JP3790835B2 - Electronic camera - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electronic camera having a plurality of focus control methods.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, electronic cameras having a contrast AF (autofocus) type focus control mechanism are known.
In this type of electronic camera, an image signal of a subject image is sequentially captured by an internal solid-state image sensor. The electronic camera selects a signal in the focus detection area from the image signal, and then extracts a high-frequency component of the image signal through a spatial frequency band-pass filter or the like.
[0003]
Next, the electronic camera performs detection processing, integration processing, and the like on the high frequency component to detect a peak value or an amplitude average value of the high frequency component.
These peak values and average amplitude values are amounts that change according to the contrast of the subject image (hereinafter, such amounts are referred to as “contrast amounts”).
[0004]
The electronic camera searches the in-focus position in a hill-climbing manner by extending the photographing optical system little by little in the direction in which the contrast amount increases. By repeatedly performing such focus movement, the photographing optical system of the electronic camera reaches the in-focus position.
On the other hand, a range finder type silver salt camera or the like is known that measures the distance to a subject by using an outside light type ranging such as a known passive ranging or active ranging.
[0005]
In this type of silver halide camera, the in-focus position of the photographing optical system can be directly calculated based on the value of the subject distance, and the photographing optical system can be moved in a straight line to the in-focus position.
[0006]
[Problems to be solved by the invention]
By the way, in such a contrast AF type electronic camera, it has been necessary to intermittently move the photographing optical system many times in order to find the in-focus position in a hill-climbing manner. For this reason, there is a problem that the time until the in-focus state is reached (hereinafter referred to as “focus time”) is generally long.
[0007]
In addition, since individual differences in the contrast amount for each subject are large, it is difficult to predict in general where the contrast amount takes the maximum value. Therefore, even if the contrast amount is low, the photographing optical system cannot be extended greatly. For this reason, there is a problem that the focusing time becomes longer in proportion to the moving distance to the focusing position.
[0008]
In particular, recently, an electronic camera that covers a wide range from a normal photographing area to a macro area with one photographing optical system is increasing. In such an electronic camera, since the taking-out length of the photographing optical system becomes long, the average moving distance to the in-focus position is also long. Therefore, such an electronic camera has a problem that the average focusing time becomes very long.
[0009]
Recently, in order to respond to voices that require higher precision in focus control, there are an increasing number of electronic cameras that finely control the number of steps of focus adjustment of the photographing optical system. In such an electronic camera, there is a problem that the contrast amount must be actually measured for each number of steps, and the focusing time is excessively long.
For the reasons described above, if the focusing time of the electronic camera becomes long, the release time lag (the time lag from when the release is pressed until the start of shooting) cannot be ignored, and problems such as missing valuable shutter opportunities frequently occur. .
[0010]
On the other hand, in order to solve the above-described problems, it is conceivable that the focus control of the electronic camera is performed at high speed by using an external light type distance measurement that has been put to practical use in a silver halide camera or the like.
However, in the outside light type distance measurement, a positional shift between the distance measurement area and the subject (hereinafter referred to as “parallax”) occurs greatly for a familiar subject. In particular, with an electronic camera, there are generally more opportunities to photograph familiar items (such as documents and timetables) instead of notes. For this reason, the frequency of shooting in a large parallax state is high, and problems such as shooting out-of-focus images frequently occur.
[0011]
  In addition, in order to eliminate such parallax mechanically, it is necessary to mount a mechanism for moving the ranging area according to the subject distance in the electronic camera, which increases the size of the electronic camera, etc. There was a problem.
  Accordingly, in order to solve the above-described problems, the electronic camera according to claim 1 provides an electronic camera that can reduce the influence of the parallax in the outside light type distance measurement while efficiently reducing the focusing time. The purpose is to do.
  Furthermore, it is an object of the present invention to provide an electronic camera that can further improve the focusing accuracy.
[0012]
  It is an object of the present invention to provide an electronic camera that allows a photographer to freely select a focus adjustment method within a specific range of subject distance.The
[0013]
[Means for Solving the Problems]
  FIG. 1 is a principle block diagram corresponding to the first to third aspects of the present invention.
