JP2004085843A - Camera - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a camera which is capable of accurately quickly deciding that a subject is a body in motion. <P>SOLUTION: The camera has a defocusing extent detection means which detects an extent of defocusing of a photographic lens, an image surface position calculation means which calculates an image surface position on the basis of the detected extent of defocusing and lens position information of the photographic lens corresponding to the extent of defocusing, and a body in motion decision means which decides the subject to be a body in motion in the case that a plurality of image surface positions calculated on the basis of extents of defocusing smaller than a prescribed extent, which are detected a plurality of times, and lens position information corresponding to these extents of defocusing are monotonously changed. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an optical device such as a camera, and more particularly to an improvement in an automatic focusing device.
[0002]
[Prior art]
Conventionally, in an automatic focusing device of a camera, a light flux from a subject that has passed through different exit pupil regions of a photographing lens is combined on a pair of line sensors, and a pair of image signals obtained by photoelectrically converting the subject image are obtained. The defocus amount, which is the amount of defocus of the subject (the difference between the image forming position of the photographing lens and the image plane position of the photographing lens at which the photographing operation is to be performed), is obtained by calculating the image shift amount, which is the relative position displacement amount, by correlation calculation. There is widely known an automatic focus adjustment method for detecting the image and driving the photographing lens based on the detected image.
Many of them have a one-shot mode suitable for photographing a stationary subject and a servo mode suitable for photographing a moving subject.
[0003]
In the one-shot mode, as shown in FIG. 6, when the time is taken on the horizontal axis and the defocus amount is taken on the vertical axis, the detection of the defocus amount is performed not only during the stop of the lens driving but also during the driving of the lens. To update the lens drive amount.
[0004]
This is because, first of all, the larger the defocus amount, the more blurred the obtained subject image itself, so that sufficient detection accuracy cannot be obtained. Second, the larger the defocus amount is, the larger the image shift amount is. Therefore, the obtained subject image appears toward the end on the line sensor and further protrudes from the line sensor. Third, in order to actually drive the photographing lens, the amount of defocus must be converted into the amount of lens drive. However, as is well known, these two amounts have a non-linear relationship, so There is also a reason that it is difficult to obtain an accurate lens drive amount as the value is larger.
[0005]
In order to solve these problems, by performing overlap control, the photographing lens is accurately driven to the in-focus position, and focusing is performed when the defocus amount becomes equal to or less than a predetermined amount.
[0006]
Incidentally, the detection of the defocus amount requires a time corresponding to the brightness and contrast of the subject to accumulate charges in the line sensor. Therefore, when the overlap control is performed as shown in FIG. 9, the lens driving amount is updated from the center of the charge accumulation instead of updating the lens driving amount based on the simply obtained defocus amount. I must consider the amount of free running up to. In order to determine the amount of free running, it is necessary to obtain the lens position at the time that is the center of charge accumulation.
[0007]
However, since the time required for charge accumulation depends on the subject, as shown in FIG. 9, only when the photographing lens is driven at a constant speed or a state that can be regarded as a constant speed, the charge accumulation start and end times are limited. In general, the average of the lens positions is used as the lens position at the center of charge accumulation. As shown in FIG. 6, when the horizontal axis represents time and the vertical axis represents the lens position, as shown in FIG. 7, the image is obtained by adding the horizontal axis to time and the vertical axis to the defocus amount and the lens position. FIG. 8 shows the surface position. As shown in this figure, the image plane position obtained when the subject is stationary is almost a straight line. The reason why a perfect straight line is not obtained is that it is difficult to obtain a detection error of the defocus amount and, as described above, to obtain a sufficient detection accuracy and an accurate lens drive amount as the defocus amount is large.
[0008]
In the servo mode, as shown in FIG. 10, the detection of the defocus amount and the driving of the lens are continuously performed alternately. Similarly to the one-shot mode, FIG. 11 shows the time on the horizontal axis and the lens position on the vertical axis, and FIG. 12 shows the image plane position on the horizontal axis with time on the vertical axis. As shown in this figure, the image plane position obtained when the subject is moving increases almost monotonously. Here, the complete non-monotonic increase may occur not only for the same reason as in the one-shot mode, but also when the subject itself does not necessarily move monotonously.
