JPS63266434A - Automatic focusing device - Google Patents

Abstract

PURPOSE:To obtain an automatic focusing device with high focusing rate by discriminating whether or not an object on the range binding point of the nearest point is a main object from the range finding point of the nearest point and a range finding ured value and weighting the range finding result of the center and the periphery of a screen so as to obtain a focusing position. CONSTITUTION:In an active range finding system, light beams are sequentially radiated, for example, from three light projecting elements 1a, 1b and 1c. Then the reflected lights from the object are received in a light receiving element 3, passing through a range finding circuit 4 and an interface 5 and the focusing distance is arithmetically processed as follows by an MPU 6 so as to focus. Namely, the MPU 6 decides that it is the scene of giving importance to the point when the detected values of three points such as the nearest one, the middle one and the farthest one are in approximate distances and the nearest point is the central range finding point of the screen. Otherwise, it decides that it is not regarded as the scene of giving importance to the nearest point by considering possibility that the nearest point is an obstacle. Since the optimum focusing distance is computed, the which the device is adjusted, the automatic focusing device with high focusing rate can be obtained.

Description

Detailed Description of the Invention (Field of Application of the Invention) The present invention relates to an automatic focusing device used in still cameras, video cameras, etc. The present invention relates to an automatic focusing device that determines a focus based on a plurality of distance measurement results.

(Background of the Invention) The drawback of the conventional single-point distance measuring autofocus device is that in scenes where two people are lined up or where the person is biased toward the edge, Subject (person)
In order to solve the disadvantages of video cameras, such as "because the main subject is out of focus, the focus is at infinity instead of the main subject," a so-called wide-field ranging method is used that measures multiple points within the screen. is proposed.

Examples of conventionally known autofocus devices that use such wide-field distance measurement include: (1) one that focuses on the closest distance measurement result among multiple distance measurement results (for example, General and MechanicalCGENERAL&M
ECHANICAL) 4582424, JP-A-61-8
(No. 8211, Japanese Unexamined Patent Publication No. 61-55618) (2) If multiple distance measurement results are within the depth of field determined by the focal length and aperture of the photographing lens, focus on the average value and A method that focuses on all subjects corresponding to individual distance measuring points (Japanese Patent Laid-Open No. 61-8
No. 8211, JP-A-81-55619, JP-A-61-
(No. 53614) (3) A method that determines whether it is outdoors or indoors based on brightness information, and if it is outdoors, it focuses on the farthest object based on multiple distance measurement results, and if it is indoors, it focuses on the closest object. (Japanese Unexamined Patent Publication No. 61-55619, special song No. 61-53614), etc.

However, with method (1) mentioned above, in most cases the person (main subject) is in focus in scenes where two people are lined up or where the person is closer to the edge.
For example, when there are obstacles in front or in the foreground, there is a problem in that these obstacles are in focus and the person (main subject) is not in focus.

With method (2) above, it is rare for all of the multiple distance measurement results to fall within the depth of field, except when using a short focus lens or under high-brightness shooting conditions. However, when using a long focal length lens or shooting under low brightness conditions, the image may be affected by camera shake or none of the multiple distance measurement results may be in focus.

Furthermore, with method (3) above, the background is in focus when outdoors, while the person (main subject) is not in focus when indoors, such as an obstacle in front of the camera being in focus. This has the disadvantage of causing the problem.

In this way, conventionally proposed autofocus devices using the wide-field distance measurement method often focus on a person (the main one) in a scene where two people are side by side or in a scene where the person is biased towards the edge. However, on the other hand, the main subject will no longer be in focus in scenes that were in focus with the conventional single-point distance measurement method (the foreground and background may be out of focus). This may lead to another problem:

In addition, as an autofocus device that solves the problems with conventional wide-field distance measurement as described above, it uses distance measurement results that can be considered similar from the distance measurement results corresponding to multiple points within the screen. As explained by the method of determining the focal point, specifically the algorithm shown in FIG.
An automatic focusing device has also been considered in which the focus is determined based on the algorithm shown in FIG. 11 by obtaining information about LM).

However, even when using this method, if the main subject is near the above-mentioned intermediate point and is a certain distance away,
There remains the problem that the main subject is not in focus, and when taking close-up shots, the focus is drawn to the rear (the focus is on the side farther away from the main subject).