  According to the first aspect of the present invention, the optical image formed through the photographing optical system Z is captured, the imaging unit 1 that generates an image signal, the image signal generated by the imaging unit 1 is captured, Contrast detection means 2 for detecting the contrast amount of the image signal, contrast focus control means 3 for moving the focus of the photographing optical system Z to a position where the contrast amount detected by the contrast detection means 2 takes a maximum value, and photographing optics An outside light type distance measuring means 4 for measuring the distance to the subject via an optical system different from the system Z, and the photographing optical system based on the distance to the subject measured by the outside light type distance measuring means 4 The focus position of the photographing optical system Z is obtained by obtaining the in-focus position of Z and the focal point of the photographing optical system Z is moved to the in-focus position, and the feeding range of the photographing optical system Z is changed according to the switching operation from the outside. Macromo for close-up A macro configuration unit 6 for switching between de and non-macro mode, with the non-macro mode is set by the macro setting means 6, focus control due to external light type focus control unit 5After that, the focus control by the contrast focus control means 3 is supplementarily performed.In a state where the macro mode is set, control means 7 for executing focus control by the contrast focus control means 3,The contrast focus control means 3 includes a correction value storage means for storing a correction value of the focus movement according to the focus movement amount when the supplemental focus control is performed. The in-focus position is corrected based on correction values stored in the past in the correction value storage means.
[0014]
According to a second aspect of the present invention, in the electronic camera according to the first aspect, the extension range of the photographing optical system Z has an overlapping range in the macro mode and the non-macro mode.
According to a third aspect of the present invention, in the electronic camera according to the second aspect, the feeding range in the macro mode is a feeding range focusing on a subject distance of 50 cm or less, and the feeding range in the non-macro mode is a subject distance of 30 cm. The feeding range is in focus as described above.
[0017]
(Function)
In the electronic camera according to the first aspect, the macro setting means 6 accepts an external switching operation and switches between the macro mode for close-up photography and the non-macro mode.
In the non-macro mode state, the control means 7 drives the outside light focus control means 5 to perform focus control based on outside light distance measurement. On the other hand, in the macro mode, the contrast focus control means 3 is driven to perform contrast AF type focus control.
[0018]
By such an action, in the non-macro mode, it is possible to quickly move the focal point to the in-focus position based on the outside light type distance measurement, and the in-focus time of the electronic camera is remarkably shortened.
On the other hand, in the macro mode, since contrast AF type focus control is performed, no parallax occurs between the distance measurement area and the subject, and problems such as blurring due to the parallax are eliminated.
[0019]
  Furthermore, since the range in which the contrast AF focus control is performed is narrowly limited from the conventional whole area to the macro area, the average focusing time required for the contrast AF focus control is also shortened.
Further, in the electronic camera according to claim 1, the control unit 7 supplementarily executes the focus control by the contrast focus control unit 3 subsequent to the focus control by the external light type focus control unit 5.
Further, in the electronic camera according to the first aspect, when the supplemental focus control is performed by the contrast focus control means 3, the correction value storage means stores a correction value corresponding to the focus movement amount at this time.
The external light focus control means 5 corrects the in-focus position calculated from the distance measurement value using the correction value stored in the past in this way.
  In the electronic camera according to the second and third aspects, the extension range of the photographing optical system Z overlaps in the macro mode and the non-macro mode.
[0020]
  Therefore, for the subject that is in focus within this overlapping range, the "contrast AF focus control" and the "external light focus detection focus control" can be freely set by switching whether the photographer is in the macro mode or not. It becomes possible to selectThe
[0022]
DETAILED DESCRIPTION OF THE INVENTION
  Embodiments of the present invention will be described below with reference to the drawings.
  Figure 2, RealIt is a figure which shows embodiment.
  In FIG. 2, a photographing lens 12 is attached to the front surface of the electronic camera 11, and an image sensor 13 is disposed on the image space side of the photographing lens 12.
[0023]
The image pickup device 13 is connected to a control CPU 15 via a CCD drive circuit 14 and the timing of an electronic shutter or the like is controlled.
On the other hand, the image output of the image sensor 13 is input to a signal processing unit 16 that performs γ correction, color signal processing, and A / D conversion, and the digital output of the signal processing unit 16 is a JPEG processing unit that performs a known image compression process. 17 is input. These signal processing unit 16 and JPEG processing unit 17 exchange image signals with the control CPU 15.
[0024]
The PWM (pulse width modulation) output of the control CPU 15 is supplied to a motor 19 that can rotate in both forward and reverse directions via a lens drive circuit 18. The rotational force of the motor 19 is transmitted to a lens driving mechanism 20 that drives a focal lens (a moving optical system for focus adjustment provided in the photographing lens 12) back and forth.
[0025]
Further, an encoder 21 is disposed on the rotating shaft of the motor 19, and an output terminal of the encoder 21 is connected to the control CPU 15.
