JP4106485B2 - camera - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a camera that performs an AF operation using a contrast method and has a continuous AF shooting mode.
[0002]
[Prior art]
Conventionally, there is a so-called contrast method as one of AF methods of a camera. In this method, a subject is imaged by an image sensor such as a CCD, a focus evaluation value is calculated using an image signal in a focus area, and a focus position is determined based on the focus evaluation value. The AF operation mode includes a single AF mode in which a focusing operation is performed by half-pressing the release button, and a continuous AF mode in which the focusing operation is repeated at a predetermined interval regardless of the half-pressing operation.
[0003]
In general, in the case of a contrast-type camera, a focusing operation called a “mountain climbing method” is employed for the continuous AF mode. In the hill-climbing focusing operation, the focusing lens is moved by a predetermined amount, the magnitudes of the focus evaluation values before and after the movement are compared, and further moved by a predetermined amount in the direction in which the evaluation value increases, and the same processing is performed. Then, by repeatedly executing such processing, the focusing lens is moved to a position where the focus evaluation value reaches a peak.
[0004]
[Problems to be solved by the invention]
However, at the time when the hill-climbing focusing operation starts, the focus evaluation value peak position is not always near the focusing lens position. For this reason, when the focusing lens position and the peak position are largely separated, it takes time to focus and there is a possibility that a photo opportunity will be missed.
[0005]
An object of the present invention is to provide a camera capable of performing a focusing operation more quickly in a camera that performs a “mountain climbing” focusing operation.
[0006]
[Means for Solving the Problems]
(1) The camera according to the invention of claim 1 calculates the focus evaluation value of the subject image based on the imaging element that captures the subject image formed by the imaging optical system and the imaging signal of the predetermined imaging region of the imaging element. Evaluation value calculation means; Based on the focus evaluation value calculated before moving the focusing lens of the photographing optical system by a predetermined amount and the focus evaluation value calculated after the movement, the next time the focusing lens is moved Determine the direction of movement The Moving means for moving the focusing lens; transportation Mode setting means for setting the continuous AF shooting mode to move the focusing lens to the peak position of the focus evaluation value by repeatedly performing the moving operation according to the above, and the camera is activated under the condition set to the continuous AF shooting mode. If it is determined that the focusing lens has been made, the focusing lens is moved in one direction from one end to the other end within the predetermined area of the movable range, and a plurality of focus evaluation values are obtained by the evaluation value calculating means. Control means for moving the focusing lens to the closest peak position of the focus evaluation value calculated based on the focus evaluation value, and after determining that the camera has been activated and moving the focusing lens to the nearest peak position After the movement, the focus by the moving means is changed according to the degree of change in the focus evaluation value thereafter. Determining means for determining whether or not to move the lens lens, and after the photographing operation is performed after the determination by the determination means, the determination means performs the determination operation without being controlled by the control means. And
(2) The camera according to the second aspect of the invention calculates the focus evaluation value of the subject image based on the imaging element that captures the subject image formed by the imaging optical system and the imaging signal of the predetermined imaging area of the imaging element. Evaluation value calculation means; Based on the focus evaluation value calculated before moving the focusing lens of the photographing optical system by a predetermined amount and the focus evaluation value calculated after the movement, the next time the focusing lens is moved Determine the direction of movement The Switching to any one of a plurality of operation modes including a moving means for moving the focusing lens and a continuous AF shooting mode for moving the focusing lens to the peak position of the focus evaluation value by repeatedly performing a moving operation by the moving means. When it is determined by the mode switching means and the mode switching means that the mode has been switched to the continuous AF shooting mode, the focusing lens is moved in one direction from one end to the other end within a predetermined area of the movable range. Control means for acquiring a plurality of focus evaluation values by the evaluation value calculation means and moving the focusing lens to the closest peak position of the focus evaluation value calculated based on the acquired focus evaluation values; and a continuous AF shooting mode Focusing to the nearest peak position after determination of switching to And determining means for determining whether or not to move the focusing lens by the moving means in accordance with the degree of change in the focus evaluation value thereafter, and the photographing operation is performed after the determination by the determining means. Thereafter, the determination unit performs a determination operation by the determination unit without being controlled by the control unit.
(3) The invention according to claim 3 is the camera according to claim 2, further comprising a display monitor for displaying an image, and a playback mode for playing back and displaying the image recorded in the recording means on the display monitor as an operation mode. Is.
(4) According to the invention of claim 4, in the camera according to claim 2, as an operation mode, a setup mode for setting an operation condition of the camera and a communication mode for transmitting image data based on an image pickup signal of the image pickup device to an external device Having at least one of the following.
(5) The invention according to claim 5 is the camera according to claim 2, further comprising instruction means for instructing execution of the focusing operation, and as an operation mode, a single AF shooting mode for performing the focusing operation in accordance with an instruction from the instruction means. It is what has.