[0009]
In the servo mode, furthermore, a plurality of changes in the image plane position in the past are regarded as a predetermined function depending on time, and a moving object predictive drive of the photographing lens is performed by obtaining the function. This is because the mirror-movable single-lens reflex camera cannot detect the defocus amount unless the mirror is down due to its configuration. On the other hand, exposure cannot be performed unless the mirror is raised.
[0010]
That is, there is a release time lag of a certain amount or more from the last focus detection to the start of exposure. In the moving object prediction drive, by completing lens driving by adding the moving object prediction correction amount to the defocus amount at the time of the last focus detection before exposure, the release time lag from the last focus detection to the start of exposure is reduced. Focusing can be performed in anticipation of the movement of the subject.
[0011]
Taking FIG. 12 as an example, focus detection after the in-focus state is performed three times. A quadratic curve passing through these three points may be used as a prediction function, or only the latest two points may be obtained and predicted by a linear line. An expression may be obtained.
[0012]
Various proposals have already been made as to what kind of prediction formula is optimal from a plurality of changes in the image plane position in the past. The present applicant has also disclosed in Japanese Patent Application Laid-Open No. 2001-021794 and is actually widely practiced.
[0013]
[Problems to be solved by the invention]
As a method of selecting the one-shot mode and the servo mode, it is general to provide a mode called a manual switch by a switch of a camera or a mode called an auto mode, which automatically switches between the two modes according to the situation of a subject. If it is not known whether the subject to be photographed is moving or stationary, or if it is a beginner unfamiliar with the photographing operation, the auto mode is preferable.
[0014]
What is important in the auto mode is how to accurately and quickly switch between the one-shot mode and the servo mode.
[0015]
As a first conventional example having a configuration focusing on this point, as shown in FIG. 13, focusing is first performed in a one-shot mode, and then detection of a defocus amount is performed a plurality of times while a photographing lens is fixed. When the defocus amount changes continuously, there is a method in which a “moving object determination mode” in which a subject is regarded as a moving object and the mode is shifted to the servo mode is set between the one-shot mode and the servo mode.
[0016]
According to this method, the moving object determination is started when the photographing lens is stopped and in the focused state, so that the moving object determination can be reliably performed. However, in the case of a rapidly approaching subject such as a train, or a subject such as a child approaching slowly but in the vicinity of the closest end of the taking lens, the defocus amount that changes per unit time is large, In the one-shot mode, since the in-focus state is not reached forever, there is a problem that the release cannot be performed even after a long time. Even if the subject is in focus, the moving object determination is performed while the lens is stopped. It does not follow the subject until driving is completed. Furthermore, even if the camera starts following the subject, as described above, it is necessary to detect the defocus amount a plurality of times in the past until the moving object prediction drive is performed. The state that becomes becomes continued.
[0017]
As a second conventional example in which the above-described problem of the first method is improved, when the focusing is not achieved even if the photographing lens is driven a predetermined number of times during the one-shot mode, the subject is regarded as a moving object. There is a method to shift to the deemed servo mode. In this method, when the subject is stationary, it is necessary to guarantee that the lens will be focused within a predetermined number of times. However, when performing the overlap control, since the driving amount is updated even during driving of the photographing lens, it is difficult to guarantee focusing within a predetermined number of times, and it is necessary to estimate a considerably large number of times. Alternatively, it is necessary not to count the lens drive during the overlap control. In addition, regardless of the presence or absence of the overlap control, hunting occurs in which the photographing lens moves back and forth near the in-focus position, depending on the detection error of the defocus amount and the stopping accuracy of the lens. There is a possibility that it is erroneously determined as a moving object.
[0018]
In any case, it takes a considerable amount of time to determine a moving object without making an error. Also, since the one-shot mode is repeated only while the judgment is being made, even if the shutter is released, the photograph will have a sweet focus.
[0019]
The present invention has been made in view of such a problem, and has as its object to provide a camera that can accurately and quickly determine a moving object of a subject.