On the other hand, a passive distance measuring unit 22 and an AF auxiliary light irradiating unit 23 are disposed on the front surface of the electronic camera 11, and these are connected to the control CPU 15, respectively.
Further, the following switch groups 25 to 30 are arranged in the casing of the electronic camera 11.
[0026]
First, the close-up switch (CUS) 25 is a switch in which a macro mode for close-up photography is set by an on operation and a non-macro mode for normal photographing is set by an off operation.
The half-press switch (S1) 26 is a switch that is turned on when the release is half-pressed.
[0027]
The full press switch (S2) 27 is a switch that is turned on when the release is fully pressed.
A power switch (MSW) 28 is a main power switch of the electronic camera 11.
The focus lock selection switch (AFC) 29 is a switch for selecting whether focus lock is performed at the time of focusing (single AF mode) or whether focus control is continued intermittently until shooting (continuous AF mode). .
[0028]
A focus mode selection switch (AFM) 30 is a switch for selecting whether focus control is always performed (always AF mode) or focus control is performed only when the release is half-pressed (half-press AF mode).
In addition, the electronic camera 11 includes a memory card 31 for recording image signals and the like, an aperture driving unit 32 for opening and closing the lens aperture, a flash unit 33 for supplying a driving voltage to the speedlight 34, and the like. Each is connected to the control CPU 15.
[0029]
As for the correspondence relationship between the present embodiment and the inventions described in claims 1 to 3, the image pickup means 1 corresponds to the image pickup element 13, and the contrast detection means 2 corresponds to “from the image signal of the signal processing section 16 of the control CPU 15. Corresponding to the “function for detecting the contrast amount”, the contrast focus control means 3 corresponds to the “function for performing focus control according to the contrast amount” of the lens driving circuit 18, the motor 19, the lens driving mechanism 20 and the control CPU 15. The outside light type distance measuring means 4 corresponds to the “function for calculating the subject distance based on the phase difference between the pair of light images” of the passive distance measuring unit 22 and the control CPU 15, and the outside light type focus control means 5 is driven by the lens. Corresponding to the “function for performing focus control according to the subject distance” of the circuit 18, the motor 19, the lens driving mechanism 20, the encoder 21 and the control CPU 15, macro setting means Corresponds to the close-up switch 25, the control means 7 controls CPU15 of corresponding to "in accordance with the switching state of the close-up switch 25, function to switch the focus control method."
[0030]
3 to 6 are flowcharts for explaining the operation of this embodiment.
FIG. 7 is a diagram illustrating an example of a focusing range in the present embodiment.
Hereinafter, the operation of the electronic camera 11 in the constant AF mode will be described with reference to the flowchart shown in FIG.
(Operation in normal AF mode)
First, main power is supplied to the electronic camera 11 via the power switch 28. When the half-push switch 26 is pressed in this state (S1 in FIG. 3), the control CPU 15 determines the mode selection in the focus mode selection switch 30 (S2 in FIG. 3).
[0031]
Here, when the half-press AF mode is selected, the control CPU 15 shifts the operation to step S20 shown in FIG.
On the other hand, if the constant AF mode is selected in step S2, the control CPU 15 continues to determine mode selection in the close-up switch 25 (S4 in FIG. 3).
[0032]
Here, when the non-macro mode (the mode for photographing a subject separated by 30 cm or more) is selected, the control CPU 15 shifts the operation to step S10 after completing the passive AF described later (S5 in FIG. 3).
On the other hand, when the macro mode (photographing mode for a close subject with a subject distance of 20 cm to 50 cm) is selected in step S4, the control CPU 15 sets the inside of the taking lens 12 at the in-focus position corresponding to the subject distance of 50 cm. The focal lens is moved for the time being (S6 in FIG. 3).
[0033]
After such lens movement, the control CPU 15 determines the mode selection in the focus lock selection switch 29 (S7 in FIG. 3). If the continuous AF mode is selected, the control CPU 15 confirms that the full-press switch 27 is not pressed (NO side in FIG. 3 S8), and then shifts the operation to step S9. If the full-press switch 27 is pressed at this time (YES side in S8 in FIG. 3), the operation shifts to step S16 in order to give priority to the shutter operation, and the photographing process is immediately executed.
[0034]
On the other hand, if the single AF mode is selected in step S7, the control CPU 15 executes a contrast AF operation described later (S9 in FIG. 3).