(6) The invention of claim 6 is the camera according to any one of claims 1 to 5, wherein the movement of the focusing lens is started from the closest end of the movable range.
(7) The invention of claim 7 is the camera according to any one of claims 1 to 5, wherein the movement of the focusing lens is started from the infinite end of the movable range.
(8) The invention according to claim 8 is the camera according to any one of claims 1 to 7, further comprising a changing unit that changes a focal length of the photographing optical system, and the focal length is changed to the shortest focal length by the changing unit. Later, the movement of the focusing lens is started.
[0007]
DETAILED DESCRIPTION OF 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 AF (autofocus) digital camera according to an embodiment of the present invention. Reference numeral 101 denotes an electric zoom type photographing lens, which has a focusing lens for performing focus adjustment and a variable magnification lens for changing the focal length, although not shown. The focusing lens is driven by a driver 113, and the variable power lens is driven by a driver 118. Each of the drivers 113 and 118 includes a driving mechanism and a driving circuit for driving the lens, and is controlled by the CPU 112, respectively.
[0008]
The photographing lens 101 forms a subject image on the imaging surface of the image sensor 103. The image sensor 103 is a photoelectric conversion image sensor that outputs an electrical signal corresponding to the light intensity of the subject image formed on the image pickup surface, and a CCD type or MOS type solid state image sensor is used. The image sensor 103 is driven by a driver 115 that controls the timing of signal extraction. A diaphragm 102 is provided between the photographing lens 101 and the image sensor 103. The diaphragm 102 is driven by a driver 114 equipped with a diaphragm driving mechanism and its driving circuit.
[0009]
An imaging signal from the imaging element 103 is input to the analog signal processing circuit 104, and processing such as correlated double sampling processing (CDS processing) is performed in the analog signal processing circuit 104. The imaging signal processed by the analog signal processing circuit 104 is converted from an analog signal to a digital signal by the A / D converter 135 and then input to the digital signal processing circuit 106. The digital signal processing circuit 106 includes signal processing circuits such as a gain control circuit, a luminance signal generation circuit, and a color difference signal generation circuit, and performs various functions such as edge enhancement, gamma correction, and white balance adjustment on the input imaging signal. Perform image processing.
[0010]
The imaging signal input to the digital signal processing circuit 106 is temporarily stored in the buffer memory 105, read out from the buffer memory 105 for each process described above, and the processed signal is stored in the buffer memory 105 again. The buffer memory 105 is a frame memory that can store data for a plurality of frames captured by the image sensor 103.
[0011]
Image data that has undergone a series of processing in the digital signal processing circuit 106 is stored in the buffer memory 105. Thereafter, the data is recorded on an external storage medium 111 such as a memory card via the recording / reproduction signal processing circuit 110. When image data is recorded in the external storage medium 111, data compression is generally performed in a predetermined compression format, for example, the JPEG method. The recording / reproduction signal processing circuit 110 performs data compression when recording image data on the external recording medium 111 and data expansion processing when reading compressed image data from the external storage medium 111. The recording / playback signal processing circuit 110 also includes an interface for performing data communication with the external storage medium 111.
[0012]
Reference numeral 109 denotes a monitor for displaying a subject image. For example, a liquid crystal display device is used. In a shooting mode, which will be described later, an image signal captured by the image sensor 103 at predetermined time intervals is subjected to signal processing by the analog signal processing circuit 104, the A / D converter 135, and the digital signal processing circuit 106, and then the buffer memory. An image based on the image data stored in the VRAM 108 and transferred to the VRAM 108 is displayed on the monitor 109. Therefore, the photographer can visually recognize the subject from the image displayed on the monitor 109. On the other hand, in the reproduction mode, the image read from the external storage medium 111 is transferred to the VRAM 108 and reproduced and displayed on the monitor 109.
[0013]
The CPU 112 is connected to the digital signal processing circuit 106 and drivers 113 to 115, 118 and the like, and performs sequence control of camera operation. The AE calculation unit 1121 of the CPU 112 performs automatic exposure calculation based on the image signal from the image sensor 103, and the AWB calculation unit 1122 calculates a white balance adjustment coefficient. A band pass filter (BPF) 1124 extracts a high frequency component in a predetermined band based on an imaging signal in a focus detection area provided in the imaging region. When a plurality of focus detection areas are set, signals in each area are read in order, and extraction processing for each area is performed by a bandpass filter (BPF) 1124. Hereinafter, a case where there is one focus detection area will be described as an example.
[0014]
The output of the BPF 1124 is input to the evaluation value calculation unit 1125. The evaluation value calculator 1125 integrates the absolute value of the high frequency component to calculate a focus evaluation value for the subject image in the focus detection area. The AF calculation unit 1126 performs AF calculation by the contrast method based on the calculated focus evaluation value. The CPU 112 controls the driver 118 based on the calculation result of the AF calculation unit 1126 and adjusts the position of the focusing lens provided in the photographing lens 101 to perform the focusing operation.