[0020]
[Means for Solving the Problems]
In order to achieve the above object, according to the present invention, a defocus amount detecting means for detecting a defocus amount of a photographing lens, and a defocus amount detected based on the detected defocus amount and lens position information of the photographing lens corresponding to the defocus amount. An image plane position calculating means for calculating an image plane position by using a plurality of image plane positions calculated based on a defocus amount equal to or less than a predetermined amount detected a plurality of times and lens position information corresponding to these defocus amounts. When it is changing, a moving object determining means for determining that the subject is a moving object is provided.
[0021]
As described above, since it is determined whether or not the subject is a moving object within the range of the defocus amount at which sufficient detection accuracy can be obtained and by a change in the image plane position, accurate moving object determination can be performed. Also, in comparison with the conventional method of determining a moving object when focusing is not achieved even after driving the taking lens a predetermined number of times or more, the detection of the defocus amount a plurality of times and the lens position corresponding to this defocus amount Since it is only necessary to acquire information, it is possible to perform a moving object determination more quickly than in the past.
[0022]
Here, the above-mentioned moving object determining means monotonically changes at least three image plane positions calculated based on the defocus amount equal to or less than the predetermined amount detected at least three times and the lens position information corresponding to these defocus amounts. In such a case, the configuration is preferably such that the subject is determined to be a moving object.
[0023]
The detection of each defocus amount for calculating a plurality of image plane positions and the acquisition of lens position information corresponding to these defocus amounts may be performed at intervals of a predetermined time or more.
[0024]
Further, the moving body determination means described above may be configured to use the lens position information for calculating the respective image plane positions and the detection time of the defocus amount for determining whether the photographing subject is a moving body. .
[0025]
The above-described moving object determination means may be configured to determine that there is a change in the image plane position when, for example, the amount of change in the image plane position is equal to or more than a predetermined amount. In this way, even if there is some error in the defocus amount detection value by the defocus amount detection means, the determination is made based on a sufficient change amount effective for determining whether or not the subject is a moving object. By doing so, accurate moving body determination can be performed.
[0026]
When the moving object determining means determines that the subject is not a moving object, the focusing mode is set to a still mode suitable for shooting a still object, and when the subject is determined to be a moving object, the focusing mode is set to suitable for shooting a moving object. A photographing mode switching unit for automatically switching to a moving object mode, wherein the photographing mode switching unit detects a moving object when the moving object judging unit determines that the subject is a moving object even during the photographing in the still mode; Preferably, the mode is switched to the mode. With this configuration, the focusing mode can be appropriately switched by performing the moving object determination quickly and accurately even for the moving subject, and sufficient focusing performance and tracking performance can be exhibited. A camera can be provided.
[0027]
In addition, there is provided image plane position prediction means for predicting a future image plane position based on a plurality of calculated image plane positions, lens position information for calculating these image plane positions, and detection time of the defocus amount. Alternatively, the image plane position in the moving object mode may be predicted based on part or all of the image plane position and the detection time obtained in the stationary mode. With such a configuration, it is possible to provide a camera that exhibits sufficient focusing performance on a moving subject.
[0028]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an automatic focusing device according to an embodiment of the present invention and an optical apparatus including the same will be described in detail.
[0029]
FIG. 1 is a functional block diagram showing the configuration of an interchangeable lens type single-lens reflex camera as an example of the optical apparatus according to the present embodiment.
[0030]
In FIG. 1, reference numeral 1 denotes a lens MPU (micro processing unit) for performing all calculations and controls in the photographing lens unit L, 2 denotes a lens driving unit for driving the photographing lens, 3 denotes a lens position detecting unit, and 4 denotes an autofocus 5 is an optical information table for storing optical information necessary for adjustment.
[0031]
In an actual photographing lens unit, an aperture driving unit for driving the aperture is required, but the description is omitted because it is not relevant in the present embodiment. The photographing lens unit L is constituted by these 1 to 4.
