JPH1172818A - Multi-point range finder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multi-point range finder strong in a shutter chance by excluding the locking of a release and a warming as much as possible, while accurately focusing it on a subject and while maintaining a high reliable deciding function. SOLUTION: A multi-point range finder for measuring the distances up to respective objects to be photographed located at plural points in a photographic picture, to uniquely decide the focusing position of a photographic lens 6 is provided with an image deciding means 2 for comparing respective reliable values in a range-finding calculation process for the plural points with a prescribed value and a CPU 10 capable of controlling a series of range-finding sequence including the decision of the focusing point of the photographic lens 6 and changing the prescribed value.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a multi-point distance measuring apparatus, and more particularly to a multi-point distance measuring apparatus capable of judging the reliability of a result of distance measurement in auto focus (AF) of a camera.

[0002]

2. Description of the Related Art The AF method of a camera is roughly divided into an active type in which a signal is projected from the camera side to a subject and distance measurement is performed using reflected signal light, and a passive type in which an image signal of the subject is used. There are two methods.

In particular, the passive type can easily determine the reliability of distance measurement depending on the shape of an image signal. For example, Japanese Utility Model Laid-Open Publication No. 59-101231 discloses a method in which when the reliability of distance measurement is low, a result of the distance measurement at that time is not used and the camera is set to a fixed focus. Also, a method has been proposed in which a release lock is used when the reliability of distance measurement is low.

[0004] Japanese Patent Application Laid-Open No. 8-262317 discloses that
A so-called multi-AF function-equipped camera capable of measuring a distance at a plurality of points in a picture screen is disclosed in which the reliability determination technology is combined.

[0005]

However, the method described in Japanese Utility Model Application Laid-Open No. 59-101231 can only focus on a certain distance if the reliability of distance measurement is low. There is a problem.

[0006] Also, Japanese Patent Application Laid-Open No. 8-262317 discloses that
When all points are unreliable, there is a problem that a warning is issued and a photo opportunity is missed.
In addition, a camera that performs release lock processing has a problem that the shutter cannot be released when the user wants to take a picture.

The multipoint distance measuring apparatus of the present invention has been made in view of such a problem, and an object thereof is to accurately measure an object while maintaining a high reliability judgment function. It is an object of the present invention to provide a multi-point distance measuring device that is resistant to a photo opportunity by eliminating a release lock and a warning while focusing.

In addition, the multi-point distance measuring apparatus of the present invention is capable of focusing on a main subject without being confused with a rough subject in front of the subject and enhancing the ability to reduce a failed photograph as much as possible by the enhancement of the reliability judgment function. An object of the present invention is to provide a multi-point distance measuring device that can be reduced.

[0009]

In order to achieve the above object, a multipoint distance measuring apparatus according to a first aspect of the present invention measures distances to respective objects located at a plurality of points in a photographing screen. A multi-point distance measuring device for uniquely determining the focus position of the photographing lens, comparing means for comparing each of the reliability values and a predetermined value in the distance measurement calculation process for the plurality of points, and determining the focus position of the photographing lens. And a control means capable of changing the predetermined value while controlling a series of distance measurement sequences including:

[0010] The multipoint distance measuring apparatus according to the second invention comprises:
In the multipoint distance measuring apparatus according to the first invention, there is provided detecting means for detecting a shooting state of the camera, and the control means changes the predetermined value in response to an output of the detecting means.

A multipoint distance measuring apparatus according to a third aspect of the present invention
In the multipoint distance measuring apparatus according to the first invention, the predetermined value is a first determination level designed so that the comparing means generates an output only when the reliability value is higher than the predetermined value. Even if the confidence value is lower than the predetermined value, the comparison means is switched to at least two levels of a second determination level set to generate an output, and the control means When determining the focus position of the photographing lens based on the distance measurement result of the point, first, the first determination level is selected, and the reliability values of the respective distance measurement results for the distance measurement point are all the predetermined values. If it is determined to be lower than the above, the first determination level is switched to the second determination level.

Further, a multipoint distance measuring apparatus according to a fourth aspect of the present invention comprises:
In the multipoint distance measuring apparatus according to the first invention, a detecting means for detecting a state of a subject image signal is provided, and the control means selects the subject image signal when selecting a point to be focused from among the plurality of points. It is determined whether or not the state of the signal meets a predetermined condition, and points determined not to be matched are excluded from the point selection range.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First, an outline of the present embodiment will be described. The distance measuring apparatus for a camera according to the present invention can determine a distance between a plurality of points on a screen and determine the reliability of a distance measurement result to each subject existing at the plurality of points in a plurality of steps. Having. The control means for controlling the sequence of the cameras determines the focusing distance from the plurality of points while switching the judgment steps of the judgment means.