[0015]
An operation unit 116 connected to the CPU 112 includes a power switch 1161 for turning on / off the camera, a full-push switch 1162 and a half-push switch 1163 that are turned on / off in conjunction with a release button (not shown), and according to the shooting scene. A scene setting button 1164 for selecting the set conditions, a monitor button 1165 for turning on / off the monitor 109, a menu button 1166 for displaying a menu such as a setup menu on the monitor 109, and a select dial 1167 for selecting a mode. Is provided.
[0016]
When these switches and buttons are operated, a signal corresponding to the operation is input to the CPU 112. The select dial 1167 can switch the camera mode to any one of a shooting mode, a reproduction mode, a setup mode, and a communication mode by rotating the dial. Details of the operation mode of the camera will be described later.
[0017]
The AF auxiliary light 122 illuminates the subject when the luminance is low. The CPU 112 has a storage unit 1123 for storing various data and a timer 1127. The timer 1127 is generally called a half-press timer, and starts counting when the half-press operation of the release button is released or after the first focusing after power-on as described later. In addition, the camera of this embodiment has an auto power off function. For example, the timer 1127 starts counting when the operation of the operation unit 116 is completed, and automatically enters a power off state (sleep mode) when a predetermined time elapses. Called the state). If the release button is pressed halfway or the monitor button 1165 is operated in the sleep state, the sleep state is canceled and the power is turned on. That is, the camera is restarted.
[0018]
A communication unit 123 is connected to the CPU 112, and image data can be transmitted to and / or received from an external device 124 such as a PC (personal computer). When the select dial 1167 described above is set to the communication mode, the communication unit 123 is activated and establishes communication with the external device 124. As a communication form, in addition to the wireless type as shown in FIG. 1, communication with the external device 124 may be performed via a communication cable. In the case of using a communication cable, when the communication unit 123 and the external device 124 are connected by the communication cable, the communication unit 123 is activated to enter a communication mode, and communication with the external device 124 is established. On the contrary, when the connection between the communication cable and the communication unit 123 is released, the operation mode before the connection is restored.
[0019]
In the camera of the present embodiment, AF calculation is performed by the contrast method. In the contrast method, there is a correlation between the degree of image blur and the contrast, and focusing is performed using the fact that the contrast of the image is maximized when the image is focused. The magnitude of the contrast can be evaluated based on the magnitude of the high frequency component of the imaging signal. That is, the high-frequency component of the imaging signal is extracted by the BPF 1124 and the absolute value of the high-frequency component is integrated by the evaluation value calculation unit 1125 as the focus evaluation value. This focus evaluation value becomes the maximum value when the focus is reached and the contrast becomes maximum.
[0020]
As described above, the AF calculation unit 1126 performs AF calculation based on the focus evaluation value. The CPU 112 controls the driver 113 based on the calculation result of the AF calculation unit 1126 to drive the focusing lens of the photographing lens 101 to the in-focus position. FIG. 2 is a diagram illustrating an example of the focus evaluation value, and the focus evaluation value L0 has a peak at the in-focus position P. In FIG. 2, the horizontal axis represents the lens position of the focusing lens. When searching for the peak of the focus evaluation value, a scanning operation and a mountain climbing operation described later are performed. If the peak position P of the focus evaluation value is obtained by these operations, the position of the focusing lens of the photographing lens 101 is driven to the peak position P.
[0021]
<< Explanation of modes >>
In the camera of the present embodiment, as a mode, in addition to the shooting mode, playback mode, setup mode, and communication mode selected by operating the select dial 1167, the AF mode is a single AF mode (S-AF mode). And a continuous AF mode (C-AF mode). In the S-AF mode, the AF operation is performed only when the half-push switch 1163 is half-pressed, and once focused, the focused state is maintained until the half-push is released.
[0022]
On the other hand, in the C-AF mode, the AF operation is repeatedly performed at a predetermined interval even if the half-press switch 1163 is not operated. The AF mode is set by operating the menu button 1166 in the shooting mode state to call up the setup menu in the shooting mode on the monitor 109. The state where the setup menu is displayed is called a setup mode and is treated as one of the operation modes.
[0023]
In the present embodiment, the case where the C-AF mode is set and the shooting mode is selected with the select dial 1167 is referred to as a C-AF shooting mode. On the other hand, when the S-AF mode is set and the shooting mode is selected, the S-AF shooting mode is called. When the playback mode is selected by the select dial 1167, the playback mode is called regardless of the AF operation mode. These C-AF shooting mode, S-AF shooting mode, playback mode, setup mode, and communication mode are referred to as operation modes.
