JP2002244025A - Focusing device for camera - Google Patents

Abstract

(57) [Problem] To provide a camera focusing device that reduces the complexity of focusing while looking at an electronic viewfinder and improves the focusing accuracy. SOLUTION: In an electronic viewfinder 10 divided into a plurality of small areas, a focus area is sequentially set to small areas including a subject to be focused, and a subject distance is detected. From the combination data of the subject distance and the F value prepared in advance in the depth of field calculation circuit 7, the subject distance and the F value including all the detected subject distances are selected. The obtained F value is supplied to the aperture adjustment circuit 8 and the gain adjustment circuit, and the aperture 3 is set to the selected F value, whereby a focused depth of field can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a camera focusing device for focusing a subject while looking at an electronic viewfinder.

[0002]

2. Description of the Related Art When photographing a subject using a broadcast video camera, a photographer looks at the subject image displayed on an electronic viewfinder provided in the video camera.
Focusing is performed by empirically determining the distance to the subject. However, in general, the electronic viewfinder has a small screen and a low resolution, so that focusing is difficult and a complicated operation requiring skill is required.

[0003] In order to generate a contour emphasis signal by detecting a contour portion from an image pickup signal output from an image pickup apparatus,
There is a method of providing an aperture circuit. By adding the contour emphasis signal output from the aperture circuit to the imaging signal, the contour of the subject can be emphasized, and the subject can be easily focused. FIG. 8 is a signal waveform diagram showing the principle of such an outline emphasis operation. FIG.
(A) is an imaging signal a output from the imaging device. FIG. 8B shows an image signal b obtained by delaying the image signal a by one clock. FIG. 8C shows an image signal c obtained by delaying the image signal b by one clock. FIG. 8D shows the operation ｛b− (a +
c) / 2}, and the resulting edge enhancement signal d
It is. FIG. 8E shows an image signal e obtained by adding the outline emphasis signal d to the image signal b.

[0004]

As shown in FIG. 8, when the contrast between the subject and the background is large, the amplitude of the contour emphasizing signal d increases, and an image signal e in which the contour of the subject is emphasized is obtained. However, when the contrast between the subject and the background is small, only the contour emphasizing signal d having a small amplitude can be obtained. For this reason, there is a problem that the contour of the subject is not emphasized, and it is difficult to focus.

Further, when it is desired to focus on a plurality of subjects at different distances, a conventional video camera uses a high-definition television for a high-definition television even if there is another subject within the depth of field that can be regarded as being in focus. In the video camera described above, the resolution is higher and the depth of field is shallower than that of a conventional video camera.

SUMMARY OF THE INVENTION The present invention has been made in view of such a conventional problem, and greatly reduces the complexity of performing focusing while looking at an electronic viewfinder, and improves the accuracy of automatic focusing. It is an object of the present invention to provide an improved camera focusing device.

[0007]

According to a first aspect of the present invention, there is provided a lens for forming an optical image of a subject, a diaphragm for adjusting the amount of light transmitted through the lens, and an optical image of the subject whose light amount is adjusted by the diaphragm. Imaging means for photoelectrically converting and outputting an imaging signal, focus area setting means for setting a focus area on the optical image of the subject, and subject distance detection means for detecting the distance of the subject existing in the focus area, Depth-of-field calculating means for selecting an F value at which the S / N value of the imaging signal increases in accordance with the subject distance detected by the subject-distance detecting means, and F selected by the depth-of-field calculating means. Aperture adjusting means for adjusting the aperture according to a value; and a gain adjusting means for adjusting the gain of an image signal output from the image capturing means in accordance with an F value selected by the depth of field calculating means. When, it is characterized in that it comprises a an electronic viewfinder for displaying the image signal output from said gain adjusting means.

According to a second aspect of the present invention, there is provided a lens for forming an optical image of a subject, a diaphragm for adjusting the amount of light transmitted through the lens, and an optical image of the subject for which the amount of light is adjusted by the diaphragm is photoelectrically converted and imaged. An imaging unit that outputs a signal; a focus area setting unit that sets a focus area on the optical image of the subject; a subject distance detection unit that detects a distance of a subject existing in the focus area; and the subject distance detection unit. Depth-of-field calculating means for selecting an F-number at which the S / N value of the imaging signal increases in accordance with the detected subject distance; and the F-number selected by the depth-of-field calculating means. Aperture adjusting means for adjusting the aperture, gain adjusting means for adjusting the gain of an imaging signal output from the imaging means in accordance with the F value selected by the depth of field calculating means, and the gain Image pickup signal outputted from the integer unit, the focus area, and is characterized in that it comprises a an electronic viewfinder for displaying the object distance, and the F value.

