JP2018026607A - Image blur correction device and control method therefor, optical instrument, and imaging device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a panning quantity of a background from not varying even when panning quantity settings are changed according to conditions of a subject as an object of panning photography while a panning photography mode is provided and a plurality of panning quantity settings are available.SOLUTION: An image blur correction device has: imaging optical means; focal length detecting means for detecting a focal length of the imaging optical means; acquiring means for acquiring a shake state of instrument; detecting means for detecting a plurality of motion vectors from image information between frames; angular velocity detecting means for detecting an angular velocity of a subject from output of the acquiring means and output of the detecting means; calculating means for calculating a shutter speed for obtaining a predetermined background panning quantity from output of the angular velocity detecting means and output of the focal length detecting means; limiting means for limiting output of the calculating means; selecting means for selecting a level of the background panning quantity; and changing means for changing a limitation quantity of the limiting means according to the background panning quantity selected by the selecting means.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an image shake correction apparatus mounted on a camera or the like and a control method therefor, and more particularly, to an imaging assistance technique for suitably performing panning.

  The panning shot by a camera is a method of shooting a subject (moving object) at a shutter speed slower than usual while following the subject. According to this method, an image in which the background flows and the subject is stationary can be obtained. The photographer can take pictures with a sense of speed through panning. However, since long-time shooting is performed, it is difficult to match the speed of the subject and the speed of shaking the camera during the exposure period, which is one of the shooting techniques that require skill.

  In order to easily realize panning, Patent Document 1 discloses a method for detecting a difference between a subject speed and a camera shaking speed and correcting a shift amount corresponding to the difference using a camera shake correction function. Is disclosed. Immediately before shooting, the angular velocity sensor detects the angular velocity with respect to panning of the camera that is tracking the subject. At the same time, a motion vector corresponding to the amount of movement of the main subject image on the imaging surface is detected. Then, the angular velocity of the main subject is calculated from the detected panning angular velocity and the motion vector of the main subject image. During exposure, an image blur correction operation is performed according to the difference between the calculated angular velocity of the main subject and the angular velocity sensor output.

  As a result, the difference in panning speed between the main subject and the camera and the amount of camera shake are corrected, so that image blurring of the main subject that is the subject of panning can be suppressed.

JP 2006-317848 A

  By the way, the shutter speed (exposure time) set at the time of panning shooting can be calculated from the angular velocity of the subject and the focal length of the lens as to what percentage of the angle of view to flow in the photographed photograph. For example, if the flow amount is about 3% of the horizontal angle of view, the flow amount δ on the image plane is a blur amount of about 1 mm in a full-size camera. Now, assuming that 35 mm equivalent focal length f is 300 mm and the subject's angular velocity ω is 20 deg / sec, the exposure time is calculated as follows.

Exposure time [sec] = tan ⁻¹ (δ / f) / ω
= Tan ⁻¹ (1/300) / 20
≒ 0.01
That is, if the shutter speed is set to 1/100, a photograph with a predetermined flow amount can be taken. However, when chasing a very slow subject while slowly panning, if the shutter speed is calculated in the same way, the calculation result becomes very long, for example, a low-speed shutter such as 1/4 second or 1/2 second. When the shutter speed is low, the effect of camera shake correction is reduced, and the subject itself is blurred due to the influence of camera shake during the exposure period. To prevent this blur. Usually, a limiter on the long second side with respect to the exposure time is provided.

  On the other hand, an amount of about 3% of the angle of view set as the background sink amount is an amount that can sufficiently confirm the effect of the panning shot. However, in order to deal with photographers who want to increase the sinking amount, The sink setting can be changed. The photographer changes the setting of the background sink amount so that a panorama photograph suitable for the photographer's intention can be obtained.

  However, due to the long-second limiter for the subject blur countermeasure, the situation of the subject to be photographed, particularly in the slow subject, the situation where the shutter speed does not change even if the setting of the background flow amount is changed occurs. For this reason, there is a problem in that the background flow amount does not change even though the setting is switched, and an intended photograph cannot be taken.

  Accordingly, an object of the present invention is to provide a system in which when a photographer changes a background flow amount setting, a difference due to the setting change can be clearly recognized.

