JP4894162B2 - camera - Google Patents

Description

  The present invention relates to a camera that automatically performs focus adjustment.

2. Description of the Related Art Conventionally, a camera having a so-called tracking function that performs focus adjustment by predicting the image plane position of a subject when capturing a moving subject is known. Some cameras perform focus adjustment by statistically processing tracking and focusing in order to perform tracking according to the subject (see, for example, Patent Document 1). In addition, in order to avoid unnecessary tracking, a camera having a function of prohibiting tracking according to a user operation is known (for example, see Patent Document 2).
JP-A-8-75989 Japanese Patent Laid-Open No. 7-218818

However, in the technique of Patent Document 1 described above, when the subject moves unexpectedly for the camera, the image plane position of the subject cannot be accurately predicted, and as a result, inappropriate focus adjustment is performed. May end up.
Further, in the technique of Patent Document 2 described above, it is left to the user's judgment as to when tracking is prohibited, and when used by a user who does not have sufficient knowledge, at an appropriate timing. Tracking prohibition may not be executed.

  An object of the present invention is to provide a camera that can easily set a subject tracking force during focus adjustment according to a subject.

The camera of the present invention has a plurality of shooting modes depending on how the subject moves, and each shooting mode is set with a shooting condition and a subject tracking force at the time of focus adjustment that is different for each shooting mode. The focus adjustment is performed based on a mode setting unit that selects a specific shooting mode from among the plurality of shooting modes, and the subject tracking force that is associated with the specific shooting mode selected by the mode setting unit. A focus adjustment unit, and the mode setting unit as the plurality of shooting modes, a fixed direction moving shooting mode for shooting the subject moving in a substantially fixed direction in front of the camera, and the camera Can be selected from either a moving direction change shooting mode for shooting the subject that moves in a direction other than a moving direction that moves in a substantially constant direction in front of the camera. , In association with the certain movement shooting mode, the object tracking force is set larger than the movement direction change shooting mode.

Preferably, the mode setting unit randomly moves in front of the camera, as the moving direction change shooting mode , in a second shooting mode for shooting the subject moving around in front of the camera. One of the third shooting modes for shooting the subject that moves can be selected, and the subject tracking force larger than that in the second shooting mode is set in association with the fixed-direction moving shooting mode. In addition, the subject tracking force larger than that in the third shooting mode may be set in association with the second shooting mode.
Another camera according to the present invention has a plurality of shooting modes corresponding to how the subject moves, and each shooting mode associates a shooting condition with a subject tracking force at the time of focus adjustment that is different for each shooting mode. Based on the subject tracking force associated with the specific shooting mode selected by the mode setting unit, a mode setting unit for selecting a specific shooting mode from the plurality of shooting modes set in the above, A focus adjustment unit that performs focus adjustment, and the mode setting unit captures the subject that moves in a substantially constant direction in front of the camera as the plurality of shooting modes. A second shooting mode for shooting the subject that moves around in front of the camera, and a movement mode that moves randomly in front of the camera. At least two shooting modes can be selected from among the third shooting modes for shooting the subject, and the subject tracking force larger than that of the second shooting mode is associated with the first shooting mode. is set, in association with the second imaging mode, the subject tracking force greater than the third imaging mode is it is configured.
Preferably, the focus adjustment unit predicts a position of the image plane of the subject according to a predetermined function and performs the focus adjustment, and a change in acceleration of the image plane among the predetermined function is performed. At least one of the coefficient related to the image plane and the coefficient related to the change in the moving speed of the image plane is changed based on the subject tracking force, and the coefficient related to the change in acceleration is set larger as the subject tracking force increases. You may make it do.

  ADVANTAGE OF THE INVENTION According to this invention, the camera which can set the subject tracking force at the time of focus adjustment simply according to a to-be-photographed object can be provided.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In this embodiment, a single lens reflex digital camera will be described as an example of the camera of the present invention. The technique of the present invention may be applied to a silver halide camera, a compact camera, a camera having a moving image shooting function, and the like.
FIG. 1 is a functional block diagram of the camera 100 of the present embodiment. As shown in FIG. 1, a camera 100 includes a photographing optical system 1 having a photographing lens (not shown), a diaphragm, a photographing lens driving unit 2 that drives the photographing lens, and a quick return mirror that branches a light beam from the photographing optical system 1. 3, a sub-mirror 4, an imaging unit 5 that captures an image, a focus detection unit 6 that performs focus detection, an operation unit 7 that receives a user operation, a display unit 8 that displays an image or a menu screen, and a CPU 9 that controls each unit. The imaging unit 5 includes a shutter, an image sensor, an image processing unit, and the like (not shown), and the operation unit 7 includes a power button, a release button, and the like (not shown).

