. 6, when the setting of the AE control area is completed, subsequently, the SAE control data is calculated using the SAE data in the set AE control area (# 7).

FIG. 12 is an example of a subroutine for calculating the SAE control data, in which the calculation of the SAE control data is switched according to the subject distance D. That is, it is determined whether or not the subject distance D exceeds an appropriate predetermined distance a ′ (> a) of, for example, 4 m or more (# 3
1) If the subject distance D exceeds the predetermined distance a '(YES in # 31), the lowest brightness value min {of the brightness values B1, B2, ... Of the AE area selected as the AE control area. B1, B2, ...} are set as SAE control data (# 32), and the subject distance D is equal to or less than the predetermined distance a '(NO in # 31), the brightness value of the AE area selected as the AE control area. Average value B of B1, B2, ...
_AVE (= ΣBi / m, Bi; i-th luminance value, m; number of luminance values) is set as SAE control data (# 3
3) Return.

In the above method, when the subject is at a long distance,
When the subject distance D is longer than the predetermined distance a ′, the lowest luminance value is used as the SAE control data because the subject image in the shooting screen is small and the influence of the subject edge is large. The effect of is reduced. In this case also, the subject distance D
Alternatively, the image magnification β can be used to determine the perspective of the subject.

Further, a constant arithmetic expression is irrespective of the subject distance D, for example, (1) "average value 1" to (5) shown in Table 1 above.
You may make it calculate SAE control data by the arithmetic expression of "minimum value."

In the method of "average value 1", the brightness in the AE control area is averaged, so that even when the SAE control data is calculated in the widest possible area, the variation in the calculation result can be reduced. The method of “average value 2” is a method of improving “average value 1” and can reduce the influence of the abnormal value even when the luminance balance is abnormally large. Also,
The “minimum value” method is easier than the “average value 1” method when the retrograde scene is determined by comparing the photometric data for the entire photographic screen obtained by the photometric unit 4 with the SAE control data. There is an advantage that discrimination can be performed. In addition, since the methods of “average value 3” and “average value 4” extract the bright part or the dark part based on the threshold value based on the average photometric value, the backlight discrimination can be easily and accurately performed. There is.

When the SAE control data is calculated, subsequently, the correction data ΔB _B or the correction data ΔB _C is added to this SAE control data for correction (# 8).

In this embodiment, the level difference of the standard light source B or the standard light source C with respect to the standard light source A when the standard light sources A, B, and C are directly received by the AE sensor is used as the correction data. AF when the standard light sources A, B, and C are applied to the actual subject and the reflected light of the standard light source A is received
Output and standard light source C in the AF sensor 9 when it receives the reflected light of the difference .DELTA.B _B 'and standard light source A of the output of the AF sensor 9 when it receives the reflected light of the output and the standard light source B sensor 9
Difference from the output of the AF sensor 9 when the reflected light of
The correction data may be B _C ′. In the former case, the light from the standard light source is directly received, so the correction data is for the standard reflectance of 18%. In the latter case, however, the reflected light from the subject is received. Is closer to the correction data for the subject, and SAE with higher accuracy
The control data can be corrected.

Next, the calculation of the control brightness value for exposure control based on the photometric data obtained by the photometry unit 4 and the AE control data obtained from the image picked up by the distance measurement unit 5 will be described with reference to FIG.
This will be described with reference to the flowchart of.

The flowchart of FIG. 13 calculates the brightness difference data ΔBV for backlight determination (# 41 to # 43), and calculates the photometric data (luminance value) BV _S for the entire photographing screen by the photometric unit 4 (# 44 to # 44). # 48) and control brightness value B
It is composed of calculation of V _S 2 (# 49 to # 55).

