JPH11174521A - Video camera system, photographing method, camera device and lens unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a video camera system and a photographing method, capable of correcting the out of focus caused by the use of automatic focusing auxiliary light, even if an interchangeable lens having a part of an automatic focusing function is used. SOLUTION: When the interchangeable lens 50 having a part of the automatic focusing function is used, the presence of the emission of the automatic focusing auxiliary light of a stroboscope 13 can not be recognized on the side of the interchangeable lens 50, so that a signal on the emission of the auxiliary light is transmitted to the side of the interchangeable lens 50 from the camera microcomputer 11-1 of a camera main body 60, to correct the out of the focus in automatic focusing caused by the use of the auxiliary light (a red LED, a wavelength of 700 nm, etc.), by the lens microcomputer 14 of the interchangeable lens 50.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video camera system capable of photographing a still image and a method of photographing the same, and more particularly to a focus correction thereof.

[0002]

2. Description of the Related Art Conventionally, video cameras have been automated and multifunctional in all aspects, such as AE (auto exposure) and AF (auto focus), so that good photographing can be easily performed.

In recent years, the performance of video cameras has been improved, and the number of video cameras capable of recording still images, such as digital still cameras, has been increasing. The demand for still image recording has been increasing due to the rapid spread of personal computers. . In addition, some flashes have a built-in flash or can be mounted externally so that still images can be taken more clearly.

FIG. 5 shows an example of the configuration of a video camera capable of recording a still image using a conventional strobe. In FIG. 5, reference numeral 1 denotes a focus lens for focusing, which is moved by a lens driving driver 16 in the optical axis direction to perform focusing. The light passing through the focus lens 1 is adjusted to an appropriate light amount by the diaphragm 2. Reference numeral 3 denotes a variable power lens (also called a zoom lens) for changing the angle of view magnification. The light adjusted to an appropriate amount by the aperture 2 is C
An image is formed on the imaging surface of the CD 4 and photoelectrically converted into an electric signal. The photoelectrically converted signal is read out from the CCD 4 by a reference clock, sampled / held by a CDS (correlated double sampling) 5 and an AGC (automatic gain control) 6, and simultaneously amplified by an optimum gain. The converter 7 converts the digital signal into a digital signal synchronized with the reference clock. Then, only a specific frequency component is extracted by a BPF (bandpass filter) 8, and a signal of a specific portion in the captured image is extracted by a GATE 9. Reference numeral 10 denotes a recorder control circuit that controls image recording. The signal output from the GATE 9 is input to the camera microcomputer 11 and the auto focus control is performed so that the signal value becomes maximum.
Here, if the strobe 13 is mounted, the camera microcomputer 11 exchanges data such as the light emission amount, ON / OFF of the auxiliary light, and the charging state by communication, and the two-stage switch (release button) 12 for the still image is half-pressed. When the subject is dark and the subject is dark, the camera microcomputer 11
Communication is performed to emit auxiliary light. If focus is achieved, the camera microcomputer 11 locks the focus lens 1 and waits until the still image two-stage switch 12 is fully pressed. After confirming the focus, the photographer switches the two-stage switch 1 for still images.
When the button 2 is fully pressed, the camera microcomputer 11 controls the amount of light emitted from the strobe to emit light so that the subject is properly exposed. The video synchronized with the light emission is written into the memory in the recorder control circuit 10 and written as a still image on the tape for about 6.5 seconds. However, if the subject is dark,
A video camera equipped with auto focus (a method of using a specific spatial frequency component of a video signal obtained from an image sensor for distance measurement) or the like cannot perform auto focus because a subject on a screen has no contrast. For this purpose, the camera microcomputer 11 controls the strobe 13 to emit AF auxiliary light so as to brighten the subject. Usually, a red LED (wavelength 700 nm) or the like is used as an auxiliary light source, so that the focus is blurred due to the chromatic aberration of the lens. Make corrections. As described above, in a system using a strobe with a built-in AF auxiliary light for photographing a still image in a dark place, a system has been proposed in which an infrared LED is emitted as AF auxiliary light for autofocusing to perform focus correction. .

Next, a conventional camera microcomputer 1 shown in FIG.
6 is shown in FIG.

# 600 This is the start of this flow, which is repeatedly started at a predetermined timing.

# 601 It is determined whether a still image is being recorded.

In step # 602, it is determined whether the camera is in the focus locked state.

