JP2002341232A - Camera, interchangeable photographic lens, and camera system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate trouble due to a shift in imaging plane positions between a 1st and 2nd sensors. SOLUTION: The 1st and 2nd sensors are arranged extending in mutually different directions so as to perform focus detection in the same focus detection area; and it is decided whether the quantity of the shift between the imaging plane position of an image whose focus is detected by the 1st sensor and the position of the imaging plane position of an image whose focus is detected by the 2nd sensor exceeds a specific value and when so, one of the 1st and 2nd sensor is made ineffective.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a camera for detecting a focus in the same focus detection area by first and second sensors extending in mutually different directions, and an interchangeable photographing lens mountable to this type of camera. And a camera system comprising a camera and a taking lens.

[0002]

2. Description of the Related Art A horizontal sensor extending in a horizontal direction and a vertical sensor extending in a vertical direction with respect to a photographing screen are arranged in a cross shape, and focus detection in the same focus detection area is performed by these vertical and horizontal sensors. Cameras are known. In such a focus detection method, a shift may occur between the image plane position of the image whose focus is detected by the horizontal sensor and the image plane position of the image whose focus is detected by the vertical sensor. The amount of the deviation varies depending on the photographing lens mounted on the camera, but generally becomes larger as the focus detection area is farther from the optical axis and as the photographing magnification is higher.

[0003]

Originally, the focusing position of the photographing lens for an object at the same distance is only one point in the direction of the optical axis. The judgment is made in two places. For this reason, for example, in a camera employing a focus aid, the focus indication is turned on at two different positions during manual focusing, and the photographer may be confused.

SUMMARY OF THE INVENTION An object of the present invention is to provide a camera which eliminates the inconvenience caused by the displacement of the imaging plane position between two sensors.
An interchangeable photographing lens and a camera system are provided.

[0005]

According to the first aspect of the present invention, there is provided a first and a second sensor which are arranged so as to extend in different directions from each other so as to perform focus detection in the same focus detection area.
It is determined whether or not the amount of deviation between the image formation plane position of the image detected by the first sensor and the image formation plane position of the image detected by the second sensor exceeds a predetermined value. A control device that invalidates one of the first and second sensors in the event that this occurs, thereby solving the above problem. “Invalidating either one of the first and second sensors” means prohibiting focus detection by one of the sensors (Claim 2).
Alternatively, focus detection is permitted, but the focus detection output is not used (claim 3). The invention of claim 4 is
The above-described determination is performed based on information from an interchangeable photographing lens mounted on the camera. The interchangeable photographing lens according to the invention of claim 5 can be mounted on a camera having first and second sensors arranged to extend in different directions from each other in order to perform focus detection in the same focus detection area. And an output device for outputting, to a camera, shift information relating to a shift amount between an image plane position of an image focus-detected by the first sensor and an image plane position of an image focus-detected by the second sensor. Things. According to a sixth aspect of the present invention, information indicating whether or not the shift amount exceeds a predetermined value is output as the shift information. According to a seventh aspect of the present invention, information indicating a shift amount is output as shift information. An eighth aspect of the present invention is an interchangeable lens having a variable photographing magnification, and outputs displacement information according to the set photographing magnification. In the camera system according to the ninth aspect of the present invention, first and second sensors arranged to extend in different directions from each other to perform focus detection in the same focus detection area, and focus detection is performed by the first sensor. An output device for outputting shift information relating to a shift amount between the image forming surface position of the image and the image forming surface position of the image whose focus is detected by the second sensor; and outputting whether or not the shift amount exceeds a predetermined value. Judgment is made from the output result of the device.
A control device for invalidating one of the second sensors.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to FIGS. FIG. 1 shows a configuration of a camera system including a camera body 10 and an interchangeable photographing lens 20. First, the optical system will be described. The taking lens 20 has first to third lens units L1, L2, and L3, and zooming is performed by moving each of the lens units L1 to L3 individually in the optical axis direction. Focusing is performed when the two lens units L2 move alone.

The light beams transmitted through the lens groups L1 to L3 are incident on the camera body 10 and a part thereof is
The light is reflected at 1 and guided to a finder optical system (not shown), and the other part is transmitted through the main mirror 11, reflected by the sub-mirror 12 and made incident on the focus detection device 13.