Further, the photographing state of the camera is detected, and the determination step is switched according to the photographing state, so that distance measurement is performed with reliability in accordance with the photographing scene. According to the above-described method, since it is not impossible to perform distance measurement due to the need for more reliability than necessary, it is possible to take an image with a correct focus and to prevent the distance measurement from being impossible.

An embodiment of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a diagram showing a configuration of a multipoint distance measuring apparatus according to a first embodiment of the present invention, wherein a passive type distance measuring apparatus 1, an image determining means 2, and an arithmetic control means ( CPU) 10 and photographing lens 6
And a subject luminance measuring circuit 5 and a mode detecting means 4. The CPU 10 is connected to a release switch 3 for detecting a pressing operation of a release button by a photographer. The CPU 10 detects the pressing timing of the release switch 3, activates the distance measuring means 1 and the image judging means 2 and detects its output, determines the focus position of the taking lens 6, and determines the position of the focusing lens. Control.

FIG. 2A is a diagram showing the configuration of the passive type distance measuring apparatus 1 described above. 11a of FIG.
Reference numeral 11b denotes a light receiving lens corresponding to both eyes of a human being, which is arranged at a distance between base points (base length) B and forms an image of the subject 9 on the sensor arrays 12a and 12b.

If the subject 9 is a black and white chart as shown in the figure, a step-like image as shown in FIGS. 2B and 2C is formed on both sensor arrays 12a and 12b. You. This is because the light signal in the white part is strong and the light signal in the black part is weak.
When the relative image position difference x is obtained, the subject distance L is obtained from the focal length f of the light receiving lens and the base line length B according to the principle of triangulation, and the subject distance L is obtained from the relationship of L = (B · f) / x (1) You can ask.

That is, the distance measuring apparatus 1 shown in FIG. 1 comprises the pair of light receiving lenses 11a and 11b and the sensor arrays 12a and 1a.
2b, and an arithmetic unit for A / D converting the outputs of the sensor arrays 12a and 12b and digitally performing an operation called a correlation operation to detect the relative image position difference x.

Further, in the case of the passive type distance measuring apparatus having a configuration as shown in FIG. 2, by performing a distance measurement using a window of figure W _1, although the light receiving lens 11a in front of the object can be ranging, FIG by performing the distance measurement using the medium-W ₂ window,
A subject in a direction having an angle of θ can be measured. If the distance is measured by sequentially switching the windows by applying this principle, it is possible to measure the distance (multi-AF) of a plurality of points in the photograph screen.

In the case of a camera having this function, even if there are two subjects as shown in FIG. 3 and the center of the screen is the background as shown in FIG. . For example, if three points in the screen are measured and the closest distance is focused, the background will not be focused.

Another advantage of the multi-AF distance measuring apparatus is that even if there is a subject having an image pattern as shown in FIG. There is a merit that the focus can be adjusted to that position. As a result, it is possible to provide a more user-friendly camera that focuses on a blind position and shoots an out-of-focus photograph or prohibits release, thereby avoiding a situation where a photo opportunity is missed.

Next, the function of the image determining means 2 will be described. The image judging means 2 of the present embodiment detects an image pattern which the passive AF has, as described later, and outputs digital values of the sensor arrays 12a and 12b to detect a contrast. The position of the maximum value and the minimum value of the signal, and the magnitude of the difference between them, or the regularity of the subject pattern, or the correlation function obtained from the correlation calculation when calculating the image position difference x It has a function of determining whether the result of the image position difference x obtained by the distance measuring device 1 is reliable or not.

In general, it is known that the passive type distance measuring apparatus as described above cannot accurately measure distance when an image pattern as shown in FIG. 5 is used. This non-measurable state is referred to as a default state. In this case, a default signal is output.

FIG. 5A shows a so-called low-contrast subject without a clear contrast in the subject image. Such a state can be detected by detecting the maximum value and the minimum value (MAX, MIN) of the sensor data by the image determination means 2 and comparing the difference with a predetermined value.