[0032]
The photographing lens unit L is connected to the camera body C via a mount section indicated by a dotted line in the center of the figure. Reference numeral 5 denotes a camera MPU (micro processing unit) that performs all calculations and controls in the camera body, is connected to the lens MPU 1 via a signal line of the mount, and obtains an operation state and a lens position of the lens with respect to the lens MPU 1. It is possible to drive the lens, acquire unique optical information for each photographing lens unit (interchangeable lens), and the like.
[0033]
Reference numeral 6 denotes a defocus amount detection unit, reference numeral 7 denotes a shutter drive unit, reference numeral 8 denotes a film feed unit, and reference numeral 9 denotes a dial unit for performing various settings (shutter speed, aperture value, shooting mode, etc.) of the camera.
[0034]
The camera MPU 5 and the defocus amount detection unit 6 have a role as a defocus amount detection unit. Further, the camera MPU 5 has a role as a storage unit, a moving object determination unit, a timing unit, an image plane position calculation unit, and an image plane position prediction unit.
[0035]
SW1 is turned on by the first stroke operation (half press) of the release button, and performs an automatic focusing operation. SW2 is turned on by the second stroke operation (full press) of the release button to perform a release operation.
[0036]
Various shooting modes can be set by operating the dial unit 9. In the present embodiment, the auto mode for automatically switching between the one-shot mode and the servo mode according to the present invention will be described with reference to the flowchart of FIG. explain.
[0037]
When SW1 is turned on, the process proceeds to step # 101 to start the auto mode process. First, the process proceeds to the one-shot mode process of step # 102. Details of the one-shot mode processing will be described with reference to the flowchart of FIG.
[0038]
First, the process proceeds from step # 201 to step # 202, and it is determined whether SW1 is turned on. Here, if the switch SW1 is turned off, the process proceeds to step # 214 to exit the processing. If the switch SW1 has been turned on, the process proceeds to step # 203, and lens position information indicating the lens position is obtained from the lens position detection unit 3. This is performed by communicating from the camera MPU5 to the lens MPU1. At this time, the detection time is obtained by a timer built in the camera MPU5.
[0039]
Next, charge accumulation is performed in step # 204. After the end of the charge accumulation, in step # 205, the lens position and its detection time are acquired again.
[0040]
The defocus amount necessary for the automatic focus adjustment is calculated from the image shift amounts of two images formed from the subject light flux passing through two different regions sandwiching the optical axis of the photographing lens. Specifically, the light beams of these two images pass through a main mirror M which is a half mirror, are reflected by a sub-mirror S located behind the half mirror M, and are transmitted to a defocus amount detection unit 6 by a focus detection optical system (not shown). Be guided. The defocus amount detection unit 6 is a photoelectric conversion element, and the camera MPU 5 reads out the signals of these two images in step # 206, and calculates an image shift amount by performing a correlation operation.
[0041]
The camera MPU 5 communicates with the lens MPU 1 to obtain optical information such as a defocus amount per image shift amount required for automatic focusing from the lens and a defocus amount per pulse. Specifically, the lens MPU 1 transmits information necessary for automatic focus adjustment to the camera MPU 5 by referring to the optical information table 4. From these pieces of information, the amount of image shift, the amount of defocus, and the number of focus pulses (lens drive amount) that is a drive waveform to the photographing lens are obtained. As described above, since the defocus amount and the actual lens driving amount have a non-linear relationship, the defocus amount is approximated by a function corresponding to the defocus amount, and the coefficient is stored in the optical information table 4 of the photographing lens.
[0042]
The lens drive amount necessary for focusing is obtained in this manner. In step # 207, it is first determined whether or not the camera is in focus at the present time, and if the camera is in focus, the process proceeds to step # 214 to exit the process. If not, the process proceeds to step # 208, where the acquisition of the lens position and its detection time and the correction of the driving amount of the overlap control are performed.
[0043]
This is because, as described above, when performing the overlap control, the lens driving is not performed simply by the obtained defocus amount, but the idle running from the center of the charge accumulation until the lens driving amount is updated is performed. The quantity must be taken into account. Therefore, the average of the lens positions in Steps # 203 and # 204 is defined as the lens position at the center of charge accumulation, and the number of focus pulses corresponding to the displacement from this position to the lens position in Step # 208 is defined as the idling amount. Subtract from. It is needless to say that when the overlap control is not performed, there is no change in the lens position between steps # 203 and # 208, and the free running amount becomes 0, and no correction is performed.