The imaging unit 5 and the focus detection unit 6 are mutually connected to the CPU 9, and the CPU 9 detects the state of the operation unit 7. The output of the CPU 9 is connected to the photographing lens driving unit 2 and the display unit 8. Each control program of the CPU 9 is recorded in advance in a memory (not shown) in the CPU 9.
At the time of shooting, the quick return mirror 3 is flipped up, and the light beam from the subject is imaged on the imaging surface of an imaging element (not shown) of the imaging unit 5 by the imaging optical system 1. The imaging unit 5 performs A / D conversion on the captured image signal, and performs image processing by an image processing unit (not shown).

  On the other hand, the quick return mirror 3 is lowered at times other than shooting, that is, during composition confirmation, and a part of the light flux from the subject is reflected by the quick return mirror 3. This light beam is used by each unit (not shown) for composition confirmation, acquisition of exposure information, and the like. A part of the light beam from the subject that has passed through the lowered quick return mirror 3 is guided to the focus detection unit 6 by the sub mirror 4. The focus detection unit 6 acquires image plane information of the subject based on the light beam passing through the photographing optical system 1 and performs focus detection. The CPU 9 performs the AF operation by sequentially controlling the photographing lens driving unit 2 and the photographing optical system 1 based on the result of focus detection by the focus detection unit 6. In the AF operation, the CPU 9 performs subject tracking, which is a feature of the present invention, according to a shooting mode described later. Subject tracking is a process of predicting the image plane position based on the movement of the subject when continuously performing AF, and driving the photographing lens so as to focus on the predicted image plane position. In the prediction of the image plane position of the subject, the function shown in the following formula is used.

y (image plane position) = ax ² + bx + c Equation 1
In Equation 1, x ² represents a change in the acceleration of the image plane position, and x represents a change in the speed of the image plane position. A, b, and c are coefficients. Further, the prediction of the image plane position using Expression 1 is performed in the same manner as in the known technique.
Hereinafter, setting of the subject tracking force, which is a feature of the present invention, will be described. The camera 100 of the present embodiment has three types of shooting modes in which shooting conditions are set according to how the subject moves. The first shooting mode is a shooting mode for shooting a subject that moves in a substantially constant direction in front of the camera 100, and the second shooting mode is a movement method that circulates in front of the camera 100. The third shooting mode is a shooting mode for shooting a subject that moves in a random manner in front of the camera 100. Each photographing mode will be described with reference to FIGS.

  FIG. 2A is a diagram illustrating the first shooting mode. In the first shooting mode, as shown in FIG. 2A, the subject moves in a substantially constant direction in front of the camera 100 at a time Ta1, Ta2,... It is a shooting mode. Examples of such subjects include moving airplanes, cars, trains, and the like. In shooting such a subject, a higher effect can be expected by tracking.

  FIG. 2B is a diagram illustrating the second shooting mode. As shown in FIG. 2B, the second shooting mode is a shooting mode for a subject that moves around in front of the camera 100 at times Tb1, Tb2,... Tb6. Examples of such subjects include athletes in athletic meet / skate / track competitions. In photographing such a subject, since the corner portion and the straight line portion are included, the speed change seen from the camera 100 is large, and the motion vector changes between the corner portion and the straight line portion. Lower than the shooting mode.

  FIG. 3 is a diagram illustrating the third shooting mode. As shown in FIG. 3, the third shooting mode is a shooting mode for a subject moving at random in front of the camera 100 at times Tc1, Tc2,... Tc6. Examples of such subjects include soccer / rugby players, chasing children, playing children, and the like. In such shooting of a subject, a change in speed and a change in motion vector occur continuously or intermittently, so that the effect of tracking is very low. In addition, since there are a plurality of subjects (such as persons), there is a problem that erroneous detection is likely to occur.

  In the three types of shooting modes described above, shooting conditions are set in advance in association with each of the shooting modes, and subject tracking power at the time of focus adjustment that is different for each shooting mode (different for each movement method) is set in advance. . Specifically, the largest subject tracking force is set in association with the first shooting mode, is smaller than the first shooting mode in association with the second shooting mode, and is in the third shooting mode. Larger (medium) subject tracking force is set, and the smallest subject tracking force is set in association with the third shooting mode.

  Then, the user selects a specific mode from these shooting modes by an operation via the operation unit 7. The shooting mode is selected by displaying a menu screen on the display unit 8. FIG. 4A shows an example of the menu screen. In FIG. 4A, icons indicating five types of shooting modes are displayed. The user selects a specific mode via the operation unit 7 while viewing the display unit 8. “Airplane / car / train mode” corresponds to the first shooting mode described above, and “athletic / skate / track competition mode” corresponds to the second shooting mode described above, and “soccer / rugby mode”. "Corresponds to the third shooting mode described above. The “still subject mode” is a mode for photographing a still subject, and is a photographing mode suitable for portrait photography, landscape photography, and the like, for example. The “auto mode” is a shooting mode in which the camera 100 sets an appropriate subject tracking force by subject recognition or the like.