FIG. 5B shows a state in which a difference occurs between images viewed by the two light receiving lenses due to optical noise and electric noise, and a correlation cannot be obtained. Such a state can be detected by the image determination means 2 by comparing the minimum value of the correlation function with a predetermined value.

Here, the correlation function can be obtained by the following method. That is, first, the sensor arrays 12a, 1
The output data of each pixel constituting 2b is extracted for a certain range (window) of the sensor arrays 12a and 12b, and the difference between the sensor arrays 12a and 12b is calculated for each pixel of this window. Next, a correlation function is obtained by adding the difference for the window. If the position of the window is shifted one pixel at a time, the correlation function takes the minimum value at the position where the images match most. Therefore, as shown in FIG. 5B, when the degree of coincidence between the two images is poor, the difference between the pixels of the left and right sensor arrays 12a and 12b does not become small at any window position. The function also does not fall below the predetermined value.

In a repetitive pattern as shown in FIG. 5C, a similar image pattern appears even if the position of the window is changed. Therefore, the correlation function decreases at a plurality of window positions. Accurate ranging becomes difficult.
Such a state can be determined by the image determination unit 2 by detecting the periodicity of the MAX value and the MIN value of one of the left and right sensor arrays.

In the example of the image signal shown in FIG. 5 described above, the CPU 10 changes, for example, the contrast determination level in FIG. By changing the minimum value level of the correlation function in FIG. 5B, a default signal is easily output or hardly output. If the default signal is difficult to output, the focusing accuracy is degraded, but it is possible to shoot with a reasonable focus.

On the other hand, if the default signal is set so as to be easily output, the reliability is high when no default signal is output, so that the distance can be measured with high accuracy. However, the default signal is output at all points. Since the distance measurement is no longer possible, the focusing lens is set to a fixed focus, the release is prohibited, or a warning is issued.

As described above, in the first embodiment, by changing the judgment level of the default signal, at first, a point at which the default signal is easily output and strict and accurate focusing is selected is selected. In some cases, the default signal determination level is loosened to prevent the release from being cut off or to prohibit shooting at a focus that does not actually comply.

FIG. 6 is a flowchart showing details of the first embodiment. Step S1 is a multi-AF step in which the distance measuring apparatus 1 shown above changes the direction of distance measurement while switching windows to perform distance measurement at a plurality of points. In step S2, the image determination means 2 first performs default determination in a state where default is likely to occur, and selects a point at which distance measurement can be reliably performed. Next, in step S3, it is determined whether or not all points are default. If NO, the nearest distance is selected from non-default points in next step S4, and the distance selected in next step S5 is selected. Is used to perform focusing.

On the other hand, if it is determined in step S3 that all points are the default, step S6
Go to, for example, lower the level of contrast judgment,
In the next step S7, default determination is performed again. If all points are not in the default state, the process branches again to S4. If it is determined that all points are in the default state again, the focusing distance is set to a fixed focus in step S8, and step S5 is performed. To focus.

As described above, in the first embodiment, the level setting for performing the default determination is switched between two levels. Therefore, if there is a subject suitable for focusing, that priority is given to the subject and accurate. The focus point can be selected. On the other hand, in a state where focusing cannot be performed, the default determination level is lowered to make it difficult to output a default. Although this method degrades accuracy, focusing can be performed in accordance with an actual scene. This makes it possible to provide an easy-to-use camera that avoids large out-of-focus or a state where the release cannot be cut.

Hereinafter, a second embodiment of the present invention will be described.
In the first embodiment, the multi-AF is selected based on the result when the reliability judgment is strictly performed, for example, on the assumption that the higher the contrast, the more accurate the distance measurement can be performed. However, the second embodiment In this case, the opposite restriction is imposed that, even when the contrast is extremely high, it is unnatural as the main subject. This switching of the reliability determination value is also a feature of the present embodiment.

For example, in a subject scene as shown in FIG. 4C, a pillar 9c having a large contrast stands in front of a person 9a as a main subject. The subject is in focus, and the person 9a cannot be focused. In order to focus on the person 9a in such a scene,
It may be determined that the contrast of the column 9c is too strong and is not appropriate as the main subject.