Thus, after executing the focus control in step S5 or S9, the control CPU 15 starts the second timer to measure the elapsed time after the focus control (S10 in FIG. 3). The second timer is a timer in which the time measurement result is sequentially updated by the timer interrupt routine of the control CPU 15.
[0035]
Here, when the half-press switch 26 has already been released (NO side in FIG. 3 S11), the control CPU 15 shifts the operation to step S15.
On the other hand, when the half-press switch 26 is continuously pressed (YES side in FIG. 3 S11), the control CPU 15 displays the focus state and the like in the viewfinder (S12 in FIG. 3).
After performing such a finder display, the control CPU 15 determines the switch state of the full push switch 27 (S13 in FIG. 3).
[0036]
Here, when the full push switch 27 has not been pushed yet (NO side in FIG. 13 S13), the control CPU 15 determines again the mode selection by the focus lock selection switch 29 (S14 in FIG. 3). If the single AF mode is selected at this time, the control CPU 15 returns the operation to step S11 regardless of the timing result of the second timer, and repeats the loop of steps S11 to 14 until the full-pressing operation is performed. .
[0037]
If the continuous AF mode is selected in step S14, the control CPU 15 determines whether or not the time measurement result of the second timer has reached the focus control repetition period (S15 in FIG. 3). If the repetition period has not been reached (NO side in S15 in FIG. 3), the control CPU 15 returns the operation to step S11. As a result, the operations in steps S11 to S15 are repeated until the full pressing operation is performed or the repetition cycle is reached. During the repetition period, when the time measurement result of the second timer reaches the repetition period of the focus control (YES side of S15 in FIG. 3), the control CPU 15 shifts the operation to step S18 and then returns to step S2. Execute focus control again.
[0038]
On the other hand, when the full push switch 27 is pressed in step S13, the control CPU 15 performs an operation such as reducing the aperture value to an appropriate exposure via the aperture drive unit 32 and then via the CCD drive circuit 14. The imaging process is executed by driving the image sensor 13 (S16 in FIG. 3). When an APT flag (aperture flag), which will be described later, is set, this is a case where focus control is not performed accurately, so that the photographing process is performed with the depth of field as deep as possible by closing the aperture as much as possible. .
[0039]
The image signal thus captured is subjected to a known image compression process through the signal processing unit 16 and the JPEG processing unit 17 and is recorded in the memory card 31 through the control CPU 15.
[0040]
When these series of photographing processes are completed, the control CPU 15 returns the aperture to the open state and moves the focal lens in the photographing lens 12 to a standby position such as an infinite end in preparation for the next photographing (S17 in FIG. 3). Next, the APT flag (a flag set when focus control is inaccurate) is reset (S18 in FIG. 3).
After completing such post-shooting processing, the control CPU 15 returns the operation to step S2.
[0041]
With the operations described above, focus control and shooting operations are always performed in the AF mode.
Next, the operation of the electronic camera 11 in the half-press AF mode will be described with reference to the flowchart shown in FIG.
(Operation in half-press AF mode)
First, in step S20, if the half-press switch 26 has already been released (NO side in FIG. 4 S20), the control CPU 15 once ends the operation and waits for the half-press switch 26 to be pressed again.
[0042]
On the other hand, if the half-press switch 26 continues to be pressed in step S20 (YES side in FIG. 4S20), the control CPU 15 determines the mode selection in the close-up switch 25 (S21 in FIG. 4).
Here, when the non-macro mode is selected, the control CPU 15 shifts the operation to step S26 after completing the passive AF described later (S22 in FIG. 4).
[0043]
On the other hand, when the macro mode is selected in step S21, the control CPU 15 moves the focal lens in the photographing lens 12 for the time being to the in-focus position corresponding to the subject distance 50 cm (S23 in FIG. 4).
After such movement of the lens, the control CPU 15 confirms that the half-press switch 26 is continuously pressed (YES side in S24 in FIG. 4), and then executes a contrast AF operation described later (S25 in FIG. 4). ). At this point, if the half-press switch 26 has already been released (NO side in FIG. 4 S24), the control CPU 15 ends the operation once and waits for the half-press switch 26 to be pressed again.
[0044]
Thus, after executing the focus control in step S22 or S25, the control CPU 15 starts the second timer to measure the elapsed time after the focus control (S26 in FIG. 4).
Next, at this time, if the half-push switch 26 has already been released (NO side in FIG. 4 S27), the control CPU 15 shifts the operation to step S35.
[0045]
On the other hand, if the half-press switch 26 is continuously pressed in step S27, the focus state is displayed in the viewfinder (S28 in FIG. 4).