According to a third aspect of the present invention, there is provided a zoom lens for forming an optical image of a subject, zoom value setting means for changing a zoom value of the zoom lens, and a diaphragm for adjusting the amount of transmitted light of the zoom lens. Imaging means for photoelectrically converting an optical image of a subject whose light amount is adjusted by the aperture to output an imaging signal; focus area setting means for setting a focus area on the optical image of the subject; and a subject existing in the focus area Subject distance detecting means for detecting the distance of the object, depth of field calculating means for selecting an F-value at which the S / N value of the image pickup signal increases in accordance with the subject distance detected by the subject distance detecting means, Aperture adjusting means for adjusting the aperture according to the F value selected by the depth of field calculating means, and the imaging means according to the F value selected by the depth of field calculating means A gain adjusting means for adjusting the gain of the imaging signal al outputted, is characterized in that it comprises a an electronic viewfinder for displaying the image signal output from said gain adjusting means.

According to a fourth aspect of the present invention, there is provided a zoom lens for forming an optical image of a subject, zoom value setting means for varying a zoom value of the zoom lens, and a diaphragm for adjusting the amount of transmitted light of the zoom lens. Imaging means for photoelectrically converting an optical image of a subject whose light amount is adjusted by the aperture to output an imaging signal; focus area setting means for setting a focus area on the optical image of the subject; and a subject existing in the focus area Subject distance detecting means for detecting the distance of the object, depth of field calculating means for selecting an F-value at which the S / N value of the image pickup signal increases in accordance with the subject distance detected by the subject distance detecting means, Aperture adjusting means for adjusting the aperture according to the F value selected by the depth of field calculating means, and the imaging means according to the F value selected by the depth of field calculating means A gain adjusting means for adjusting the gain of the imaging signal et output, imaging signals output from the gain adjusting means, the focus area, and an electronic view finder for displaying the object distance, and the F value,
It is characterized by having.

[0011] The invention of claim 5 of the present application is the invention of claim 1 or 2.
In the camera focusing apparatus, the focus area setting means divides the display screen of the electronic viewfinder into a plurality of small areas, and includes a first focus area including an optical image of the subject having a minimum subject distance; A second focus area including an optical image of a subject having a maximum distance is arbitrarily set.

The invention of claim 6 of the present application is directed to claim 3 or 4
In the camera focusing apparatus, the focus area setting means divides the display screen of the electronic viewfinder into a plurality of small areas, and includes a first focus area including an optical image of the subject having a minimum subject distance; Arbitrarily setting a second focus area including an optical image of a subject having a maximum distance, and setting a size of the focus area according to a zoom value output from the zoom value setting means. It is.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of a camera focusing device according to the present invention will be described with reference to the drawings.

(Embodiment 1) FIG. 1 is a block diagram showing a main configuration of a focusing device for a camera according to Embodiment 1 of the present invention. The focusing device of this camera includes a lens 2, an aperture 3, an image sensor 4, a focus area setting circuit 5a, an object distance detection circuit 6, a depth of field calculation circuit 7, an aperture adjustment circuit 8, a gain adjustment circuit 9, an electronic view. Finder 10
It is comprised including.

The lens 2 is a focusing lens that forms an optical image of the subject 1. The diaphragm 3 adjusts the amount of light transmitted through the lens 2. The imaging device 4 is a device that photoelectrically converts the optical image of the subject 1 whose light amount has been adjusted and outputs an imaging signal.
The focus area setting circuit 5a is a circuit that sets a focus area on the optical image of the subject 1. The subject distance detection circuit 6 is a circuit that detects the distance of the subject existing in the focus area. The depth-of-field calculating circuit 7 is a circuit that selects and outputs an F-number according to the subject distance from a table. The aperture adjustment circuit 8 is a circuit that adjusts the aperture 3 according to the F value. The gain adjustment circuit 9 is a circuit that adjusts the gain of the imaging signal output from the imaging device 4 according to the F value. The electronic viewfinder 10 displays an image of a subject using an image signal output from the gain adjustment circuit 9.