# 603 It is determined whether the still image recording switch 12 is half-pressed.

In step # 604, the exposure is locked when the camera is half-pressed in step # 603.

In step # 605, it is determined whether the brightness of the subject is less than the reference value.

In step # 606, if it is less than the reference value in step # 605, the AF auxiliary light is emitted.

# 607 A focus shift due to the auxiliary light emission is corrected.

# 608 It is determined whether or not focus has been achieved.

In step # 609, if focus is achieved in step # 608, the focus is locked.

# 610 Turn off the auxiliary light.

# 611 It is determined whether the still image recording switch 12 is fully pressed.

At step # 612, if it is in the fully-pressed state at step # 611, pre-emission is performed.

In step # 613, the main light emission amount is calculated based on the result of the pre-light emission.

# 614 Main light emission is performed with the light emission amount based on the calculation.

In step # 615, recording of the image captured by the main light emission is started.

# 616 Indicates the end of this flow.

Here, the processing of the flow of the conventional example shown in FIG. 6 will be described.

# 600 Indicates that this processing is performed at a certain fixed cycle.

# 601 If a still image is being recorded, # 616
And ends this flow without performing any processing. If a still image is not being recorded, the process of # 602 is performed.

In step # 602, it is determined whether the camera is in the focus locked state. If it is in the focus locked state, the process jumps to step # 611 to determine whether or not it is in the fully pressed state. If the focus is not locked, the process proceeds to step # 603, and a half-press determination of the still image recording switch 12 is performed.

# 603 It is determined whether the still image recording switch 12 is half-pressed. # 6 if half-pressed
Move on to step 04, and lock the exposure. If it is not half-pressed, the process jumps to step # 616, and ends this flow without performing any processing.

# 604 Lock the exposure.

In step # 605, if the brightness of the object is less than the reference value, the process proceeds to step # 606, where the auxiliary light is emitted. If the value is equal to or more than the reference value, it is determined that the auxiliary light is not necessary for the autofocus, and the process jumps to step # 608 to determine the focus.

In step # 606, auxiliary light for autofocus is emitted, and the flow advances to step # 607.

In step # 607, the focus position is corrected in consideration of the chromatic aberration of the lens when the infrared auxiliary light is emitted, and the process proceeds to step # 608.

In step # 608, it is determined whether or not the subject is in focus. If the subject is just in focus, the process proceeds to step # 609 to lock the focus. If it is not in focus, the auto focus operation is continued, and this flow ends.

In step # 609, it is determined that focus has been achieved, the focus is locked, and the flow advances to step # 610.

In step # 610, the auxiliary light for auto focus is not required, so that the light is turned off, and the process proceeds to step # 611.

In step # 611, it is determined whether the still image recording switch 12 has been fully pressed. If the switch 12 has been fully pressed, the process proceeds to step # 612 to perform pre-emission. If the button has not been fully pressed, this flow ends without performing any processing.

In step # 612, pre-light emission for determining the amount of main light emission is performed, and the flow advances to step # 613.

In step # 613, the brightness of the object is calculated from the result of the pre-light emission, and the main light emission amount is determined. And # 614
Move on to processing.

In step # 614, light emission of the main light emission amount is performed based on the calculation, and the process proceeds to step # 615.

# 615 The image synchronized with the main light emission is recorded in a memory (not shown) via the recorder control circuit 10,
The memory image is recorded on a tape.

# 616 Indicates the end of this flow.

As described above, in the conventional example, the camera microcomputer 11 determines the brightness of the subject, and irradiates the infrared LED to perform focusing even for a dark subject so that autofocus control can be performed. Is adjusted, the image is out of focus at the time of main light emission due to chromatic aberration of the lens. Therefore, the camera microcomputer 1
No. 1 performs focus correction according to the chromatic aberration of the lens.

[0042]

However, when the lens is an interchangeable lens, and this interchangeable lens carries a part of an autofocus function (arithmetic circuit, program, etc.), a strobe assist attached to the body is provided. Since it cannot be determined whether or not light is emitted, the lens cannot correct the focus shift due to the infrared auxiliary light. Also, if the focus is adjusted with infrared light when using the strobe auxiliary light, the focus will shift when the main flash is used, and still images will be captured.
There is a problem that a still image captured by the main flash is out of focus.

The present invention has been made under such circumstances, and a video camera capable of correcting a defocus due to the use of an auxiliary light for autofocus even when using an interchangeable lens having a part of an autofocus function. It is intended to provide a system and a shooting method.