[0024]
Scene conditions that can be set with the scene setting button 1164 are also referred to as modes, and a normal shooting mode that can cover a wide range of normal shooting conditions, a distant shooting mode that is suitable for landscape shooting, and a person who can shoot with a person floating against the background There are a shooting mode, a close-up mode for shooting a subject from a very short distance, and a night view shooting mode for beautifully shooting a night view. When the scene setting button 1164 described above is operated in the shooting mode, a scene setting menu is displayed on the monitor 109. These modes are considered separately from the operation modes described above.
[0025]
<Operation description>
Next, specific operation examples of the camera will be described with reference to FIGS. FIG. 3 is a flowchart showing processing in the operation mode. In the present embodiment, at least five modes of C-AF shooting mode, S-AF shooting mode, playback mode, setup mode, and communication mode are provided as operation modes. FIG. 4 is a flowchart for performing processing according to camera setting switching. When a setting is changed, the condition is stored, and the operation of FIG. 3 is performed based on the stored condition. The process shown in FIG. 4 is started at predetermined time intervals.
[0026]
First, FIG. 4 will be described. In step S200, it is determined whether or not the auto power-off has been canceled, that is, whether or not the half-press switch 1163 or the monitor button 1165 has been operated when the auto power-off is activated and the power is off. If it is determined in step S200 that the release has been made, the process proceeds to step S203. If it is determined that the release has not been made, the process proceeds to step S201.
[0027]
In step S201, the mode setting stored in the storage unit 1123 in FIG. 1 is compared with the current mode setting to determine whether or not the operation mode setting has been changed. For example, when the mode is switched by the select dial 1167 shown in FIG. 1 or when the mode is switched between the C-AF mode and the S-AF mode, it is determined that the setting has been changed. If it is determined in step S201 that the mode setting has been changed, the process proceeds to step S202. If it is determined that there has been no change, the process of FIG. In step S202, the mode setting stored in storage unit 1123 is replaced with the current mode setting. After that, when the processing of the operation mode in FIG. 3 is restarted in step S203, the series of processing ends. The restart instruction in step 203 is generated when the mode is switched among the S-AF shooting mode, C-AF shooting mode, playback mode, setup mode, and communication mode.
[0028]
Next, the flowchart of FIG. 3 will be described. The flowchart of FIG. 3 starts when the power switch 1161 of the camera is turned on. Note that the processing is also started from step S100 when a restart instruction is given by the processing of step S203 in FIG. In step S100, it is determined whether or not the operation mode is a communication mode. If it is determined in step S100 that the communication mode is selected, the process proceeds to step S102, and communication mode processing is executed. In the communication mode, the communication unit 123 of FIG. 1 is activated, and for example, a process of transferring image data stored in the external storage medium 111 to the external device 124 is executed. Details of the communication mode process will not be described.
[0029]
On the other hand, if it is determined in step S100 that the communication mode is not selected, the process proceeds to step S101, and the operation mode is any of (a) S-AF shooting mode or C-AF shooting mode, (b) playback mode, and (c) setup mode. It is determined whether or not. If it is determined in step S100 that the mode is (a) S-AF shooting mode or C-AF shooting mode, that is, if the select dial 1167 is set to the shooting mode, the process proceeds to step S103. If it is determined that the playback mode is (b), the process proceeds to step S104, and a series of processing relating to the playback mode is executed. Further, (c) in the setup mode, the process proceeds to step S105, and a process related to the setup is executed.
[0030]
(b) The reproduction mode is a mode in which an image based on the image data stored in the external storage medium 111 is reproduced on the monitor 109. It is set by switching the select dial 1167 to the reproduction mode. The (c) setup mode is a mode for performing various camera settings. The setup menu is displayed on the monitor 109 to set each item. As described above, when the select dial 1167 is set to the shooting mode or the playback mode and the menu button 1166 is operated, a setup menu corresponding to each mode is displayed on the monitor 109.
[0031]
For example, the setup menu items when the shooting mode is set include folder setting of the attached external storage medium 111, setting of the monitor 109, power-off setting, and the like. Note that description of the reproduction processing in step S104 and details of step S105 will be omitted, and in the following, description will be given of the case where (a) the S-AF shooting mode or the C-AF shooting mode is determined and the process proceeds from step S101 to step S103. To do.
[0032]
In step S103, readout of the imaging signal from the CCD 103 and A / D conversion of the imaging signal by the A / D converter 135 are performed. Further, the data is taken from the digital signal processing circuit 106 into the buffer memory 105, and the AE calculation unit 1121 performs the AE calculation. In step S106, it is determined whether the subject brightness calculated by the AE calculation unit 1121 is equal to or lower than a predetermined level. That is, it is determined whether or not the brightness is low. If it is determined in step S106 that the subject brightness is equal to or lower than the predetermined level, the process proceeds to step S107, and if it is determined that the subject brightness is higher than the predetermined level, the process proceeds to step S112.
