JPH0439636A - Automatic exposure controller for camera - Google Patents

Abstract

PURPOSE:To make the possibility of photographing with appropriate exposure high by calculating an exposure value based on the result of divided photometry without adding photographic distance related information in the case that the photographic distance related information cannot be detected. CONSTITUTION:In the case that the decision means 105 decides that the photographic distance related information cannot be detected, an exposure value arithmetic means 103 calculates the exposure value based on a brightness value from a divided photometry means 101 without adding the photographic distance related information. Then, a photographing means 104 executes photographing based on the exposure value calculated by the means 103. Thus, sure photographing is executed and the possiblity of obtaining a the appropriate exposure is made high even in the case that the photographic distance cannot be detected.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to an automatic exposure control device for a camera that is capable of determining an exposure value based on luminance values and photographing distances in multiple areas of a photographic field. .

B. Prior Art A conventional example of this type of automatic exposure control device is disclosed in Japanese Patent Laid-Open No. 1-154133 by the present applicant. This measures the light by dividing the subject into multiple areas.
The brightness for each area is determined from the photometry results. Then, the three parameters are ■the maximum value of these brightnesses (maximum brightness), ■the maximum brightness difference (difference between the large brightness and the minimum brightness), and ■the photographing distance detected by a well-known detection member (photographing distance related information). The exposure value is determined based on the

The reason why the photographing distance is taken into consideration in determining the exposure value is as follows.

That is, when taking photographs, for example, when the photographing distance is 5 m or less, people are generally photographed, and in this case, it is necessary to determine the exposure with emphasis on low luminance. On the other hand, when the photographing distance is 5 m or more, landscape photography is often performed, and in this case, balanced exposure across the entire screen is required.

Therefore, in the automatic exposure control device, by taking the photographing distance into consideration when determining the exposure value, it is possible to photograph any subject with proper exposure.

C1 Problems to be Solved by the Invention However, 1. For example, if the attached photographic lens is an old model and does not have a photographic distance detection function, it is impossible to detect the photographic distance.

Further, even if the camera has a shooting distance detection function, depending on the detection method, the shooting distance may not be detected during MF (manual focusing) mode. In this case, since the shooting distance information is not transmitted to the camera body, the camera body determines the shooting distance as Om, that is, macro photography, and determines the exposure value, which may result in an undesired photo being taken. be. Alternatively, the exposure value cannot be calculated because the photographing distance information is not input, and photographing may be prohibited due to the release lock. In other words, the lenses that can be used with a camera body equipped with the above-mentioned exposure control device are limited, and even if you purchase the camera body, you may not be able to use the lens you currently own, or you may end up taking photos with extremely inappropriate exposure. There is an inconvenience.

A technical object of the present invention is to increase the possibility of photographing with proper exposure even when the photographing distance is undetectable.

00 Means for Solving the Problems To explain with reference to FIG. 1, which is a diagram corresponding to the claims, the present invention includes a divided photometry means 101 that divides a field into a plurality of regions and outputs a luminance value for each region, Distance information detection means 102 and 1 for detecting information related to shooting distance
Exposure value calculation means 103 that calculates an exposure value based on the luminance value from the divisional photometry means 101 and photographing distance related information detected by the distance information detection means 102; and the exposure value calculated by the n ratio value calculation means 103. The present invention is applied to an automatic exposure control device for a camera equipped with a photographing means 104 that performs photographing based on the following. The above-mentioned problem is solved by providing a determining means 105 for determining whether or not the distance information detecting means 102 can detect photographing distance related information, and by configuring the exposure value calculating means 103 as follows.

That is, when the determination means 105 determines that the photographic distance-related information cannot be detected, the exposure W calculation means 103 calculates the exposure value based on the brightness value from the split metering means 101 without taking the photographic distance-related information into consideration. Calculate.

When it is impossible to detect the E0 effect photographing distance related information, the n output value is calculated based on the luminance value from the divided photometry means 101 without taking the photographing distance related information into consideration. As a result, even when using a lens whose shooting distance cannot be detected or when the focusing mode is MF mode, you can take pictures reliably.
In addition, the possibility of proper exposure is increased.

