JP4272717B2 - Video camera system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a video camera system that can still image capturing, and more particularly to the focus correction.
[0002]
[Prior art]
Conventionally, a video camera has been automated and multi-functional in all respects such as AE (auto exposure), AF (auto focus), etc., so that good shooting can be easily performed.
[0003]
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 increased, and the demand for still image recording has been increasing due to the rapid spread of personal computers. In addition, there are some built-in strobes and external strobes that allow you to take still pictures more clearly.
[0004]
FIG. 5 shows an example of a 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 in the optical axis direction by a lens driving driver 16 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 referred to as a zoom lens) for changing the field angle variable magnification. The light adjusted to an appropriate amount of light by the diaphragm 2 is imaged on the imaging surface of the CCD 4 and photoelectrically converted into an electric signal. This photoelectrically converted signal is read 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 with an optimum gain, and A / D The signal is converted into a digital signal synchronized with the reference clock by the converter 7. Then, only a specific frequency component is extracted by a BPF (band pass filter) 8, and a signal of a specific part in the photographed image is extracted by GATE 9. A recorder control circuit 10 controls image recording. The signal output from the GATE 9 is input to the camera microcomputer 11 and the autofocus control is performed so that the signal value becomes maximum. Here, if the camera microcomputer 11 is equipped with a strobe 13, it exchanges data such as the amount of light emission, ON / OFF of auxiliary light, and charging state by communication, and the two-stage switch (release button) 12 for still images is half-pressed. If the subject is dark and the subject is dark, the camera microcomputer 11 communicates with the strobe 13 to emit AF auxiliary light. When focus is achieved, the camera microcomputer 11 locks the focus lens 1 and waits for the still image two-stage switch 12 to be fully pressed. When it is confirmed that the subject is in focus and the photographer fully presses the two-stage switch 12 for still images, the camera microcomputer 11 controls the amount of light emitted from the strobe so that the subject is exposed properly. The video synchronized with the light emission is written in the memory in the recorder control circuit 10 and is written as a still image on the tape for about 6.5 seconds. However, in the case of a dark subject, a video camera equipped with TV autofocus (a method using a specific spatial frequency component of a video signal obtained from an image sensor for distance measurement) or the like cannot perform autofocus because the subject on the screen has no contrast. . For this purpose, the camera microcomputer 11 controls the flash 13 to emit the AF auxiliary light and brighten the subject. Since a red LED (wavelength 700 nm) or the like is usually used as an auxiliary light source, the lens chromatic aberration causes a defocus, and the camera microcomputer 11 is focused so that the red LED emits light and the flash main light emits just focus. Make corrections. In such a system using a strobe with built-in AF auxiliary light for still image shooting in the dark, an infrared LED is emitted as AF auxiliary light for focusing by autofocus, and focus correction is proposed. .
[0005]
Next, FIG. 6 shows a flow of the conventional camera microcomputer 11 shown in FIG.
[0006]
# 600 This is the beginning of this flow, and is repeatedly started at a predetermined timing.
[0007]
# 601 Determine whether still image recording is in progress.
[0008]
# 602 Determine whether the focus is locked.
[0009]
In step # 603, it is determined whether the still image recording switch 12 is half pressed.
[0010]
# 604 The exposure is locked when it is half-pressed at # 603.
[0011]
# 605 It is determined whether the brightness of the subject is less than the reference value.
[0012]
# 606 When # 605 is less than the reference value, AF auxiliary light is emitted.
[0014]
# 608 Determine whether the subject is in focus.
[0015]
# 609 If focus is achieved in # 608, the focus is locked.
[0016]
# 610 Turn off the auxiliary light.
[0017]
# 611 It is determined whether the still image recording switch 12 is fully pressed.
[0018]
# 612 When # 611 is fully pressed, pre-flash is performed.
[0019]
In step # 613, the main flash amount is calculated based on the result of the pre-flash.
[0020]
# 614 Main light emission is performed with the light emission amount based on the calculation.
[0021]
# 615 Start recording the video captured by the main flash.
[0022]
# 616 Indicates the end of this flow.
[0023]
Here, processing of the flow of the conventional example shown in FIG. 6 will be described.
[0024]
# 600 Indicates that this processing is performed at a certain cycle.
[0025]
# 601 If still image recording is in progress, the process jumps to # 616 to terminate this flow without performing any processing. If the still image is not being recorded, the process of # 602 is performed.