In the calculation of the brightness difference data ΔBV for the backlight determination, the taking lens 3 detected by the focal length detecting section 14 is used.
Focal length FL is a predetermined threshold FL1 (for example, 60 mm)
It is discriminated whether or not it exceeds (# 41), and FL> FL
If it is 1 (YES in # 41), the peripheral photometric data BV _C obtained by the photometric unit 4 (hereinafter, peripheral photometric data BV _C
That. ) And SAE control data (luminance value of the spot metering area) brightness difference between BV _AF (BV _C -BV _AF) is set to the luminance difference data .DELTA.BV (# 42), if the FL ≦ FL1 (at # 41 NO ), photometric data BV _O of the central portion obtained by the photometric unit 4 (hereinafter, the heart photometric data BV _O.)
The luminance difference between the SAE control data BV _AF (BV _O -B
V _AF ) is set to the brightness difference data ΔBV (# 43).

When FL> FL1, the size of the subject image in the photographic screen is estimated to be substantially the same as or larger than the central photometric region, and therefore peripheral photometric data BV _C and SAE control data BV are used as the brightness difference data. Taking the brightness difference from _AF, and if FL ≦ FL1, the size of the subject image in the shooting screen is estimated to be smaller than the central photometric region,
Taking the luminance difference between the central portion photometric data BV _C and SAE control data BV _AF as the luminance difference data.

Subsequently, in the calculation of the photometric data BV _S for the entire photographic screen by the photometric section 4, the size of the subject image in the photographic screen is divided into three stages according to the focal length of the photographic lens 3, and peripheral photometry is performed according to each size. the weighted logarithmic mean value of the data BV _O and the central portion photometric data BV _C are to be computed.

That is, the focal length FL is the predetermined threshold FL.
It is determined whether or not 2 is exceeded (# 44), and FL ≦ F
If L2 (NO in # 44), central photometric data BV _C
The brightness value ((BV _C + 3 · BV _O ) / 4) obtained by weighted logarithmic averaging of the peripheral photometric data BV _O and 1: 3 is set as the photometric data BV _S (# 45). FL> FL2
If so (YES in # 44), it is further determined whether or not the focal length FL exceeds a predetermined threshold value FL3 (# 4
6), if FL3 ≧ FL> FL2 (N in # 46)
O), the central photometric data BV _C and the peripheral portion photometric data BV _O and 5: weighted log average luminance value at a ratio of 3 ((5 · BV
_C + 3 · BV _O ) / 8) is set as the photometric data BV _S (# 47), and if FL> FL3 (YE in # 46)
S), the central portion photometric data BV _C is set as the photometric data BV _S (# 48).

The shorter the focal length FL of the taking lens 3 is, the wider the angle of view is and the wider the taking range is. Therefore, the weighting of the luminance of the peripheral portion with respect to the central portion in the photographic movie plane is increased to favor the luminance balance of the entire photographic screen. I am trying to become.
The focal length FL of the taking lens 3 is a predetermined threshold value FL3.
If it exceeds (if the size of the subject image in the photographing screen is estimated to be greater than the metering area of the center) in order to reduce the effect of background luminance to the luminance of the object, photometric data of the central unit only BV _O I am trying to use.

Subsequently, in the calculation of the control brightness value BV _S 2,
When the shooting scene is normal light, the brightness data BV _{S is set} to the control brightness value BV _S 2, and when the shooting scene is backlight, the brightness data BV _S is controlled by performing necessary correction according to the light source information and the subject distance. The brightness value is calculated.

That is, first, the brightness difference data ΔBV is 0.
It is determined whether it is smaller (negative) (# 4).
9). This determination is whether or not the shooting scene is backlit. If 0 ≦ ΔBV, that is, if the backlight is selected (N in # 49,
O), whether or not the brightness data BV _S is smaller than a predetermined threshold value BV _K (# 50), the subject distance D is a predetermined threshold value D2.
Whether the correction data P (= 0.75 · (BV _S −BV _AF )) exceeds the upper limit P1 of the correction data P (# 5) (# 5).
2) and are sequentially determined.