In order to achieve the above object, the present invention provides:
An imaging optical system (101);
A focal length detection means (105) for detecting a focal length of the imaging optical system, an acquisition means (111) for acquiring a shake state of the device,
Detection means (141) for detecting a plurality of motion vectors from image information between frames;
Angular velocity detection means (152) for detecting the angular velocity of the subject from the output of the acquisition means and the output of the detection means;
A calculation means (153) for calculating a shutter speed for obtaining a predetermined flow amount from the output of the angular velocity detection means and the output of the focal length detection means;
Limiting means (153) for limiting the output of the calculating means;
Selection means (131) for selecting the magnitude of the flow amount;
Change means (153) for changing the limit amount of the limit means in accordance with the amount of flow selected by the selection means;
It is characterized by having.

  According to the present invention, by switching the long-second limiter according to the background flow amount setting, the difference in the background flow amount between the standard setting and the long setting becomes clear. It is possible to provide a photograph that provides a panning effect according to the desire of the user.

1 is an overall configuration diagram of an imaging apparatus according to Embodiment 1 of the present invention. Flowchart for explaining a shutter speed setting method according to the first embodiment of the present invention. Flowchart for explaining a shutter speed setting method according to the second embodiment of the present invention. Simplified flowchart of panning mode control Figure showing an example of warning display

  Embodiments of the present invention will be described with reference to the accompanying drawings. In each embodiment, an image shake correction apparatus that performs image shake correction of a captured image is illustrated. Image blur correction devices that drive and control movable members of image blur correction optical systems can be mounted on imaging devices such as video cameras, digital cameras, and silver halide still cameras, and optical devices such as interchangeable lenses for digital SLR cameras. It is. Therefore, an optical apparatus and an imaging device also constitute one aspect of the present invention.

[Example 1]
FIG. 1 is a diagram illustrating a configuration example of an imaging measure according to the first embodiment of the present invention, and illustrates a configuration of a mirrorless camera (hereinafter referred to as a camera) equipped with a panning mode function. The interchangeable lens 100 having an image shake correction function is an optical device that can be attached to the camera body 120. The interchangeable lens 100 includes a photographing lens unit 101 including a main photographing optical system 102, a zoom lens group 103 that can change a focal length, and a shift lens group 104.

  The zoom encoder 105 detects the position of the zoom lens 103 and outputs a detection signal to a lens system control microcomputer (hereinafter referred to as a lens control unit) 113. The lens control unit can obtain the focal length of the photographic lens unit 101 based on the detection signal of the zoom encoder 105. The shift lens group 104 optically corrects camera shake by moving in the direction perpendicular to the optical axis of the photographing lens unit 101.

  An angular velocity sensor (hereinafter referred to as a gyro) 111 serving as a first detection unit detects a shake of the entire camera and outputs a shake detection signal to the amplifier 112. The amplifier 112 amplifies the shake detection signal and outputs it to the lens control unit 113. The lens control unit 113 captures the output of the amplifier 112 as gyro data by A / D or the like. The lens control unit 113 includes a camera shake correction control unit 117 that performs camera shake correction control, and a panning mode control unit 118 that performs control for the panning mode.

  The lens control unit 113 also performs focus lens control, aperture control, and the like, but is omitted for simplification of illustration. The first driver 114 drives the shift lens group 104 in order to correct camera shake or the like according to a control signal from the lens control unit 113. The driver 114 constitutes an image blur correction unit together with a drive mechanism unit of the shift lens group 104 (correction member). The amplifier 115 amplifies the output of the position sensor 106 of the shift lens group 104 and outputs it to the lens control unit 113. The lens control unit 113 includes a camera shake correction control unit 117 that performs camera shake correction control, and a panning control unit 118 that performs control for the panning mode.

  The lens control unit 113 also performs focus lens control, aperture control, and the like, but is omitted for simplification of illustration. As for camera shake correction, detection and correction are performed with respect to two orthogonal axes, for example, the horizontal direction and the vertical direction. However, since the same configuration is used, only one axis will be described below.

  The camera body 120 includes a shutter 121 used for exposure control and an image sensor 122 such as a CMOS (complementary metal oxide semiconductor) sensor. The imaging signal output from the imaging element 122 is processed by the analog signal processing circuit 123 and then sent to the camera signal processing circuit 124. A timing generator (TG) 125 sets operation timings of the image sensor 122 and the analog signal processing circuit 123. The operation unit 131 includes a power switch, a release switch, a switch for setting whether to set the panning mode, and a switch for selecting a background sink amount in the panning mode.