[0044]

In order to achieve the above object, the present invention provides a video camera system having the following (1) to (5).
As described in (4), the shooting method was changed as shown in (5) below.
The camera device is configured as in the following (6), and the lens unit is configured as in the following (7).

(1) A video camera system including a camera body and an interchangeable lens having a part of an autofocus function, capable of photographing a still image, wherein the camera body emits auxiliary light for autofocus. A first communication unit capable of transmitting a signal to the interchangeable lens, wherein the interchangeable lens has a second communication unit capable of receiving the signal, and a focus unit when the signal is received by the second communication unit. A video camera system comprising a focus correction unit for performing correction.

(2) In the video camera system according to the above (1), the first communication means can transmit photometric information, and the second communication means can be used for auto-focusing based on the photometric information. A video camera system capable of transmitting a signal requesting emission of auxiliary light.

(3) The video camera system according to (1), wherein a part of the autofocus function extends the autofocus function of the camera body.

(4) In a replaceable video camera system having an autofocus function on the lens side,
The camera body includes a strobe control unit for controlling a strobe with an auxiliary light for autofocus, a switch for recording a still image, and a communication unit for sending a signal indicating whether or not the auxiliary light for autofocus is emitted to the lens side. A focus control means for performing focus control on the lens side;
A video camera system comprising: communication means for communicating with the camera body; and focus correction means for performing focus correction based on the signal received by the communication means.

(5) A method for photographing a still image by a video camera system including a camera body and an interchangeable lens having a part of an autofocus function, wherein a step of emitting an auxiliary light for autofocus, Correcting the focus shift due to the auxiliary light later.

(6) A camera device used in a video camera system having an autofocus function on the lens side and having interchangeable lenses, the camera device comprising: a strobe control means for controlling a strobe with auxiliary light for autofocus; A camera device comprising: a still image recording switch; and a communication unit that sends a signal indicating whether or not the autofocus auxiliary light is emitted to the lens side.

(7) A lens unit used in a replaceable lens video camera system having an autofocus function on the lens side. The lens unit is for communicating with a focus control means for performing focus control and a camera body. A lens unit comprising: a communication unit of (1); and a focus correction unit that performs focus correction based on a signal indicating whether or not the auxiliary light for autofocus is received by the communication unit.

[0052]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to embodiments of a video camera system. Although the embodiment is in the form of an apparatus, the present invention is not limited to this, and can be similarly implemented in the form of an imaging method. Further, although the embodiment is directed to the auxiliary light for autofocus provided on the strobe, the present invention is not limited to this, and the present invention can be similarly applied to the auxiliary light for autofocus provided on the camera body. it can.

[0053]

FIG. 1 is a block diagram showing the configuration of a "video camera system" according to an embodiment.

In FIG. 1, the same components as those in the conventional example shown in FIG. 5 are denoted by the same reference numerals, and detailed description thereof will be omitted. Since the camera microcomputer is different from the conventional example in software, the camera microcomputer is distinguished by adding a branch number "-1".

In FIG. 1, the difference from the conventional example is that the lens microcomputer 14 having a part of the autofocus function is built in the lens 50 and communicates with the camera microcomputer 11-1 on the main body 60 side. It is. As described above, in a video camera system having an autofocus function on the lens (the autofocus function of the camera body is extended by the autofocus function of the lens), the video information is extracted from the image information via communication from the camera body side. The auto focus evaluation value is sent to the lens side, and focusing is performed on the lens side. FIG. 2 shows a part of communication contents between the lens and the camera body. In the camera body-to-lens communication, in addition to a photometric evaluation value used for controlling the aperture of the lens 50 and an AF evaluation value for performing autofocus control, a strobe status indicating whether or not a strobe is attached, a still image 2 The status indicating the pressed state of the step switch 12 and the REC status indicating whether the recorder is in the recording state are transmitted. The strobe status has a bit indicating whether the strobe is mounted and a bit indicating whether or not the strobe auxiliary light is turned on. The two-stage switch status for a still image is the two-stage switch 12 for the still image of the camera body 60.
Indicates a half-pressed state or a fully-pressed state. The REC status indicates whether or not the recorder of the camera body 60 is recording. The lens 50 recognizes that a still image is to be recorded based on the REC status and the two-stage switch status for the still image, determines the brightness of the screen based on the photometric information transmitted from the camera body 60, and provides an auxiliary light for auto focus. Is transmitted to the camera body 60. At this time, the camera body 60 responds to the auxiliary light emission request transmitted from the lens 50 and
The auxiliary light is turned on / off. The camera body 60
Transmits the light emission / extinction state of the auxiliary light to the lens 50 via the camera body → lens communication. The lens 50 performs focus correction when focusing is performed in a state where the auxiliary light is emitted, and focuses without performing focus correction when focusing is performed in a state where the auxiliary light is emitted, and focuses / defocuses on the camera body 60. Reply the focus information. As described above, the lens 50 identifies whether a strobe is attached to the camera body 60 or not, and requests the camera body 60 via communication to emit an auxiliary light if the screen is dark at the time of shooting a still image. Reference numeral 60 performs light emission / extinguishing of the auxiliary light according to the request of emitting / extinguishing the auxiliary light from the lens 50. At this time, the camera body 60 returns status information of the emission / extinction of the auxiliary light to the lens 50. If the lens 50 is in focus with the auxiliary light being emitted, the lens 50 performs focus correction for the main light emission, If focusing is performed while the light is off, the operation is performed so that focus correction is not performed.

