JP2003295039A - Camera - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a camera performing photography using an AF auxiliary light source when a C-AF (continuous-AF) mode is set. <P>SOLUTION: When subject luminance is equal to or under a specified value even though the C-AF mode is set by a mode setting means 19, the mode of the camera is switched from the C-AF mode to an S-AF (single-AF) mode state. When the subject luminance is equal to or under the specified value in a focusing action by the half depressing operation of a release button 20, the AF auxiliary light source 17 is lit. Further, power consumption by the light source 17 is reduced by changing the lit light quantity of the light source 17 in accordance with the luminance or changing a restart interval instead of switching the mode from the C-AF mode to the S-AF mode. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an AF-type camera for detecting focus by generating AF auxiliary light when subject brightness is low.

[0002]

2. Description of the Related Art In a conventional camera, a single AF mode in which a focusing operation is performed by half-pressing a release button,
Some have a continuous AF mode in which the focusing operation is repeated at predetermined intervals regardless of the half-press operation.
At the time of focusing operation, a photoelectric conversion element such as a CCD image pickup element receives subject light, and focus detection calculation is performed based on the signal. However, if the subject brightness is low, the AF calculation may not be performed properly. For this reason, there has been a device which is provided with an AF auxiliary light source and turns on the AF auxiliary light source to perform a focusing operation when the subject brightness is low in the S-AF mode.

[0003]

However, in the conventional camera, the AF auxiliary light source is not turned on in the C-AF mode, which has a drawback that the AF accuracy is lowered.

An object of the present invention is to provide a camera for taking an image using an AF auxiliary light source when the C-AF mode is set.

[0005]

(1) A camera according to the invention of claim 1 is an image pickup device for picking up a subject image formed by a photographing optical system, and the subject image of the subject image based on an image pickup signal of the image pickup device. Focusing state calculating means for calculating a focus evaluation value, focus adjusting means for adjusting the focus adjusting state of the photographing optical system based on the calculation result of the focusing state calculating means, and illuminating the object by illuminating during the focus adjusting operation. Auxiliary light source, mode selecting means for selecting a continuous AF mode for repeatedly performing the focus adjusting operation and a single AF mode for performing the focus adjusting operation by inputting the focus adjusting operation instruction, and a brightness detecting means for detecting the brightness of the subject. And Continuous A
When the brightness detected by the brightness detecting means in the F mode is equal to or lower than a predetermined value, the mode changing means for changing the continuous AF mode to the single AF mode is provided to achieve the above-mentioned object. (2) According to the invention of claim 2, in the camera according to claim 1, when the brightness detected by the brightness detection means after the change to the single AF mode exceeds a predetermined value, the mode changing means changes from the single AF mode. The AF mode is changed to the continuous AF mode. (3) The invention according to claim 3 is the camera according to claim 1, further comprising control means for turning on the auxiliary light source from the start to the end of the input operation in the single AF mode. (4) According to the invention of claim 4, in the camera according to claim 1, the focus adjustment state adjusted by the focus adjustment operation at the time of input operation is fixed in the single AF mode, and after the input operation is fixed. A control means for turning on the auxiliary light source is provided until a predetermined time elapses. (5) The camera according to the invention of claim 5 is an image pickup device for picking up a subject image formed by a photographing optical system, and a focus state calculation for calculating a focus evaluation value of the subject image based on an image pickup signal of the image pickup device. Means, a focus adjusting means for adjusting the focus adjusting state of the photographing optical system based on the calculation result of the focus state calculating means, and a continuous A for repeatedly performing the focus adjusting operation.
A mode setting means for setting the F mode, a brightness detecting means for detecting the brightness of the object, and an auxiliary light source for illuminating the object by lighting with a light amount according to the brightness detected by the brightness detecting means in the continuous AF mode. The above object is achieved by providing (6) The invention according to claim 6 is the camera according to claim 5, wherein in the continuous AF mode, when the brightness detected by the brightness detecting means is below a predetermined value, the light is turned on, and after the turning on, the brightness detecting means is turned on. When the brightness detected by exceeds a predetermined value, the light is turned off. (7) The invention according to claim 7 is the camera according to claim 5, wherein in the continuous AF mode, the light is turned off when the focus adjustment operation after lighting is completed. (8) The invention according to claim 8 is the camera according to claim 5, wherein in the continuous AF mode, the light is turned on at the start of the focus adjustment operation and turned off at the end of the focus adjustment operation. (9) The invention according to claim 9 is the camera according to claim 8, wherein the focus adjustment operation is performed at a first interval when the brightness exceeds a predetermined value, and the first interval when the brightness is equal to or less than the predetermined value. Interval setting means for performing the focus adjustment operation at the second longer interval is provided.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a functional block diagram of an electronic camera according to the present invention. In FIG. 1, reference numeral 1 denotes a taking lens, which includes a focusing lens for adjusting a focus position. The taking lens 1 is drive-adjusted by a driver 14 including a focus lens driving mechanism and a driving circuit thereof. The driver 14 is the CPU 7
Controlled by.