[0026]
# 602 Determine whether the focus is locked. If it is in the focus lock state, the process jumps to the processing of # 611 to determine whether it is in the fully pressed state. If the focus is not locked, the process proceeds to step # 603 to determine whether the still image recording switch 12 is half-pressed.
[0027]
In step # 603, it is determined whether the still image recording switch 12 is half pressed. If it is in the half-pressed state, the process moves to # 604 to lock the exposure. If it is not half-pressed, the process jumps to # 616, and this flow is terminated without performing any processing.
[0028]
# 604 Lock the exposure.
[0029]
# 605 If the brightness of the subject is less than the reference value, the process proceeds to # 606 to emit auxiliary light. If it is equal to or greater than the reference value, it is determined that no auxiliary light is required for autofocus, and the process jumps to step # 608 to determine in-focus.
[0030]
# 606 Auxiliary light for autofocus is emitted, and the process proceeds to # 607.
[0031]
In step # 607, the focus position is corrected in consideration of the lens chromatic aberration when the infrared auxiliary light is emitted, and the process proceeds to step # 608.
[0032]
In step # 608, it is determined whether or not the subject is in focus. If the focus is in focus, the process proceeds to step # 609 to lock the focus. If it is not in focus, the autofocus operation is continued and this flow is terminated.
[0033]
# 609 It is determined that the subject is in focus, the focus is locked, and the process proceeds to # 610.
[0034]
# 610 Since the auxiliary light for autofocus is not necessary, the light is turned off, and the process proceeds to # 611.
[0035]
# 611 It is determined whether the still image recording switch 12 is fully pressed. If the switch is fully pressed, the process proceeds to # 612 to perform pre-flash. If it is not fully pressed, this flow is terminated without performing any processing.
[0036]
# 612 Pre-light emission for determining the main light emission amount is performed, and the process proceeds to # 613.
[0037]
In step # 613, the brightness of the subject is calculated from the result of the pre-flash to determine the main flash amount. Then, the process proceeds to # 614.
[0038]
# 614 The main light emission amount is emitted based on the calculation, and the process proceeds to # 615.
[0039]
In step # 615, the video synchronized with the main light emission is recorded in a memory (not shown) via the recorder control circuit 10, and the memory image is recorded on the tape.
[0040]
# 616 Indicates the end of this flow.
[0041]
As described above, in the conventional example, the camera microcomputer 11 determines the brightness of the subject, and irradiates the infrared LED so that the autofocus control can be performed even with a dark subject. Due to the chromatic aberration of the lens, the image is out of focus during the main light emission. For this reason, when autofocus is performed by irradiating infrared auxiliary light, the camera microcomputer 11 performs focus correction in accordance with the chromatic aberration of the lens.
[0042]
[Problems to be solved by the invention]
However, if the lens is an interchangeable lens and this interchangeable lens is responsible for part of the autofocus function (arithmetic circuit, program, etc.), check whether the strobe auxiliary light mounted on the body is emitting light. Since it cannot be determined, the lens cannot correct the focus shift caused by the infrared auxiliary light. There is also a problem that if you use the flash auxiliary light to focus with infrared light, the main flash will be out of focus and still images will be captured, and still images captured by the main flash will be out of focus. It was.
[0043]
The present invention has been made under such circumstances, be used to replace lens having a portion of the auto-focus function, defocus can be corrected by autofocus auxiliary light using a video camera system The issue is to provide.
[0044]
In order to solve the above problems, in the present invention, a video camera system is configured as follows (1).
(1) A video camera system comprising a camera body and an interchangeable lens having a function of receiving an evaluation value based on a frequency component of an image signal from the camera body and controlling a focus lens position,
The camera body is capable of transmitting photometric data to the interchangeable lens and receiving a first signal instructing emission of auxiliary light for auto-focusing, and according to the received first signal, A first communication means capable of transmitting a second signal indicating a light emitting / extinguishing state to the interchangeable lens;
The interchangeable lens transmits the first signal and receives the photometric data and the second signal, and based on the photometric data received by the second communication unit. It is determined whether or not to transmit the first signal, and when the auxiliary light is emitted based on the second signal sent from the camera body , the focus shift caused by the auxiliary light emission is reduced. A video camera system comprising correction means for performing correction during focus adjustment.
[0052]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to examples of video camera systems. 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 a photographing method. In addition, the embodiment relates to the auxiliary light for autofocus provided in the strobe, but the present invention is not limited to this, and the same can be applied to the auxiliary light for autofocus provided in the camera body. it can.