After performing such a finder display, the control CPU 15 determines the switch state of the full push switch 27 (S29 in FIG. 4).
Here, when the full push switch 27 has not been pushed yet (NO side in FIG. 4 S29), the control CPU 15 determines the mode selection in the focus lock selection switch 29 (S30 in FIG. 4). If the single AF mode is selected at this time, the control CPU 15 returns the operation to step S27 regardless of the timing result of the second timer, and repeats the loop of steps S27 to 30 until the full-pressing operation is performed. .
[0046]
If the continuous AF mode is selected in step S30, the control CPU 15 determines whether or not the time measurement result of the second timer has reached the repetition period of the focus control (S31 in FIG. 4). Control CPU15 returns operation | movement to step S11, when the time-measurement result has not yet reached the repetition period (NO side of FIG. 4 S31). As a result, the operations in steps S27 to S31 are repeated until the full pressing operation is performed or the repetition cycle is reached. During the repetition period, when the time measurement result of the second timer reaches the repetition period of the focus control (YES side of S31 in FIG. 4), the control CPU 15 confirms that the half-push switch 26 is continuously pressed. After confirming (YES side of S32 in FIG. 4), the process returns to step S2 again to repeat the focus control. When the half-push switch 26 is released (NO side in FIG. 4 S32), the control CPU 15 shifts the operation to step S35.
[0047]
On the other hand, if the full press switch 27 is pressed in step S29, the control CPU 15 performs an operation such as appropriately reducing the aperture value via the aperture drive unit 32 and then imaging via the CCD drive circuit 14. The element 13 is driven to execute a photographing process (S33 in FIG. 4).
The image signal thus captured is subjected to a known image compression process through the signal processing unit 16 and the JPEG processing unit 17 and is recorded in the memory card 31 through the control CPU 15.
[0048]
When these series of imaging processes are completed, the control CPU 15 returns the aperture to the open state in preparation for the next imaging (S34 in FIG. 4), and moves the focal lens in the imaging lens 12 to a standby position such as an infinite end (FIG. 4). 4S35). Next, after resetting the APT flag (S36 in FIG. 4), the operation is terminated.
With the operations described above, focus control and shooting operations in the half-press AF mode are executed.
[0049]
Next, the operation of the above-described passive AF will be described in detail with reference to the flowchart shown in FIG.
(Passive AF operation)
First, the control CPU 15 drives the passive distance measuring unit 22 to capture a pair of optical image patterns (S41 in FIG. 5).
[0050]
The control CPU 15 detects the phase difference between the patterns for the pair of optical images thus captured. The control CPU 15 calculates the subject distance R from this phase difference using the principle of triangulation (S42 in FIG. 5).
If the distance can be detected (YES side in S43 in FIG. 5), the control CPU 15 determines whether or not the subject distance R is 30 cm or less. If it is 30 cm or less, the value of the subject distance R is uniformly replaced with “the shortest shooting distance 30 cm in the non-macro mode” (S44 in FIG. 5).
[0051]
Next, the control CPU 15 stores the value of the subject distance R in the internal data area D (S45 in FIG. 5).
Based on the subject distance R stored in the data area D in this way, the control CPU 15 moves the focal lens to the corresponding in-focus position (S46 in FIG. 5).
On the other hand, if it is not possible to detect the distance in step S43 due to insufficient contrast of the subject (NO side in FIG. 5), the control CPU 15 determines the mode selection in the focus lock selection switch 29 (FIG. 5). 5S47).
[0052]
Here, in the case of the continuous AF mode, the control CPU 15 omits the following pin pin operation and goes directly to step S50 in order to increase the number of repetitions of distance measurement and improve the focus followability with respect to the subject.
On the other hand, in the single AF mode, the control CPU 15 performs passive distance measurement (so-called “pica pin operation”) with the AF auxiliary light irradiated from the AF auxiliary light irradiation unit 23 (S48 in FIG. 5).
[0053]
When distance detection is performed by such a pica pin operation (YES side in FIG. 5 S49), the control CPU 15 shifts the operation to step S44.
In addition, when the distance cannot be detected even though the pica pin operation is performed (NO side in FIG. 5S), the control CPU 15 gives up the standard detection assumed from the focal length f of the photographing lens 12 without giving up distance detection. The subject distance A is calculated based on the following formula.
[0054]
Standard subject distance A = 40 · α · f (1)
In equation (1), α is a ratio between the screen size of the image sensor 13 and the screen size of the 135 type silver salt camera, and f is the focal length of the photographing lens 12.