  A camera system control microcomputer (hereinafter referred to as a camera control unit) 132 controls the entire imaging apparatus. For example, the camera control unit 132 outputs a control signal to the second driver 133 for shutter, and drives and controls the motor 134 for driving the shutter. However, here, for simplification of the drawing, only the part related to panning in the camera control unit is displayed.

  The memory card 171 is a recording medium for recording captured image data. The display unit 172 includes a display device such as a liquid crystal panel (LCD) that monitors an image that the photographer intends to capture with the camera and displays the captured image. The camera body 120 includes a mount contact portion 161 with the interchangeable lens 100. The lens control unit 105 and the camera control unit 132 perform serial communication at a predetermined timing via the mount contact units 106 and 161.

  The camera signal processing circuit 124 includes a motion vector detection unit 150 as a second detection unit, and detects the motion of the captured image based on the image data of a plurality of frames. A detection signal of the motion vector detection unit 150 is output to the camera control unit 132.

  The camera control unit 132 includes a main subject determination unit 151 and a main subject angular velocity calculation unit 152 that calculates a panning angular velocity (hereinafter, referred to as a main subject angular velocity) of a camera for stopping a subject that is a panning target. The main subject determination unit 151 uses the output of the motion vector detection unit 141 and the gyro data of the camera detected by the gyro received from the lens control unit, and the area on the screen where the main subject to be shot for panning shot exists. Select. The main subject angular velocity calculation unit 152 converts the motion vector information about the main subject selected by the main subject determination unit 151 into an angular velocity using a focal length, a frame rate, a sensor pixel pitch, and the like, and gyro data. Based on this, the main subject angular velocity is calculated.

  In the camera of FIG. 1, when the photographer turns on the camera using the operation unit 131, the camera control unit 132 detects the change in state. The camera control unit 132 performs power supply to each circuit of the camera body 120 and initial setting processing. Power is supplied to the interchangeable lens 100, and the lens control unit 113 executes an initial setting process in the interchangeable lens 100. Communication between the lens control unit 113 and the camera control unit 132 starts at a predetermined timing. Through this lens-camera communication, camera status, shooting settings, and the like are transmitted and received from the camera body 120 to the interchangeable lens 100.

  Further, focal length information, angular velocity information, and the like of the interchangeable lens are transmitted and received from the interchangeable lens 100 to the camera body 120 at necessary timings. Further, during the panning mode, information indicating that the panning mode is in progress and the angular velocity data of the main subject image calculated by the subject angular velocity calculation unit 152 are transmitted from the camera body 120 to the interchangeable lens 100. The lens control unit 113 switches whether the shift lens drive control is controlled by the camera shake correction control unit 117 or the control by the panning control unit 118 based on the information about whether the panning mode is in progress.

  FIG. 4 is a flowchart schematically showing the operations of the lens control unit 113 and the camera control unit 132 relating to the panning mode control. Here, S401 to S407 indicate operations in the lens control unit 113, and S411 to S416 indicate operations in the camera control unit 132.

  Hereinafter, the operation flow in the panning mode will be described with reference to FIG. The lens control unit 113 in the interchangeable lens 100 samples the output of the angular velocity sensor (gyro) 111 at 4 kHz, for example. In S401, the camera side transmits the gyro data average value in a period synchronized with the frame for performing vector detection to the camera, and the camera control unit 132 receives the gyro data in S411 (broken line 421). In step S412, the camera control unit 132 calculates a main subject angular velocity from the gyro data received in step S411 and the main subject vector selected by the subject determination unit 151. Then, as indicated by a broken line 422, the calculation result is transmitted to the lens in S413, and the lens control unit 113 receives the object angular velocity from the camera in S402.

  Next, in S413, a predetermined flow amount is obtained from the subject angular velocity information calculated in S412 and the focal length data (not shown) transmitted from the lens control unit 113 to the camera control unit 132 at another timing. The exposure time is calculated.