F. Example An embodiment of the present invention will be described with reference to FIGS. 2 to 8.

FIG. 2 is a block diagram showing the overall configuration of an automatic exposure control device for a camera according to the present invention. As shown in FIG. 3, the camera of this embodiment divides the field 30 into five photometric areas 30a.
A method of measuring light by dividing it into ~30e (split metering method)
The photometric element 1 (FIG. 2) consists of five divided photometric elements 1a to 1e corresponding to the five photometric areas 308 to 30e. Each of the photometric elements 1a to 1e receives subject light in the respective photometric areas 30a to 30e, and outputs an electric signal to the photometric circuit 2 according to the amount of the received light. The photometric circuit 2 logarithmically compresses the outputs of the divided photometric elements 18 to 1e to obtain brightness values B1 to B5, which are converted into C
Input to PU3. Here, B1 is the central photometric area 3
0a brightness value, B2-B5 is the photometry area 3 around 1
The brightness values range from 0b to 30e.

Reference numeral 10 denotes an exchangeable photographic lens, which includes a focusing optical system (hereinafter simply referred to as a lens) 11, a distance detection member 12 that detects the photographing distance X from the position of the lens 11, and a lens ROM.
13, the lens ROM 13 has a focal length storage section 13a that stores the focal length f of the photographic lens 10, and autofocus compatible identification data (information indicating whether autofocus is possible, hereinafter referred to as AFmFm-taper). It has an identification data storage section 13b that stores the information (referred to as "ID"). Distance detection member 12
Detects the relative position of the lens 11 from the amount of rotation of the AF motor 5, which will be described later, when the lens 11 is at the infinity position (the most retracted position). It depends on the shooting distance X.

Here, the photographing lens 10 is capable of autofocus, and when the photographing lens 10 is attached to the camera body, the photographing distance X, focal length f, and A indicating that AF is possible are set.
FmFm-data can be input to the CPU 3. This kind of photographic lens 10 is capable of AF and has a lens ROM.
13 and a distance detection member 12, but the camera of this embodiment has a photographing lens that cannot be AFed and a lens ROM 13.
It is said that it is also possible to attach older photographic lenses that do not have a camera.

Reference numeral 20 denotes an AF sensor having a pair of re-imaging lenses 22a and 22b arranged behind the planned focal plane 21 and a pair of photoelectric conversion element arrays 23a and 23b. The object light is the lens 22a
, 22b, and are received by the photoelectric conversion element arrays 23a and 23b, respectively. The outputs of the arrays 23a and 23b are input to the focus detection circuit 4, and the focus detection circuit 4 calculates the defocus amount and defocus direction for moving the photographic lens 10 to the in-focus position based on the input signals. , and inputs the calculation results to the CPU 3. The CPU 3 performs AF according to the defocus amount and defocus direction.
The motor 5 is parked, and the lens 11 is thereby opened and moved by a predetermined amount in a predetermined direction to focus on the subject.

Further, an exposure control circuit 6 is connected to the CPU 3, and this exposure control circuit 6 displays the aperture value and shutter speed on a display device (not shown) via the display circuit 7, and also opens the aperture 8 and shutter 9. and take a picture.

Next, based on the flowcharts in Figures 4 to 6, CP
The procedure of exposure value determination control by U3 will be explained.

When the release button (not shown) is pressed halfway in step #101, the program shown in FIG. 4 is started.

In step 0102, a photometric operation is performed. That is, the photometric circuit 2 is operated to calculate the luminance values B1 to B5 from the outputs of the divided photometric elements 18 to 1e.

Next, in step #1o3, the set photometry mode is determined. In this embodiment, this photometry mode is
Center-weighted (CW) metering mode that determines exposure with emphasis on the brightness value B1 of the central part of the field, and split mode (CW) that determines exposure based on the brightness values B1 to B5 of the five photometric areas mentioned above.
MP) photometry mode can be set, and switching is performed by operating a photometry mode changeover switch (not shown).

If the center-weighted metering mode is selected, the process proceeds to step #115, where the brightness value B obtained by the divided metering element 1a is
An exposure value Ban5 is calculated based on the exposure value Ban5, and then, when the release button is operated, a photograph is taken based on the exposure value Ban5. To be more specific, the exposure value B an
The aperture value and shutter speed are calculated from s, and the aperture 8 and shutter 9 are parked via the exposure control circuit 6 based on the calculation results. Thereafter, the process ends in step #116.