[0033]
If the process proceeds from step S106 to step S107, it is determined in step S107 whether the gain setting is an upper limit value. The gain here is multiplied by the A / D output in the digital signal processing circuit 106. If it is determined in step S107 that the gain setting is not the upper limit value, the process proceeds to step S108, and the gain setting is increased by one step. For example, if the ISO sensitivity is set to 100, the sensitivity is set to 200 by one step.
[0034]
Thereafter, the process returns from step S108 to step 106, and it is determined whether or not the subject luminance after the gain setting is changed is equal to or lower than a predetermined level. On the other hand, if it is determined in step S107 that the gain setting is the upper limit value, that is, if it is determined that the ISO sensitivity is at the final stage (for example, 800), the AF auxiliary light 122 is turned on in step S109. The auxiliary light lighting is continued until the focusing operation is completed.
[0035]
In a succeeding step S110, it is determined whether or not the frame rate setting of the imaging signal output from the CCD 103 is a lower limit value. If it is determined in step S110 that the value is the lower limit value, the process proceeds to step S112. If it is determined that the value is not the lower limit value, the process proceeds to step S111. If the process proceeds to step S111, the frame rate is decreased by one step in step S111, and then the process returns to step S106. That is, since the subject brightness is low, the frame rate is lowered in step S111 to increase the accumulation time of the CCD 103. Similar to the gain setting, a plurality of settings are prepared in advance for the frame rate setting. In step S112, the absolute position of the focusing lens is detected by a photocoupler or the like to determine the lens reference position.
[0036]
In step S113, it is determined whether the AF mode is set to the C-AF mode or the S-AF mode. If it is determined to be the S-AF mode, the process proceeds to step S114, and if it is determined to be the C-AF mode, the process proceeds to step 115. In step S114, it is determined whether or not the half-press switch 1162 is on. If it is determined to be off (no), the process returns to step S113. If it is determined to be on (yes), the process proceeds to step S116. In step S116, the focusing lens is moved to the initial position. As the initial position of step S116, for example, the infinite side end position or the close side end position is selected. In the present embodiment, a description will be given assuming that the closest end position is the initial position.
[0037]
On the other hand, when the process proceeds from step S113 to step S115, in step S115, the magnifying lens of the photographic lens 101 is moved to the widest end position so that the focal length of the photographic lens 101 becomes the shortest. Thereafter, if the focusing lens is moved to the initial position in step S116, the process proceeds to step S117 in FIG.
[0038]
In the processing from step S117 to step S120, the focus evaluation value is sampled over the entire lens position. First, in step S117, the photographic lens 101 starts to move toward the infinity side of the focusing lens. In step S <b> 118, the imaging signal in the focus detection area is processed by the BPF 1124, and the integration within the area is performed by the evaluation value calculation unit 1125 for the signal. These results are stored in the storage unit 1123 in pairs with the lens position at the time of sampling.
[0039]
In step S119, it is determined whether or not the lens position has reached the infinite end position. If it is determined in step S119 that the position is the infinity side end position, the process proceeds to step S120 and lens driving is stopped. On the other hand, if it is determined in step S119 that the position is not the infinite endmost position, the process returns to step S118, and the focus evaluation value is calculated and stored again. Therefore, the focus evaluation value is stored in the storage unit 1123 for each sample position from the closest end of the focusing lens to the infinite end position by the processing of steps S117 to S120.
[0040]
In step S121, a predetermined weighting process is performed on each calculated focus evaluation value. 8 and 9 are diagrams showing an example of weighting. FIG. 8 is a diagram illustrating a weighting curve, in which the horizontal axis indicates the lens position and the vertical axis indicates the weight. The origin side of the horizontal axis is the infinity side, and the positive direction of the horizontal axis is the near side. The weighting curve in FIG. 8 relates to an AF mode in which priority is given to the subject at the farthest end, and the weight at the farthest end is set to 1, and the weight becomes a straight line that becomes smaller toward the infinity side. Yes.
[0041]
When the weighting shown in FIG. 8 is performed on the focus evaluation value as shown by the curve L1 in FIG. 9, the focus evaluation value as shown by the curve L2 is corrected. Since the focus evaluation value is discrete data, the curves L1 and L2 are estimated by interpolation. Both the curves L1 and L2 have two peaks, and the focus evaluation value of the infinity-side peak P2 of the curve L1 is larger than the close-side peak P1.
[0042]
On the other hand, in the weighted focus evaluation value curve L2, the focus evaluation value of the closest peak P11 is larger than the infinity peak P12. Therefore, when the lens position with the maximum focus evaluation value is selected as the in-focus position, the closest peak P11 is selected. As described above, the weighting curves in FIG. 8 are weights suitable for close-up photography such as portrait and close-up photography.
[0043]
The weighting curve in FIG. 10 shows another example, and is a weighting curve in the distant shooting mode. The weighting curve changes stepwise with the lens position x1 as a boundary, and the weight on the near side is smaller than the weight on the infinity side than the lens position x1.