Reference numeral 2 is a diaphragm, 4 is a CCD image pickup device, and C
The CD image pickup device 4 outputs an electric signal according to the light intensity of the subject image formed on the image pickup surface. As the image sensor 4,
Not limited to the CCD type, a MOS type solid-state imaging device may be used. The CCD image pickup device 4 is a color image pickup device, and an on-chip color filter is formed for each pixel. In the case of the primary color filter, an R (red) filter, a G (green) filter and a B (blue) filter are formed in a predetermined arrangement.

The subject light from the taking lens 1 is focused on the CCD image pickup device 4 after passing through the diaphragm 2. Aperture 2
Is a driver 15 equipped with a diaphragm drive mechanism and its drive circuit.
Driven by. The CCD image pickup device 4 is driven by a driver 16 which controls the timing of signal extraction. The CCD image pickup device 4 can drive the electronic shutter at a variable speed by controlling the charge storage time by the driver 16.

Since a color filter is formed in each pixel of the CCD image pickup device 4, a signal corresponding to the color filter is output from each pixel. That is, the R signal is output from the pixel on which the color filter R is formed, and similarly, the G signal and the B signal are output from the pixels on which the color filters G and B are formed, respectively. These image pickup signals output from the CCD image pickup device 4 are input to the analog signal processing circuit 5.

The analog signal processing circuit 5 includes a CDS circuit,
An AGC circuit and the like are provided, and the CDS circuit performs correlated double sampling (CDS) processing.
The CCD output signal level is adjusted. The image pickup signal processed by the analog signal processing circuit 5 is converted from an analog signal to a digital signal by the A / D converter 6.

The A / D converted signal is input to the digital signal processing circuit 8 and the CPU 7. The CPU 7 is connected to the digital signal processing circuit 8 and the drivers 14 to 16 and controls the entire camera. The CPU 7 includes an AE calculation unit 71, an AF calculation unit 73, and an AWB (auto white balance) calculation unit 72. AE calculation and A
For the F calculation, the image pickup signals of the entire image pickup area of the CCD image pickup device 4 are not used, but the calculation is performed using the image pickup signals of a partial area, for example, the central area of the screen.

The focusing lens of the photographing lens 1 is
It is driven based on the calculation result of the AF calculation unit 73. The camera of the present embodiment relates to a single AF mode (hereinafter, referred to as S-AF mode) in which a focusing operation is performed by half-pressing the release button 20 as an AF operation, and a half-pressing operation of the release button 20. Instead, a continuous AF mode (hereinafter, referred to as C-AF mode) in which the focusing operation is repeatedly performed at a predetermined interval is provided. The AF setting is selected and set by the mode setting unit 19. In addition, according to the subject brightness obtained by the AE calculation unit 71, the AF
Lighting of the auxiliary light source 17 and switching of the AF mode state are controlled. Details of the control will be described later.

There are a phase difference method, a contrast method, etc. as a method for detecting the focused state by the AF calculation unit 73, but the contrast method will be described below as an example. In the contrast method, focusing is performed by utilizing the fact that there is a correlation between the degree of blurring of an image and the contrast, and the contrast of the image is maximized when the image is in focus. The size of the contrast can be evaluated by the size of the high frequency component of the image pickup signal.

The AF calculator 73 is provided with a bandpass filter (not shown) for extracting high frequency components in a predetermined band from the image pickup signal. The bandpass filter extracts a high frequency component in a predetermined band from the image pickup signal in the focus detection area provided in the image pickup area. This high frequency component is called a focus evaluation value, and the focus evaluation value L0 has a peak at the focus position P as shown in FIG. In FIG. 2, the horizontal axis represents the lens position of the focusing lens.

When the peak of the focus evaluation value is searched for, the focusing lens is slightly moved to the infinity side or the near side, and the focus evaluation value calculated at that time is compared with the focus evaluation value before the movement. When the focus evaluation value after the movement is larger, the focusing lens is further moved in the same direction to perform the same calculation and comparison. On the other hand, when the focus evaluation value after the movement is smaller, the focusing lens is moved in the opposite direction to perform the same calculation and comparison. By repeatedly performing such processing, the peak of the focus evaluation value, that is, the in-focus position is searched. Such an operation is called a hill climbing operation.

Returning to FIG. 1, in the AWB calculation unit 72, A /
Image signal from the D converter 6 (R signal, G signal, B signal)
The white balance adjustment gain (R gain and B gain) is set based on the above. Digital signal processing circuit 8
Includes a signal processing circuit such as a gamma correction circuit and a luminance signal and color difference signal generation circuit. A / D converter 6
From the digital signal processing circuit 8 to the R signal, G signal and B
When a signal is input, the digital signal processing circuit 8 interpolates the R signal for all pixels of the CCD image sensor 4,
G and B signals are provided.