Next, the operation of the camera 100 when a specific shooting mode is selected by the above-described method will be described for each shooting mode.
(1) Airplane / car / train mode When the plane / car / train mode is selected, the CPU 9 reads out and reads out the shooting conditions set in association with the plane / car / train mode and the subject tracking power. Focus adjustment is performed based on shooting conditions and subject tracking power. As described above, the largest subject tracking force is set in the airplane / car / train mode. Therefore, the CPU 9 performs the focus adjustment by setting a coefficient relating to the change in the acceleration of the image plane, that is, the coefficient a in Expression 1 to be larger than the standard state. By setting the coefficient a large, the prediction of the image plane position can be sufficiently reflected in the focus adjustment. In addition, as described above, the airplane / car / train mode is intended for a subject moving in a substantially constant direction, so a higher effect can be expected by tracking. It can be expected to be good.

(2) Sports Day / Skate / Track Competition Mode When the Sports Day / Skate / Track Competition Mode is selected, the CPU 9 reads out the shooting conditions set in association with the Sports Day / Skate / Track Competition Mode and the subject tracking force. Then, focus adjustment is performed based on the read photographing condition and subject tracking force. In the athletic meet / skate / track competition mode, as described above, a medium subject tracking force is set. Therefore, the CPU 9 sets a coefficient related to the change in the image plane acceleration, that is, the coefficient a in Equation 1, smaller than the standard state, and sets a coefficient related to the change in the image plane speed, that is, the coefficient b, smaller than the standard state. Then, adjust the focus. By setting the coefficient a and the coefficient b small, the influence of tracking in the focus adjustment can be suppressed. As described above, the athletic meet / skate / track competition mode is intended for a subject that moves around, so the speed of the subject may change or the motion vector of the subject may change. Even in such a case, it is possible to prevent the image plane position from being largely deviated by suppressing the influence of tracking in the focus adjustment.

(3) Soccer / Rugby Mode When the soccer / rugby mode is selected, the CPU 9 reads out the shooting conditions and subject tracking power set in association with the soccer / rugby mode, and reads out the shooting conditions and subject tracking power. Adjust the focus based on. As described above, the smallest subject tracking force is set in the soccer / rugby mode. Therefore, the CPU 9 performs focus adjustment by setting a coefficient relating to the change in the image plane acceleration, that is, the coefficient a in Formula 1 to 0. By setting the coefficient a to 0, the influence of tracking in the focus adjustment can be made very small. As described above, since the soccer / rugby mode is intended for a subject that moves in a random manner, it is considered that a change in the speed of the subject and a change in the motion vector occur frequently. Therefore, by making the influence of tracking in focus adjustment very small, it is possible to prevent erroneous detection in the prediction of the image plane position when the speed changes or the motion vector of the subject changes. Can do. For example, in the example of FIG. 3, the motion vector is inverted from time Tc5 to time Tc6. Even in such a case, erroneous detection can be prevented. Also, in the soccer / rugby mode, as described above, there are many cases where a plurality of subjects (such as persons) exist. Even in such a case, it is possible to prevent erroneous detection of tracking another subject.

(4) Still Subject Mode When the still subject mode is selected, the CPU 9 reads out the shooting conditions set in association with the still subject mode, and performs focus adjustment based on the read out shooting conditions. In the still subject mode, no subject tracking power is set. That is, when the still subject mode is selected, normal focus adjustment is performed based on the result of focus detection by the focus detection unit 6 without tracking the subject. This is because the stationary subject mode is a mode for photographing a stationary subject and does not require tracking of the subject.

(5) Auto mode When the auto mode is selected, the CPU 9 performs processing such as subject recognition, selects one of the shooting modes (1) to (4) described above, and processes the selected shooting mode. I do.
Note that the shooting mode and menu screen described with reference to FIG. 4A are examples, and the contents of the shooting mode and menu screen are not limited to this example. For example, as shown in FIG. 4B, a plurality of shooting modes having different subject tracking forces may be provided, and the user may select the subject tracking force directly. In addition, the setting by the user may be assisted by displaying help such as the contents of each shooting mode and how to move the subject suitable for shooting in each shooting mode. With such a configuration, the user can more easily set the subject tracking force. Further, instead of displaying the menu screen on the display unit 8, selection may be made using an operation member or the like.

  As described above, according to the present embodiment, there are a plurality of shooting modes in which shooting conditions are set in accordance with how the subject moves, and different focal points are associated with each of the plurality of shooting modes for each movement method. The subject tracking force at the time of adjustment is set, and a specific shooting mode is selected from a plurality of shooting modes. Then, focus adjustment is performed based on the subject tracking force associated with the selected specific shooting mode. Therefore, the subject tracking force at the time of focus adjustment can be easily set according to the subject.