(Object of the Invention) The present invention has been made from the above-mentioned viewpoints, and its purpose is to measure distances to multiple points within a screen in an automatic focusing device that determines focus by performing wide-field distance measurement. Using the results, it is possible to practically identify scenes in which the main subject is in the center, scenes in which two people are lined up, or scenes in which the characters are biased towards the edges, etc., as well as to classify cases based on this determination result. Accordingly, it is an object of the present invention to provide an automatic focusing device with a high focusing rate, which can bring the main subject in each of the above scenes into focus at a high rate.

(Summary of the Invention) The wide-field distance measuring automatic focusing device of the present invention, which has been made to achieve the above object, is characterized by focusing on at least three points including one point approximately in the center of the screen. A distance measuring means for detecting the distance between the above points and the subject;
a comparison means for detecting the closest point, the farthest point, and an intermediate point by comparing a plurality of distance values obtained by the distance measuring means; The focal position determining means includes a focal position determining means for determining a focal position at which a subject is focused, and a lens driving means for moving a photographing lens unit so as to match the focal position given by the focal position determining means. The system consists of a means for separating cases that require different focus positions depending on the distance measurement value, and a plurality of calculation means for calculating the focus position. In a wide-field distance measuring automatic focusing device that selects one suitable calculation means from among the plurality of calculation means according to the case, in the above case, the means at least a first determining means for determining whether the closest point and the farthest point are within a predetermined constant value range;
If the first determination means determines that the closest point, the farthest point, and the intermediate point are within a predetermined value range, the closest point is further determined to be the center distance measuring point in the screen. and a second determining means for determining whether or not there is a
When the distance measurement point at the center of the screen is determined to be the closest point by the determination means, the calculation means for calculating the focal position by weighting the center distance measurement result is selected.

(Embodiments of the Invention) The present invention will be described in detail below based on embodiments shown in the drawings.

Embodiment 1 FIG. 1 is a diagram showing the principle of active distance measurement applicable to the present invention, and this method utilizes the triangulation method used in, for example, lens-shutter cameras.

In FIG. 1, the output light of the light emitting element 22 is
The spot light is focused as a narrow beam onto the subject 25, and the spot light reflected by the subject 25 is caused to form a real image on the surface of the light receiving element 24 by the light receiving lens 23. The deviation d of the spotlight from the center position shown in Fig. 1 is inversely proportional to the distance to the subject, and the closer it gets, the larger d becomes.
This relationship is expressed as f/L=d/S (where f is the focal length of the light receiving lens 23,
S is the baseline length).

Note that the number of points within the screen to be measured in the wide-field distance measurement method is determined as appropriate depending on the purpose of the camera using the autofocus device, cost, etc., but in the following example, for convenience, the method shown in Fig. 3 is used. The following explanation will be given by taking as an example the case where distance measurement is performed on three points in the screen shown in FIG.

FIG. 2 is a block diagram showing the configuration of the automatic focusing device according to the first embodiment of the present invention, and in this figure, la, lb
, lc designate a block of a light projecting element and a light projecting lens for performing distance measurement corresponding to the three points on the screen, and the light emission is controlled by the light emission control circuit 2. Reference numeral 3 indicates a block of a light receiving element and a light receiving lens, and an output terminal from the light receiving element is connected to a distance measuring circuit 4 that calculates the distance to the subject. Reference numeral 5 denotes an interface circuit having a ^/D conversion function, which connects a microprocessor unit (hereinafter referred to as MPII) 6 and various circuits.

Reference numeral 7 denotes a drive circuit that moves the photographing lens unit 8 to a focusing position based on a control signal from the MPU.

The operation of the automatic focusing device in this example configured as described above is first performed by turning on the main switch (not shown).
A light emission start signal is given from the PU 6 to the light emission control circuit 2 via the interface circuit 5. Thereby, the light emission control circuit 2 sequentially lights up the light emitting elements 1a, lb, and Ic at timings given by various constants preset in the circuit.

The output light from the light emitting element is reflected by the subject and passes through the light receiving element 3.
A real image is formed on the surface of the object, and the distance to the subject corresponding to each distance measurement point shown in FIG. be done.

The distance measurement information calculated in the distance measurement circuit 4 is read into the MPU 6 via the interface circuit 5 in synchronization with the lighting timing of the light projecting element, and the focal position is calculated in the MPIJ 6 as described below. Based on the calculation result, the driving circuit 7 moves the photographing lens unit 8 to a predetermined position.