On the other hand, if it is determined in step #103 that the split (A M P ) metering mode is set, the process proceeds to step #104, where the first lens identification is performed, that is, if the attached photographic lens 10 is the lens R. ○Identify whether or not it has M13. Having the lens ROM 13 means that the focal length f and AF identification data can be detected, and in this case, the process advances to step #1o5. In step #105, the AFWt-specific data stored in the lens ROM 13 is read to identify the second lens, that is, to identify whether or not the loaded photographic lens 1o is capable of AF. If the photographing lens 10 is capable of AF, step #
Proceeding to step 106, it is determined whether the focusing mode of this photographic lens 10 is AF mode (autofocus mode) or MF mode (manual focus mode), and AF mode is determined.
If it is the mode, the process advances to step #107. Here, the determination in step #106 is based on, for example, AF/MF (not shown).
Judging from the state of the changeover switch.

In step #107, the focal length f is read from the lens ROM 13, and it is determined whether the focal length f is 35 mm or more and 210 mm or less. If this is affirmed, step #1
Proceed to 08.

On the other hand, in the case of a photographic lens without lens ROM 13, in the case of a photographic lens that has lens ROM 13 but cannot AF,
Alternatively, even if AF is possible, if the mode has not been switched to MF mode, the process proceeds to step 113, the 2D algorithm. Also, if the focal length f is less than 35 m or more than 210 am, the process proceeds to step #113. Step #1
Processing No. 13 will be explained in detail later.

In step #1o8, the lens 11 of the photographing lens 10 is driven to the infinity position, so-called infinity reset 6, that is, the distance detection member 12 in this embodiment Since the relative position of the lens 11 is detected from the amount of rotation of the motor 5b, and the photographing distance X is thereby detected, it is necessary to perform this infinity reset before performing focusing, which will be described later. Here, since the above-mentioned infinity reset cannot be performed when the above-mentioned photographing lens that cannot be AF is attached or when the MF mode is set, it is impossible to detect the photographing distance.

After that, focusing is performed in a routine not shown. That is, the focus detection circuit 4 includes the AF sensor 20 described above.
The defocus amount and defocus direction for driving the photographing lens 10 to the in-focus position are calculated based on the outputs of the photoelectric conversion element arrays 23a and 23b, and the calculation results are input to the CPU 3. The CPU 3 drives the AF motor 5 according to the defocus amount and the defocus direction, and drives the lens 11 to the in-focus position.

In step #109, the output of the distance detection member 12 is read to detect the position of the photographing lens after focusing, that is, the photographing distance X, and then the process proceeds to step #110, the 3D algorithm. This process will be detailed later.

After the 3D algorithm, it is determined in step #11.1 whether the flag FLG is 1 or not, and if it is 1, step;
Proceed to step 12. In step #112, the aperture value and shutter speed are calculated based on the exposure value Ban5 obtained as a result of the 3D algorithm, and as described above, when the release button is operated, the aperture value and shutter speed are calculated based on the calculated aperture value and shutter speed. and take a picture. On the other hand, if the flag FLG is not 1, the process proceeds to the 2D algorithm in step #113, and then in step #114, the aperture value and shutter speed are calculated based on the exposure value obtained as a result of the 2D algorithm, and based on the results. and take a picture.

Next, the 3D algorithm of step #112 will be explained based on FIG.

First of all, the contents of the variables used in this process are shown below.

X: Shooting distance f: Focal length B1: Brightness 82 to B5 of central region 30a: Brightness Bma of peripheral regions 306a to 360e
x: Maximum brightness value (maximum brightness) of the above five areas B
win: Minimum value of brightness of the above five areas (minimum brightness) BM: Average value of brightness of the five areas above (average brightness) Δ: Maximum brightness difference (Bmax-Bmin) Ba
ns: tt Output value This 3D algorithm has shooting distance X, maximum brightness B w
The exposure value is calculated based on three parameters: ax and the maximum brightness difference Δ. First, in step #202, it is determined whether the shooting distance X is 5 m or more (whether X≧5 or not). x If <5, the process proceeds to step 2o3, and thereafter, the exposure value is determined based on the maximum brightness Bmax and the maximum brightness difference Δ, and the control result is as shown in FIG. 7(a).

That is, when Bmax>9 and Δ≧4 (step #2
03 and #204 are both affirmed), in step #205, the exposure value B ans is set to the brightness B1 of the central area.
and when 7<Bmax≦9 and 2≦Δ×4 (if both steps #206 and #207 are affirmed)
In step #208, the exposure value B ans is set to the average brightness BM. After steps #205 and #208,
In step #215, flag FLG is set to 1, and in step #
At step 217, the process returns to the process shown in FIG. In other cases, proceed to step #216 without setting the exposure value, and flag F.
The process returns to the process shown in FIG. 4 with LG set to zero.