The determination in step # 50 is to estimate whether or not the light source of the subject is natural light. That is, a fluorescent lamp, since the light source under artificial such as incandescent bulbs the luminance data BV _S is substantially 2 to 5 (EV) extent, when the luminance data BV _S is equal to or greater than a predetermined luminance, the subject of the light source is natural light It is assumed that there is.

Further, the correction data P is the brightness data BV _S
And a brightness difference ΔBV ′ between the SAE control data BV _AF and a predetermined coefficient k (k = 0.75 in the present embodiment), which is a control brightness value BV according to the degree of backlight (ΔBV ′). It corrects _S 2 to the over side. this is,
Since the latitude of the film is wide on the overexposed side,
By correcting to the over side according to the degree of backlighting within the limit of correction, the exposure of the subject at the center of the shooting screen is made as appropriate as possible. Further, this makes it possible to obtain proper exposure for the main subject even when the flash light does not easily reach the main subject in rush shooting.

The brightness difference ΔBV ′ is used as the correction data P.
The reason why the correction amount is increased in proportion to the brightness difference ΔBV ′ is that the spectral sensitivity of the AF sensor is biased in the infrared region as compared with the spectral sensitivity of the AE sensor, and Accurate luminance information in the visible region is not obtained (that is, the accuracy of the SAE control data BV _AF is the photometric unit 4).
(It is lower than the photometric data BV _C and BV _O obtained in 1.). Further, for the same reason, the correction data P has an upper limit value.

Further, in the determination of step # 51, when the subject is at a long distance, the size of the subject image K in the photographing screen becomes too small, and the spot metering area (AF control area) surely covers the subject. Since it is unknown whether the subject distance D exceeds a predetermined threshold value D2,
The correction of the control brightness value BV _S 2 to the over side is prohibited.

Therefore, in a backlight scene, BV _S ≧ B
V _K (natural light source), D1 ≧ D (not long distance) and P
If 1 ≧ P (correction value is within the upper limit value) (# 50 to # 52)
NO), data obtained by subtracting the correction data P from the brightness data BV _S (BV _S −0.75 · (BV _S −B
V _AF )) is set as the control brightness value BV _S 2 (# 5
3). Also, in a backlit scene, BV _S ≧ BV _K and D
Even if 1 ≧ D (NO in # 50 to # 51), P> P1
If the correction value is larger than the upper limit value (YE in # 52)
S), data obtained by multiplying the brightness data BV _{S by} the upper limit value P1 of the correction data is set as the control brightness value BV _S 2 (# 54).

On the other hand, when it is a normal light scene (Y in # 49)
ES), when BV _S <BV _K (artificial light source) in the backlight scene (YES in # 50), or BV _S <BV _K (artificial light source) and D> D2 in the backlight scene.
When it is (long distance) (YES in # 51), the brightness data BV _S is set as the control brightness value BV _S 2 without being corrected by the correction data P (# 55). That is, under the above conditions, the exposure control is performed only with the photometric data calculated by the photometric unit 4, without considering the SAE control data BV _AF as the control brightness value.

Particularly, when the subject light source is estimated to be an artificial light source in a backlit scene, the SAE control data BV _AF is not taken into consideration. For example, since there is almost no long wavelength component of 700 nm or more under a fluorescent lamp, SAE control is performed. Data BV _AF
By but comparison whereas the under-Pounds, many long wavelength components of the infrared region under incandescent bulbs, SAE control data BV _AF becomes over-Pounds, the photometric data BV _C or BV _O and SAE control data BV _AF Since the backlight determination cannot be accurately performed, the correction of the control brightness value according to the degree of backlight is prohibited.

Next, the backlight detection based on the brightness difference data ΔBV will be described. This backlight detection is used for the determination of automatic light emission control of the built-in flash 7 described later, and is performed according to the "backlight detection" flowchart shown in FIG.

