JPH10186442A - Camera provided with automatic focusing mode - Google Patents

Abstract

PROBLEM TO BE SOLVED: To execute a photographing in a state where a subject is brought into focus even in the case of photographing the subject which is hardly brought into focus in an automatic focusing mode (AF mode), by providing a focusing mode switching means for switching the AF mode and a fixed focus mode (PN mode). SOLUTION: By pressing a mode button 2, the AF mode and the PN mode are switched over each other. In the AF mode, range-finding and focusing are performed by half-pressing a release button 4, and a shutter is actuated by pressing the button 4 further. In the PN mode, the shutter is immediately actuated by pressing the button 4. A liquid crystal display screen 5 is a screen for displaying various kinds of information at the time of photographing; for example, shutter speed, a diaphragm and film sensitivity are displayed. Furthermore, when the AF mode is selected, 'AF' is displayed and when the PN mode is selected, 'PN' is displayed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a camera with an automatic focusing mode having a fixed focusing mode.

[0002]

2. Description of the Related Art Conventionally, in a camera with an automatic focusing mode (hereinafter referred to as an AF camera), at the time of shooting, the subject is automatically adjusted so that the subject is in focus, and the image is shot. When the photographer aligns the distance measurement frame in the center of the viewfinder with the subject and presses the release button halfway, distance measurement to the subject and focusing on the subject are performed automatically, and if the photographer presses the release button further, The shutter operates and the picture is taken.

[0003]

In an AF camera, a distance measurement frame located at the center of a viewfinder is adapted to measure a distance to an object, so that the object to be focused is located at the center of the entire image. It will be positioned and the composition will be fixed. To increase the degree of freedom in this composition, there is a distance information hold function such as focus lock.To make this work, first press the release button while the subject to be focused is located in the center of the distance measurement frame. It is necessary to perform an operation such as changing the direction of the camera and releasing the shutter to the composition that you want to shoot while holding the half-pressed state while holding the half-pressed state.
It requires complicated operability contrary to the original purpose of the camera. Also, when shooting with the self-timer using a tripod,
The focus lock may fail due to the need to lock the focus before fixing the camera.

[0004] For example, at a travel destination, a third party can use his / her own A
When handing over the F camera and requesting a picture, a third party is often unfamiliar with the handed camera and simply presses the release button as it is, so if there are two subjects, the scenery between the two people Sometimes, the subject is in focus, and the "subject" photo is out of focus. Furthermore, the camera may not be able to focus on a target subject even when the subject is through glass, a subject without contrast, a subject with depth, or the like.

[0005] As described above, since the AF camera can automatically adjust the focus and shoot, there is an inconvenience that the focus is focused on a place different from the position desired by the user.

On the other hand, a fixed-focus camera in which the photographing lens is fixed without the automatic focusing mode is also used as a compact camera. In the case of this camera, focusing is not required, and even a beginner who is unfamiliar with the camera can easily shoot.

If an AF camera is provided with a fixed focus mode like a fixed focus camera, the AF camera focuses on a fixed focus in the above-described situation where it is difficult to focus and shoots. AF that can
The inconvenience of the camera can be eliminated.

An object of the present invention is to provide a fixed focus mode even though the camera is an AF camera, so that the camera is in focus even when a person who does not operate the camera takes a picture or a subject which is hard to focus in the AF mode. It is an object of the present invention to provide a camera capable of taking a picture in a state where the camera is in a state where the camera is in a state where the camera is in a state where the camera is in a state where the camera is in a standing state.

[0009]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the invention according to claim 1 of the present invention is directed to a camera having an automatic focus adjustment mode having a fixed focus mode, wherein the camera has an automatic focus adjustment mode. A focus mode switching means for switching between the fixed focus mode and the fixed focus mode; and an aperture so that the depth of field becomes a value including a range that can be photographed by the strobe light when flash photography is performed in the state switched to the fixed focus mode. An aperture stop setting means for setting an aperture diameter of the aperture, setting the aperture diameter of the aperture stop so that the rear depth of field becomes infinity when flash photography is not performed in a state switched to the fixed focus mode, It is characterized by having.

Although the focus of the lens should theoretically only be in one plane, in practice it appears to be in focus over a considerable depth. That is, there is a depth before and after the position of the photographing lens (depth of focus) which does not feel blurred on the film surface even if the focus is slightly shifted, and the corresponding depth on the subject side is the depth of field. The depth of field becomes deeper as the aperture stop of the taking lens is stopped down (smaller stop). Then, by controlling the aperture stop,
Ultimately, the depth of field behind (the depth of field behind the subject with respect to the camera) can be set to infinity.