FIG. 3 shows a flow of the lens microcomputer 14 showing this operation.

# 300 This is the beginning of this flow, which is repeatedly started at a predetermined timing.

# 301 Communication with the camera body 60 is performed.

# 302 It is determined whether or not a still image is being recorded based on the REC status.

# 303 It is determined whether or not the focus is locked.

In step # 304, it is determined whether or not the switch is half-pressed according to the status of the two-stage switch for the still image.

In step # 305, the degree of screen brightness is determined based on the photometric value.

Step # 306: A request is made to the camera body 60 to emit auxiliary light.

In step # 307, a request to turn off the auxiliary light is made to the camera body 60.

# 308 It is determined whether or not the auxiliary light is emitted.

# 309 Focus correction is performed when the auxiliary light has been emitted.

# 310 It is determined whether or not the camera is in focus.

# 311 An operation is performed to lock the focus when the subject is in focus.

# 312 After the focus lock, a request to turn off the auxiliary light is made.

# 313 Indicates the end of this flow.

The processing of the lens microcomputer 14 in this case will be described with reference to the flowchart of FIG.

Step # 300 is the start of this flow, which is repeatedly started at a predetermined timing. Step # 301 performs lens-camera communication. It is determined whether or not the camera body 60 is recording a still image based on the REC status of the data received in the communication performed in # 301. If the still image is being recorded, the process jumps to step # 313, and this flow ends. If the still image is not being recorded, the process proceeds to step # 303, and it is determined whether the focus is locked. If the focus is locked in step # 303, the process jumps to step # 313 and ends this flow. If the focus is not locked, the process proceeds to step # 304. In # 304, the camera body 6
It is determined whether the two-stage switch 12 for still image recording is half-pressed or fully pressed based on the data received in the communication with 0. If it is half-pressed, the process proceeds to step # 305 to determine the brightness. If it is not half-pressed, the process jumps to step # 313 and the flow ends. # 30
In step 5, the brightness of the screen is compared with the reference value based on the photometry data from the camera body 60. If the brightness is less than the reference value, the process proceeds to step # 306, and an auxiliary light emission request is made. If the value is equal to or more than the reference value, it is determined that the auxiliary light is unnecessary because the subject is bright and # 30
Then, the process proceeds to step 7, and an auxiliary light extinguishing request is made. # 30
In step 8, it is determined whether or not the auxiliary light is emitted based on the flash status from the camera body 60. If the auxiliary light has been emitted, the process proceeds to step # 309, where the focus shift due to the auxiliary light emission is corrected so that the focus shift does not occur in the still image during the main light emission. If the auxiliary light has not been emitted, the process jumps to the process of # 310 without performing the focus correction of # 309. In step # 310, it is determined whether or not the subject is in focus. If the subject is in focus, the process proceeds to step # 311 to perform focus lock. If the camera is not in focus, the process jumps to step # 313 and ends this flow. In step # 312, since the focus is locked, a request to turn off the auxiliary light is made. Next, # 31
Move to the process of No. 3 and end this flow.

As described above, the lens microcomputer 14 recognizes that the camera main body 60 is attached to the strobe by lens-camera communication, transmits an auxiliary light emission request to the camera main body 60, and outputs the auxiliary light emission status transmitted from the camera main body 60. By determining whether or not to perform focus correction, focus correction at the time of auxiliary light emission can be performed reliably, and a high-quality still image that is in focus can be captured.