[0053]
【Example】
(Example)
FIG. 1 is a block diagram showing a configuration of a “video camera system” as an embodiment.
[0054]
In FIG. 1, the same components as those of the conventional example shown in FIG. 5 are given the same reference numerals, and detailed description thereof is omitted here. Since the camera microcomputer is different from the software in the conventional example, the camera microcomputer is distinguished by attaching a branch number “−1”.
[0055]
In FIG. 1, the difference from the conventional example is that a lens microcomputer 14 having a part of an autofocus function is built in a lens 50 and communicates with a camera microcomputer 11-1 on the main body 60 side. In this way, in a video camera system that has an autofocus function in the lens (the autofocus function of the camera body is extended by the autofocus function of the lens), it is extracted from the image information via communication from the camera body side. The autofocus 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 → lens communication, in addition to the photometric evaluation value used for aperture control of the lens 50 and the AF evaluation value for performing autofocus control, a strobe status indicating whether a strobe is attached, etc. A status indicating the pressed state of the stage switch 12 and a REC status indicating whether the recorder is in a recording state are transmitted. The strobe status includes a bit indicating that the strobe is mounted and a bit indicating whether or not the strobe auxiliary light is lit. The two-stage switch status for the still image indicates whether the two-stage switch 12 for the still image of the camera body 60 is half-pressed or not. Indicates whether the button is pressed. The REC status indicates whether or not the recorder of the camera body 60 is recording. The lens 50 recognizes that still image recording is to be performed based on the REC status and the two-step switch status for still images, determines the brightness of the screen based on the photometric information transmitted from the camera body 60, and uses the auxiliary light for autofocus. Is transmitted to the camera body 60. At this time, the camera body 60 emits / turns off the auxiliary light to the strobe 13 based on the auxiliary light emission request transmitted from the lens 50. The camera body 60 transmits the auxiliary light emission / extinguishing state to the lens 50 via the camera body → lens communication. The lens 50 performs focus correction when focusing is performed with the auxiliary light being emitted, and focus is performed without performing focus correction when focusing is performed while the light is off, and the camera body 60 is focused / not focused. Reply the focus information. In this way, the lens 50 identifies whether or not a strobe is attached to the camera body 60, and requests the camera body 60 via communication to emit auxiliary light if the screen is dark during still image shooting. 60 emits / extinguishes auxiliary light according to an auxiliary light emission / extinction request from the lens 50. At this time, the camera body 60 returns status information on whether the auxiliary light is turned on or off to the lens 50. If the lens 50 is in focus with the auxiliary light emitting, the lens 50 performs focus correction for the main light emission, If focusing is performed with the light off, the operation is performed so as not to perform focus correction.
[0056]
The flow of the lens microcomputer 14 showing this operation is shown in FIG.
[0057]
# 300 This is the beginning of this flow, and is repeatedly started at a predetermined timing.
[0058]
# 301 Communication with the camera body 60 is performed.
[0059]
# 302 Whether or not still image recording is in progress is determined based on the REC status.
[0060]
# 303 It is determined whether the focus is locked.
[0061]
In step # 304, it is determined whether the half-pressed state is obtained or not based on the still image two-stage switch status.
[0062]
# 305 The degree of screen brightness is determined based on the photometric value.
[0063]
# 306 Request the camera body 60 to emit auxiliary light.
[0064]
# 307 Request the camera body 60 to turn off the auxiliary light.
[0065]
# 308 It is determined whether or not auxiliary light is emitted.
[0066]
# 309 Focus correction is performed when auxiliary light is emitted.
[0067]
# 310 It is determined whether or not the subject is in focus.
[0068]
# 311 Performs an operation to lock the focus when in-focus.
[0069]
# 312 Make a request to turn off the auxiliary light after focus lock.
[0070]
# 313 Indicates the end of this flow.
[0071]
The processing of the lens microcomputer 14 in this case will be described using the flowchart of FIG.