Further, according to the present embodiment, focus adjustment is performed by predicting the position of the subject according to a predetermined function, and among the predetermined function, a coefficient related to a change in the image plane acceleration and a change in the moving speed of the image plane. The focus adjustment is performed by changing at least one of the coefficients relating to the subject based on the subject tracking force. Therefore, focus adjustment with tracking can be performed more accurately according to the subject.
Further, according to the present embodiment, as a plurality of shooting modes, the first shooting mode for shooting a subject that moves in a substantially constant direction in front of the camera, and the way of movement in a circle in front of the camera are provided. The first shooting mode has at least two shooting modes of a second shooting mode for shooting a subject to be photographed and a third shooting mode for shooting a subject moving in a random manner in front of the camera. A subject tracking force greater than that in the second shooting mode is set in association with the mode, and a subject tracking force greater than that in the third shooting mode is set in association with the second shooting mode. Therefore, the user can simply set the subject tracking force at the time of focus adjustment simply by selecting a shooting mode suitable for the subject to be shot.

In the present embodiment, an example in which Expression 1 (y = ax ² + bx + c) is used as a function for predicting the image plane position of the subject has been shown. However, a coefficient related to a change in the image plane acceleration and a moving speed of the image plane. Other functions may be used as long as at least one of the coefficients related to the change in the number can be changed based on the subject tracking force. Further, in this embodiment, an example in which each coefficient is changed to change the subject tracking force is shown, but this change is an example, and the coefficient to be changed according to the configuration of the camera 100 and the type of shooting mode. Alternatively, the change method may be set appropriately.

  In the present embodiment, an example in which a shooting mode is provided according to how the subject moves is shown. However, a combination with a so-called scene shooting mode such as a portrait mode or a sports mode may be used.

It is a block diagram which shows the structure of the camera 100 of this embodiment. It is a figure explaining how a subject moves. It is a figure explaining how a subject moves. It is a figure which shows the example of a menu screen.

Explanation of symbols

1, photographing optical system 2, photographing lens drive unit 5, imaging unit 6, focus detection unit 9, CPU

Claims (4)

A plurality of shooting modes according to the movement of the subject, each of the shooting modes being set in association with shooting conditions and subject tracking power for different focus adjustments for each shooting mode. A mode setting section to select a specific shooting mode from home,
A focus adjustment unit that performs the focus adjustment based on the subject tracking force associated with the specific shooting mode selected by the mode setting unit ;
The mode setting unit includes, as the plurality of shooting modes, a fixed direction moving shooting mode for shooting the subject moving in a substantially constant direction in front of the camera, and a substantially constant direction in front of the camera. The moving direction change shooting mode for shooting the subject that moves in a manner other than the moving direction can be selected, and the movement direction change shooting mode is associated with the fixed direction moving shooting mode. A camera having a larger subject tracking force . The camera of claim 1 ,
The mode setting unit performs, as the moving direction change shooting mode , a second shooting mode for shooting the subject that moves around in front of the camera, and a movement direction that moves randomly in front of the camera. Any one of the third shooting modes for shooting the subject can be selected, and the subject tracking force larger than that in the second shooting mode is set in association with the fixed-direction moving shooting mode, and the second The subject tracking force larger than that in the third shooting mode is set in association with the shooting mode. A plurality of shooting modes according to the movement of the subject, each of the shooting modes being set in association with shooting conditions and subject tracking power for different focus adjustments for each shooting mode. A mode setting section to select a specific shooting mode from home,
A focus adjustment unit that performs the focus adjustment based on the subject tracking force associated with the specific shooting mode selected by the mode setting unit;
The mode setting unit includes, as the plurality of shooting modes, a first shooting mode for shooting the subject that moves in a substantially constant direction in front of the camera, and a movement method that circulates in front of the camera. At least two shooting modes can be selected from a second shooting mode for shooting the subject to be photographed and a third shooting mode for shooting the subject that moves in a random manner in front of the camera. Yes, the subject tracking force larger than that of the second shooting mode is set in association with the first shooting mode, and is larger than that of the third shooting mode in association with the second shooting mode. The camera, wherein the subject tracking force is set. The camera according to any one of claims 1 to 3,
The focus adjustment unit is configured to perform the focus adjustment by predicting the position of the image plane of the subject according to a predetermined function, and among the predetermined function, a coefficient related to a change in acceleration of the image plane and the At least one of the coefficient related to the change in the moving speed of the image plane is changed based on the subject tracking force, and the coefficient related to the change in acceleration is set larger as the subject tracking force becomes larger. Camera.

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