In the camera of the present invention, the aperture diameter of the aperture stop is set so that the depth of field becomes a value including a range that can be photographed by the strobe light when performing flash photography with the mode switched to the fixed focus mode. The configuration is made for the following reason.

Normally, when the brightness of the subject is insufficient,
If the shutter speed is reduced, insufficient exposure can be compensated. However, if the shutter speed is too slow, the effect of camera shake is likely to occur, so there is naturally a limit. If the shutter speed is insufficient to cope with the light amount, flash photography is performed (flash photography).
Since the current strobe light only reaches the subject within a range of about 2 to 3 m from the camera, it is not possible to take an appropriate exposure for the subject located farther than it.
In this case, it is limited to short-distance shooting, and it is sufficient if a depth of field can be obtained such that only a range that can be shot with strobe light is in focus.

On the other hand, the configuration in which the aperture diameter of the aperture stop is set such that the rear depth of field becomes infinity when flash photography is not performed in the state switched to the fixed focus mode is as follows. When shooting a bright object that does not require strobe light, there is no limit to the shooting range of the strobe light, and there is a possibility that subjects from close to far away from the camera may be targeted. There is a need to set the depth to infinity.

According to the first aspect of the present invention, there is provided a camera with an automatic focus adjustment (AF) mode having a fixed focus mode, comprising a focus mode switching means for switching between the automatic focus adjustment mode and the fixed focus mode. Therefore, by switching to the fixed focus mode when the user determines that there is a possibility of being out of focus or when requesting a third party who cannot use the AF mode for shooting,
You can take pictures without blur. Further, the invention according to claim 1 includes an aperture stop setting means, which can switch the fixed focus mode to a strobe light to set a depth of field by a strobe light in a flash mode. Since the aperture diameter of the aperture stop is set to a value that includes the range, a subject that requires flash photography can be photographed in focus if it is within a range where flash photography is possible. Further, the aperture stop setting means sets the aperture diameter of the aperture stop so that the rear depth of field becomes infinity when flash photography is not performed in the state switched to the fixed focus mode.
A subject that does not require flash photography can be photographed in focus, no matter where it is from a short distance to infinity, or even if it is quite deep.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a camera according to the present invention will be described below with reference to FIGS.

First, the configuration will be described.

FIGS. 1A and 1B are top views of a camera according to the present invention, schematically showing the position of a taking lens in the camera in the optical axis direction. In FIG. 1, 1 is a camera body, 2 is a mode button, 3 is a taking lens, 4 is a release button, and 5 is a liquid crystal display screen.

The mode button 2 constitutes a part of a mode selection section (FIG. 2) of a control system built in the camera body 1,
By pressing, it is possible to switch between the automatic focus adjustment mode (hereinafter, referred to as AF mode) and the fixed focus mode (hereinafter, referred to as PN mode) of the camera of the present invention.

The photographing lens 3 includes a lens driving unit 1 of a control system.
6 (FIG. 2) is driven to a predetermined position. The type of lens can be appropriately selected.
A lens having a number 4 (hereinafter, this lens is referred to as an F4 lens) is used.

The position of the release button 4 is detected by a release button position detector (FIG. 2) of the control system. Then, in the AF mode, the distance measurement and focusing are performed by half-pressing the release button 4, and when the release button 4 is further pressed, the shutter operates. In the PN mode, when the release button 4 is pressed, the shutter is activated immediately.

The liquid crystal display screen 5 is a screen for displaying various information at the time of photographing. For example, the liquid crystal display screen 5 displays a shutter speed, an aperture, and a film sensitivity (ISO value). When the AF mode is selected, FIG. a) As shown in FIG.
FIG. 1 when the PN mode is selected.
“PN” is displayed as shown in FIG.

FIG. 2 is a block diagram showing a main configuration of a control system 11 built in the camera body 1 of FIG.

The control system 11 provides a control unit 12 with a mode selection unit 13, a release button position detection unit 14, a distance measurement unit 1
5, a lens driving unit 16, a luminance detecting unit 17, a shutter driving unit 18, and a strobe light emitting circuit 19 are connected to each other.

The control unit 12 has a CPU (Central Process
ng Unit), ROM (Read Only Memory) and RAM (R
and a microcomputer having an andom access memory). The ROM stores various programs and individual photographing programs corresponding to the AF mode and the PN mode, respectively.
In accordance with these programs, various types of arithmetic processing are performed while exchanging data with the RAM and each part of the control system. The control unit 12 controls the control system 1 based on these calculation results.
1 controls the overall operation.