The control CPU 15 stores the subject distance A thus calculated in the data area D instead of the actual measurement value (S50 in FIG. 5). Further, the control CPU 15 sets the APT flag (S51 in FIG. 5).
[0055]
Next, the control CPU 15 moves the focal lens to the in-focus position based on the subject distance A in step S46.
Passive AF is completed by the operation as described above.
Next, the above-described contrast AF operation will be described in detail with reference to the flowchart shown in FIG.
[0056]
(Contrast AF operation)
First, the control CPU 15 starts the first timer in order to count the time until the contrast AF is terminated (S61 in FIG. 6).
Subsequently, the control CPU 15 finely moves the focal lens back and forth via the motor 19 (S62 in FIG. 6).
[0057]
In this state, the control CPU 15 drives the image sensor 13 via the CCD drive circuit 14 and acquires an image signal. The control CPU 15 uses a digital filter (calculation) such as a transversal filter to extract a high frequency component of the spatial frequency from this image signal. The peak value of this high frequency component is detected as the contrast amount (S63 in FIG. 6).
[0058]
The control CPU 15 moves the focal lens one step toward the direction in which the contrast amount increases (S64 in FIG. 6).
Here, when it is detected from the monitoring result of the encoder 21 that the focal lens has reached the drive end (YES side in FIG. 6 S65), the control CPU 15 shifts the operation to step S73.
[0059]
On the other hand, when the focal lens has not reached the driving end (NO side in FIG. 6 S65), the control CPU 15 determines whether or not the contrast amount has reached the maximum point from the values of the previous and next contrast amounts (S66 in FIG. 6). .
[0060]
Here, when the contrast amount reaches the maximum point (YES side in S66 in FIG. 6), the control CPU 15 determines that the focal lens has reached the in-focus position, stops lens driving (S67 in FIG. 6), and performs contrast AF. To complete.
On the other hand, when the contrast amount is changing monotonously (NO side in FIG. 6 S66), the control CPU 15 determines the mode selection in the focus lock selection switch 29 (S68 in FIG. 6).
[0061]
Here, when the continuous AF mode is selected, the control CPU 15 determines whether or not the full press switch 27 is pressed in order to give priority to the shutter operation (S69 in FIG. 6). At this time, when the full push switch 27 is pressed (YES side in S69 in FIG. 6), the shooting process in each mode is executed in accordance with the mode selection in the focus mode selection switch 30 (S70 in FIG. 6). If the full push switch 27 has not been pressed yet (NO side in FIG. 6 S69), the control CPU 15 shifts the operation to step S71 in order to continue the contrast AF.
[0062]
On the other hand, if the single AF mode is selected in step S68, the control CPU 15 determines whether or not the time measurement result of the first timer has exceeded the contrast AF cutoff time (S71 in FIG. 6).
Here, when the time measurement result of the first timer has not reached the cutoff time (NO side in FIG. 6 S71), the control CPU 15 returns the operation to step S62 and continues the operation of the contrast AF.
[0063]
On the other hand, when the time measurement result of the first timer exceeds the cutoff time (YES side in FIG. 6 S71), the control CPU 15 gives up the focus adjustment by contrast AF and moves the focal lens to the in-focus position corresponding to the subject distance of 30 cm. (S72 in FIG. 6).
After the movement of the focal lens is completed, the control CPU 15 stops lens driving (S73 in FIG. 6). Subsequently, after setting the APT flag (S74 in FIG. 6), the control CPU 15 stops the contrast AF operation.
[0064]
With the above operation, contrast AF is completed.
(Effects of this embodiment)
According to the above-described operation, in this embodiment, it is determined whether or not the macro mode is set in step S4 or S21, and the focus control method is switched according to the determination result.
[0065]
As a result, in the non-macro mode, the focal point is moved in a straight line to the in-focus position based on the passive distance measurement, and the in-focus time can be shortened compared to the conventional case.
On the other hand, in the macro mode, since contrast AF type focus control is performed, there is no parallax between the distance measurement area and the subject, and the blurring caused by parallax during macro photography can be eliminated accurately. Can do.
[0066]
Further, since the range in which the contrast AF focus control is performed is narrowly limited from the conventional whole area to the macro area, the average focusing time required for the contrast AF focus control can be shortened.
Further, in the macro mode and the non-macro mode, as shown in FIG. 7, the range of the subject distance of 30 to 50 cm is set to overlap.