The focus detection device 13 employs a well-known phase difference detection method. In the present embodiment, as shown in FIG. 2, three areas (focus detection areas) AR1, AR2, AR
3 focus detections are possible. The focus detection area AR1 is located at the center of the screen, and the focus detection areas AR2 and AR3 are set at positions left and right separated by a distance h. Reference numerals 13h and 13v in the figure denote images obtained by projecting the sensors constituting the focus detection device 13 on a shooting screen, and three areas AR1 to AR
3, a horizontal sensor 13h extending in the horizontal direction of the screen and a vertical sensor 13v extending in the vertical direction are arranged in a cross shape. Each of the sensors 13h and 13v is composed of a pair of CCDs, receives the incident light beam, and outputs a focus detection signal corresponding to the amount of received light. Less than,
Sensor 13 for detecting focus of left and right areas AR2 and AR3
h and 13v are called side area sensors.

The camera performs focusing based on a focus detection result of any one of the three areas AR1 to AR3. Which area to select may be determined by the operation of the photographer, or may be determined by the camera based on the focus detection result.

The focus detection signals (electric signals corresponding to the received light beam of the subject) from the sensors 13h and 13v are input to a microprocessing unit (hereinafter, referred to as MPU) 14. The MPU 14 inputs a focus detection signal in response to, for example, a half-press operation of a release button (not shown), and calculates a defocus amount corresponding to a shift amount of the photographing lens 20 from a focus position based on the input signal. The calculation result is sent to the MPU 21 on the photographing lens 20 side, and the lens side M
The PU 21 outputs a drive signal corresponding to the defocus amount to the motor drive circuit 22. The motor drive circuit 22 rotates the motor 23 based on the input drive signal, and drives the lens groups L1 to L3 via the transmission mechanism 24. The motor encoder 25 detects the amount of rotation of the focusing motor 23 and inputs the rotation amount to the lens side MPU 21, based on which the MPU 21 performs feedback control of the motor 23. By this focusing control, the taking lens 20 is focused on the subject.

[0011] The zoom encoder 26 is connected to the photographing lens 20.
Is detected and input to the MPU 21. The distance encoder 27 detects the position of the second lens unit L2 as photographing distance related information, and inputs the information to the MPU 21. The MPU 21 previously stores image plane position shift information (described later) according to each focal length and shooting distance as a table.

Next, a description will be given of the deviation of the image plane position between the vertical sensor 13v and the horizontal sensor 13h. In general, in a photographing optical system, for a subject at the same distance, the position of the image forming plane (M image plane) of a meridional light beam and
Ideally, the position of the image plane (S image plane) of the sagittal light beam coincides, but at present, it does not always coincide. Whether or not the image forming position is shifted depends on the lens to be mounted. In recent years, with the demand for a high-magnification zoom lens and the downsizing of the photographing optical system, for example, as shown in FIG. There are many photographing lenses in which deviation occurs. Such a shift amount of the imaging position becomes larger as the imaging magnification becomes higher, that is, as the telephoto side and the imaging distance become shorter, and as shown in FIG. It is assumed that the photographing lens 20 of the present embodiment has the characteristics shown in FIG.

FIG. 2 shows an example in which the side area sensor exists at the position of the image height h, and the shift amount of the image plane position of the S / M image at this position is ΔD (FIG. 3). Now, consider a case where a person (subject) wearing a horizontal stripe shirt exists at the position of the image height h as shown in FIG. The horizontal sensor 13h cannot detect the focus because of the low contrast, but the vertical sensor 13v can detect the focus because the horizontal sensor 13v can detect the contrast. S for horizontal stripes
Since an image is formed, the image forming position is Ds in FIG. On the other hand, in the case of a person wearing a vertical striped shirt as shown in FIG. 5,
Contrary to the above, the focus can be detected only by the horizontal sensor 13h. In this case, since the image is an M image, the image forming position is Dm. In each of the examples shown in FIGS. 4 and 5, since the focus detection cannot be performed by one of the sensors, the problem caused by the shift of the imaging position does not occur.

Next, consider a case where a person wearing a diagonally striped shirt exists at the position of the image height h as shown in FIG. In this case, the image is not an S image nor an M image but an intermediate image, and the focus can be detected by both the vertical sensor 13v and the horizontal sensor 13h. For this reason, the conventional camera may recognize the image formation position as Ds or Dm in some cases, and even for the same subject, the in-focus position of the lens differs depending on the timing of focus detection. is there.
For example, if focus detection and focusing are attempted again on the same subject while the shooting lens 20 is in focus on the subject, the shooting lens 20 should not move if the shooting distance is unchanged. However, the photographing lens 20 may move by an amount corresponding to the deviation amount ΔD of the image forming position, which gives the photographer distrust. In a camera with a focus aid, if the lens is driven from one end (infinity or closest), the focus mark is displayed at two places (Ds, Dm), and the photographer is confused. There is. In order to eliminate such a shift of the image plane position, the zoom range must be narrowed and the lens barrel must be enlarged.