[0044]
Returning to FIG. 5, in step S122, the nearest peak is selected based on the focus evaluation value weighted in step S121. For example, when the focus evaluation value is the curve L2 in FIG. 13, the lens position of the peak P11 is selected as the closest peak. In step S123, the focusing lens is moved to the lens position of the nearest peak selected in step S122. After the lens movement, in step S124, a focus evaluation value after the lens movement is obtained, and it is reconfirmed that the lens is in focus.
[0045]
Next, in step S125 of FIG. 6, it is determined whether the AF mode setting of the camera is the C-AF mode or the S-AF mode. If it is determined in step S125 that the C-AF mode is selected, the process proceeds to step S132 in FIG. 7, and if it is determined that the S-AF mode is selected, the process proceeds to step S126. First, the case of the S-AF mode, that is, the case where the process proceeds from step S125 to step S126 will be described.
[0046]
In step S126, AF lock is performed at the in-focus position confirmed in step S124. If AF lock is performed in step S126, a flag indicating the release permission state is set in subsequent step S127. In step S128, it is determined whether or not the half-press switch 1163 is on. If the half-pressed state is continued and YES is determined in step S128, the process proceeds to step S129. If the half-pressed state is released and NO is determined, the process proceeds to step S131.
[0047]
If the process proceeds from step S128 to step S129, it is determined in step S129 whether or not the full push switch 1162 is on. If YES is determined in the step S129, the process proceeds to a step S130 so as to perform a photographing process operation, and then returns to the step S125. On the other hand, when the process proceeds from step S128 to step S131, it is determined in step S131 whether the AF mode setting is the C-AF mode or the S-AF mode. If the C-AF mode is determined in step S131, the process returns to step S125. If the S-AF mode is determined, the process returns to step S113 in FIG.
[0048]
Next, a case where the C-AF mode is set and the process proceeds from step S125 to step S132 in FIG. 7 will be described. In step S132, the timer 1127 of FIG. 1 starts counting. In step S133, the driving of the focusing lens is stopped. In step S134, it is determined whether or not the half-press switch 1163 has been turned on. If it is determined in step S134 that the press switch 1163 is turned on, the process proceeds to step S135, and if it is determined that the half-press switch 1163 is not pressed halfway, the process proceeds to step S139.
[0049]
If the half-press switch 1163 remains off and the process proceeds from step S134 to step S139, it is determined in step S139 whether restart is necessary. For example, it is determined whether or not the restart is necessary depending on whether or not the restart time interval Δt has elapsed. If it is determined in step S139 that Δt has not elapsed, the process returns to step S133, and if it is determined that Δt has elapsed, the process proceeds to step S140. In step S140, a well-known hill-climbing focusing operation is executed. A general description of the hill-climbing focusing operation will be described later.
[0050]
In the subsequent step S141, it is determined whether or not the in-focus position has been found and in-focus has been achieved. Since the in-focus position is not necessarily found by the hill-climbing operation in step S140, if it is determined that in-focus has not been achieved, the process proceeds to step S142 to move the focusing lens to a predetermined position, and then the process returns to step S133. On the other hand, if it determines with focusing in step S141, it will return to step S133. It should be noted that the focus evaluation value data obtained during the hill-climbing focusing operation is stored in the storage unit 1123 separately from the data for the entire area sampling stored in step S118. The data obtained and stored by this hill-climbing focusing operation is replaced with new data every time the hill-climbing focusing operation is performed.
[0051]
On the other hand, when the process proceeds from step S134 to step S135, it is determined in step S135 whether or not the focus evaluation value is within the release permission range. This is a step of checking the degree of change in the focus evaluation value from the time of focusing. If it is determined that the change is greater than the predetermined value, that is, if the focus evaluation value exceeds the release permission range, the process proceeds from step S135 to step S136, and a hill climbing operation similar to step S140 is performed. On the other hand, if it is determined in step S135 that it is within the release permission range, the process proceeds to step S126 in FIG.
[0052]
In step S137, it is determined whether or not focusing has been achieved by the hill-climbing operation as in step S141. If it is determined in step S137 that the focus is achieved, the process proceeds to step S126 in FIG. 6, and if it is determined that the focus is not achieved, the process proceeds to step S138 and the lens is moved to a predetermined position. Thereafter, the process proceeds to step S126 in FIG.
[0053]
(Explanation of hill-climbing focusing operation and scanning focusing operation)
Here, the difference between the focusing operation by the hill-climbing movement performed in step S136 or step S140 and the focusing operation by the scanning movement performed by the processing from step S117 to step S123 in FIG. 5 will be described.