[0067]
Therefore, for subjects that are in focus within this overlapping range, the photographer can freely switch between macro mode settings to freely select “contrast AF focus control” and “passive focus detection focus control”. It becomes possible to do.
In the above-described embodiment, an example of passive distance measurement has been described, but the present invention is not limited to this. Generally, any object distance may be used as long as the subject distance is measured via an optical system other than the photographing optical system. For example, a known active distance measurement may be employed instead of the passive distance measurement described above.
[0068]
In the above-described embodiment, FIG. 7 is given as an example of the focusing range, but is not limited to the numerical values shown in FIG. Generally, the extension range of the macro mode is determined in accordance with the optical design specifications of the electronic camera. For example, the extension range in the macro mode may be set to a range that focuses on a subject distance of 1 to 30 cm, and the extension range in a non-macro mode may be set to a range that focuses on a subject distance of 20 to ∞ cm.
[0069]
  Next, another embodiment will be described.
(Another embodiment)
  FIG. 8 is a flowchart showing the passive AF operation in another embodiment.The
  The configuration of the present embodiment is the same as the configuration shown in FIG. 2 except for the operation routine stored in the control CPU 15, and the description thereof is omitted here.
[0070]
The operation of this embodiment is the same as that shown in FIGS. 3, 4, and 6 except for the passive AF routine.
Hereinafter, the operational characteristic points of this embodiment will be described with reference to FIG.
First, in the non-macro mode, the subject distance is measured (S81 to S91 in FIG. 8).
[0071]
The control CPU 15 calculates a focus position corresponding to the subject distance, and obtains a lens position Xo indicated by the focus position (S92 in FIG. 8).
If a correction value has been recorded in the past, the control CPU 15 performs calibration correction of the in-focus position here.
Next, the control CPU 15 moves the focal lens to the in-focus position via the motor 19 (S93 in FIG. 8).
[0072]
With the above operation, the focus control operation by passive AF is once completed.
Immediately thereafter, the control CPU 15 finely moves the focal lens back and forth via the motor 19. In this state, the control CPU 15 acquires an image signal from the image sensor 13 and detects the contrast amount of the image signal. The control CPU 15 determines whether or not the contrast amount is at the maximum point (S94 in FIG. 8).
[0073]
As a result of this determination, if the contrast amount is at the maximum point (YES side in S94 in FIG. 8), the control CPU 15 determines that the correct in-focus position has been reached and completes all focus control operations.
On the other hand, when the contrast amount is not at the maximum point (NO side in S94 in FIG. 8), the focal lens is moved in the contrast AF manner to the lens position Xm at which the contrast amount becomes maximum (S95 in FIG. 8).
[0074]
Next, the control CPU 15 records the lens position difference (Xm−Xo) as a correction value in a nonvolatile memory area or the like in the control CPU (S96 in FIG. 8), and completes all the focus control operations. This correction value is used for calibration correction of the in-focus position in FIG.
As described above, in the electronic camera of the present embodiment, fine adjustment by contrast AF is performed subsequent to passive AF. Therefore, high focusing accuracy can be obtained regardless of the correspondence difference between the distance measurement result and the focusing position.
[0075]
Further, since fine adjustment by contrast AF is always started from the vicinity of the focus position, the time required for fine adjustment is extremely short.
In the above-described embodiment, the fine adjustment amount for focus control is recorded as a correction value and used for calibration correction of the in-focus position. Accordingly, since the fine adjustment is started from the more accurate in-focus position from the next time onward, the time required for fine adjustment of the focus control can be further reduced.
[0076]
Note that “fine adjustment by contrast AF” and “initial recording of lens position difference” as described above may be performed at the time of shipment from the factory. In such a case, it is only necessary to perform calibration correction during actual use, and the effect of shortening the focusing time is not lost at all.
Further, “fine adjustment by contrast AF” and “update of lens position difference” may be repeated every time or periodically. In such a case, since the correction value is periodically updated every time, the deterioration of the focusing accuracy in the external light focus control can be prevented over a long period of time.
[0077]
Furthermore, in the above-described embodiment, an example of passive distance measurement has been described, but the present invention is not limited to this. Generally, any object distance may be used as long as the subject distance is measured via an optical system other than the photographing optical system. For example, a known active distance measurement may be employed instead of the passive distance measurement described above.
[0078]
【The invention's effect】
As described above, in the first aspect of the present invention, focus control based on external light ranging is performed in the non-macro mode. In the macro mode, contrast AF type focus control is performed.