[0072]
# 300 is the beginning of this flow, and is repeatedly started at a predetermined timing. In step # 301, lens-camera communication is performed. Whether or not the camera main body 60 is recording a still image is determined from the REC status of the received data of communication performed in # 301. If still image recording is in progress, the process jumps to step # 313 and this flow is terminated. If still image recording is not in progress, the process advances to step # 303 to determine whether focus lock is in progress. If the focus is locked in # 303, the process jumps to the process of # 313 and this flow is finished. If the focus is not locked, the process proceeds to # 304. In # 304, it is determined from the received data of communication with the camera body 60 whether the still image recording two-stage switch 12 is half-pressed or fully pressed. If it is in the half-pressed state, the process proceeds to the process of # 305, and the brightness is determined. In # 305, the brightness of the screen is compared with the reference value from the photometric data from the camera body 60, and if it is less than the reference value, the process proceeds to # 306 to make an auxiliary light emission request. If it is equal to or greater than the reference value, the subject is bright and it is determined that the auxiliary light is not required. In step # 308, it is determined whether or not auxiliary light is emitted according to the strobe status from the camera body 60. If the auxiliary light is emitted, the process proceeds to step # 309 to correct the focus shift caused by the auxiliary light emission so that the still image at the main light emission is not defocused. If the auxiliary light is not 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 it is not in focus, it jumps to the process of # 313 and this flow is complete | finished. In # 312, since the focus is locked, a request to turn off the auxiliary light is made. Next, the process proceeds to # 313, and this flow is terminated.
[0073]
As described above, the lens microcomputer 14 recognizes the strobe attachment of the camera body 60 through lens-camera communication, transmits an auxiliary light emission request to the camera body 60, and corrects the focus according to the auxiliary light emission status sent from the camera body 60. By determining whether or not to perform, the focus correction at the time of auxiliary light emission is surely performed, and a high-quality still image with high focus can be captured.
[0074]
FIG. 4 shows a flow of the camera microcomputer 11-1.
[0075]
# 400 This is the beginning of this flow, and is repeatedly started at a predetermined timing.
[0076]
# 401 Communication with the lens 50 is performed.
[0077]
# 402 Determine whether still image recording is in progress.
[0078]
In step # 403, it is determined whether there is an auxiliary light emission request from the lens 50.
[0079]
# 404 Set auxiliary light emission request to strobe 13.
[0080]
# 405 Set a request to turn off the auxiliary light to the strobe 13.
[0081]
# 406 Communicate with the flash 13 and send an auxiliary light emission / extinguish request to the flash 13.
[0082]
# 407 Set the status of whether or not the strobe light is emitted.
[0083]
# 408 Indicates the end of this flow.
[0084]
As shown in FIG. 2, the lens 50 attaches the strobe to the camera body 60 by transmitting / receiving the strobe mounting bit, strobe emission status bit, strobe emission request, and focus status bit as shown in FIG. If it is a dark subject, an auxiliary light emission request is sent to the camera body 60, the camera body 60 returns an auxiliary light emission status to the lens 50, and if the auxiliary light is emitted from the lens 50, the focus position is changed. Correction is performed so as not to cause a focus shift during main light emission.
[0085]
As described above, according to the present embodiment, in the video camera system, when a still image is taken with a strobe attached, the lens-camera communication has a strobe attachment bit, a strobe auxiliary light emission status bit, and a strobe emission request bit. The lens can recognize the presence or absence of the strobe and the auxiliary light emission state, and it can control whether to emit auxiliary light or not according to the strobe emission request. There is no focus shift due to infrared auxiliary light when shooting still images. Therefore, it is possible to accurately correct the focus shift and to record a high-quality still image.
[0086]
【The invention's effect】
As described above, according to the present invention, even when 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 a high-quality still image. Can be obtained.
[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. 5 is a block diagram showing the configuration of the conventional example. FIG. 6 is a flowchart showing the operation of the conventional example.
11-1 Camera microcomputer 14 Lens microcomputer 50 Lens 60 Camera body

Claims (1)

A video camera system comprising a camera body and an interchangeable lens having a function of receiving an evaluation value based on a frequency component of an image signal from the camera body and controlling a focus lens position,
The camera body is capable of transmitting photometric data to the interchangeable lens and receiving a first signal instructing emission of auxiliary light for auto-focusing, and according to the received first signal, A first communication means capable of transmitting a second signal indicating a light emitting / extinguishing state to the interchangeable lens;
The interchangeable lens transmits the first signal and receives the photometric data and the second signal, and based on the photometric data received by the second communication unit. It is determined whether or not to transmit the first signal, and when the auxiliary light is emitted based on the second signal sent from the camera body , the focus shift caused by the auxiliary light emission is reduced. A video camera system comprising correction means for performing correction during focus adjustment.

Images