FIG. 4 shows a flow of the camera microcomputer 11-1.

# 400 This is the start of this flow, which is repeatedly started at a predetermined timing.

# 401 Communication with the lens 50 is performed.

# 402 It is determined whether a still image is being recorded.

# 403 It is determined whether or not there is an auxiliary light emission request from the lens 50.

# 404 Sets an auxiliary light emission request to the strobe 13.

In step # 405, a request to turn off the auxiliary light is set for the strobe 13.

# 406 Communicates with the strobe 13 and sends an auxiliary light emission / extinguish request to the strobe 13.

# 407 Set the status of whether or not the strobe auxiliary light is emitted.

# 408 This shows the end of this flow.

By transmitting / receiving a strobe mounting bit, a strobe light emission status bit, a strobe light emission request, and a focus status bit as shown in FIG. 2 in communication with the lens 50 of # 401, the lens 50 is strobed to the camera body 60. When the subject is dark, an auxiliary light emission request is sent to the camera body 60 for a dark subject, and the camera body 6
0 returns the auxiliary light emission status to the lens 50, and if the auxiliary light is emitted, the lens 50 corrects the focus position and controls so as not to cause a defocus during main emission.

As described above, according to the present embodiment,
When shooting a still image with a flash attached to a video camera system, a flash mounted bit,
By having a strobe auxiliary light emission status bit and a strobe emission request bit, the presence / absence of a strobe and the state of the auxiliary light emission can be recognized by the lens side. It is possible to judge whether or not there is a focus shift due to the infrared auxiliary light at the time of shooting a still image and accurately correct the focus shift, thereby recording a high-quality good still image.

[0086]

As described above, according to the present invention,
Even if an interchangeable lens having a part of the autofocus function is used, it is possible to correct the focus shift due to the use of the auxiliary light for autofocus, and to obtain a high-quality good still image.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment.

FIG. 2 is a diagram showing communication contents between a lens and a camera body.

FIG. 3 is a flowchart showing processing of a lens microcomputer;

FIG. 4 is a flowchart showing processing of a camera microcomputer.

FIG. 5 is a block diagram showing a configuration of a conventional example.

FIG. 6 is a flowchart showing an operation of a conventional example.

[Explanation of symbols]

 11-1 Camera microcomputer 14 Lens microcomputer 50 Lens 60 Camera body

Claims (7)

[Claims] 1. A video camera system including a camera body and an interchangeable lens having a part of an autofocus function, capable of taking a still image, wherein the camera body emits auxiliary light for autofocus. A first communication unit that can transmit a signal to the interchangeable lens, the interchangeable lens includes a second communication unit that can receive the signal, and a focus correction when the signal is received by the second communication unit. A video camera system comprising: 2. The video camera system according to claim 1, wherein said first communication means is capable of transmitting photometric information, and said second communication means is an auxiliary light for auto-focusing based on said photometric information. A video camera system capable of transmitting a signal requesting light emission of the video camera. 3. The video camera system according to claim 1, wherein a part of the autofocus function extends an autofocus function of the camera body. 4. A flashable video camera system having an autofocus function on the lens side, a flash control means for controlling a flash with an auxiliary light for autofocus on a camera body, a switch for recording a still image,
Communication means for sending a signal indicating the presence or absence of emission of the autofocus auxiliary light to the lens side, focus control means for performing focus control on the lens side, and communication means for communicating with the camera body A video camera system comprising: a focus correction unit that performs focus correction based on the signal received by the communication unit. 5. A method for photographing a still image by a video camera system including a camera body and an interchangeable lens having a part of an autofocus function, the method comprising: emitting an auxiliary light for autofocus; Correcting a focus shift caused by the auxiliary light. 6. A camera device used in a lens-exchangeable video camera system having an autofocus function on a lens side, the camera device comprising: a strobe control means for controlling a strobe with an auxiliary light for autofocus; A camera device comprising: a switch for recording a still image; and communication means for transmitting a signal indicating whether or not the auxiliary light for autofocus is emitted to the lens side. 7. A lens unit used in a lens-exchangeable video camera system having an autofocus function on a lens side, the lens unit comprising: focus control means for performing focus control; A lens unit comprising: a communication unit; and a focus correction unit that performs focus correction based on a signal indicating whether or not the autofocus auxiliary light is received by the communication unit.