[0054]
First, the hill-climbing focusing operation will be described. FIG. 11 is a diagram for explaining the concept of the hill-climbing focusing operation, and L3 indicates a focus evaluation value curve obtained for the subject. x3 is a focusing lens position at the start of mountain climbing, and the focus evaluation value at that time is y3. The lens position x3 and the focus evaluation value y3 are stored in the storage unit 1123. When the focusing operation is started, for example, the lens is moved by a predetermined amount to the close side, and the focus evaluation value y4 at the moved position x4 is calculated. Note that these focus evaluation values may or may not be weighted according to the lens position.
[0055]
Next, the calculated focus evaluation value y4 and the focus evaluation value y3 at the start of movement stored in the storage unit 1123 are compared. In the case of FIG. 11, since the obtained focus evaluation value y4 is larger than the focus evaluation value y3, the focus evaluation value tends to increase in the moving direction, and the position P at which the focus evaluation value reaches a peak is closer to the lens position x4. It is determined that When it is determined that the lens is in the close side, the focusing lens is further moved to the close side by a predetermined amount, and the focus evaluation value y5 at the lens position x5 after the movement is calculated. Thereafter, the focus evaluation value y4 and the focus evaluation value y5 are compared.
[0056]
In the second movement, it is determined that the focus evaluation value y5 at the lens position x5 is smaller than the focus evaluation value y4 at the lens position x4. That is, it is determined that the peak position P is on the infinite side with respect to the lens position x5. Therefore, an interpolation calculation based on the data (x3, y3), (x4, y4), (x5, y5) is performed to calculate the peak position P of the focus evaluation value, and the focusing lens is moved to the peak position P. As described above, in the hill-climbing focusing operation, a series of processes of “lens movement” → “calculation of focus evaluation value” → “comparison of focus evaluation value” is repeatedly performed, so that the focusing lens has a peak position P of the focus evaluation value. Move to. When moving the lens, the moving direction is determined by comparing the focus evaluation value at the current position with the focus evaluation value obtained last time.
[0057]
On the other hand, in the focusing operation by scanning movement, the focusing lens is moved in one direction from one end to the other end of the scanning region. A plurality of focus evaluation values are calculated during the movement, and are stored in the storage unit 1123 in pairs with the position data. Note that the focusing lens may be moved continuously or stepwise.
[0058]
This scan focusing operation differs greatly from the hill-climbing focusing operation in the hill-climbing, which is a feedback operation in which the moving direction is determined each time by comparison with the previous focus evaluation value. The scan moves in one direction. When a plurality of focus evaluation values in the scan area are acquired, the peak position P is calculated by comparing the magnitudes of the focus evaluation values. Then, the focusing lens is moved to the calculated peak position P.
[0059]
In the above-described embodiment, when the entire area scan is performed, the focusing lens is initially moved to the nearest end position, and then scanned from the nearest end position to the infinite end position. Alternatively, the infinite side end position may be set as the initial position, and scanning may be performed from the infinite side end position to the closest side end position.
[0060]
The camera of the present embodiment described above has the following characteristics.
(1) If the C-AF shooting mode is set when the camera power switch 1161 is turned on or when the camera is released from the sleep state and restarted, the first focusing operation is performed using the focusing lens. The entire position of the movable range was scanned and the peak position of the focus evaluation value was searched. Then, the hill-climbing focusing operation is performed from the peak position detected by the whole area scan. Therefore, the focusing operation can be performed quickly even when the camera is activated, and the photographer can start the imaging operation immediately after the activation.
(2) Also, when the operation mode other than the C-AF shooting mode is switched to the C-AF shooting mode, the same whole area scan is performed, so that the same effect can be obtained.
(3) Furthermore, since the zoom position of the photographic lens 101 is automatically set to the wide side, the focusing lens is moved to the end and the whole area scan is performed, so the driving amount of the focusing lens is reduced, and the focusing is performed more quickly. Can be burnt.
[0061]
In the above-described embodiment, the electronic camera has been described as an example. However, the present invention is not limited to the electronic camera, and can be similarly applied to any camera that performs AF using a contrast method, such as a silver salt camera.
[0062]
In the correspondence between the embodiment described above and the elements of the claims, the operation unit 116 is a mode setting unit and a mode switching unit, the CPU 112 and the driver 113 are moving units and a control unit, and the half-press switch 1163 is an instruction unit. The CPU 112 and the driver 118 constitute changing means, and the external storage medium 111 constitutes recording means.
[0063]
【The invention's effect】
As explained above, according to the present invention, By means of transportation Continuous AF photograph The camera is activated in the mode, or continuous AF from other operation modes photograph When switched to mode, First Move the focusing lens in one direction from one end to the other end of the movable range to obtain the focus evaluation value, and move the focusing lens to the peak position of those focus evaluation values After that, if necessary, mountain climbing AF To do. Therefore, continuous AF photograph A focusing operation can be performed quickly at the start of the mode.
[Brief description of the drawings]
FIG. 1 is a functional block diagram of an AF digital camera according to the present invention.
FIG. 2 is a diagram showing a focus evaluation value curve L0.