  In S415, the operations of S401 to S403 and S411 to S415 are repeated until it is determined that SW2 is turned on by the camera (until the release operation is performed). When SW2ON is determined in S415, the SW2ON information and the exposure time information calculated in S414 are transmitted to the lens control unit (broken line 423). The lens control unit 113 determines SW2ON in S403 based on the received SW2ON information, and both the lens control unit 113 and the camera control unit 132 shift to an operation during exposure.

  The camera control unit 132 starts an exposure operation in S416, and in S417, performs the exposure operation until the exposure time calculated in S414 elapses (the exposure end timing is reached). On the other hand, the lens control unit 113 calculates the shift lens drive target value from the subject angular velocity received immediately before the release operation in S404 and the current gyro data. In step S405, a drive signal is output to the driver 114. The shift lens is driven until an exposure end determination is made in S406, and when the exposure is completed, the shift lens is returned to the center position in S407.

  With the above operation, the panning speed and the shift of the movement of the subject are corrected by the movement of the shift lens, and the panning assist is performed.

  FIG. 2 is a flowchart showing details of the exposure time calculation unit shown in FIG. 4 and S414. Hereinafter, the setting of the exposure time, which is a feature of the present invention, will be described in detail with reference to FIG.

  In FIG. 2, the focal length information obtained from the lens is acquired in S201. In S202, the subject angular velocity calculated in FIG. 4 and S412 is acquired. In S203, it is determined whether or not the photographer has operated the setting of the flow amount with the operation unit 131 of the camera. If it is the standard setting, the shutter speed limiter is set to a limiter value corresponding to the flow amount setting “standard” in S204. . If the set flow amount is “large” in S203, a shutter speed limiter value corresponding to the flow amount “large” is set in S205. The limiter set in S204 and S205 is set to about 1/15 for the flow rate “standard” setting and about 1/15 for the flow rate “large” setting.

  In step S206, the shutter speed is calculated from the information acquired in steps S201 and S202 and the set background flow amount. The setting of the flow amount “standard” or “large” can be calculated by changing the value of the flow amount δ on the image plane in the above-described exposure time calculation formula. In S207, it is determined whether or not the shutter speed calculated in S206 is slower than the limiter value set in S204 or S205. If the shutter speed is slower than the limiter value, the calculated shutter speed is limited to the limiter value in S208, and the final shutter speed (exposure time) is determined.

  With this setting, the background flow amount between the flow rate “Standard” and the flow rate “Large” is the difference between the limiter values, and depending on the setting, the difference is more than the difference between the limiter values. Can be confirmed clearly.

  As described above, setting the low-speed limiter for the shutter speed according to the background flow amount set by the photographer makes it possible to clearly recognize the effect of the flow amount due to the setting. This makes it possible to take a panning shot that reflects the intention of the person.

[Example 2]
The second embodiment relates to a method for enabling the effect of changing the flow amount setting to be recognized even when the background flow amount setting is “large” and the overexposure occurs. Since the shutter speed is set longer during panning, overexposure may occur. Although it is possible to cope by dimming using an ND filter or the like, here, the difference in the amount of flow is understood even when there is no ND filter.

  The configuration of this embodiment is the same as that shown in FIG. FIG. 3 is a flowchart that explains the details of the exposure time calculation corresponding to FIG. 1 and S414, which is the most characteristic part in this embodiment.

  Hereinafter, a second embodiment of the present invention will be described in detail with reference to FIG. In FIG. 3, focal length information and subject angular velocity information are acquired in S301 and S302, respectively. In step S303, photometric data is acquired.

  In step S304, the shutter speed is calculated from the information acquired in steps S301 and S302 and the maximum background flow amount that can be set by the camera in the panning mode. In S305, the camera parameter with priority on the calculated shutter speed is confirmed from the photometric data acquired in S303. In S306, it is determined from the camera parameters confirmed in S305 whether overexposure occurs. If overexposure occurs, the shutter speed at which exposure is appropriate is confirmed in S307. In S308, it is determined whether or not the difference between the shutter speed at which the exposure confirmed in S307 is appropriate and the shutter speed to be set in order to obtain the original background flow amount is greater than a predetermined value.

  The predetermined value here is given by the number of steps of the shutter speed, and it is determined whether or not the appropriate shutter speed is different by, for example, two or more steps from the shutter speed that should be originally set. For example, if there are two or more differences, the effect of the amount of flow will inevitably disappear. Therefore, in this case, a warning is set in S309. The warning display here is, for example, as shown in FIG. 5, indicating that “a predetermined flow effect cannot be obtained”.