After that, the R signal and the B signal of the R, G, and B signals are multiplied by the R gain and the B gain for the white balance adjustment, respectively, to perform the white balance adjustment. . As a result, an image pickup signal (R signal, G signal, B signal) with optimum white balance is obtained. Then, the gamma correction process is performed on the R signal, the G signal, and the B signal whose white balance has been adjusted. Further, the gamma-corrected R signal, G signal, and B signal are converted into a luminance signal (Y signal) and a color difference signal (Cr, Cb signal).

The image pickup signal input to the digital signal processing circuit 8 is temporarily stored in the buffer memory 13, is read out from the buffer memory 13 for each of the above-mentioned processes, and the processed signal is stored in the buffer memory 13 again. To be done. The buffer memory 13 is a frame memory that can store data for a plurality of frames captured by the CCD image sensor 4.

The image data that has undergone a series of processes in the digital signal processing circuit 8 is stored in the buffer memory 13. Then, it is recorded in the external storage medium 10 such as a memory card via the recording / reprocessing circuit 9. When recording image data in the storage medium 10, data compression is generally performed in a predetermined compression format, for example, the JPEG method. The recording / reproducing signal processing circuit 9 performs data compression when recording the image data on the external recording medium 10 and data decompression processing when reading the compressed image data from the storage medium 10. The recording / reproducing signal processing circuit 9 also includes an interface for performing data communication with the storage medium 10.

In the photographing mode, the CCD image pickup device 4
After being image-processed by the analog signal processing circuit 5, the A / D converter 6, and the digital signal processing circuit 8, the imaging signal imaged at every predetermined time interval is stored in the buffer memory 13 and transferred to the VRAM 11. And VRA
An image based on the image data stored in M11 is displayed on the monitor 1.
It is displayed in 2. For the monitor 12, for example, an LCD display device is used. Therefore, the photographer can visually recognize the subject by the image displayed on the monitor 12. On the other hand, in the reproduction mode, the image read from the external storage medium 10 is transferred to the VRAM 11 and reproduced and displayed on the monitor 12.

<< Regarding AF Mode Switching Control and Auxiliary Light Lighting Control >> The AF mode switching control and the auxiliary light lighting control will be described with some examples. —First Operation Example— FIGS. 3 to 6 are flowcharts for explaining the AF mode switching control and the auxiliary light lighting control in the first operation example. In step S1 of FIG. 3, it is determined whether or not the power switch of the camera is turned on, and if it is determined to be on, the process proceeds to step S2. In step S2, whether the AF mode setting set by the mode setting unit 19 is the C-AF mode or S
-Determine whether it is AF mode. C- in step S2
If it is determined that the AF mode is set, step S
If it is determined that the S-AF mode is set, the process proceeds to step S30 of FIG.

In this embodiment, as will be described later, even if the mode setting by the mode setting unit 19 is the C-AF mode, the S-AF mode state may be switched depending on the subject brightness. Therefore, in the present embodiment, the setting state by the mode setting unit 19 is called “mode setting”,
AF at each point when switching may occur depending on subject brightness
The mode state is called "mode state", and both are considered separately.

[When set to C-AF mode]
First, the case where the mode is set to the C-AF mode by the mode setting unit 19, that is, the case where the process proceeds from step S2 to step S3 will be described. Step S
In 3, the AE calculation unit 71 calculates the subject brightness based on the image pickup signal of the CCD image pickup device 4. In step S4, it is determined whether or not the subject brightness calculated in step S3 is less than or equal to a predetermined value, and if determined to be less than or equal to the predetermined value, step S5.
If it is determined that the value is larger than the predetermined value, the process proceeds to step S9.
Go to. This predetermined value is a subject brightness that serves as a reference for turning on and off the AF auxiliary light source 17, and if the subject brightness is higher than the predetermined value, the AF calculation can be performed without any trouble even if the AF auxiliary light source 17 is not turned on. .

If it is determined in step S4 that the value is equal to or less than the predetermined value and the process proceeds to step S5, the current AF mode state of the camera is C-AF mode or S- in step S5.
Determine whether it is in AF mode. If it is determined in step S5 that the state is the C-AF mode, the process proceeds to step S6 to perform the C-AF.
After switching from the mode state to the S-AF mode state, the process proceeds to step S200. On the other hand, in step S5, SA
If it is determined to be in the F mode state, step S6 is skipped and the process proceeds to step S200.

(Detailed Description of Step S200) Step S200 is a routine in which processing is executed until the photographing operation is completed by pressing the release button 20 halfway and fully, and the details thereof are shown in FIG. In FIG. 4, in step S201, it is determined whether the release button 20 is half pressed. If it is determined in step S201 that it is in the half-pressed state, the process proceeds to step S202, the AF auxiliary light source 17 is turned on, and if it is determined that it is not in the half-pressed state, the series of processes in FIG. .