The operation of focusing on a subject by the focusing device of the camera constructed as shown in FIG. 1 will be described below with reference to FIGS.

First, the optical image of the subject 1 shown in FIG. 2 is formed by the lens 2 of FIG. Then, the optical image whose light amount has been adjusted is photoelectrically converted by the imaging element 4 and output as an imaging signal. The gain of the imaging signal is adjusted by the gain adjustment circuit 9, and an image of the subject is displayed on the electronic viewfinder 10.
The electronic viewfinder 10 is divided into a plurality of rectangular portions as shown in FIG. 3, and the cameraman operates the focus area setting circuit 5a to set the focus area 17 in the rectangular portion including the optical image of the subject 1.

FIG. 4 is a table holding data indicating the relationship between the subject distance and the depth of field according to the F value. The table is stored in the depth of field calculation circuit 7.
The subject distance shown at the left end of this table is not a measured value but a representative value for selecting an F value. The subject distance detection circuit 6 in FIG. 2 irradiates infrared rays in the direction of the focus area designated by the rectangular portion including the subject 1, receives the reflected light with a light receiving element, and detects the subject distance 13 by triangulation. Here, it is assumed that, for example, 5.2 m (actually measured value) is detected. Then, given the actually measured subject distance 13, the depth of field calculating circuit 7 selects one of the combination data including the detected subject distance 5.2 m from the combined data of the subject distance and the F value shown in FIG. 4. First, an object distance of 5 m and F2.0 are selected. Here, in the row of the representative value of the subject distance of 5 m, the measured value of 5.2 m is included in all the F values of F2.0 or more, but the depth of field calculation circuit 7 of FIG. Best F-number, ie F2.0
Shall be selected.

The F value thus obtained is given to the aperture adjustment circuit 8 and the gain adjustment circuit 9 in FIG. By setting the aperture 3 to F2.0, the aperture adjustment circuit 8 obtains 4.04 m to 6.57 m as the depth of field 16 that can be regarded as being in focus. Further, even when the aperture 3 changes, the gain adjustment circuit 9 can adjust the gain so that the output level of the image becomes constant, and display the image of the subject on the electronic viewfinder 10.

With the above operation, the image displayed on the electronic viewfinder 10, that is, the object distance 13 is set to 5.
Since the subject 1 of 2 m is included in the depth of field 16 of 4.04 m to 6.57 m, a focused state is obtained.

Next, when it is desired to focus on another subject 11 shown in FIG. 3, a focus area 18 is set in a rectangular portion including an optical image of the subject 11, and as shown in FIG. For example, assume that 7.0 m is detected. Then, from the combination data of the subject distance and the F value shown in FIG. 4 by the depth of field calculation circuit 7, the best combination data of the S / N values including both the detected subject distances of 5.2 m and 7.0 m As a subject distance of 5 m, F
Select 2.8. The F value thus obtained is given to the aperture adjustment circuit 8 and the gain adjustment circuit 9. Then, the aperture adjusting circuit 8 sets the aperture 3 to F2.8 to obtain 3.75 m to 7.52 m as the depth of field 16 that can be regarded as being in focus. Further, even when the aperture 3 changes, the gain adjustment is performed by the gain adjustment circuit 9 so that the image level becomes constant, and the image of the subject can be displayed on the electronic viewfinder 10.

By the above operation, the subject 1 whose subject distance 13 displayed on the electronic viewfinder 10 is 5.2 m
And the subject 11 whose subject distance 14 is 7.0 m.
Since it is included in the depth of field 16 of 75 m to 7.52 m,
An in-focus state is obtained.

Next, when it is desired to focus on the subject 12 shown in FIG. 3, a focus area 19 is set in a rectangular portion including an optical image of the subject 12, and a subject distance 15, for example, 8.0 m is detected. Then, the depth-of-field calculating circuit 7 includes all of the detected 5.2 m, 7.0 m, and 8.0 m from the combination data of the subject distance and the F value shown in FIG. As the best combination data,
An object distance of 5 m and F4.0 are selected. The F value thus obtained is given to the aperture adjustment circuit 8 and the gain adjustment circuit 9. Then, the aperture adjustment circuit 8 sets the aperture 3 to F4.0. By doing so, as the depth of field 16 that can be regarded as being in focus, 3.40 m to 1
0.14 m is obtained. Further, even when the aperture 3 changes, the gain adjustment circuit 9 adjusts the gain so that the image level becomes constant, so that an image in which the subject is in focus can be displayed on the electronic viewfinder 10.