In the flowchart of "backlight detection" shown in the figure, the object distance D is divided into three areas of "short distance", "medium distance" and "long distance", and the backlight judgment is preset for each area. Levels P2, P3, P4 (P2>P3> P4)
And the brightness difference data ΔBV are compared to detect the backlight. Note that the relationship between the backlight determination levels P2, P3, P4 and the subject distance D is set such that the subject distance D becomes smaller as the distance becomes longer, as shown in FIG.

That is, first, it is determined whether or not the subject distance D is equal to or less than a predetermined threshold value D4 (for example, 3 m) for short distance determination (# 61), and if D ≦ D4 (short distance) (#) If YES in 61), the brightness difference data ΔBV is compared with the back light determination level P2 for short distances to detect back light (# 62). If ΔBV ≧ P2 (YE in # 62).
S), the backlight flag indicating the backlight is set (O
After N) (# 68), the process returns.

D> D4 (NO in # 61) or ΔBV <
If P2 (NO in # 62), it is determined whether or not the subject distance D is equal to or less than a predetermined threshold value D3 (for example, 7 m) for medium distance determination (# 63), and D ≦ D3 (medium distance). If there is (YES in # 63), the brightness difference data ΔBV is compared with the backlight determination level P3 for medium distance (<P2, for example, 0.7 · P2), backlight detection is performed (# 64), and ΔBV ≧. P
If it is 3 (YES in # 64), the backlight flag is set (ON) (# 68), and the process returns.

Further, D> D3 (NO in # 63) or Δ
If BV <P3 (NO in # 64), it is determined whether or not the subject distance D is equal to or less than a predetermined threshold value D2 (for example, 15 m) for long distance determination (# 65), and D ≦ D5 (long distance). )
If so (YES in # 65), the brightness difference data ΔBV and the back light determination level P4 for long distance (<P3, for example, 0.4.
P2) is compared and back light detection is performed (# 66), and Δ
If BV ≧ P4 (YES in # 66), the backlight flag is set (ON) (# 68) and the process returns. On the other hand, D> D2 (NO in # 65) or ΔBV <P4 (#
If NO in 66, the backlight flag is reset (OF
After F) (# 67), the process returns.

Next, the automatic light emission control of the built-in flash 7 will be described with reference to the flowchart of "flash light emission determination" shown in FIG.

Note that the flowchart shown in FIG. 16 shows a case where the camera 1 is provided with shooting-related modes such as a light emission prohibition mode, a night view portrait mode, and a forced light emission mode. The flash off mode forcibly prohibits flash firing in dark places where flash photography is required, and the mode to shoot under natural light.The forced flash mode, conversely, forces the flash to fire in bright places where flash photography is not always necessary. In this mode, the light is emitted for shooting. Further, the night view portrait mode is a mode for illuminating a person with the night view in the background and taking a portrait-like image.

When the flow for "flash emission determination" is entered, first, the exposure control value EV _S 2 (= BV _S 2 + SV) is calculated from the control brightness value BV _S 2 and the film sensitivity SV (# 71). Subsequently, it is determined whether or not the light emission prohibition mode is set (# 72), and if the light emission prohibition mode is set (YES in # 72), the light emission flag for instructing the flash light emission is reset (OFF). Being (# 7
8) Return. If the light emission prohibition mode is not set (NO in # 72), it is sequentially determined whether or not the night view portrait mode and the forced light emission mode are set (# 73, # 74), and either mode is selected. If it is set (YES in # 73 or # 74), the light emission flag is set (ON) (# 79), and the process returns.

If none of the modes is set (NO in # 72 to # 74), then the exposure control value EV _S
2 is smaller than the exposure limit EVh of the shake limit, whether the control brightness value BV _S 2 is smaller than the threshold value BV _K for light source estimation, and whether the backlight flag is set or not is sequentially determined (# 75- # 77), EV _S 2 <EVh, BV _S 2 <
If either BV _K or backlight flag set (# 7
If YES in 5 to # 77), the light emission flag is set (ON) (# 79), and if EV _S 2 ≦ EVh, BV _S 2 ≧ BV _K and the backlight flag reset (N in # 75 to # 77).
O), the light emission flag is reset (OFF) (# 7
8) Return.