In step S203, the focusing lens is scanned over the entire area (between the closest distance and infinity), and focus evaluation values at a plurality of positions in the entire area are calculated. As a result, a focus evaluation value curve L0 as shown in FIG. 2 is obtained.
In step S204, the focusing lens is moved to the peak position P of the focus evaluation value curve L0. Then, in step S205, the lens position is held and AF locked.

In step S206, the release button 2
It is determined whether 0 is in the fully pressed state. If it is determined in step S206 that the AF button has been fully pressed, the process proceeds to step S209 to turn off the AF auxiliary light source 17, and then step S210.
Proceed to and execute the shooting process. Since the series of processes of the photographing process in step S210 is the same as the conventional process,
Detailed description is omitted. When the process of step S210 ends, the process proceeds to step S7 of FIG.

On the other hand, if it is determined in step S206 that the release button 20 is fully pressed and the process proceeds to step S207, it is determined in step S207 whether the release button 20 is half pressed. If it is determined in step S207 that the button has been half-pressed, the process returns to step S206. If it is determined that the button has not been half-pressed, that is, the release button 20 is released, the process proceeds to step S208 to turn off the AF auxiliary light source 17. Then, it progresses to step S7 of FIG.

When the process of step S200 in FIG. 3 is completed, it is determined in step S7 whether or not the power switch of the camera is off. If it is determined in step S7 that the power switch is off, a series of processing operations ends, and if it is determined to be on, the process returns to step S2.

In the flowchart of FIG. 4, the release button 20 may be fully pressed (step S206: y
If it is determined to be es), the AF auxiliary light source 17 is controlled to be immediately turned off when the half-pushed state is released (when determined to be no in step S207), but instead of FIG. You may control auxiliary light extinction like a flowchart. In the control shown in FIG. 5, after the AF lock, the AF auxiliary light source 17 is turned on for a predetermined time so that the monitor 12 can easily confirm the subject image. In FIG. 5, the processing in steps S300 to S305 when it is determined in step S206 that the state is not the full-pressed state is different from that in FIG.

In step S300 of FIG. 5, it is determined whether the release button 20 is half pressed. Step S3
If it is determined to be half-pushed with 00, the process proceeds to step S304,
If it is determined that the button has not been pressed halfway, the process proceeds to step S301.
In step S304, it is determined whether or not a predetermined lighting time has elapsed after AF locking. If it is determined in step S304 that the predetermined lighting time has not elapsed, the process returns to step S206. If it is determined that the predetermined lighting time has elapsed, the AF auxiliary light source 17 is turned off in step S305 and then the process returns to step S206.

On the other hand, when the half-press is released, step S30
If the process proceeds from 0 to step S301, step S
At 301, it is determined whether the power is turned off. If it is determined in step S301 that the power is off, the process proceeds to step S7 in FIG. On the other hand, if it is determined in step S301 that the power is on, the process proceeds to step S302 to determine whether or not a predetermined lighting time has elapsed after AF locking. If it is determined in step S302 that the predetermined lighting time has not elapsed, the process returns to step S301. If it is determined that the predetermined lighting time has elapsed, the process proceeds to step S303 to turn off the AF auxiliary light source 17, and then to step S7 of FIG. move on.

Returning to FIG. 3, it is determined in step S4 that the subject brightness is higher than a predetermined value, that is,
A case will be described in which it is determined that the brightness of the subject is such that AF calculation can be performed without any trouble, and the process proceeds to step S9. In step S9, it is determined whether the AF mode state at that time is the C-AF mode or the S-AF mode. If it is determined in step S9 that the S-AF mode is set,
In step S10, the AF mode state is switched from the S-AF mode to the C-AF mode. On the other hand, when it is determined that the state is the C-AF mode state in step S9, step S10 is skipped and the process proceeds to step S11.

In step S11, the focusing lens is scanned over the entire area to calculate focus evaluation values at a plurality of positions in the entire area. After that, in step S12, the focusing lens is moved to a lens position where the focus evaluation value has a peak. In step S13, release button 2
It is determined whether 0 is in the half-pressed state. If it is determined that the button is half-pressed, the process proceeds to step S14. If it is determined that the button is not half-pressed, the process proceeds to step S20. In step S14, the position of the focusing lens is held at the peak position of step S12 and AF locking is performed.

In step S15, it is determined whether or not the release button 20 is half-pushed. If it is half-pushed, the process proceeds to step S16. If it is determined that the half-push is released, steps S16 and 17 are skipped. Step S7
Go to. When it is determined in step S15 that the release button 20 is half pressed and the process proceeds to step S16, it is determined in step S16 whether the release button 20 has been fully pressed.
If it is determined in step S16 that the shutter button has been fully pressed, the shooting process of step S17 is executed, and if it is determined that the shutter button has not been fully pressed, the process returns to step S15.