FIGS. 7A and 7B respectively show FIGS.
4A illustrates an image pattern obtained when the scenes of two persons shown in FIG. 4A and a scene composed of a person and a pillar shown in FIG. 4C are received by the sensor arrays 12a and 12b. FIG.
(A) Image pattern (obtained from a scene of two people)
On the other hand, in the image pattern of FIG. 7B (obtained from a scene composed of a person and a pillar), the contrast CP1 of the pillar has a steeper change and is larger than the contrast CC1 of the person, so that the camera is You can judge the difference.

That is, as shown in FIG. 7B, the judgment levels are sequentially switched to A, B, and C, and the contrast is judged. In this case, it is possible to select a multi-AF in a form ignoring the distance measurement result of the pillar.

FIG. 8 is a flowchart showing the details of the second embodiment. In steps S10 to S13, distance measurement (multi-AF) is performed at the center and periphery of the screen, and the contrast of the image pattern data in the window of each distance measurement area is detected. Here the center distance measurement result display L _c, the near distance measurement result as L _p, represents the contrast in C, and in the center represents put C, and P in the surrounding area.

In steps S14, S15 and S16, the contrasts CC and CP at the center and the periphery are compared with predetermined levels CCA and CPA. This is shown in FIG.
It is determined that the reliability level of the distance measurement result is sufficient for the distance measurement accuracy.
This level may be equal between the center and the periphery, but may be different between the center and the periphery in consideration of the priority and the existence probability of the subject.

First, in the case of YES in step S14,
Since the reliability of the center distance measurement is high, the process proceeds to step S15 to select either the center or the periphery. S
In the fifteenth step, it is determined whether or not the peripheral contrast is sufficient to perform the distance measurement. Here, if the reliability of the distance measurement is high as in the center, it can be discussed in the same row,
The step S15 becomes YES, and the process proceeds to a step S17 to determine whether or not the peripheral contrast is appropriate. here,
If the peripheral contrast is appropriate, step S20
Proceed to select the direction of short distance L _p and L _c, performs focusing at step S24.

However, if it is determined in step S17 that the peripheral contrast is too strong, it is unnatural to determine the main subject, and the flow branches to step S19. Here, performs focusing only in the middle of the distance measurement result L _c to eliminate the near distance measurement result L _p.

Here, there is no determination as to whether the contrast is too strong at the center.
This is because the specifications are based on statistics that the subjects in the vicinity are likely to be rough subjects. Also,
Similarly, when it is determined in step S15 that the periphery has low contrast, the periphery is removed from the candidate of the main subject,
Performing focusing only in the middle of the distance measurement result L _c at step S19.

If it is determined in step S14 that the center has low contrast, the flow advances to step S16 to determine the peripheral contrast. If the peripheral contrast is higher than the CPA in step S16, the peripheral is determined to be the main subject, and the peripheral distance measurement result L _p is determined in step S21.
Focusing is performed using. This means that the image pattern as shown in FIG. 7A focuses on the periphery, so that in the scene of FIG. 4A, the person is correctly focused without focusing on the background. Can be.

On the other hand, if NO in step S16, the flow branches to step S18. This means that the contrast is low at both the center and the periphery, so that the contrast is determined again at a lower contrast determination level with respect to the center in step S18. If there is any contrast, the process proceeds to step S19. Although the accuracy is degraded, focusing is performed based on the center distance measurement result.

However, if it is determined again in step S18 that the center has low contrast, the process proceeds to step S22, and the image determination is similarly performed on the peripheral objects at a low contrast level determination level. if the contrast perform focusing at near distance measurement result L _p (step S21). If it is determined that there is no contrast, the camera is fixed at the normal focus position of the camera (step S23), and the lens is controlled by focusing (step S24).

As described above, in the second embodiment, a subject is used as a main subject while switching the judgment level using a contrast value which has been conventionally used for judging the reliability of distance measurement accuracy. It is determined whether or not the focus point is more accurately controlled.

Although this embodiment has been described based on an example of switching of the contrast value determination level, FIG.
The multi-AF result selection may be performed by determining the correlation function described in (1) or the image of the repetitive pattern described in FIG. 5 (c). For example, as shown in steps S61 to S69 in FIG. 9, if the correlation function of the peripheral subject is not sufficiently small, a default may be output, and a design focusing on the center distance measurement result may be performed.

Hereinafter, a third embodiment of the present invention will be described in detail. In the first and second embodiments described above, the value of reliability determination or the determination level of image determination is switched when an AF point is selected to determine a multi-AF distance measurement signal. Although the description has been given of the case of providing a camera that performs a correct subject determination, in the third embodiment, the above-described determination value is switched according to the shooting situation of the camera to disable focusing or release lock. It is intended to suppress as much as possible.