[0044]
When the final lens drive amount is obtained, the process proceeds to step # 209, where the lens is driven. Thereafter, in step # 210, the image plane position obtained by adding the lens driving amount before the overlap correction obtained in step # 206 and the lens position at the charge accumulation center obtained in step # 208, and the detection time thereof (The average of the times acquired in # 203 and # 205) is stored in the memory of the camera MPU5 only when the defocus amount is ± 5 mm or less.
[0045]
A plurality of past image plane positions are stored in the camera MPU 5, and when the image plane position monotonically increases or decreases, the subject is regarded as a moving object. On the other hand, if not, it is assumed that the image plane position is vibrating or that this is due to a detection error of the defocus amount, and the subject is stationary. Note that a monotonic increase here means a state in which the image plane positions in the past plural times increase without decreasing, and a monotonous decrease means that the image plane positions in the past plural times decrease without increasing. It means the state of going.
[0046]
This determination is made in step # 211. If the object is a moving object, the process proceeds to step # 214 to exit the processing. Otherwise, the process proceeds to step # 212. In step # 212, it is determined whether overlap control is possible. This determination is based on the charge accumulation time, or from an operation state in which the lens MPU1 and the camera MPU5 are periodically exchanged by communication, or from the lens position information and the detection time (or the defocus amount corresponding to the lens position information). The determination is made based on the time change of the detection time.
[0047]
Specifically, when the charge accumulation time is sufficiently short, the amount of idle running itself is so small as to be negligible, so that overlap control is possible. Also, when the driving speed of the lens is the highest, the photographing lens is driven in a state that can be regarded as a constant speed, so that overlap control is possible. Furthermore, since the lens position and the detection time are obtained in steps # 203, # 205, and # 208, the overlap control can be performed if the change in the time is substantially linear.
[0048]
If it is determined in step # 212 that overlap control can be performed, the process returns to step # 202 to perform overlap control. Otherwise, the process proceeds to step # 213, and it is determined whether the lens is stopped. If the lens has stopped, the flow returns to step # 202 to perform normal automatic focus adjustment. If the lens is not stopped, the process returns to step # 212, and the determination whether overlap control is possible and the determination whether the lens is stopped are repeated.
[0049]
Returning to the auto mode process of FIG. 2, when the one-shot mode process is completed in step # 102, the process proceeds to step # 103, and it is determined whether SW1 is turned on. Here, if SW1 is turned off, the process proceeds to step # 110, and the process ends. If it is turned on, the process proceeds to step # 104. In step # 104, if the moving object is determined in the one-shot mode process in step # 102, the process proceeds to the servo mode process in step # 108. If so, the process proceeds to the moving object determination mode in step # 105. Details of the moving object determination mode processing will be described with reference to the flowchart of FIG.
[0050]
First, the process proceeds from step # 301 to step # 302 to determine whether SW1 is turned on. Here, if the switch SW1 is turned off, the process proceeds to step # 308 and exits the process. If it is turned on, the flow advances to step # 303 to acquire the lens position and the detection time.
[0051]
Next, charge accumulation is performed in step # 304. After the completion of the charge accumulation, in step # 305, image signal readout, correlation calculation, defocus amount calculation, and lens drive amount calculation are performed. When the final lens drive amount is obtained, the process proceeds to step # 306, and the image plane position and the detection time are stored in the memory of the camera MPU 5 only when the defocus amount is ± 5 mm or less.
[0052]
A plurality of past image plane positions are stored in the camera MPU 5, and when the image plane position monotonically increases or decreases, the subject is regarded as a moving object. Conversely, otherwise, the subject is considered to be stationary.
[0053]
This determination is made in step # 307, and if the object is a moving object, the flow proceeds to step # 308 to exit the processing. If not, the process returns to step # 302, and the processes from steps # 302 to # 307 are repeated until SW1 is turned off or until it is determined that the object is a moving object.