On the other hand, if it is determined in step S13 that the button is not half-pressed and the process proceeds to step S20, it is determined whether or not the restart time has elapsed after the focusing operation was performed. In the C-AF mode, the focusing operation is performed every restart time. The restart may be performed at predetermined time intervals as in the present embodiment, or may be restarted when the focus evaluation value changes by a predetermined value or more after focusing.

If it is determined in step S20 that the restart time has elapsed, the well-known hill climbing focus operation is executed in step S21. On the other hand, when it is determined in step S20 that the restart time has not elapsed, step S21 is skipped and the process proceeds to step S22. In step S22, it is determined whether or not the power of the camera is turned off, and if it is determined to be on, the process returns to step S13. As a result, the hill-climbing focus operation is repeatedly executed at each restart time until the release button 20 is half-pressed. If it is determined in step S22 that the power supply has been turned off, the series of processes ends.

[When set to S-AF mode]
Above, the camera is set to C-AF mode,
The case where the process proceeds from step S2 to step S3 in FIG. 3 has been described. When the S-AF mode is set by the mode setting unit 19, the process proceeds from step S2 in FIG. 3 to step S30 in FIG. In step S30, FIG.
The subject brightness is calculated based on the image pickup signal of the CD image pickup device 4 as in step S3. In step S31, it is determined whether or not the subject brightness calculated in step S30 is less than or equal to a predetermined value. If it is determined to be less than or equal to the predetermined value, the process proceeds to step S200, and if it is determined to be greater than the predetermined value, step S32.
Go to.

When the process proceeds from step S31 to step S200, the above-described processing of FIG. 4 or 5 is executed. The description of step S200 is omitted. Step S
In 32, the focusing lens is scanned over the entire area,
A focus evaluation value at a plurality of positions in the entire area is calculated. After that, in step S33, the focusing lens is moved to a lens position where the focus evaluation value has a peak. In step S34, the position of the focusing lens is held at the peak position of step S33 and AF locking is performed.

In step S35, it is determined whether or not the release button 20 is half-pushed. If it is half-pushed, the process proceeds to step S36. If it is decided that the half-push is released, steps S36 and 37 are skipped. It proceeds to step S38. On the other hand, if it is determined in step S35 that the release button 20 has been half pressed and the process proceeds to step S36, it is determined in step S36 whether the release button 20 has been fully pressed. If it is determined in step S36 that the shutter button has been fully pressed, the shooting process of step S37 is executed, and if it is determined that the shutter button has not been fully pressed, the process returns to step S35. Step S38
Then, it is determined whether or not the power is turned off, and if it is determined that the power is on, the process returns to step S2 in FIG. 3, and if it is determined that the power is off, a series of processes ends.

In the first operation example described above, when the C-AF mode is set and the subject brightness is less than or equal to a predetermined value, the S-AF mode state is switched to. During the focusing operation, that is, during the whole area scanning operation and the focusing operation by pressing the release halfway, A
The F auxiliary light source 17 is turned on. As a result, C-
Even if the AF mode is set, the C-AF mode state is switched to the S-AF mode state when the subject brightness is equal to or lower than a predetermined value, so that the AF auxiliary light source is always used during the focusing operation immediately before the shooting operation. 17 is turned on and there is no problem in AF calculation. Further, even if the C-AF mode is set, the AF auxiliary light source 17 does not remain lit unlike the conventional case, so that the power consumption can be reduced.

-Second Operation Example-In the first operation example described above, when the C-AF mode is set and the subject brightness is below a predetermined value, the S-AF mode is switched to. In the second operation example, such mode switching is not performed. 7 and 8 are flowcharts for explaining AF mode switching control and auxiliary light lighting control in the second operation example.

In step S50, it is determined whether or not the power switch of the camera is turned on, and if it is determined to be on, the process proceeds to step S51. In step S51, the AF mode set by the mode setting unit 19 is the C-AF mode or S-AF mode.
Determine whether it is in AF mode. In step S51, C-
If it is determined to be the AF mode, the process proceeds to step S52 and S-
If the AF mode is determined, the process proceeds to step S30 in FIG. That is, when the S-AF mode is set, the same control as in the first operation example is performed.

The case where the C-AF mode is set will be described below, and the description when the S-AF mode is set is omitted. In step S52, the AE calculator 7 is operated based on the image pickup signal of the CCD image pickup device 4.
In 1, the subject brightness is calculated. In step S53, it is determined whether or not the subject brightness calculated in step S52 is less than or equal to a predetermined value. When it is determined in step S53 that the subject brightness is less than or equal to the predetermined value, the process proceeds to step S54 and the AF auxiliary light source 17 is turned on. On the other hand, when it is determined that the subject brightness is higher than the predetermined value, step S54 is skipped and the process proceeds to step S55.