A program (shutter control program) for determining the aperture stop and the shutter speed in the photographing programs in the AF mode and the PN mode will be described.

The shutter control program executed in the AF mode includes a program mode in which both the shutter speed and the aperture are automatically determined by a photographer's selection, a shutter speed priority mode in which the shutter speed can be set arbitrarily, and an aperture. Aperture priority mode that can be set arbitrarily,
Both the shutter speed and the aperture have a manual mode that can be arbitrarily set by the photographer, and can be selected from them.

The flow of the program in the aperture priority mode when the F4 lens is used will be described with reference to FIG. The aperture stop is set to F4 by the photographer. Control unit 12
Calculates a required exposure value from the luminance of the subject detected by the luminance detection unit 17 and the film sensitivity detected by an ISO detection unit (not shown) in the control unit 12. The exposure value required for photographing can be obtained by controlling the aperture stop and the shutter speed. Here, since the aperture is already fixed, only the shutter speed is determined from the obtained exposure value.
When a shutter speed of 1/50 second is obtained, the control unit 12 outputs a shutter control signal to the shutter driving unit 18 to operate the shutter so that the shutter speed becomes 1/250 second. Here, the control unit 12
Outputs a strobe light emission control signal to the strobe light emission circuit 19 when it is determined that the exposure is insufficient,
The flash fires when the shutter is activated.

Next, a shutter control program executed in the PN mode will be described with reference to FIG. First, the control unit 12 determines an aperture stop according to the brightness of the subject detected by the brightness detection unit 17. A control unit 1 that represents the reference of the brightness of the subject for determining the aperture stop
2 is a part of the data stored in PN shown in FIG.
9 is a mode shutter control table 20. In FIG.
The figure shows a case where the F4 lens is fixed to Step 2 in Table 1 and films with film sensitivities ISO 100 and 200 are used. The reason why step 2 is fixed is that the object distance that does not cause out of focus is set to 1.2 m to infinity. As shown in the PN mode shutter table 20, when a film of ISO 100 is loaded, if BV = 6.5 or less, low brightness and BV = 6.
5 to 8.2 are classified into medium luminance, and BV = 8.2 or more are classified into high luminance. When a film of ISO 200 is loaded, BV = 5.5 or lower has low brightness, and BV = 5.5 to 7.2.
Is classified into medium luminance, and BV = 7.2 or higher is classified into high luminance. Here, BV representing luminance is a value of external light luminance.

If the luminance is low, the aperture stop is determined to be F5.4. If the luminance is medium or high, the aperture stop is determined to be F10. If the aperture is fixed at step 2 using an F4 lens and the aperture stop is F10, it is possible to take an image in such a manner that the depth of field behind becomes infinite and a subject located at 1.2 m to infinity is in focus. it can.

The controller 12 obtains a necessary exposure value from the luminance of the subject detected by the luminance detector 17 and the film sensitivity detected by an ISO detector (not shown) in the controller 12.
When the aperture stop is determined as described above, the shutter speed is obtained from the exposure value. FIG. 3B shows the shutter speed under the above conditions. When the brightness is low, the shutter speed is 1/70 second, and the control unit 12 requires that the strobe light be emitted to compensate for the light amount. Output a signal. The shutter speed is 1/70 second for medium brightness, and 1 for high brightness.
It is determined to be 1/25 second.

The reason why different apertures are set for low luminance, medium luminance and high luminance is as follows. If the brightness of the subject is insufficient, the exposure may be compensated for by lowering the shutter speed. However, if the shutter speed is too slow, the effect of camera shake is likely to occur and there is naturally a limit. In the case of a general-purpose camera, the limit is about 1/70 of a second, and in the case of low luminance, the amount of light is insufficient and the strobe light must be emitted at such a low shutter speed.
However, the current strobe light only reaches the subject within a range of 2 to 3 m from the camera, and it is not possible to take an appropriate exposure for a subject located farther from the camera. It is sufficient that a depth of field can be obtained such that only the photographable range is in focus. As a result, the aperture stop does not need to be so small because it requires less depth of field.

On the other hand, in the case of a medium-brightness / high-brightness object that does not require strobe light emission, there is no limitation on the shooting range of the strobe light, and objects from a short distance to a distant object from the camera. , That is, the rear depth of field needs to be infinity. As a result, the aperture stop is set to a considerably small stop.

The mode selection unit 13 includes the mode button 2 and outputs a signal to the control unit 12 to switch from the AF mode to the PN mode or from the PN mode to the AF mode when the user presses the mode button 2.