By the above operation, the subject 1 whose subject distance 13 displayed on the electronic viewfinder 10 is 5.2 m
And the subject 12 whose subject distance 14 is 7.0 m, and the subject 12 whose subject distance 15 is 8.0 m are 3.40 m to 1
Since it is included in the depth of field 16 of 0.14 m, a focused state is obtained.

Similarly, when focusing on four or more subjects, a focus area is sequentially set on a rectangular portion including an optical image of the subject, and the subject distance is detected. Then, the depth-of-field calculating circuit 7 selects the subject distance and the F value having the best S / N value including all the detected subject distances from the combination data of the subject distance and the F value shown in FIG. I do. The F value obtained in this way is given to the aperture adjustment circuit 8 and the gain adjustment circuit 9, and the aperture adjustment circuit 8
Sets aperture 3 to its F value. By doing this,
A depth of field that can be considered as being in focus can be obtained. Further, even when the aperture 3 changes, all the objects displayed on the electronic viewfinder 10 are included in the depth of field 16 by performing gain adjustment so that the video level is constant by the gain adjustment circuit 9. And a focused state is obtained.

In the present embodiment, the object distance and F
From the combination data of the values, the subject distance and the F value having the best S / N value including all the detected subject distances were selected. However, when the entire screen is bright, it is possible to focus at a deeper depth of field 16 by selecting an F value larger than the initially obtained F value while keeping the subject distance as it is.

Further, in the present embodiment, the electronic viewfinder 10 is divided into a plurality of rectangular portions. However, when the electronic viewfinder 10 is divided into a plurality of polygonal portions or a circular portion whose position and size can be set arbitrarily. Has the same effect.

(Embodiment 2) In the camera focusing apparatus according to Embodiment 1 of the present invention described above, if the performance of the object distance detection circuit 6 is not good, the object distance from the object differs from the actual distance. The distance may be detected.

Therefore, in the camera focusing apparatus according to the second embodiment of the present invention, information displayed on the electronic viewfinder 10 is increased. As shown in FIG. 5, the imaging signal output from the gain adjustment circuit 9, the minimum subject distance Lmin, the maximum subject distance Lmax and F
Message information 20 consisting of a value and a subject distance Lmin
The focus area 17 including the optical image of the subject and the focus area 19 including the optical image of the subject at the subject distance Lmax are displayed on the electronic viewfinder 10. By doing so, the cameraman can judge whether or not the intended imaging condition is reached while visually recognizing the electronic viewfinder 10. In some cases, the user can manually focus while viewing the information.

(Embodiment 3) A focusing device for a camera according to Embodiment 3 of the present invention will be described. FIG. 6 is a block diagram showing a configuration of a main part of a camera focusing device according to the third embodiment. The same parts as those in the first embodiment are denoted by the same reference numerals. In FIG. 6, the zoom lens 2
Reference numeral 1 denotes a focusing lens having a zoom function of forming an optical image of the subject 1. The zoom value setting circuit 22 is a circuit that varies the zoom value of the zoom lens 21. The diaphragm 3 adjusts the amount of transmitted light of the zoom lens 21. The imaging device 4 is a device that photoelectrically converts the optical image of the subject 1 whose light amount has been adjusted and outputs an imaging signal. The focus area setting circuit 5b is a circuit that sets a focus area on the optical image of the subject 1. The subject distance detection circuit 6 is a circuit that detects the distance of the subject existing in the focus area. The depth-of-field calculating circuit 7 calculates the F according to the subject distance.
This is a circuit that selects and outputs values from a table. The aperture adjustment circuit 8 is a circuit that adjusts the aperture 3 according to the F value. The gain adjustment circuit 9 is a circuit that adjusts the gain of the imaging signal output from the imaging device 4 according to the F value.
The electronic viewfinder 10 is a viewfinder that displays an image of a subject using a video signal output from the gain adjustment circuit 9.