In step S55, the focusing lens is scanned over the entire area to calculate focus evaluation values at a plurality of positions in the entire area. Then, in step S56, the focusing lens is moved to the lens position where the focus evaluation value has a peak. After that, the process proceeds to step S57 in FIG. 8 and the AF auxiliary light source 17 is turned off. In step S58,
It is determined whether the release button 20 is half pressed. If it is determined in step S58 that the release button 20 has been pressed halfway, the flow advances to step S59 to lock the AF. The focusing lens is held at the peak position of step S56. In step S60, the release button 20
Is pressed halfway, the process proceeds to step S61 if it is determined to be half-pressed, and skips steps S61 and 62 if it is determined to be released half-pressed to step S63.
Go to.

When it is determined in step S60 that the release button 20 has been pressed halfway and the process proceeds to step S61, it is determined in step S61 whether the release button 20 has been fully pressed.
If it is determined in step S61 that the shutter button has been fully pressed, the shooting process of step S62 is executed, and if it is determined that the shutter button has not been fully pressed, the process returns to step S60. In step S63, it is determined whether or not the power is turned off. If it is determined to be off, the process returns to step S51 in FIG. 7, and if it is determined to be on, the series of processes is ended.

On the other hand, if it is determined in step S58 that the release button 20 has not been pressed halfway, step S7
The process proceeds to 0 and the subject brightness is calculated. In step S71, it is determined whether the subject brightness calculated in step S70 is less than or equal to a predetermined value. If it is determined that the value is less than or equal to the predetermined value, the process proceeds to step S72, and if it is determined that the value is greater than the predetermined value, the process proceeds to step S74. When the process proceeds from step S71 to step S72, it is determined whether or not the restart time T1 has elapsed since the focusing operation was performed in step S72. If it is determined in step S72 that the time T1 has elapsed, the process proceeds to step S73 to turn on the AF auxiliary light 17,
If it is determined that the time T1 has not elapsed, step S6
Go to 6.

On the other hand, steps S71 to S74
When the process proceeds to step S74, it is determined in step S74 whether the restart time T0 has elapsed. Here, the restart times T0, T1, are set as T1> T0, and
0 is the restart time that is initially set. That is,
When the subject brightness is less than or equal to a predetermined value during the restart operation, the AF auxiliary light 17 is turned on, but the restart interval (restart time) is longer than when it is not turned on.

In step S75, a hill-climbing focusing operation is executed. When the mountain climbing focus operation is completed, step S
At 76, the AF auxiliary light 17 is turned off. Step S6
In 6, it is determined whether or not the power supply is turned off. If it is determined to be on, the process returns to step S58, and if it is determined to be off, a series of processes is ended. When the release button 20 is not half-pressed, the restart focus operation is repeatedly executed, and the AF auxiliary light 17 is turned on for each focus operation.

In the above-described second operation example, in the refocusing operation repeatedly performed, if the subject brightness is less than or equal to a predetermined value, the AF auxiliary light source 17 is turned on only in the focusing operation. . Furthermore, make the restart interval longer than when it is not lit (when the subject brightness exceeds a specified value),
The lighting frequency of the Af auxiliary light source 17 is reduced.
Therefore, the AF calculation can be performed reliably, and the power consumption can be reduced as compared with the case where the AF auxiliary light 17 is kept on.

-Third Operation Example- FIGS. 9 and 10 are flow charts for explaining the AF mode switching control and auxiliary light lighting control in the third operation example. In step S80 of FIG. 9, it is determined whether or not the power switch of the camera is turned on, and if it is determined to be on, the process proceeds to step S81. In step S81, it is determined whether the AF mode set by the mode setting unit 19 is the C-AF mode or the S-AF mode. If the C-AF mode is determined in step S81, the process proceeds to step S82, and if the S-AF mode is determined, step S3 in FIG.
Go to 0. That is, when the S-AF mode is set, the same control as in the first operation example is performed.

In the third operation example as well as in the second operation example, C-AF
S-AF will be described when the mode is set.
The description is omitted when the mode is set. In step S82, the AE calculation section 71 calculates the subject brightness based on the image pickup signal of the CCD image pickup device 4. The calculated subject brightness is represented by B. In step S83, the calculated value of the subject brightness B is "B≤B" with respect to the predetermined brightness values B1 and B2 (B1> B2).
2 ”,“ B2 <B ≦ B1 ”, and“ B> B1 ”.

Here, the predetermined brightness values B1 and B2 are set as follows. The predetermined brightness value B1 is the same as the predetermined value in the first operation example and the second operation example, and if the subject brightness is higher than the predetermined brightness value B1, reliable AF calculation can be performed. If the subject brightness is B2 <B ≤ B1, A
The light amount of the AF auxiliary light for performing the F calculation is the predetermined light amount A1, and is the predetermined light amount A2 when the subject brightness is B ≦ B2. The magnitudes of the predetermined light amounts A1 and A2 are set as A1 <A2.