The release button position detector 14 is configured to detect the position of the release button 4. When the photographer half-presses the release button 4 in the AF mode, a distance measurement start signal is sent to the controller 12. Is output, and when it is completely pressed, a shooting start signal is output to the control unit 12. In the PN mode, a distance measurement start signal is not output even if the shutter button is half-pressed, and a shooting start signal is output to the control unit 12 when the release button 4 is completely pressed.

The distance measuring unit 15 includes an infrared light emitting diode that emits infrared light and a PIN photodiode that is a light receiving element, and measures a distance to a subject by an infrared active method. That is, when the release button 4 is half-pressed and a distance measurement start signal is output to the control unit 12, the control unit 12 outputs a distance measurement control signal to the distance measurement unit 15 and receives the signal. Numeral 15 emits infrared light from the infrared light emitting diode to the subject, receives the reflected light from the subject with the PIN photodiode, and outputs a light receiving signal corresponding to the energy level of the reflected light to the control unit 12.

The lens driving section 16 drives the taking lens to a predetermined position according to the lens driving control signal input from the control section 12.

In the AF mode, the operable lens drive amount is set to the active step. For example, when an F4 lens is used, the active lens drive amount shown in Table 1 is set.
The drive amount is set in steps.

[Table 1] The set distance in Table 1 is a distance to a subject that can be photographed (focused).

In the PN mode, the lens driving unit 16
Is, for example, when an F4 lens is used, as described above,
It is driven to the position of step 2 in Table 1.

The luminance detecting section 17 includes a light receiving element, detects the brightness (luminance) of the subject, and outputs a luminance detection signal corresponding to the result to the control section 12.

The shutter driving section 18 drives a shutter according to a shutter control signal output from the control section 12.

In the strobe light emission circuit 19, when a strobe light emission control signal is output from the control unit 12, the xenon discharge tube in the circuit starts emitting light. After the light emission is completed, a capacitor in the circuit is charged. Camera body 1
May be an internal strobe built in the camera, or an external strobe attached to the camera body 1. Also,
The guide number may be one type of strobe,
A strobe which has several types of guide numbers and can be switched by a switch or the like may be used. For example, a strobe with a guide number of 8.5 may be used.

Next, the operation of the camera according to the present invention configured as described above will be described.

Turn ON / OFF switch (not shown) of the camera body 1 in which the film cartridge is loaded.
To The loaded film may be any film as long as it is a photographic film. For example, a film cartridge (film format: 27.4 × 15.6 mm) compatible with the Advanced Photo System may be used. it can. Also, as the mounted photographing lens, for example, an F4 lens is used. Control unit 1
The ISO detection unit 2 detects the film sensitivity from the bar code or the like of the film cartridge and stores the data in the RAM.

The photographer or the like switches the display of “AF” or “PN” on the liquid crystal display screen 5 by pressing the mode button 2. The mode selector 13 outputs a signal to the effect that the mode is switched to the controller 12, and the controller 12 selects a different photographing program according to those signals. When "AF" is displayed, shooting is performed in the AF mode,
When "PN" is displayed, shooting is performed in the PN mode.

First, the operation when the AF mode is displayed will be described. The operation in the AF mode is the same as that of the conventional AF camera, but the operation when the aperture priority mode is selected will be described as an example of the operation of the camera of the present invention. It is assumed that the aperture stop value is fixed at F4 by the photographer.

When the photographer presses the release button 4 halfway, a distance measurement start signal is output from the release button position detector 14 to the controller 12. Upon receiving this signal, the control unit 12 outputs a ranging start signal to the ranging unit 15. The distance measuring unit 15 emits infrared light from the infrared light emitting diode to the subject, receives the reflected light from the subject with the PIN photodiode, and outputs a light receiving signal corresponding to the energy level to the control unit 12. The control unit 12 obtains a lens drive amount necessary for focusing from the calculation according to the distance to the subject, and outputs a lens drive control signal corresponding to the lens drive amount to the lens drive unit 16. Lens drive unit 16
Drives the photographing lens to a predetermined position according to the lens drive control signal input from the control unit 12, as described above.

On the other hand, the control unit 12 causes the luminance detection unit 17 to obtain the luminance of the subject, and the luminance detection unit 17 outputs a luminance detection signal corresponding to the result to the control unit 12,
The control unit 12 stores the data as data in the RAM. Then, the control unit 12 calculates a necessary exposure value from the data and the film sensitivity data, and further determines a shutter speed from the set aperture stop based on a shutter control program.

When the photographer presses the release button 4 completely, a photographing start signal is output from the release button position detecting section 14 to the control section 12, and the control section 12 sets the shutter speed to the set aperture stop and the determined shutter speed. A corresponding shutter control signal is output to the shutter driving unit 18, and the shutter driving unit 18 drives the shutter based on the signal to perform photographing. When exposure is insufficient, the control unit 1
By the instruction of 2, the strobe emits light when the shutter is driven.