Hereinafter, an operation of focusing on a subject by the focusing device of the camera configured as described above will be described with reference to FIGS.

First, the optical image of the subject 1 shown in FIG. 2 is formed by the zoom lens 21 shown in FIG. Then, the optical image whose light amount has been adjusted is photoelectrically converted by the imaging element 4 and output as an imaging signal. The gain of the image signal is adjusted by the gain adjustment circuit 9, and the image of the subject is displayed on the electronic viewfinder 10. The electronic viewfinder 10 is divided into a plurality of rectangular portions as shown in FIG.
Is adjusted to enlarge or reduce the subject image.
The subject 1 is set by the focus area setting circuit 5b.
The focus area 17 is set in a rectangular portion including. Here, the size of the focus area is variable according to the zoom value. When the optical image of the subject is reduced as shown in FIG. 7A, the focus area is set small. When the optical image of the subject is enlarged as shown in FIG. 7B, the focus area is set large. FIG.
The subject distance detection circuit 6 irradiates infrared rays in the direction of the focus area specified by the rectangular portion including the subject 1, receives the reflected light with the light receiving element, and sets the subject distance 13 to, for example, 5.2 m by triangulation. Suppose that it was detected. And
The subject distance and F shown in FIG.
From the combination data of the values, the object distance 5 is selected from the combination data including the detected object distance 5.2 m.
m, F2.0.

Here, all values above F2.0 include the detected object distance, but the F value with the best S / N value, that is, F2.0, is selected. The F value thus obtained is given to the aperture adjustment circuit 8 and the gain adjustment circuit 9 in FIG. By setting the aperture 3 to F2.0, the aperture adjustment circuit 8 obtains 4.04 m to 6.57 m as the depth of field 16 that can be regarded as being in focus. Further, even when the aperture 3 changes, the gain adjustment circuit 9 performs gain adjustment so that the video level is constant.
An image of a subject can be displayed on the electronic viewfinder 10.

With the above operation, the image displayed on the electronic viewfinder 10, that is, the object distance 13 is set to 5.
Since the subject 1 of 2 m is included in the depth of field 16 of 4.04 m to 6.57 m, a focused state is obtained.

Next, when it is desired to focus on another subject 11 shown in FIG. 7A, a focus area 18 is set in a rectangular portion including an optical image of the subject 11. Then, for example, 7.0 m is detected as the subject distance 14.
Then, the depth-of-field calculating circuit 7 selects the best combination of the S / N values including both the detected subject distances of 5.2 m and 7.0 m from the combination data of the subject distance and the F value shown in FIG. As data, a subject distance of 5 m, F2.8
Select The F value thus obtained is given to the aperture adjustment circuit 8 and the gain adjustment circuit 9. By setting the aperture 3 to F2.8, the aperture adjustment circuit 8 sets the depth of field 16 that can be considered to be in focus to be 3.
75 m-7.52 m are obtained. Further, even when the aperture 3 changes, the gain adjustment circuit 9 adjusts the gain so that the video level becomes constant, and the electronic viewfinder 1
0 displays the image of the subject.

By the above operation, the subject 1 whose subject distance 13 displayed on the electronic viewfinder 10 is 5.2 m
And the subject 11 whose subject distance 14 is 7.0 m.
Since it is included in the depth of field 16 of 75 m to 7.52 m,
An in-focus state is obtained.

Next, if it is desired to focus on the subject 12 shown in FIG. 7A, a focus area 19 is set in a rectangular portion including an optical image of the subject 12, and a subject distance 15 of, for example, 8.0 m is detected. I do. Then, from the combination data of the object distance and the F value shown in FIG.
An object distance of 5 m and F4.0 are selected as the best combination data of the S / N value including all of 0 m and 8.0 m. The F value thus obtained is given to the aperture adjustment circuit 8 and the gain adjustment circuit 9. The aperture adjustment circuit 8 sets the aperture 3 to F
By setting the value to 4.0, the depth of field 16 that can be regarded as being in focus is 3.40 m to 3.40 m.
10.14 m are obtained. Further, even when the aperture 3 changes, the gain adjustment circuit 9 performs gain adjustment so that the image level is constant, and the electronic viewfinder 10 can display an image of the subject.