The feature of the autofocus device of the first embodiment having the above configuration and operation is that the photographing lens unit 8 is moved based on the distance measurement result information (distance measurement value) for the three points mentioned above from the distance measurement circuit 4. The operating procedure of the MPU 6 for calculating, calculating, and outputting the control signal is performed according to the flowchart shown in FIG.

The procedure will be explained in detail below.

The operating procedure of the MPU 6 in this example is roughly comprised of the following three steps. That is, the first one is to determine the closest point LN, the closest point LF, and the intermediate point L based on the distance measurement information.
This is the stage of detecting M (hereinafter referred to as the first stage). Second, by comparing these LN, LM, and LP with each other or with other conditions, the focal position required for the scene to be photographed is different from the focal position required for other scenes. This is a step (hereinafter referred to as the second step) in which the relevant scene is distinguished from other scenes. The third step is a step (hereinafter referred to as the third step) of calculating a focal position suitable for each scene divided into cases as described above using a preset calculation means.

First, to describe the first stage, in this stage, the MPU 6 reads the distance measurement information of the three points on the screen input from the distance measurement circuit 4, and calculates the closest point LN, the farthest point LF, and the intermediate point LM. Desired.

Next, talking about the second stage mentioned above, in this stage in this example, the cases are divided into two depending on the circumstances, and the priority is first the intermediate point LM and the nearest point L.
Find the difference between N and the difference (i.e. ILN-LM
I) and a constant corresponding to the depth of field determined by the focal length and aperture F value of the photographic lens, and the closest point L is determined by comparing
Determining whether the distance measurement result for N is valid or invalid (determination below)
Cases are divided according to a). Invalid here means data that is unnecessary for detecting the focal position (the same applies below).

In the above case, the following determination is made separately when the closest point LN is deemed valid and when it is deemed invalid.

In other words, for the former (when the closest point is valid), the difference between the farthest point LP and the intermediate point LM (i.e. ILN - LMI
), and calculate this difference as the focal length and aperture of the above-mentioned photographic lens.
A comparison is made with a constant corresponding to the depth of field, which is determined by a value, etc., and cases are determined based on whether the distance measurement result for the farthest point LF is valid or invalid (hereinafter referred to as determination (b)). These two determinations (a) and (b) correspond to the determination by the first determining means in the present invention described above. Then, as a result of this determination, if the farthest point LF is valid (i.e., I LM - LF I≦k), the nearest point LN
A determination is made as to whether is the center distance measuring point of the screen or another distance measuring point (hereinafter referred to as determination (C), which corresponds to the determination by the second determining means in the present invention described above).

One of the features of the present invention is to perform this determination (C), and this point will be explained in more detail below.

As described above, when the difference between the intermediate point LM and the closest point LN is smaller than k (that is, ILN-LMI≦k), three cases are ultimately performed.

On the other hand, the difference between the closest point LN and the intermediate point LM, that is, IL
If N-LMI is larger than the above constant (IL
N-LMI≧k), in this example, determination (hereinafter referred to as determination (d) and (e)) is performed by determining whether the following conditions (1) and (2) are satisfied. This determination is one of the features of this example, and is used to determine whether the object at the closest point is the main object or an obstacle.

The conditions ■ and ■ used as standards in the above determinations (d) and (e) are that the closest point LN of the condition is an obstacle estimated from the photographing conditions such as the focal length and brightness information of the photographing lens. The distance is longer than the most likely distance air (for example, a distance of about 1 m* in the case of a 38 mm lens).

Condition ■ The distance measurement point of the closest point LN is the center.

Based on these determinations (d) and (e), cases are divided into cases where at least one of these conditions (1) and (2) is satisfied and cases where neither of them is satisfied. Regarding the latter (when neither is satisfied), further case classification is performed by determining whether the distance measurement result for the farthest point LF is valid or invalid (hereinafter referred to as determination (f)).

Therefore, as described above, even in the case where ILN-LMI≧, a division into three cases is ultimately performed.

Next, the calculations performed in the next stage (third stage) will be described according to the above case classification.

When the difference (ILN-LMI) between the closest point LN and the intermediate point LM is smaller than the above constant (ILN-LMI≦k) is selected as detection 1 by the above-mentioned determination (a), the closest point LN As mentioned above, the distance measurement results for are considered to be valid information, and in this case, the cases are further divided by discrimination (b) and (C), and in short, there are three scenes. The cases are divided into cases, and the focal position is calculated by selecting the one that is most suitable for these scenes from the following three calculation methods (A), (C), and (C).