In the photographing scene shown in FIG. 3, when the camera 7 has a zoom lens, a photograph as shown in FIG.
A photograph as shown in (b) is obtained. If the focal length of the lens becomes longer due to zooming, even a distant subject can be photographed larger, and many recent cameras have this function.

In the case of an automatic exposure camera with a so-called program shutter, the aperture value of the photographing lens changes depending on the brightness of the subject. The required focus accuracy changes depending on the zooming position and the aperture diameter. In this embodiment, taking this point into consideration, when the focus accuracy may be low, the reliability determination level is changed to a direction in which the default signal is hardly generated, a warning or a release lock is performed, and the photographer is notified. I try not to give you more hassle than necessary.

FIGS. 10 (a) and 10 (b) show a situation where the photographing lens forms an image of the subject 30a at the position of 31a. Z is the focal length of the lens. FIG. 10A shows an image forming state of a lens having a large open stop and a long focal length, and FIG. 10B shows an image forming state of a lens having a small open stop and a short focal length (image forming position 31b). ). As shown in the figure, when there is an equal error of ΔL on both sides of the subject, an error of ΔZ ₁ occurs on the image forming side with the lens of FIG. 10A, and ΔZ ₂ on the image forming side with the lens of FIG. ΔZ ₁ is much larger than ΔZ ₂ .

That is, in the lens of FIG.
It can be seen that blurring is less likely to occur when a photograph is taken, even if the focus is not as accurate as when using the lens of FIG. As a result of zooming, the focal length and aperture value of the shooting lens change, and the aperture value also changes depending on the brightness of the subject.Therefore, if the precision of focusing is changed in accordance with this change, it can be used in any situation. It is possible to shoot at a fixed focus. Thus, in the third embodiment,
The level of the reliability judgment is switched to the shooting situation.

FIG. 11 is a flowchart showing details of the third embodiment. When the release operation is performed,
First, in step S30, the CPU 10 shown in FIG.
Reads the zooming position of the photographing lens 6 by a zoom position encoder (not shown) provided on the photographing lens 6, determines whether or not this is larger or smaller than a predetermined value Z0 in step S31. Since a more accurate distance measurement is required, step S32
To set the contrast judgment level high (C
A), distance measurement is performed (step S34). Then, in step S35, it is determined whether or not the subject image signal at the time of distance measurement has a sufficient contrast. If there is a sufficient contrast, the process branches to step S36 to perform focusing.

On the other hand, if it is determined in step S35 that the contrast is low, a warning is issued and a fixed focus is set (steps S37 and S38). Alternatively, the release operation itself may be prohibited.

If it is determined in step S31 that the zoom lens position is on the wide-angle side, the low contrast determination level is lowered (CC), and the default is set without increasing the distance measurement accuracy more than necessary. In this case, the process is branched from step S35 to step S36 so as not to branch to a troublesome warning operation at the time of shooting.

FIG. 12 is a diagram showing a modification of the above-described third embodiment. In this case, the level of the contrast judgment is determined based on the luminance BV as the photometric result obtained by the subject luminance measuring circuit 5 of FIG. Is switched.

In the case of a camera using a silver halide film, in practice, the aperture value is determined based on a predetermined program in consideration of the sensitivity of the film, and then the necessary focusing accuracy is determined. An example is shown in which switching is performed with luminance for the purpose of realization.

First, photometry is performed in step S50, and brightness is determined in step S51. If it is bright, the process branches to step S53, the low contrast determination level is lowered (CC), and distance measurement is performed in step S54. This is because when the image is bright, a large amount of light passes through the lens even if the aperture of the photographic lens is stopped down, so that the exposure is appropriate. If the aperture is small, the image will not be out of focus even if the focusing accuracy is slightly poor.
If it is determined in step S51 that the image is dark, the process proceeds to step S52, the low contrast determination level is increased (CA), and distance measurement is performed in step S54. Next, the process proceeds to step S55 to make a default determination. The contents of this step correspond to steps S35 to S39 shown in FIG.
Since these steps are the same as those in the above step, detailed description is omitted.

As described above, in the present embodiment, priority is given to the time lag and the photo opportunity at the time of photographing, so that it is difficult to output the default signal, thereby improving the user's feeling of using the camera.