With the above operation, even when the zoom value of the zoom lens 21 is adjusted to enlarge or reduce the optical image of the subject, the subject 1 displayed on the electronic viewfinder 10 and having the subject distance 13 of 5.2 m can be used. The subject 11 whose subject distance 14 is 7.0 m and the subject 12 whose subject distance 15 is 8.0 m are included in the depth of field 16 of 3.40 m to 10.14 m. can get.

Similarly, when focusing on four or more subjects, a focus area is sequentially set on a rectangular portion including an optical image of the subject, and the subject distance is detected. Then, from the combination data of the subject distance and the F value shown in FIG. 4, the depth of field calculation circuit 7 selects the subject distance and the F value having the best S / N value including all the detected subject distances. . The F value thus obtained is given to the aperture adjustment circuit 8 and the gain adjustment circuit 9. The aperture adjustment circuit 8 can obtain a depth of field that can be regarded as being in focus by setting the aperture 3 to the F value. Further, even when the aperture 3 changes,
The gain adjustment circuit 9 adjusts the gain so that the video level becomes constant. In this manner, all the objects displayed on the electronic viewfinder 10 are included in the depth of field 16, so that a focused state is obtained.

In the present embodiment, the object distance and F
From the combination data of the values, the subject distance and the F value having the best S / N value including all the detected subject distances were selected. However, when the entire screen is bright, it is possible to focus at a deeper depth of field 16 by selecting an F value larger than the F value selected first while keeping the subject distance as it is.

In the present embodiment, the electronic viewfinder 10 is divided into a plurality of rectangular portions. However, when the electronic viewfinder 10 is divided into a plurality of polygonal portions or a circular portion whose position and size can be set arbitrarily is used. The same effect can be obtained.

(Embodiment 4) In the camera focusing apparatus according to Embodiment 3 described above, if the performance of the subject distance detection circuit 6 is not good, a different subject distance may be detected.

Therefore, in the camera focusing apparatus according to the fourth embodiment of the present invention, information displayed on the electronic viewfinder 10 is increased. That is, as shown in FIG. 5, the imaging signal whose gain has been adjusted by the gain adjustment circuit 9, the minimum subject distance Lmin and the maximum subject distance L
The electronic viewfinder 10 stores the message information 20 including the max and the F value, the focus area 17 including the optical image of the subject at the subject distance Lmin, and the focus area 19 including the optical image of the subject at the subject distance Lmax.
To be displayed. By doing so, the cameraman can judge whether or not the intended imaging condition is reached while visually recognizing the electronic viewfinder 10. In some cases, focus can be adjusted manually.

In the above embodiment, an example in which the focusing device is applied to a video camera has been described. However, the present invention is not limited to this, and can be applied to all autofocus devices.

[0045]

As described above, the camera focusing apparatus according to the present invention can be used even when the contrast of an image signal is small, which is difficult in the past, or when there is a subject out of the center of the screen or a plurality of subjects. Focusing can be easily and accurately performed by simply setting the focus area on the subject. Further, even when the zoom value of the lens is changed to enlarge or reduce the optical image of the subject, highly accurate focusing can be easily performed.

According to the second or fourth aspect of the present invention, the photographing condition is displayed as message information on the electronic viewfinder, so that the photographer can visually check the electronic viewfinder to determine whether the intended photographing condition is present. Can be.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a main configuration of a camera focusing device according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram schematically showing a subject distance detection method according to the present invention.

FIG. 3 is an explanatory diagram schematically showing a focus area setting method according to the first embodiment.

FIG. 4 is an explanatory diagram showing a relationship between a subject distance and a depth of field according to an F value.

FIG. 5 is an explanatory diagram showing message information displayed on the electronic viewfinder.

FIG. 6 is a block diagram showing a main configuration of a camera focusing device according to a third embodiment of the present invention.

FIG. 7 is an explanatory diagram schematically showing a focus area setting method according to a third embodiment.

FIG. 8 is a waveform diagram showing an outline emphasis operation in a conventional camera focusing device.