When it is determined in step S83 that the value of the subject brightness B is "B≤B2", step S84
Then, the AF auxiliary light source 17 is turned on with a predetermined light amount A2.
In step S83, the value of the subject brightness B is “B2 <B
If it is determined that “≦ B1”, the process proceeds to step S85, and the AF auxiliary light source 17 is turned on with a predetermined light amount A1. When it is determined in step S83 that the value of the subject brightness B is "B>B1", the process proceeds to step S86.

In step S86, the focusing lens is scanned over the entire area, and focus evaluation values at a plurality of positions in the entire area are calculated. Then, in step S87, the focusing lens is moved to a lens position where the focus evaluation value has a peak. After that, the process proceeds to step S88 and AF is performed.
If the auxiliary light source 17 is turned off, step 89 in FIG.
Go to. In step S89, it is determined whether or not the release button 20 is half-pushed. If it is half-pushed, the process proceeds to step S90, and if it is not half-pushed, step S90 is performed.
Proceed to 95.

Steps S90 to S94 of FIG.
The processing procedure up to step S59 to step S59 in FIG.
Since the procedure up to 63 is exactly the same, the description is omitted here. When it is determined in step S89 that it is not in the half-pressed state and the process proceeds to step S95, it is determined in step S95 whether or not the restart time has elapsed from the focusing operation. If it is determined that the restart time has elapsed in step S95, the process proceeds to step S96, the subject brightness B is calculated, and if it is determined that the restart time has not elapsed, step S1.
Go to 02. In step S97, the above-mentioned step S
Similarly to 83, the value of the subject brightness B is equal to the predetermined brightness values B1 and B.
For 2, it is determined which of "B≤B2", "B2 <B≤B1" and "B>B1".

When it is determined in step S97 that the value of the subject brightness B is "B≤B2", step S98
Then, the AF auxiliary light source 17 is turned on with a predetermined light amount A2. In step S97, the value of the subject brightness B is "B2 <B≤.
If it is determined to be "B1", the process proceeds to step S99, and the AF auxiliary light source 17 is turned on with a predetermined light amount A1. If it is determined in step S97 that the value of the subject brightness B is "B>B1", the process proceeds to step S100. Step S
At 100, a hill-climbing focus operation is executed. When the hill climbing focus operation is completed, the AF auxiliary light source 17 is turned off in step S101. In step S102, it is determined whether or not the power source is turned off. If it is determined to be on, the process returns to step S89, and if it is determined to be off, a series of processes is ended.

In the C-AF mode, when the subject brightness is higher than B1, the focusing operation is performed without turning on the AF auxiliary light source 17. When the subject brightness is B1 or less, the AF auxiliary light source 17 is turned on with a light amount according to the subject brightness B. Specifically, when the subject brightness B is darker “B ≦ B2”, the AF auxiliary light source 17 is turned on with a large light amount A2, but when the subject brightness B is relatively bright “B2 <B ≦ B1”, a smaller light amount is obtained. The AF auxiliary light source 17 is turned on at A1. By such light amount control, it is possible to suppress an increase in power consumption even when the AF auxiliary light source 17 is turned on each time a focusing operation is performed.

FIG. 11 is a diagram showing the timing of the restart operation and the lighting of the AF auxiliary light. The case where the subject brightness B changes from B> B1 to B ≦ B2 at time t0 is shown. In this case, the AF auxiliary light source 17 may be turned on at the same time as the subject brightness B changes as shown in FIG.
It may be turned on at the same time as the restart is started as shown in (b).

Although an electronic camera has been described as an example in the above-described embodiments, the present invention is not limited to an electronic camera, and any camera having an AF auxiliary light source such as a silver halide camera and having a C-AF mode can be used. It can be applied similarly.

In the correspondence between the embodiments described above and the elements of the claims, the AF calculation unit 73 is the focusing state calculation means, the CPU 7 and the driver 14 are the focus adjustment means, and the mode setting unit 19 is the mode selection unit. The AE calculation unit 71 constitutes a luminance detecting unit, and the CPU 7 constitutes a mode changing unit, a control unit and an interval setting unit. Also,
The half-press operation of the release button 20 corresponds to the input operation of the focus adjustment operation. Further, the restart time T0 that determines the restart interval corresponds to the first interval, and the restart time T1 corresponds to the second interval.

[0062]

As described above, according to the present invention,
When the subject brightness is equal to or lower than the predetermined value, the auxiliary light source is turned on even in the continuous AF mode. Therefore, even if the brightness is equal to or lower than the predetermined value, AF can be performed more accurately. Furthermore, when the subject brightness is less than or equal to a predetermined value, the continuous AF mode is switched to the single A mode.
The power consumption of the auxiliary light source can be reduced by switching to the F mode, changing the lighting amount of the auxiliary light source according to the brightness, or changing the restart interval.