B. (When ILM-LFI≧) Calculate the focal position from the average value of LM and LN.

Mouth, (When ILM-LFI≦ and determination (C) shows that the closest point LN is the distance measurement point at the center of the screen) The focal position is calculated by a center-weighted average method of three points.

C. (When ILM-LFI≦ and determination (C) shows that the closest point LN is a distance measurement point other than the center of the screen) The focal point position is calculated by a simple average method of three points.

On the other hand, in the above, if the difference (l LN-LMI ) between the closest point t, N and the intermediate point LM is larger than the above constant (ILN-LMI≧k) according to determination (a), detection 9 is detected.
Regarding the selected case, the distance measurement result for the closest point LN is considered to be invalid information as described above. And in this case, further discrimination (d) and (e
), three scenes for which different focal positions are to be determined are classified, and the focal position is calculated by selecting one of the calculation methods for the following three aspects 2, 4, and 5 that is compatible with the scene.

2. (When at least one of the above conditions ① and ② is satisfied) Calculate the focal point position from the LN.

E, (none of the above conditions ■ and ■ are satisfied and ILM
- When LFI≧) Calculate the focal position from LM.

to (, neither of the above conditions ■ and ■ are satisfied and l L
(If M-Ljl≦) The focal position is calculated from the average value of LM and LF.

In the above embodiments, the first feature of the present invention described above. Discrimination by the second discrimination means (that is, 1 discrimination (a) ~
The result of (C)) is selected as an operation whose operation mode is suitable for the mouth of the cases divided above.

In other words, in the case of these ports, it can be said that it is a scene in which the three points are at similar (approximate) distances, and the conditions ILN-LMI≦ and lLM-LF l≦ are satisfied. Even in such scenes, for example, in close-up shots or scenes where the background is directly behind the main subject, calculating the focus position based on a simple three-point average value may cause the focus position to be pulled backwards. has already been mentioned. Therefore, in the automatic focusing device of this example, we consider (assuming) that the main subject is normally in the center in close-up shots and scenes where the background is immediately behind the main subject, such as the one described above. First, when the closest point is the center distance measurement point of the screen, center-oriented averaging is performed instead of simple averaging to determine the focal position, and in other cases, the simple averaging method is used.

In other words, if the three points are at similar (approximate) distances and the closest point is the center distance measurement point of the screen, it is considered a scene that emphasizes the closest point, and in other cases, the closest point is an obstacle. This can be said to be a method that takes into consideration the possibility that the scene is not considered to be a scene that emphasizes the closest point.

The calculation of the focal point position in the above center-weighted case is as follows:
This is performed by determining the focus position LP, for example, by using the following formula in which data at the closest point is weighted.

However, a is a value determined by considering the use of the camera, the focal length of the lens, etc., and a>1, and a value of about 2 to 3 is desirable. Also, LN, LM, LP, LP in the above formula
are all values converted to the amount of extension in lens control.

Embodiment 2 The distance measuring device used in the present invention may be based on the principle shown in FIG. 345 in addition to the one shown in FIG.

The principle of this distance measurement method is a passive method called SST, and the distance measurement operation is basically based on a double match method.

That is, distance data is obtained by looking at the positional correlation between two images obtained by two optical systems.

FIG. 5 schematically shows the principle, and numeral 25 in the figure is an object to be measured.

The projecting lens 26 and mirrors 28 and 29 aim the object 25 on its optical axis B, and are called a reference side optical system. On the other hand, the light receiving lens 27, the mirror 30.
Reference numeral 31 is arranged at a distance of a reference length S from the reference side optical system, and is called a reference side optical system.

In the above configuration, the image of the subject 25 captured by the projection lenses 26 and 27 is formed on the image sensor 32, and the image based on the reference side optical system is formed on the reference field of view A, and the image based on the reference optical system is formed on the reference field of view A. The images are respectively formed on the reference field of view B.