In the above flash emission control, steps # 72 to # 74 control the flash emission based on the photographer's intention. In addition, step # 75
Since proper exposure control cannot be performed without auxiliary light for a subject that is darker than the camera shake limit, step # 76 is to emit a flash light. If it is estimated that the subject light source is an artificial light source, as described above, The reliability of the SAE control data of the spot that detects the brightness of the subject is low, and since the subject brightness is lower than outdoor daylight, the flash is always activated to prevent exposure control failure as much as possible. To do. In addition, step # 77
When the backlight flag is set, the main subject becomes darker than the background, so the flash is emitted to properly expose the main subject.

FIG. 17 shows the photometric data BV from the photometric unit 4.
It is a diagram showing a relationship between a range of subject brightness of _S and distance measuring unit 5 according to the exposure control only by the scope and the photometric unit 4 according to the photometric data BV _S of object brightness exposure control by the spot of SAE control data.

In the figure, the threshold value BV _K for estimating whether or not the subject light source is an artificial light source is BV = 4 EV. Therefore, in the region of BV _S > 4 EV, the exposure control is performed using the photometric data BV _S based on the output of the photometric sensor and the SAE control data based on the output of the distance measuring sensor 9, and in the region of BV _S ≦ 4 EV, The exposure control is performed using only the photometric data BV _S based on the output of the photometric sensor.

Further, the curve of is a line of subject brightness which requires flash emission due to the hand shake limit. In addition,
The line is calculated by BV = AV + TV-SV (EV). Where SV is film sensitivity, AV is aperture value, and TV
Is the shutter speed.

With a zoom lens, F is approximately proportional to the zoom ratio.
_{Since No} increases, AV = log ₂ (F _No ) ²
Since the shutter speed is inversely proportional to the focal length f, TV = 1
It becomes og ₂ (1 / f). Therefore, the line of BV =
It is calculated by 2 · log ₂ (F _No ) −log ₂ (f) −Sv. In the figure, the film sensitivity ISO = 400 is assumed, and BV = 7 is calculated.

Therefore, in the exposure control in the flash photography shown in the flowchart of FIG. 16, BV = 4 (EV)
In the area shown by the diagonal line surrounded by the line and the line, the built-in flash 7 is automatically made to emit light and flash photography is performed.

[0094]

As described above, according to the present invention,
First photometric means for detecting overall luminance information based on the amount of light received by the photometric light receiving means having spectral sensitivity characteristics in the visible region, and imaging for distance measurement having spectral sensitivity characteristics in the area deviated from the visible region The overall brightness is provided with distance measuring means for detecting distance information of the object based on the imaged image of the means, and second light measuring means for detecting spotwise brightness information based on the amount of light received by the imaging means for distance measurement. In a camera that performs exposure control based on information and spot-like brightness information, when the whole brightness information is equal to or greater than a predetermined threshold value, control for exposure control based on the whole brightness information and spot-like brightness information When the brightness value is set and the overall brightness information is smaller than the predetermined threshold value, the control brightness value is set based only on the overall brightness information. Therefore, the light source of the subject is an artificial light source such as a fluorescent lamp. Presumed to If you is lower spot photometric information reliable as the luminance information is not used as exposure control allows exposure control with high accuracy.

In the above camera, when the overall luminance information is smaller than a predetermined threshold value, that is, when the light source of the subject is an artificial light source and it is dark, the flash light of the built-in flash light generating means is always emitted. Since this is set, more appropriate exposure control is possible.

Further, in the above camera, the control brightness value is corrected by the correction data based on the brightness difference between the overall brightness information and the spot-like brightness information. By performing overexposure with a correction amount according to the difference, proper exposure of the main subject in the shooting screen becomes possible.