Therefore, in the present embodiment, the MPU 21 of the taking lens 20 stores information on the deviation of the imaging plane position unique to the lens, and invalidates one of the vertical and horizontal sensors based on the information. The above-described problem is prevented from occurring even in a camera in which the image plane position shifts. Hereinafter, the details will be described.

FIG. 7 shows an example of shift information stored in the lens side MPU 21. In this example, the zooming state of the lens (Z0 (WIDE) to Z10 (TELE))
A flag (1 or 0) is assigned corresponding to the shooting distance (D0 (infinity) to D10 (closest)). When the deviation amount ΔD of the image plane position (here, the best image plane position) is relatively small, the flag is more than the range (image plane position width) in which the camera body determines to focus. When it is considered that the deviation amount is small and the above-described problem does not occur, “0” is set. On the other hand, if the shift amount ΔD is larger than the focus determination range and it is considered that the above problem may occur, “1” is set. As can be seen from the figure, the flag is set to 1 on the telephoto side and on the close side, that is, when the shooting magnification is high. The state of this flag is determined in advance by calculating the deviation amount ΔD by an experiment or the like, and based on the result.

FIG. 8 is a flowchart showing the focus detection operation in this embodiment. In step S1, the side area (AR2 or AR3) is selected as the focus detection area, and when the half-press operation of the release button is confirmed in step S2, the processing after step S3 is executed. In step S3, the image plane position deviation information (flag) is read from the lens-side MPU 21. That is, the lens side MP
U21 reads the outputs of the zoom encoder 26 and the distance encoder 27 to determine the current state of the photographing lens 20 (focal length and photographing distance), and selects the state of the flag corresponding to that state from the table of FIG. This is output to the MPU 14 on the camera body side.

The main body side MPU 14 is provided with a lens side MPU 21
It is determined whether or not the flag input from is 1 (step S
4) If the flag is 0, it is determined that the deviation amount ΔD of the imaging plane position is equal to or smaller than a predetermined value in the current state of the photographing lens 20, and the vertical / horizontal sensor 1 corresponding to the focus detection area is determined.
Both 3v and 13h are made valid (step S5). On the other hand, if the flag is 1, it is determined that the deviation amount ΔD of the image plane position exceeds the predetermined value in the current state of the photographing lens 20, and one of the vertical and horizontal sensors (here, the horizontal sensor) is invalidated. (Step S6).

In step S7, focus detection processing and focusing processing are performed based on the settings in steps S5 and S6. That is, when the process passes step S6,
Focusing is performed based on only the focus detection output of one sensor. In this case, focus detection by the other sensor may be prohibited, or focus detection may not be prohibited and its output may not be used. On the other hand, when step S5 is passed, focusing is performed based on the focus detection outputs of the vertical and horizontal sensors as before.

Here, when the flag is determined to be 1, either the vertical or horizontal sensor may be basically invalidated. However, if one of the sensors cannot detect the focus due to low contrast, the sensor is inevitably disabled. The sensor becomes invalid. And above,
Immediately after the half-press operation, the processes of steps S3 to S6 are performed. Immediately after the half-press operation, both sensors are enabled to perform focus detection. If both sensors can detect the focus, the processes of steps S3 to S6 are performed. If one of the sensors cannot detect the focus due to low contrast, the processing of steps S3 to S6 may not be performed.

The above description is based on the side areas AR2 and AR3.
Is selected in the central area AR
When 1 is selected, the image height is almost zero, so that the image plane position does not shift, and the processing shown in steps S3 to S6 is not performed.

As described above, the deviation ΔD between the image plane position of the image detected by the horizontal sensor 13h and the image plane position of the image detected by the vertical sensor 13v exceeds a predetermined value. In this case, one of the sensors becomes invalid, so that the focus determination is not performed at two places as in the related art. Therefore, for example, when focus detection and focusing are attempted again on the same subject while the shooting lens 20 is in focus on the subject, the shooting lens 20 does not move if the shooting distance is unchanged. Further, there is no inconvenience that the focus mark is displayed at two places in the focus aid.

In the above embodiment, the vertical and horizontal sensors 13
v, 13h are the first and second sensors, and the main body side MPU 1
4 constitutes a control device, and the lens side MPU 21 constitutes an output device.

The shift information input from the lens side MPU 21 is not limited to the flag as shown in FIG. 7, but may be, for example, information in which the shift amount ΔD itself is quantified as shown in FIG. In this case, the body-side MPU 14 inputs the shift amount ΔD from the lens-side MPU 21, and if the shift amount ΔD is equal to or less than a predetermined value, both sensors are enabled. If the shift amount ΔD exceeds the predetermined value (in the case of FIG. ), One of the sensors may be disabled. According to this method, there is an advantage that a threshold value for determining whether to invalidate one of the sensors can be set depending on circumstances of the camera body. For example, in a camera having a narrow focus determination range (imaging position width), that is, a camera in which focus determination is severe, a focus determination mark is easily lit at two places when using a focus aid. May be set to a lower value, and conversely, for a camera whose focus determination is not so severe, the threshold value of the determination may be set higher.