[0054]
Returning to the auto mode process of FIG. 2, when the moving object determination mode process is completed in step # 105, the process proceeds to step # 106, and it is determined whether or not SW1 is turned on. Here, if SW1 is turned off, the process proceeds to step # 110, and the process ends. If it is turned on, the process proceeds to step # 107. In step # 107, if the moving object is determined in the moving object determination mode process in step # 105, the process proceeds to the servo mode process in step # 108. If so, the process returns to the moving object determination mode in step # 105. Details of the servo mode processing will be described with reference to the flowchart of FIG.
[0055]
First, the process proceeds from step # 401 to step # 402, and it is determined whether SW1 is turned on. If the switch SW1 has been turned off, the process proceeds to step # 412, and the process exits. If it is turned on, the process proceeds to step # 403, where the acquisition of the lens position and the detection time thereof are acquired.
[0056]
Next, charge accumulation is performed in step # 404. After completion of the charge accumulation, in step # 405, image signal readout, correlation calculation, defocus amount calculation, and lens drive amount calculation are performed. When the lens drive amount is obtained, the process proceeds to step # 406, and the image plane position and the detection time are stored in the memory of the camera MPU5.
[0057]
Subsequently, in step # 407, it is determined whether or not the subject is in focus. If the subject is in focus, the flow advances to step # 412 to exit the process. Otherwise, the process proceeds to # 408, and it is determined whether the moving object can be predicted.
[0058]
If the moving object can be predicted, the lens drive amount is corrected according to the moving object predicted amount in step # 409, and the process proceeds to step # 410. If the moving object cannot be predicted, the process directly proceeds to step # 410.
[0059]
When the lens is driven in step # 410, the process proceeds to step # 411, where it is determined whether the lens is stopped. If the lens has not stopped, the process returns to step # 411, and the determination is repeated until the lens stops. If the lens has stopped, the process returns to step # 402 and repeats the servo mode processing until SW1 is turned off.
[0060]
Returning to the auto mode process of FIG. 2, when the servo mode process is completed in step # 108, the process proceeds to step # 109, and it is determined whether SW1 is turned on. Here, if SW1 is turned off, the process proceeds to step # 110, and the process ends. If it is on, the process returns to step # 108 and repeats the servo mode processing until SW1 is turned off.
[0061]
In the present embodiment, when charge accumulation is repeatedly performed in steps # 204, # 304, and # 404, if necessary, the detection of the defocus amount is performed by the timer built in the camera MPU 5 at a time interval of 100 ms or more. The weight that becomes That is, detection of each defocus amount for calculating a plurality of image plane positions and acquisition of lens position information of the photographing lens corresponding to these defocus amounts are performed at intervals of a predetermined time or more.
[0062]
In the present embodiment, in the determination of the moving object, the subject is regarded as the moving object when the image plane position monotonously increases or decreases, but when the time interval of the detected defocus amount is too short, This is because the image plane position may not monotonously change even if the subject moves.
[0063]
In steps # 210, # 306, and # 406, the number of image plane positions to be stored may be any number as long as there is a margin, but since the storage capacity is limited, the defocus amount is ± 5 mm. It is assumed that the latest six times are stored from the following image plane positions. If the image plane position is two or more points in the past, it is possible to determine whether the image plane position is monotonically increasing or decreasing. However, if the image plane position is too small, there is a possibility of erroneous determination. The moving object is determined from the stored time.
[0064]
If it is desired to shorten only the defocus amount detection time interval without erroneously determining a moving object, the detection time is also stored when the image plane position is stored. May be stored in advance, and six points may be sequentially selected from the latest image plane position so as to have a time interval of 100 ms or more, and the moving object may be determined based on the six points. For example, in combination with the method of the present embodiment, a weight is inserted so that the detection of the defocus amount becomes a time interval of 50 ms or more, and the past 12 image plane positions are stored. Six points may be selected in order from every other position. Further, since the detection of the defocus amount includes an error that cannot be ignored, it may be determined that there is a change in the image plane position when the change amount of the image plane position is equal to or more than a predetermined amount. For example, when the displacement amount of the adjacent image plane position is 0.050 mm or more and the past six image plane positions are monotonically changing, it may be determined that the object is a moving object. In this way, even if there is some error in the defocus amount detection value by the defocus amount detection means, the determination is made based on a sufficient change amount effective for determining whether or not the subject is a moving object. By doing so, accurate moving body determination can be performed.