Next, the operation when the mode is switched to the PN mode will be described.

When the mode button 2 is pressed, the PN mode is selected. The control unit 12 outputs a lens drive control signal to the lens drive unit 16, and in response to this, the lens drive unit 16 fixes the taking lens at a predetermined position.

When the photographer presses the release button 4, a photographing start signal is output from the release button position detector 14 to the controller 12. In response, the control unit 12 causes the luminance detection unit 17 to obtain the luminance of the subject, and the luminance detection unit 17 outputs a luminance detection signal corresponding to the result to the control unit 12. The control unit 12 stores the data as data in the RAM, and first determines the aperture stop based on the shutter control program. Control unit 1
In step 2, an exposure value required for photographing is obtained from the luminance of the subject and the film sensitivity. Next, the control unit 12 determines a shutter speed from the exposure value and the aperture stop, and outputs a shutter control signal corresponding to the aperture stop and the shutter speed to the shutter driving unit 18. The shutter driving unit 18 drives the shutter based on the driving, and the photographing is performed. If the brightness of the subject is low, the flash is emitted when the shutter is driven.

As described above, according to the camera of the present invention,
A camera with an automatic focus adjustment (AF) mode having a fixed focus mode and a focus mode switching means for switching between the automatic focus adjustment mode and the fixed focus mode, so that it is determined that the user may be out of focus. And
By switching to the fixed focus mode when, for example, requesting a third party who cannot use the AF mode to take a picture, a picture without blur can be taken. Further, the image forming apparatus further includes an aperture stop setting unit. The aperture stop setting unit is configured to set the depth of field to a value including a range that can be captured by the strobe light when performing flash photography in a state where the mode is switched to the fixed focus mode. Since the aperture diameter of the aperture stop is set, a subject requiring flash photography can be photographed in focus if it is within a range where flash photography is possible. Further, the aperture stop setting means sets the aperture diameter of the aperture stop so that the rear depth of field becomes infinity when the flash mode is not set and the flash mode is switched to the fixed focus mode. Unnecessary subjects can be photographed in focus regardless of where they exist from near distance to infinity, or even if they are quite deep. Therefore, according to the camera with the AF mode of the present invention, when a person who is not familiar with the camera operation takes an image or when shooting an object that is difficult to focus on in the AF mode, the camera is switched to the fixed focus mode to focus. You can shoot with the camera in the upright position.

In the embodiment of the present invention described above, an example is described in which a lens having an F-number of 4 is used as a photographing lens. However, the present invention is not limited to this, and various types of lenses can be used. The driving amount of the lens in the AF mode, the fixed position of the lens in the PN mode, the value of the aperture stop, and the like are changed depending on the photographic lens used. Further, the camera of the present invention is not limited to the above as long as it can embody the present invention,
Needless to say, specific functions can be appropriately changed.

[0054]

According to the camera of the first aspect of the present invention, even if the camera is an AF camera, it has a fixed focus mode, and it is difficult to focus on a person who is not operated by the camera or in the AF mode. Even when shooting a subject, it is possible to shoot in focus by switching to the fixed focus mode.

[Brief description of the drawings]

FIG. 1 is a top view of a camera body of the present invention, schematically showing a position of a taking lens in the camera in an optical axis direction.

FIG. 2 is a block diagram showing a main configuration of a control system built in the camera body of FIG. 1;

FIG. 3 is a diagram illustrating an example of an operation of a shutter of the camera in FIG. 1;

FIG. 4 is a PN mode shutter control table stored in a control unit of FIG. 2;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Camera main body 2 Mode button 3 Shooting lens 4 Release button 5 Liquid crystal display screen 11 Control system 12 Control unit 13 Mode selection unit 14 Release button position detection unit 15 Distance measurement unit 16 Lens drive unit 17 Brightness detection unit 18 Shutter drive unit 19 Strobe Light emitting circuit

Claims (1)

[Claims] 1. A camera with an automatic focus adjustment mode having a fixed focus mode, wherein focus mode switching means for switching between the automatic focus adjustment mode and the fixed focus mode, and wherein the camera is switched to the fixed focus mode. When shooting with a strobe, the aperture diameter of the aperture stop is set so that the depth of field becomes a value including the range that can be shot with the strobe light. A camera with an automatic focus adjustment mode, comprising: aperture stop setting means for setting the aperture diameter of the aperture stop so that the rear depth of field becomes infinity.