Now, assuming that the object 25 is at infinity, the object 25 will be on the axes a and b of the reference side and reference side optical systems, respectively, so the object image by each optical system will be on the reference field of view A. It is formed as an IMB on the reference field of view B, and as an IMRI on the reference field of view B. On the other hand, when the subject 25 approaches the reference optical system on the axis a, the optical path from the subject 25 with respect to the reference optical system becomes inclined. Therefore, the image of the subject 25 formed by the reference side optical system shifts onto the reference side field of view B as shown in IMR2. Therefore, by detecting where on the reference field of view B the same image as the image IMB on the reference field of view A is formed, it is possible to know the distance to the subject.

FIG. 6 shows a block diagram of an automatic focusing device room according to a second embodiment of the present invention using this distance measuring device.

In this figure, 9a, 9b, 9c are lenses and mirrors.
, a distance measuring device consisting of an image sensor, 10a.

The fob 10c is a distance measuring circuit that calculates the distance from the output of the image sensor, and 11 is an interface circuit.

MP[I6 in this example also reads the distance measurement results of three points via the interface circuit 11 as in the first embodiment, and calculates the focal position according to the flowchart of FIG. 4 explained in the first embodiment.

A control output to the drive circuit 7 that controls the photographing lens unit 8 is given based on the above calculation result.

Embodiment 3 FIG. 7 shows an optical layout diagram of an automatic focusing device according to Embodiment 3 of the present invention. In this figure, 41 is a lens element, and 42 is a lens element for recombining images of the pupil planes of the lens elements. This is a group of small lenses, and generally consists of 20 or more lenses. 43 to 46 indicate each pixel of a light receiving element consisting of a CCD (charge coupled device) element, etc. For the small lens 42a, pixels 43 and 44, and the small lens 42b
In contrast, pixel 43, to which pixels 45 and 46 correspond, faces the aperture 48 portion through the small lens 42a, and pixel 44 faces the aperture 47 portion through the small lens 42a. Similarly, the pixel 45 faces the aperture 48 through the small lens 42b, and the pixel 46 faces the small lens 42b.
The aperture 47 is visible through the lens.

Here, if we assume that the small lens 42a is the nth small lens and 42b is the n-1th small lens, then the pixel facing the aperture 48 through the nth lens is An.

Let the pixel facing the aperture 4 be Bn, the pixel facing the aperture 48 through the n-1st lens be An-1, and the pixel facing the aperture 47 be Bn-1. Further, the F plane corresponds to the focal plane of the lens 41, and therefore, as the lens 41 changes its position in the horizontal direction in the drawing, the object distance at which an image is correctly formed on the F plane differs. Also, when capturing the image of an object at the focusing distance as the output of the sensor, then n=Bn,
n-1+-Bn-1, whereas when capturing an image of an object that is not within the focusing distance, ^nwBm (however, n 9
6111).

Figure 's8 shows a block diagram of an automatic focusing device according to a third embodiment of the present invention. In this figure, 12 is a sensor unit consisting of the small lens group and light receiving element array explained in FIG. 7 above, 13 is an A/D converter, and 14 is a gate that distributes the output of the A/D converter 13 to three memories. , 15
, 16 and 17 are memories, and 18 are interface circuits.

In the above configuration, the signal obtained from the sensor unit 12 is converted into a digital signal by the A/D converter 13, and the pixels are distributed to three memories by the gate 14. With this, it is possible to measure the distance to three points, and these three
The MPU 6 reads the memory contents of 1 and 2 according to the flowchart explained in FIG. 4 above.
Similarly, the focal position is calculated, and the drive circuit 7 drives and controls the lens unit 8 based on this calculated value.

Note that the present invention is not limited to the above embodiments,
It goes without saying that it can be realized in various modified embodiments. For example, the discrimination means for other case classification that is combined with the first discrimination and the second discrimination, and the calculation means prepared to be suitable when each case is divided, are limited to those of the above embodiment. Rather, known technical means can be appropriately selected and adopted in accordance with the performance required for the camera or the like to be designed.

Furthermore, as mentioned above, there may be three or more distance measurement points on the screen, and when there are four or more points, the intermediate point, farthest point, and closest point are determined using the distance measurement points, for example. If there are four points as shown in Figure 9, the average value of the distance measurement results for the two points in the center or the distance measurement results near those two points is taken as the distance measurement result for the center, and the distance measurement results for the left and right periphery are Department,
The intermediate point, the farthest point, and the closest point may be determined from the three distance measurement results at the center.