[0079]
Therefore, in the non-macro mode, it is possible to execute the focus control at high speed up to the in-focus position based on the outside light type distance measurement, and the in-focus time can be significantly shortened. On the other hand, in the macro mode, since contrast AF type focus control is performed, there is no parallax between the distance measurement area and the subject, and the blurring caused by parallax during macro photography can be eliminated accurately. Can do.
[0080]
Further, since the range in which the contrast AF focus control is performed is narrowly limited from the conventional whole area to the macro area, the average focusing time in the contrast AF focus control can be significantly shortened.
In the second and third aspects of the present invention, the feeding ranges of the photographing optical system Z are set to overlap in the macro mode and the non-macro mode.
[0081]
Therefore, for subjects that are in focus within this overlapping range, the photographer deliberately switches whether the macro mode is set, so that “contrast AF focus control” and “external light focus detection” are controlled. "Can be freely selected.
[0082]
  Claim 1In the above-described invention, the focus control by the contrast focus control means is supplementarily executed following the focus control by the external light focus control means.
  Usually, in order to increase the focusing accuracy in the external light type focus control, the distance measuring system and the lens driving system must strictly correspond to each other. However, if the distance measurement value of the subject distance varies due to a temperature change or the installation interval between the lens and the imaging surface is deviated, the one-to-one correspondence is deviated.
[0083]
  However,Claim 1In the electronic camera, after the high-speed movement to the in-focus position by the external light focus control means, fine adjustment is performed by the contrast focus control means. Therefore, even if the one-to-one correspondence between the distance measuring system and the lens driving system is shifted, high focusing accuracy can be obtained. Further, since the fine adjustment by the contrast focus control means starts from the vicinity of the focus position, the effect of shortening the focus time is not greatly impaired.
[0084]
  Further claim 1In the invention described in (1), the correction value is stored in correspondence with the supplemental focus movement amount by the contrast focus control means 3, and is used for the correction of the in-focus position from the next time.
  This eliminates the need for fine adjustment by the contrast focus control means from the beginning each time. Therefore, it is possible to obtain high focusing accuracy while further reducing the time required for fine adjustment.
  With the above effects, the electronic camera employing the present invention can appropriately and rationally solve the problems related to focus control such as focusing time and parallax.
[Brief description of the drawings]
FIG. 1 is a principle block diagram corresponding to the first to third aspects of the present invention.
[Figure 2]FruitIt is a figure which shows embodiment.
FIG. 3 is a flowchart (1/4) for explaining the operation of the embodiment;
FIG. 4 is a flowchart (2/4) illustrating the operation of the embodiment.
FIG. 5 is a flowchart (3/4) illustrating the operation of the embodiment.
FIG. 6 is a flowchart (4/4) illustrating the operation of this embodiment.
FIG. 7 is a diagram illustrating an example of a focusing range.
FIG. 8 is a flowchart showing a passive AF operation in another embodiment.

Claims (3)

An imaging unit that captures a light image formed through the imaging optical system and generates an image signal;
Contrast detection means for capturing an image signal generated by the imaging means and detecting a contrast amount of the image signal;
Contrast focus control means for moving the focus of the photographing optical system to a position where the contrast amount detected by the contrast detection means takes a maximum value;
An outside light type distance measuring means for measuring a distance to a subject through an optical system different from the photographing optical system;
Based on the distance to the subject measured by the outside light type distance measuring means, the focus position of the photographing optical system is obtained based on the distance to the subject, and the focus position of the photographing optical system is moved to the focus position. When,
Macro setting means for changing between the macro mode for close-up photography and the non-macro mode by changing the feeding range of the photographing optical system according to the switching operation from the outside,
In a state where the non-macro mode is set by the macro setting means , after the focus control by the external light focus control means, the focus control by the contrast focus control means is supplementarily executed, and the macro mode is set. Then, the control means for executing the focus control by the contrast focus control means,
Correction value storage means for storing a correction value of focus movement according to the amount of focus movement when supplemental focus control is performed in the contrast focus control means,
The external light focus control means includes
An electronic camera , wherein the focus position is corrected based on the correction value stored in the correction value storage means in the past . The electronic camera according to claim 1,
The electronic camera according to claim 1, wherein a feeding range of the photographing optical system has an overlapping range in a macro mode and a non-macro mode. The electronic camera according to claim 2,
An electronic camera characterized in that the feeding range in the macro mode is a feeding range that focuses on a subject distance of 50 cm or less, and the feeding range in the non-macro mode is a feeding range that focuses on a subject distance of 30 cm or more.

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