Further, since the correction data is made proportional to the brightness difference, proper correction data can be obtained even when the reliability of spot-like brightness information is low.

[Brief description of drawings]

FIG. 1 is a front view showing an appearance of a camera according to the present invention.

FIG. 2 is a diagram illustrating a ranging area in a shooting screen.

FIG. 3 is a diagram showing a schematic configuration of a distance measuring unit.

FIG. 4 is a block diagram showing a photometry and distance measurement control system of the camera.

FIG. 5 is a diagram showing an example of an AF area and an AE area set in an imaging area of a line image sensor of a reference portion.

FIG. 6 is a main flow of arithmetic control of AF data and SAE data using an image captured by an AF sensor.

FIG. 7 is a chart diagram for selecting an AE control area based on an AF control area and a subject distance.

FIG. 8 is a diagram showing spot photometric positions by a distance measuring sensor at each subject distance.

FIG. 9 is a diagram showing a preferable maximum number of pixel data in an AE control area with respect to a subject distance.

FIG. 10 is a subroutine of “AE control area setting”.

FIG. 11 is a subroutine of “AE control area setting”.

FIG. 12 is a subroutine for calculating SAE control data.

FIG. 13 is a flowchart for calculating a control brightness value for exposure control.

FIG. 14 is a flowchart of “backlight detection”.

FIG. 15 is a diagram showing a relationship between a subject distance and a backlight judgment level.

FIG. 16 is a flowchart of “flash emission determination”.

[17] the relationship between the range of subject luminance exposure control by only the photometric data BV _S by the scope and photometry of subject brightness of exposure control by the spot of SAE control data by a distance measuring unit photometric data BV _S by the photometry unit FIG.

[Explanation of symbols]

1 Camera 2 Camera Main Body 3 Photographing Lens 4 Photometer (First Photometer) 5 Distance Meter (Distance Means) 6 Viewfinder Objective Window 7 Built-in Flash (Flash Generation Means) 7 Shooting Screen 8 Distance Measurement Area 9 AF Sensor ( Image pickup means, discrimination means, control brightness value setting means, light emission control means, correction data setting means, correction means 91,92 Line image sensor 10 Lens system 101,102 Microlens array 11 Finder optical system 12 CPU (second photometry) 121) Distance calculation unit 122 Photometry calculation unit 123 Light source correction unit 124 Exposure correction unit 125 Memory 125a Standard portion data area 125b Reference portion data area 125c AF data area 125d SAE data area 125e Correction data area 13 AF control unit 14 Focal distance detection Part K Subject L Optical axis

Claims (4)

[Claims] 1. A first photometric unit that receives light in a photographic screen by a light receiving unit having a spectral sensitivity characteristic in the visible region, and detects first luminance information for the entire photographic screen based on the received light amount; Based on the amount of light received by the distance measuring unit that detects a distance information of the object based on the captured image by capturing an image of a partial region of the photographic screen with an image capturing unit having a spectral sensitivity characteristic in a region deviated from the region. In a camera provided with second photometric means for detecting second brightness information for a subject in a distance measurement area, and exposure control being performed based on the first and second brightness information, the first brightness information is predetermined. Discriminating means for discriminating whether or not it is equal to or more than the threshold of
When the brightness information is equal to or higher than the threshold value, a control brightness value for exposure control is set based on the first and second brightness information, and when the first brightness information is lower than the threshold value, the first brightness information is set to the first brightness information. A camera comprising: a control brightness value setting means for setting the control brightness value based on brightness information. 2. The camera according to claim 1, further comprising: a flash light generation means; and a light emission control means for causing the flash light generation means to emit light when the first luminance information is smaller than the threshold value. camera. 3. The camera according to claim 1, wherein the correction data setting means sets correction data based on a brightness difference between the first brightness information and the second brightness information.
A camera comprising: a correction unit that corrects the control brightness value with the correction data. 4. The camera according to claim 3, wherein the correction data is proportional to the brightness difference.