In addition, when there are 5 distance measurement points as shown in Figure 10, the average value of the distance measurement results of the 3 points in the center like the 4 points in Figure 9, or the measurement of the closest distance of the 3 points. The distance result may be taken as the distance measurement result for the central part, and the intermediate point, farthest point, and closest point may be determined from the three distance measurement results for the left, right periphery, and center, or the middle point, farthest point, and closest point may be determined from the three distance measurement results for the left, right periphery, and center. , the nearest point is the nearest point,
The third point may be the midpoint, and the third point may be the farthest point.

(Effects of the Invention) According to the automatic focusing device according to the present invention, it is possible to determine whether the subject at the closest distance measurement point is the main subject or an obstacle.
The focus position is determined by determining the closest distance measurement point and distance measurement value, and weighting the distance measurement results at the center and periphery of the screen, so when shooting close-up or when the main subject (
When there is a person (mainly a person) and the background is relatively close,
The true focus on the main subject is affected by the background (
This eliminates the tendency for out-of-focus in a mode similar to one-point distance measurement, which was a problem with conventional wide-field distance measuring autofocus devices, and also The characteristics of wide-field distance measurement can be fully demonstrated in scenes where people are lined up or where people are biased towards the edges, and as a result, it is possible to provide an autofocus device with a high overall focusing rate. .

[Brief explanation of the drawing]

Figure 1 is a diagram explaining the distance measurement principle used in the automatic focusing device of the first embodiment of the present invention, and Figure 's2 is the diagram of the first embodiment.
3 is a diagram showing an example of the light projection device used in the first embodiment, and FIG. 4 is a diagram showing the focus detection performed in the microcomputer of the first embodiment. FIG. 5 is a diagram explaining the distance measurement principle used in the automatic focusing device of the second embodiment, and FIG. 6 is a block diagram showing the outline of the configuration of the automatic focusing device of the second embodiment. FIG. 7 is a diagram illustrating the distance measurement principle used in the automatic focusing device of the third embodiment, and FIG. 8 is a block diagram showing an outline of the configuration of the automatic focusing device of the third embodiment. FIGS. 9 and 10 are diagrams illustrating cases in which the number of distance measurement points on the screen is four or five. FIG. 11 is a flowchart illustrating a procedure for focus detection performed by an automatic focusing device using conventional wide-field distance measurement. la, lb, lc: Light projecting element 2; Light emission control circuit 3:
Light receiving element 4: Distance measurement circuit 5: Interface circuit 6: Microprocessor unit (MPU) 7: Drive circuit 8: Photographic lens unit 9a, 9b, 9
c: Light receiving element 10a, 10b, 10c: Distance measuring circuit 1
1: Interface circuit 12: Sensor unit 13: A/D GI converter 1
4: Gate 15.16.17: Memory 18
: Interface circuit 21: Light emitting lens 22: Light emitting element 23: Light receiving lens 24: Light receiving element 25; Subject 26 Two light emitting lenses 27: Light receiving lens 28, 29: Mirror 30. 31: Mirror 32: Image sensor 41
: Lens element 42: Small lens groups 42a, 42b:
Small lens 43.44.45.48: Pixel 47.48
Near Perchaia "Kohonda Kodaira," Figure 1 ■ Figure 3 Figure 4 Figure 7

Claims (1)

[Claims] Distance measuring means for detecting the distance to a subject at least three points including one point in the approximate center of the screen, and a plurality of distance measurement values obtained by the distance measuring means. a comparison means for detecting the closest point, the farthest point, and an intermediate point by comparing them; and a focus position determining means for determining a focal point to focus on the main subject based on the measured distance values of the closest point, the farthest point, and the intermediate point. and a lens driving means for moving the photographing lens unit to match the focal position given by the focal position determining means, and the focal position determining means moves the photographing lens unit to a different focal position depending on the distance measurement value. It consists of a case dividing means that separates cases that require In a wide-field distance measuring automatic focusing device that selects two calculation means, the above-mentioned case-sorting means is such that at least the closest point and the farthest point with respect to the above-mentioned intermediate point are within a predetermined constant value range. a first determining means for determining whether the closest point, the farthest point, and the intermediate point are within a predetermined value range; and second determining means for determining whether or not the closest point is the center distance measuring point in the screen, and the second determining means determines whether the center distance measuring point in the screen is the closest point. 1. An automatic focusing device of a wide-field distance measuring method, characterized in that, when the determination is made, a calculating means for calculating a focal position by weighting the central distance measuring result is selected.