On the other hand, if it is determined in step #202 that X≧5, the process proceeds to step #209, and the exposure value B ans is determined based on the maximum brightness Bmax, the maximum brightness difference Δ, and the focal length f. The result is as shown in FIG. 7Cb). That is, in the case of B ll1ax > 10 and Δ≧3 (when both steps #2o9 and ;210 are affirmed), the exposure value B ans is set to a value weighted to low brightness (B1 + B win) / 2 in step key 211, 8 again
When <Bn+ax≦10 and f≦100 (110) (
If both steps #212 and #213 are affirmative), the exposure value B ans is set to the brightness B1 of the central area in step =214. Step #210.3213
After that, in step #215, the flag FLG is set to 1 and the process returns to the process shown in FIG. In other cases, the process proceeds to step #216 without setting the brightness value, sets the flag FLG to zero, and returns to the process of FIG. 4.

According to the above 3D algorithm, the exposure value is calculated taking the photographing distance X into consideration, so that, as described above, when photographing a person or a landscape, for example, an exposure value Ban5 suitable for the photographing scene is determined. Note that this 3D algorithm is an example, and if the exposure value B ans is calculated based on the brightness values B1 to B5 and the shooting distance X, the content is limited to that shown in Figure 5. Not done.

Next, the 2D algorithm of step #113 will be explained with reference to FIG.

This process determines the exposure value B ans based on the maximum brightness Bmax and the maximum brightness difference Δ without considering the photographing distance X, and the result is shown in FIG. That is, (1) When Bmax≦5 (when step #302 is negative): ■ When ∆>4 (step group 303 is affirmative).

Bans=BM (Step #304) ■When 2Δ≦4 (Step #30S affirmative), Ban
5=B L M (step g306) - When Δ≦2 (step group 305 negative).

Ban5=B1 (step #307) (2) If 5<B+wax≦8 (step tS308
is denied): ■When Δ>4 (step #309 is affirmative).

Bans=BM (step t!310) ■2kuΔ≦4(
Step 3311fr), B ans=B
M (step 0312) ■Δ≦2 (step group 31)
Ban5 = B1 (step 0313)
(3) When 8<Bmax≦10 (step: !314
); ■When Δ〉4 (step #315 affirmative), B ans
= B win (Step 0316) ■2kuΔ≦4(
Step #317 (affirmative), Ban5=B LM
(Step a31.8) Here, BLM is the average value of the minimum brightness Bmin and the average brightness BM, that is, Bmin+BM.

■When Δ≦2 (Step 1: 317 negative), Ban5
=B1 (step #319) (4) When 10<B+aax (when step #314 is negative): ■When Δ>4 (step = 320 affirmative), B ans
= B l1lin (Step 0321) ■2kuΔ≦
4 (step #322 affirmative), Ban5=Ba
+in (S' = Tsubu 0323) ■Δ≦2 (Step #
322 negative), then Ban5=B1 (step #32
4) Unlike the 3D algorithm, the above 2D algorithm does not take into account the shooting distance X when determining the exposure value, but since it is based on the split metering results, it is possible to obtain the appropriate exposure with a high probability. Note that the content is not limited to that shown in FIG. 6 as long as the exposure value B ans is determined based on the brightness values B1 to B5 without taking into account the photographing distance.

According to the processing procedure of FIGS. 4 to 6 explained above, the AF
If a disabled shooting lens is attached or the focusing mode is MF mode (in both cases, the shooting distance cannot be detected), a 2D algorithm is executed and the exposure value is determined based on the brightness value obtained from the split metering results. decided,
Photographing is performed based on this exposure value. Therefore, even if it is impossible to detect the shooting distance, the image will be taken reliably, and since the exposure value is determined based on the split metering results, there is a high possibility that the correct exposure will be obtained. It can be used with confidence.

On the other hand, if the photographing distance can be detected, the 3D algorithm is executed and the exposure value is determined by taking the photographing distance into consideration, as in the past, so that the possibility of obtaining proper exposure is further increased.

Furthermore, in the above description, even when the lens ROM 13 is not provided, the process proceeds to the 2D algorithm. That is, in the 3D algorithm of this embodiment, the focal length f is used to determine the exposure value B ans (step 321
3) The absence of the lens ROM 13 means that the focal length f cannot be detected. Therefore, in this case as well, the exposure value B ans is determined by the 2D algorithm.