[Explanation of symbols]

 1, 11, 12 subject 2 lens 3 aperture 4 image sensor 5a, 5b focus area setting circuit 6 subject distance detection circuit 7 depth of field calculation circuit 8 aperture adjustment circuit 9 gain adjustment circuit 10 electronic viewfinder 13, 14, 15 subject Distance 16 Depth of field 17, 18, 19 Focus area 20 Message information 21 Zoom lens 22 Zoom value setting circuit

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H04N 5/232 G02B 7/11 B 5/235 K G03B 3/00 A

Claims (6)

[Claims] A lens that forms an optical image of a subject; a diaphragm that adjusts the amount of light transmitted through the lens; and an imaging unit that photoelectrically converts an optical image of the subject whose light amount is adjusted by the diaphragm and outputs an imaging signal. A focus area setting unit that sets a focus area on the optical image of the subject; a subject distance detection unit that detects a distance of a subject existing in the focus area; and a subject distance detected by the subject distance detection unit. Depth-of-field calculating means for selecting an F-number at which the S / N value of the image signal increases, and aperture adjusting means for adjusting the aperture according to the F-number selected by the depth-of-field calculating means Gain adjustment means for adjusting the gain of an image signal output from the imaging means in accordance with the F value selected by the depth of field calculation means; Camera focusing device, characterized by comprising an electronic viewfinder, the displaying the image signal that. 2. A lens that forms an optical image of a subject, a diaphragm that adjusts the amount of light transmitted through the lens, and an imaging unit that photoelectrically converts an optical image of the subject whose light amount is adjusted by the diaphragm and outputs an imaging signal. A focus area setting unit that sets a focus area on the optical image of the subject; a subject distance detection unit that detects a distance of a subject existing in the focus area; and a subject distance detected by the subject distance detection unit. Depth-of-field calculating means for selecting an F-number at which the S / N value of the image signal increases, and aperture adjusting means for adjusting the aperture according to the F-number selected by the depth-of-field calculating means Gain adjustment means for adjusting the gain of an image signal output from the imaging means in accordance with the F value selected by the depth of field calculation means; Imaging signal that, the focus area, the object distance, and the focusing device for a camera, characterized by comprising an electronic viewfinder that displays the F value. A zoom lens that forms an optical image of a subject; a zoom value setting unit that changes a zoom value of the zoom lens; an aperture that adjusts a transmitted light amount of the zoom lens; Imaging means for photoelectrically converting an optical image of a subject to output an imaging signal; focus area setting means for setting a focus area on the optical image of the subject; and a subject distance for detecting a distance of the subject present in the focus area. Detecting means; depth-of-field calculating means for selecting an F value at which the S / N value of the imaging signal increases in accordance with the subject distance detected by the subject distance detecting means; Aperture adjusting means for adjusting the aperture according to the selected f-number; imaging output from the imaging means according to the f-number selected by the depth-of-field calculating means No. of the gain adjustment means for adjusting the gain, the gain and electronic view finder for displaying an image signal output from the adjusting means, a camera focusing device, characterized by comprising. A zoom lens that forms an optical image of a subject; a zoom value setting unit that changes a zoom value of the zoom lens; an aperture that adjusts a transmitted light amount of the zoom lens; Imaging means for photoelectrically converting an optical image of a subject to output an imaging signal; focus area setting means for setting a focus area on the optical image of the subject; and a subject distance for detecting a distance of the subject present in the focus area. Detecting means; depth-of-field calculating means for selecting an F value at which the S / N value of the imaging signal increases in accordance with the subject distance detected by the subject distance detecting means; Aperture adjusting means for adjusting the aperture according to the selected f-number; imaging output from the imaging means according to the f-number selected by the depth-of-field calculating means Gain adjustment means for adjusting the gain of the signal, and an electronic viewfinder for displaying the imaging signal output from the gain adjustment means, the focus area, the subject distance, and the F-number. Camera focusing device. 5. The focus area setting means divides a display screen of the electronic viewfinder into a plurality of small areas, and includes a first focus area including an optical image of a subject with a minimum subject distance, and a first focus area with a maximum subject distance. 3. The camera focusing device according to claim 1, wherein the second focusing area including an optical image of the subject is set arbitrarily. 6. The focus area setting means divides a display screen of the electronic view finder into a plurality of small areas, a first focus area including an optical image of a subject having a minimum subject distance, and a first focus area having a maximum subject distance. And a second focus area including an optical image of the subject to be set arbitrarily, and a size of the focus area is set according to a zoom value output from the zoom value setting means. Item 5. The focusing device for a camera according to item 3 or 4.