[0065]
In the present embodiment, the data of the image plane position and its detection time used for the determination of the moving object are shared with the data of the image plane position and its detection time used for moving object prediction in the servo mode. The determination of whether the moving object can be predicted in step # 408 is also made based on whether the data of the image plane position and the detection time has been stored up to six times in the past. Moving object prediction can be performed if the image plane position and its detection time are two or more in the past, but if it is too small, erroneous prediction may be performed. Therefore, from the point in time when the data of the image plane position and its detection time is stored up to the past six times, the moving object is statistically predicted by the least square method using the data. The statistical moving object prediction itself by the least-squares method has been disclosed by the present applicant in Japanese Patent Application Laid-Open No. 2001-021794, and a detailed description thereof will be omitted.
[0066]
In the above configuration, when it is determined that the defocus amount is equal to or less than the predetermined amount and the image plane position is monotonously changing, the subject is determined to be a moving object. With such a configuration, the determination is performed only in a state where the detection error is smaller than the predetermined amount and the defocus amount is equal to or smaller than the predetermined amount, so that the moving object can be accurately determined.
[0067]
In the auto mode, the moving object can be determined during the one-shot mode, and the mode is switched to the servo mode during the one-shot mode without going through the moving object determination mode. As a result, the moving object can be determined quickly, and the ability to follow a moving subject is improved.
[0068]
Furthermore, since part or all of the data of the image plane position and the detection time obtained during the one-shot mode is used as the data of the moving object prediction in the servo mode, the moving object prediction can be performed quickly. Sufficient focusing performance can be exhibited even when the shutter is released in such a situation.
[0069]
Here, the plurality of image plane positions described above include, for example, at least three image plane positions calculated based on defocus amounts equal to or less than a predetermined amount detected at least three times and lens position information corresponding to these defocus amounts. There may be.
[0070]
In the above-described embodiment, a film-type single-lens reflex camera has been described as an example of the optical apparatus. However, the present invention is not limited to this, and it is needless to say that the present invention can be applied to other optical apparatuses such as a digital single-lens reflex camera. No.
[0071]
Further, here, the photographing lens unit L is configured to be detachable from the camera body C, but is not limited to this, and the photographing lens unit L and the camera body C are integrated. However, the same effect can be obtained.
[0072]
As described above, a camera according to an embodiment of the present invention includes a defocus amount detection unit that detects a defocus amount of a photographic lens, a detected defocus amount, and lens position information of the photographic lens corresponding to the defocus amount. Image plane position calculating means for calculating an image plane position based on the plurality of image plane positions, and a plurality of image plane positions calculated based on lens position information corresponding to the defocus amounts equal to or less than a predetermined amount detected a plurality of times and these defocus amounts. When the change is monotonous, a moving object determining unit that determines that the subject is a moving object is provided.
[0073]
As described above, since it is determined whether or not the subject is a moving object within the range of the defocus amount at which sufficient detection accuracy can be obtained and by a change in the image plane position, accurate moving object determination can be performed. Also, in comparison with the conventional method of determining a moving object when focusing is not achieved even when the photographing lens is driven a predetermined number of times or more, detection of a defocus amount a plurality of times and lens position information corresponding to the defocus amount are performed. Since it is only necessary to obtain the moving object, it is possible to perform the moving object determination more quickly than before.
[0074]
As described above, when the moving object determining unit determines that the subject is not a moving object, the focusing mode is set to a one-shot mode (still mode) suitable for photographing a still subject, and when the subject is determined to be a moving object, the focusing mode is determined. A photographing mode switching unit for automatically switching a focus mode to a servo mode (moving object mode) suitable for photographing of a moving object; When the subject is determined to be a moving object, the mode is switched to the servo mode, so that the moving mode can be quickly and accurately determined even for a moving subject, so that the focusing mode can be appropriately switched. And sufficient focusing performance and tracking performance can be exhibited.