As described above, in the third embodiment, the reliability determination level is switched according to the shooting scene,
The camera is designed to minimize the hassle of checking the focus when using the camera without sacrificing focus. Further, the mode detection means 4 in FIG. 1 detects the mode in which a moving subject is photographed, or the mode in which priority is given to immediate shooting, such as continuous shooting, by the CPU 10, and switches the reliability determination level accordingly. You may.

Hereinafter, a fourth embodiment of the present invention will be described with reference to FIGS. In the distance measuring apparatus 1 having the configuration shown in FIG. 2, even at the same object distance, FIGS.
As shown in FIG. 13, the size of the subject changes depending on the zoom position of the photographing lens of the camera, but when the multi-ranging points have a fixed angle, zooming is performed as shown in FIGS. The arrangement of the distance measurement points on both sides changes.

FIG. 13A shows the case of the wide-angle side in FIG.
(B) shows the case on the telephoto side. In the situation as shown in FIG. 13B, it is extremely rare that the main subject exists at the outermost distance measurement points LL and RR. Therefore, the level of the reliability determination is strict and the reliability is higher. If not, the camera will not focus on this point to prevent failed photos.

FIG. 14 is a flowchart for explaining the details of the fourth embodiment. First, step S
At 71, the zooming position is detected, and at the next step S72, it is determined whether it is on the telephoto side or the wide-angle side. On the telephoto side, at the RR and LL ranging points farthest from the center of the screen, default data will be output if the reliability is a little low,
The distance is measured by switching the determination level to increase the reliability level (step S73). On the other hand, in the case of the wide angle side, the reliability level is set to the same determination level as the other points (step S74).

Next, in step S75, a default is determined, and the point at which the default is set is excluded from the focus target, the closest distance is selected from non-default points, and focus is performed (steps S76 and S7).
7). As described above, at the time of telephoto, a distance measurement with a low weight of LL and RR is performed to prevent a failed photograph.

As described above, in the fourth embodiment,
At any zoom position and angle of view, it is possible to provide a multi-AF camera that can easily prevent a failed photograph without specially devising a distance measuring device.

The specific embodiment described above includes an invention having the following configuration. (1) In a multi-point distance measuring apparatus that measures distances to respective objects located at a plurality of points in a photographing screen and uniquely determines a focus position of a photographing lens, in a distance measuring calculation process for the plurality of points, Comparing means for comparing each confidence value with a predetermined value, and control means capable of controlling a series of distance measurement sequences including determination of the focus position of the taking lens and changing the predetermined value. Features a multi-point ranging device. (2) a detecting means for detecting a state of the subject image signal;
The control means, when selecting a point to focus from among the plurality of points, determines whether or not the state of the subject image signal matches a predetermined condition, and determines a point determined not to match the state. The multipoint distance measuring apparatus according to (1), wherein the multipoint distance measuring apparatus is excluded from the point selection range. (3) The exclusion of the points is performed only for the points arranged in the peripheral portion of the shooting screen (2).
The multipoint distance measuring device as described. (4) In a multi-point distance measuring apparatus capable of measuring a plurality of points in a shooting screen, a control means for controlling a camera sequence including a distance measuring operation; a distance measuring means for performing a distance measuring operation on the plurality of points; Determining means for comparing the reliability value of the distance calculation process with a plurality of determination values, wherein the control means switches the determination value in accordance with an output of the determination means and then measures the distance to the plurality of points. A multi-point distance measuring apparatus, which performs an operation and determines a focusing position of a photographing lens based on the result. (5) In a multi-point distance measuring device for a camera, a calculating means for inputting a subject image and performing focus detection calculation for a plurality of points in a shooting screen is compared with a parameter value in the focus detection calculation process and a predetermined determination value. Control means for switching the predetermined determination value when the distance calculation result is determined to be inappropriate by the determination means;
A multi-point distance measuring device comprising: (6) The parameter value is at least one of a contrast value of a subject image and a correlation operation value, and the predetermined determination value is initially set according to a focal length of a photographing lens or an aperture value at the time of exposure. (5) The multipoint distance measuring apparatus according to (5). (7) A multipoint ranging apparatus that sets conditions for focusing on each subject located at a plurality of points in a shooting screen and uniquely determines a focus position of a shooting lens, receives a subject image, Calculating means for performing a distance measuring operation on each of the plurality of points; determining means for comparing a parameter value in the distance measuring operation process by the calculating means with a predetermined value and determining a focusing position of the photographing lens based on the comparison result Control means for determining the focus position after changing the predetermined value based on a necessary focus accuracy or a contrast state in a photographing screen when the focus position of the photographing lens cannot be uniquely determined. And a multi-point ranging device. (8) A multipoint ranging apparatus that measures conditions for focusing on each subject located at a plurality of points in a shooting screen and uniquely determines a focus position of a shooting lens, receives a subject image, A distance measuring means for performing a predetermined distance measurement operation on each of the plurality of points, comparing a parameter value in the operation process with a predetermined value, and outputting distance measurement data for the plurality of points based on the comparison result; When the distance measurement means cannot output the distance measurement data for a point in the photographing screen, the predetermined value is changed according to the necessary focusing accuracy or the contrast state in the photographing screen, and the distance measuring calculation is performed again. And control means for uniquely determining a focus position of the photographing lens based on a plurality of distance measurement data output from the distance measurement means. Multi-point distance measuring apparatus according to claim. (9) The multipoint distance measuring apparatus according to (7) or (8), wherein the necessary focusing accuracy is determined according to the focal length of the photographing lens and the aperture value at the time of exposure.