  If the difference in the number of shutter steps is equal to or smaller than the predetermined value in S308, no warning is displayed. In S310, the shutter for each setting of the amount of flow is set based on the shutter speed at which the exposure setting is appropriate when the amount of flow setting is “large”. Set the speed limiter value. The limit value of the flow amount “Large” is the shutter speed at which the appropriate exposure is obtained, but the flow amount “Standard” is set to a shutter speed that is, for example, one step faster than the appropriate exposure. In this way, by setting the lower limit value of the shutter speed on the basis of the appropriate exposure, the difference in the background flow amount due to the flow amount setting appears.

  If it is determined in S306 that the overexposure does not occur even when the flow amount setting is “Large”, the limiter value setting of the same shutter speed as in the first embodiment is performed in S311.

  In step S312, the shutter speed is calculated based on the flow amount setting actually set by the photographer, and the shutter speed calculated in step S313 is compared with the limit value. If the result of comparison in S313 is that the shutter speed is slower than the limiter value, the shutter speed is limited to the limiter value in S314.

  With the above settings, even in the case of overexposure, the difference in the background flow amount is clear between the flow amount “Standard” and the flow amount “Large”, and the difference in effect due to the setting change is clearly confirmed it can. As a result, since the effect of the sink amount set by the photographer can be recognized, it is possible to take a panning shot that reflects the photographer's intention.

  As mentioned above, although preferable embodiment of this invention was described, this invention is not limited to these embodiment, A various deformation | transformation and change are possible within the range of the summary.

DESCRIPTION OF SYMBOLS 100 Interchangeable lens 101 Shooting lens unit 104 Shift lens 106 Shift lens position detection sensor 111 Angular velocity sensor (gyro)
113 Lens control unit 114 Shift lens driver 120 Camera main body 124 Camera signal processing circuit 131 Camera operation unit 132 Camera control unit 141 Motion vector detection unit 151 Main subject determination unit 152 Main subject angular velocity calculation unit 153 Exposure time setting unit

Claims (5)

An imaging optical system (101);
A focal length detection means (105) for detecting a focal length of the imaging optical system, an acquisition means (111) for acquiring a shake state of the device,
A calculation means (153) for calculating a shutter speed for obtaining a predetermined background flow amount at the time of shooting from the output of the acquisition means and the output of the focal length detection means;
Limiting means (153) for limiting the output of the calculating means;
Selection means (131) for selecting the size of the background flow amount;
Change means (153) for changing the restriction amount of the restriction means according to the background flow amount selected by the selection means;
An image pickup apparatus comprising: An imaging optical system (101);
A focal length detection means (105) for detecting a focal length of the imaging optical system, an acquisition means (111) for acquiring a shake state of the device,
Detection means (141) for detecting a plurality of motion vectors from image information between frames;
Angular velocity detection means (152) for detecting the angular velocity of the subject from the output of the acquisition means and the output of the detection means;
A calculation means (153) for calculating a shutter speed for obtaining a predetermined background flow amount at the time of photographing from the output of the angular velocity detection means and the output of the focal length detection means;
Limiting means (153) for limiting the output of the calculating means;
Selection means (131) for selecting the size of the background flow amount;
Change means (153) for changing the restriction amount of the restriction means according to the background flow amount selected by the selection means;
An image pickup apparatus comprising: The limiting unit limits the shutter speed calculated by the calculating unit so that the shutter speed does not become a predetermined value or longer, and sets the limiting amount so that the shutter speed increases as the flow amount selected by the selection unit decreases. The imaging device according to claim 1, wherein the imaging device is set. It further has an exposure state determination means for determining that the exposure is in an appropriate state,
When it is determined by the exposure state determination means that the image to be shot at the shutter speed calculated by the calculation means is not appropriate exposure,
The imaging apparatus according to claim 1, wherein a restriction amount restricted by the restriction means is reset with respect to a background flow amount selectable by the selection means. The limit amount is reset based on the maximum background flow amount that can be selected by the selection unit, and the limit amount is determined so that the shutter speed increases as the selected background flow amount decreases. The imaging apparatus according to claim 4, wherein the imaging apparatus is characterized.