Although the above description has been made of a camera whose lens is interchangeable, the present invention can be applied to a camera having a fixed lens. In this case, the information on the shift of the image plane position may be stored in the MPU on the main body side. Although the description has been given of a camera capable of auto-focusing, the present invention can be applied to a manual focus camera as long as it has a focus aid. Alternatively, an autofocus camera having no focus aid function may be used. Further, the arrangement of the first and second sensors does not necessarily have to be in the horizontal direction and the vertical direction, and may not be in the shape of a cross.

[0026]

According to the present invention, the amount of shift between the image plane position of the image detected by the first sensor and the image plane position of the image detected by the second sensor exceeds a predetermined value. Is determined, and if it is determined to exceed, either one of the first and second sensors is invalidated, so that any photographing lens causes a problem due to the displacement of the image plane. (For example, the problem that the focus determination mark is lit at two places during focus aid) can be avoided. According to this, it is not necessary to design the photographing lens so that the above-described displacement does not occur, and it does not hinder high magnification and miniaturization of the photographing lens.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a camera system according to an embodiment.

FIG. 2 is a diagram showing an arrangement of a focus detection area and a focus detection sensor in the camera.

FIG. 3 is a view for explaining a shift of an imaging plane position between an S image and an M image.

FIG. 4 is a diagram showing an example in which a horizontally striped subject exists in a side area.

FIG. 5 is a diagram showing an example in which a vertically striped subject exists in a side area.

FIG. 6 is a diagram illustrating an example in which a diagonally striped subject exists in a side area.

FIG. 7 is a view showing displacement information stored in a lens-side MPU.

FIG. 8 is a flowchart showing the procedure of focus detection and focusing processing.

FIG. 9 is a diagram showing another example of shift information.

[Explanation of symbols]

 Reference Signs List 10 camera body 13 focus detection device 14 camera body side MPU 20 photographing lens 21 lens side MPU 23 focusing motor L1 to L3 lens group

Continued on the front page F term (reference) 2H011 AA01 BA21 BB02 CA01 CA28 2H051 AA05 AA06 BA02 BA18 CB20 CE21 CE28 DA07 DA31 DA32 DB01 EB13 5C022 AB27 AB29 AB44 AC54 AC74

Claims (9)

[Claims] 1. A first and a second sensor arranged so as to extend in different directions so as to detect a focus in the same focus detection area, and an image forming surface of an image focus detected by the first sensor. It is determined whether or not the amount of deviation between the position and the image plane position of the image detected by the second sensor exceeds a predetermined value, and if it is determined that the amount of deviation is larger than one of the first and second sensors, And a control device for invalidating the camera. 2. The control device according to claim 1, wherein the control device prohibits focus detection by one of the first and second sensors when determining that the deviation amount exceeds a predetermined value. Camera. 3. The control device according to claim 1, wherein when the control device determines that the deviation amount exceeds a predetermined value, the control device disables an output of one of the first and second sensors.
The camera according to. 4. The control device according to claim 1, wherein the control device performs the determination based on information on the image plane position from an interchangeable photographing lens mounted on a camera. Camera. 5. An interchangeable photographing lens attachable to a camera having first and second sensors arranged to extend in different directions to perform focus detection in the same focus detection area, wherein An output device for outputting, to the camera, shift information relating to a shift amount between an image plane position of an image whose focus is detected by one sensor and an image plane position of an image focus detected by the second sensor; An interchangeable photographing lens characterized by the following. 6. The interchangeable photographing lens according to claim 5, wherein the output shift information is information indicating whether or not the shift amount exceeds a predetermined value. 7. The interchangeable photographic lens according to claim 5, wherein the output shift information is information indicating the shift amount. 8. The interchangeable type according to claim 5, wherein the photographing magnification is variable, and the output shift information is information corresponding to the set photographing magnification. Shooting lens. 9. A first and a second sensor arranged so as to extend in different directions so as to detect a focus in the same focus detection area, and an image forming surface of an image focus-detected by the first sensor. An output device that outputs shift information related to a shift amount between a position and an imaging plane position of an image that is focus-detected by the second sensor; and an output device that determines whether the shift amount exceeds a predetermined value. Judging from the output result, if it is judged to exceed, the first,
A camera system comprising: a control device that invalidates one of the second sensors.