[0075]
Further, the image processing apparatus includes image plane position prediction means for predicting a future image plane position based on the calculated plural image plane positions and lens position information for calculating these image plane positions and the detection time of the defocus amount, By providing a configuration in which the image plane position is predicted in the servo mode based on part or all of the image plane position and the detection time obtained in the one-shot mode, sufficient focusing performance on a moving subject is exhibited. be able to.
[0076]
【The invention's effect】
As described above, according to the inventions of the present application, it is possible to provide a camera that can accurately and quickly determine a moving object of a subject.
[Brief description of the drawings]
FIG. 1 is a functional block diagram of a camera according to an embodiment of the present invention.
FIG. 2 is a flowchart showing an operation in an auto mode according to the embodiment.
FIG. 3 is a flowchart showing an operation in a one-shot mode according to the embodiment.
FIG. 4 is a flowchart showing an operation in a moving object determination mode according to the embodiment.
FIG. 5 is a flowchart showing an operation in a servo mode according to the embodiment.
FIG. 6 is a diagram showing a relationship between time and a defocus amount in a one-shot mode.
FIG. 7 is a diagram showing a relationship between a time and a lens position in a one-shot mode.
FIG. 8 is a diagram showing a relationship between time and image plane position in a one-shot mode.
FIG. 9 is a diagram for explaining overlap control in a one-shot mode.
FIG. 10 is a diagram illustrating a relationship between time and a defocus amount in a servo mode.
FIG. 11 is a diagram illustrating a relationship between a time and a lens position in a servo mode.
FIG. 12 is a diagram illustrating a relationship between a time and an image plane position in a servo mode.
FIG. 13 is a diagram illustrating a relationship between a time and a lens position in a moving object determination mode.
[Explanation of symbols]
1 Lens MPU
2 Lens drive unit
3 Lens position detection unit
4 Optical information table
5 Camera MPU
6 Defocus amount detection unit
7 Shutter drive unit
8 Film feeding unit
9 Dial unit

Claims (7)

Defocus amount detection means for detecting the defocus amount of the taking lens,
Image plane position calculating means for calculating an image plane position based on the detected defocus amount and lens position information of the photographing lens corresponding to the detected defocus amount;
It is determined that the subject is a moving object when the defocus amounts detected a plurality of times or less and the plurality of image plane positions calculated based on the lens position information corresponding to the defocus amounts monotonically change. A camera comprising: a moving object determining unit. The moving body determination means may determine that at least three image plane positions calculated based on the defocus amounts equal to or less than a predetermined amount detected at least three times and the lens position information corresponding to these defocus amounts are monotonically changing. The camera according to claim 1, wherein it is determined that the subject is a moving object. 2. The method according to claim 1, wherein the detection of the respective defocus amounts for calculating the plurality of image plane positions and the acquisition of lens position information corresponding to these defocus amounts are performed at intervals of a predetermined time or more. Or the camera according to 2. The moving object determining means uses the lens position information for calculating each image plane position and the detection time of the defocus amount to determine whether the photographing subject is a moving object. 3. The camera according to any one of 3. The camera according to any one of claims 1 to 4, wherein the moving body determination unit determines that there is a change in the image plane position when the amount of change in the image plane position is equal to or more than a predetermined amount. When the moving object determining means determines that the subject is not a moving object, the focusing mode is set to a stationary mode suitable for shooting a still subject, and when the subject is determined to be a moving object, the focusing mode is set to a moving mode suitable for shooting a moving object. A shooting mode switching means for automatically switching to a mode,
6. The photographing mode switching unit switches to a moving object mode even when the moving object determining unit determines that the subject is a moving object even during photographing in a still mode. The camera according to any of the above. An image plane position prediction unit that predicts a future image plane position based on the plurality of calculated image plane positions and lens position information for calculating these image plane positions and the detection time of the defocus amount,
7. The camera according to claim 1, wherein the image plane position in the moving object mode is predicted based on a part or all of the image plane position and the detection time obtained in the stationary mode. .

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