[0067]

As described above, according to the present invention, the reliability of the distance measurement state is switched according to the situation, and the selection of the distance measurement point and the validity / invalidity of the distance measurement are determined.
It is possible to provide an AF camera that can focus on a correct subject and shoot an image without missing a photo opportunity.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a multipoint distance measuring apparatus according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a configuration of a passive type distance measuring device shown in FIG. 1;

FIG. 3 is a diagram illustrating an example of a shooting scene.

FIG. 4 is a diagram illustrating an example of a subject scene.

FIG. 5 is a diagram illustrating an example of an image pattern when accurate distance measurement cannot be performed.

FIG. 6 is a flowchart showing details of the first embodiment of the present invention.

FIG. 7 is a diagram showing an image pattern obtained when the scene shown in FIG. 5A and the scene shown in FIG. 5C are received by a sensor array.

FIG. 8 is a flowchart showing details of a second embodiment of the present invention.

FIG. 9 is a flowchart illustrating a modification of the second embodiment of the present invention.

FIG. 10 is a diagram illustrating a situation in which a photographic lens forms a subject image at a specific position.

FIG. 11 is a flowchart showing details of a third embodiment of the present invention.

FIG. 12 is a view showing a modification of the third embodiment of the present invention.

FIG. 13 is a diagram illustrating a state in which the arrangement of distance measurement points in a screen changes due to zooming.

FIG. 14 is a flowchart illustrating details of a fourth embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Distance measuring device, 2 ... Image determination means, 3 ... Release switch, 4 ... Mode detection means, 5 ... Subject luminance measurement circuit, 6 ... Photographing lens, 10 ... CPU.

Claims (4)

[Claims] 1. A multi-point distance measuring device that measures distances to respective objects located at a plurality of points in a photographing screen and uniquely determines a focus position of a photographing lens. Comparing means for comparing each reliability value and a predetermined value in the process, and control means for controlling a series of distance measurement sequences including determination of the focus position of the photographing lens and capable of changing the predetermined value. A multipoint distance measuring apparatus characterized by the above-mentioned. 2. The multi-point measurement system according to claim 1, further comprising detection means for detecting a photographing state of the camera, wherein said control means changes said predetermined value in response to an output of said detection means. Distance device. 3. The method according to claim 2, wherein the predetermined value is a first determination level designed so that the comparing means generates an output only when the confidence value is higher than the predetermined value, and the confidence value is the predetermined value. Even when the value is lower than the second determination level, the comparison means is switched to at least two levels of the second determination level set so as to generate an output, and the control means based on the distance measurement results of the plurality of points. When determining the focus position of the photographing lens, first, the first determination level is selected, and it is determined that all the reliability values of the respective distance measurement results for the distance measurement points are lower than the predetermined value. 2. The multipoint distance measuring apparatus according to claim 1, wherein the first determination level is switched to the second determination level. 4. A detecting means for detecting a state of a subject image signal, wherein the control means determines a condition of the subject image signal when a point to be focused is selected from the plurality of points. 2. The multi-point distance measuring apparatus according to claim 1, wherein it is determined whether or not the point matches, and points determined as not matching are excluded from the point selection range.