[Brief description of drawings]

FIG. 1 is a functional block diagram of an electronic camera according to the present invention.

FIG. 2 is a diagram showing a profile of a focus evaluation value.

FIG. 3 is a flowchart for explaining AF mode switching control and auxiliary light lighting control in the first operation example.

FIG. 4 is a flowchart showing a detailed processing procedure of step S200 of FIG.

5 is a flowchart showing a modification of the flowchart of FIG.

FIG. 6 is a flowchart showing a procedure following FIG.

FIG. 7 is a flowchart for explaining AF mode switching control and auxiliary light lighting control in a second operation example.

8 is a flowchart showing a procedure following FIG.

FIG. 9 is a flowchart for explaining AF mode switching control and auxiliary light lighting control in a third operation example.

10 is a flowchart showing a procedure following FIG.

FIG. 11 is a diagram showing a timing of a restart operation and lighting of AF auxiliary light.

[Explanation of symbols]

1 Shooting lens 4 CCD image sensor 5 Analog signal processing circuit 6 A / D converter 7 CPU 8 Digital signal processing circuit 12 monitors 14-16 drivers 17 AF auxiliary light source 19 Mode setting section 20 Release button 71 AE arithmetic circuit 72 Auto white balance calculation circuit 73 AF arithmetic circuit

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Toshiaki Maeda             Marunouchi 3 2-3 No. 3 shares, Chiyoda-ku, Tokyo             Ceremony Company Nikon (72) Inventor Hideomi Hibino             Marunouchi 3 2-3 No. 3 shares, Chiyoda-ku, Tokyo             Ceremony Company Nikon (72) Inventor Masaru Ota             Tokyo Stock Exchange 1-325, Futaba 1-32             Company Nikon technical workshop F term (reference) 2H011 AA03 BA31 BB04 DA01 DA08                 2H051 AA00 BA47 BA70 CC10 CC19                       EA02 EA03 EA11 EA22 EB01                       EB19                 5C022 AB28 AC42 AC69

Claims (9)

[Claims] 1. An image pickup device for picking up a subject image formed by a photographing optical system; a focus state calculation means for calculating a focus evaluation value of the subject image based on an image pickup signal of the image pickup device; Focus adjusting means for adjusting the focus adjustment state of the photographing optical system based on the calculation result of the focus state calculating means, an auxiliary light source that lights up to illuminate the subject during the focus adjusting operation, and a continuity for repeating the focus adjusting operation. Ass AF
A mode selection unit that selects a single AF mode in which the focus adjustment operation is performed by inputting a mode and a focus adjustment operation instruction, a brightness detection unit that detects the brightness of the subject, and the brightness detection unit in the continuous AF mode. And a mode changing means for changing the continuous AF mode to the single AF mode when the brightness detected by the above is less than a predetermined value. 2. The camera according to claim 1, wherein the mode changing means changes from the single AF mode when the brightness detected by the brightness detecting means after the change to the single AF mode exceeds the predetermined value. A camera characterized by changing to the continuous AF mode. 3. The camera according to claim 1, further comprising control means for turning on the auxiliary light source from the start to the end of the input operation in the single AF mode. 4. The camera according to claim 1, wherein, in the single AF mode, a focus adjustment state adjusted by a focus adjustment operation at the time of the input operation is fixed, and a predetermined after the fixation is started from the start of the input operation. A camera provided with a control means for turning on the auxiliary light source until a lapse of time. 5. An image pickup device for picking up a subject image formed by a photographing optical system, a focus state calculation means for calculating a focus evaluation value of the subject image based on an image pickup signal of the image pickup device, and the focusing device. Focus adjusting means for adjusting the focus adjusting state of the photographing optical system based on the calculation result of the focus state calculating means, and continuous AF for repeating the focus adjusting operation.
Mode setting means for setting a mode, brightness detecting means for detecting the brightness of the object, and auxiliary for illuminating the object by lighting with a light amount according to the brightness detected by the brightness detecting means in the continuous AF mode. A camera provided with a light source. 6. The camera according to claim 5, wherein the auxiliary light source is turned on when the brightness detected by the brightness detecting means is less than or equal to a predetermined value in the continuous AF mode, and the auxiliary light source is turned on after the lighting. A camera which is turned off when the brightness detected by the brightness detecting means exceeds the predetermined value. 7. The camera according to claim 5, wherein the auxiliary light source is turned off at the end of the focus adjustment operation after the lighting in the continuous AF mode. 8. The camera according to claim 5, wherein, in the continuous AF mode, the auxiliary light source is turned on when a focus adjustment operation is started, and is turned off when the focus adjustment operation is completed. 9. The camera according to claim 8, wherein when the brightness exceeds a predetermined value, the focus adjustment operation is performed at a first interval, and when the brightness is below a predetermined value, the first adjustment is performed.
A camera provided with an interval setting means for performing the focus adjustment operation at a second interval longer than the interval.