Furthermore, in this embodiment, if the combination of the maximum brightness Bmax and the maximum brightness difference Δ does not satisfy a predetermined condition in the 3D algorithm, the exposure value B ans is not determined even if the shooting distance X can be detected. Since the exposure value B ans is determined by proceeding to the 2D algorithm, it is possible to further increase the possibility of obtaining an appropriate exposure.

Furthermore, when the focal length f of the photographic lens is 35 mm or less, the depth of field is deep, so the photographic scene (portrait photography, landscape photography, etc.) is classified by the photographing distance X and the exposure value B an
There is no need to determine s, and in this case the exposure value B ans is determined by a 2D algorithm. Furthermore, when the focal length f is 210 mm or more, it is difficult to determine the photographic scene based on the photographing distance X, so the exposure value B ans is determined by the 2D algorithm in this case as well.

In the configuration of the above embodiment, the divided photometric elements 1a to 1e
The photometry circuit 2 constitutes a divided photometry means 101, the distance detection member 12 constitutes a distance information detection means 1.02, the CPU 3 constitutes an exposure value calculation means 103 and a determination means 105, and the exposure control circuit 6 constitutes a photographing means 104. .

Note that the method of dividing the field is not limited to that shown in FIG. 3. Further, the distance detection member 12 is not limited to the one described above, and for example, a distance encoder that detects the i-shadow distance by a known method using an encoder brush and an encoder pattern provided on the photographing lens may be used.

This distance encoder can be used with shooting lenses that are only capable of MF,
Since the shooting distance can be detected even in F mode, the determination as to whether or not the shooting distance can be detected depends on, for example, whether or not the above-mentioned distance encoder is provided. Further, if a distance encoder is provided, the above-mentioned infinite distance reset is not necessary.

Furthermore, similar effects can be obtained by using the defocus amount and defocus direction detected by the focus detection circuit 12 instead of the photographing distance. Therefore, the shooting distance related information in this specification also includes the defocus amount and defocus direction.

G1 Effects of the Invention According to the present invention, when photographing distance related information can be detected, the exposure value is calculated by adding the photographing distance to the divided photometry result (brightness value), and the photographing distance related information can be detected. If this is not possible, the exposure value is calculated based on the above-mentioned split metering results without taking into account information related to the shooting distance, so if the shooting distance can be detected, it is possible to take pictures with proper exposure. Further, even when the photographing distance cannot be detected, photographing can be performed reliably and the possibility of obtaining proper exposure can be increased. Therefore, there are no restrictions on the lenses that can be used, and even older lenses can be used with confidence.

[Brief explanation of the drawing]

FIG. 1 is a complaint correspondence diagram. 2 to 8 show an embodiment of the present invention, FIG. 2 is a block diagram showing the overall configuration of an automatic exposure control device for a camera according to the present invention, and FIG. 3 is a divisional photometering in the field. FIG. 4 to FIG. 6 are diagrams showing regions, and FIG. 7(a) is a flowchart showing a procedure for determining an exposure value. (b) is a diagram showing exposure values determined by the 3D algorithm, and FIG. 8 is a diagram showing exposure values determined by the 2D algorithm. 1: Photometric element 1a to 1e: Split photometric element 2: Photometric circuit 3: CPU 4: Focus detection circuit 5: AF motor 6: Exposure control circuit ]O: Photographic lens 11: Focusing optical system (lens) 12: Distance detection Component 13: Lens ROM20: A
F sensor 30: Field of view 30a to 30e: Photometry area 101: Division photometry means 102: Distance information detection means 103: n output value calculation means 105: Judgment means: Photographing means

Claims (1)

[Scope of Claims] 1) Divisional photometry means that divides the field into a plurality of regions and outputs brightness values for each region, and distance information detection means that detects information related to shooting distance; an exposure value calculation means for calculating an exposure value based on the brightness value from the photometry means and the shooting distance related information detected by the distance information detection means; and an exposure value calculation means for calculating the exposure value based on the exposure value calculated by the exposure value calculation means. An automatic exposure control device for a camera, comprising: a determining means for determining whether photographing distance related information can be detected by the distance information detecting means; If it is determined by the means that the photographing distance related information cannot be detected, the exposure value is calculated based on the luminance value from the split metering means without taking into account the photographing distance related information. Automatic exposure control device. 2) Even if the exposure value calculation means can detect the photographing distance related information, if the luminance value from the divided photometry means does not satisfy a predetermined condition, the exposure value calculating means takes the photographing distance related information into account. 2. The automatic exposure control device for a camera according to claim 1, wherein the exposure value is calculated based on the luminance value from the divided photometry means.