FIG. 3 is a flowchart showing processing in an operation mode.
FIG. 4 is a flowchart showing processing related to setting switching.
FIG. 5 is a flowchart showing processing subsequent to the flowchart of FIG. 3;
6 is a flowchart showing processing subsequent to the flowchart of FIG.
FIG. 7 is a flowchart showing processing following the flowchart of FIG. 6;
FIG. 8 is a diagram illustrating an example of a weighting curve.
FIG. 9 is a diagram showing focus evaluation value curves before and after weighting processing;
FIG. 10 is a diagram illustrating a weighting curve in a distant view shooting mode.
FIG. 11 is a diagram illustrating a hill-climbing focusing operation.
[Explanation of symbols]
101 Photography lens
102 Aperture
103 Image sensor
104 Analog signal processing circuit
106 Digital signal processing circuit
109 monitor
111 External storage media
112 CPU
113-115, 118 drivers
116 Operation unit
123 communication unit
124 External equipment
135 A / D converter
1125 Evaluation value calculator
1126 AF calculation unit
1161 Power switch
1162 Full push switch
1163 half-press switch
1167 Select dial

Claims (8)

An image sensor that captures a subject image formed by the photographing optical system;
Evaluation value calculation means for calculating a focus evaluation value of the subject image based on an imaging signal of a predetermined imaging region of the imaging element;
Based on the focus evaluation value calculated before moving the focusing lens of the photographing optical system by a predetermined amount and the focus evaluation value calculated after the movement, a moving direction when the focusing lens is moved next is determined. moving means for determining to move the focusing lens in the direction of movement,
Mode setting means for setting the continuous lens to a continuous AF photographing mode in which the focusing lens is moved to the peak position of the focus evaluation value by repeatedly performing the moving operation by the moving means;
When it is determined that the camera has been activated under the condition set to the continuous AF shooting mode, the focusing lens is moved in one direction from one end to the other end within a predetermined area of the movable range. A plurality of the focus evaluation values obtained by the evaluation value calculating means, and a control means for moving the focusing lens to the closest peak position of the focus evaluation value calculated based on the acquired focus evaluation value;
After it is determined that the camera has been activated and after the focusing lens is moved to the nearest peak position, the focusing by the moving unit is performed according to the degree of change in the focus evaluation value thereafter. Determination means for determining whether or not to move the lens,
The camera according to claim 1, wherein after the shooting operation is performed after the determination by the determination unit, the determination unit performs the determination operation without being controlled by the control unit. An image sensor that captures a subject image formed by the photographing optical system;
Evaluation value calculation means for calculating a focus evaluation value of the subject image based on an imaging signal of a predetermined imaging region of the imaging element;
Based on the focus evaluation value calculated before moving the focusing lens of the photographing optical system by a predetermined amount and the focus evaluation value calculated after the movement, a moving direction when the focusing lens is moved next is determined. moving means for determining to move the focusing lens in the direction of movement,
Mode switching means for switching to any one of a plurality of operation modes including a continuous AF shooting mode for moving the focusing lens to a peak position of a focus evaluation value by repeatedly performing a moving operation by the moving means;
When it is determined by the mode switching means that the mode has been switched to the continuous AF shooting mode, the focusing lens is moved in one direction from one end to the other end within a predetermined area of the movable range, and the evaluation is performed. Control means for acquiring a plurality of the focus evaluation values by the value calculating means and moving the focusing lens to the closest peak position of the focus evaluation value calculated based on the acquired focus evaluation values;
After the determination to switch to the continuous AF shooting mode and after the focusing lens is moved to the closest peak position, the moving means is used according to the degree of change in the focus evaluation value thereafter. Determining means for determining whether or not to move the focusing lens;
The camera according to claim 1, wherein after the photographing operation is performed after the determination by the determination unit, the determination unit performs the determination operation by the determination unit without being controlled by the control unit. The camera according to claim 2,
A camera comprising a display monitor for displaying an image, wherein the operation mode includes a reproduction mode for reproducing and displaying an image recorded in a recording means on the display monitor. The camera according to claim 2,
The camera having at least one of a setup mode for setting an operation condition of the camera and a communication mode for transmitting image data based on an image pickup signal of the image pickup device to an external device as the operation mode. The camera according to claim 2,
A camera comprising instruction means for instructing execution of a focusing operation, wherein the operation mode includes a single AF shooting mode for performing a focusing operation in accordance with an instruction from the instruction means. The camera according to any one of claims 1 to 5,
The camera, wherein the control means starts the movement from the closest end of the movable range. The camera according to any one of claims 1 to 5,
The camera, wherein the control means starts the movement from an infinite end of the movable range. The camera according to any one of claims 1 to 7,
A changing means for changing a focal length of the photographing optical system;
The control means starts the movement after changing the focal length to the shortest focal length by the changing means.

Images