JPH04175738A - Focal point adjusting device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to a focus adjustment device that corrects out-of-focus that occurs when a composition is changed after focusing on an object.

B. Prior Art Conventionally, cameras equipped with an automatic focus adjustment device (hereinafter referred to as an autofocus device) have been put into practical use. For example, when shooting with this autofocus camera,
As shown in the figure, there is a case where it is desired to place the main subject 50 on the left side of the photographic screen 51 and sufficiently capture the background in the center and right portions of the screen 5o.

In such a case, adjust the focus by aligning the main subject 50 with the focus detection area (hereinafter referred to as the distance measurement frame) 52a in the center of the photographic screen 5]-d, and then adjust the focus after locking the focus. The camera is panned so that the subject is located on the left side of the screen 51, and a photograph is taken with a desired composition.

Problems to be Solved by the C0 Invention However, if the photographic composition is changed after once focusing on the main subject as described above, there is a problem that the main subject will be out of focus as described below.

That is, as shown in FIG. 8, if the photographing distance when the main subject 50 is aligned within the distance measuring frame 52a at the center of the screen and the focus is adjusted is dl, then the composition shown in the photographing screen 51 of FIG. 7 is obtained. The shooting distance to the main subject 50 when the camera 53 is panned until d2 is expressed by the following equation.

c32 = d1. *cosθ−
--(1,) Here, θ is the amount of change in the angle of the optical axis of the photographic lens due to a change in composition. However, at this time, the photographic lens is focused at a photographing distance fidl that is behind the photographing distance (2). , If you take a picture in this state, there will be a difference in shooting distance (dl).

-d2) the main subject is out of focus.

To solve this problem, the depth of field is deepened by increasing the aperture value, and the difference in shooting distance (cl, 1-d
, 2) or leave the desired composition as is without using an autofocus device! It is conceivable to focus using IJ. However, depending on the photographing conditions, it may not be possible to increase the aperture value, and in such a case, the former method cannot be used for photographing. Moreover, according to the latter method, the operation is complicated and the equipped autofocus function is not utilized.

SUMMARY OF THE INVENTION An object of the present invention is to provide a focus adjustment device that automatically corrects out-of-focus caused by a change in composition and adjusts the focus even if the composition is changed after focusing on a main subject.

00 Means for Solving the Problems The present invention will be explained in conjunction with FIG. 1, which is a diagram corresponding to the claims. A calculation means 101 that calculates a lens driving amount for moving the photographing lens to focus based on the photographing distance information detected by the distance information detection means 100; The present invention is applied to a focus adjusting device including a lens driving means 102 for driving a lens driving means 102 for driving a lens driving means 102 for driving a lens driving means 102 for driving a lens driving means 102 for driving a lens driving means 102 for driving a lens driving means 102 for driving a lens driving means 102 for driving a lens driving means 102 for driving a lens driving means 102 for driving a lens driving means 102 for driving a lens driving means 102 for driving a lens driving means 102;

The calculation means 101A includes an attitude detection means 103 that detects the amount of angular change in the optical axis of the photographing lens due to a change in the attitude of the camera, and the calculation means 101A detects the amount of angular change in the optical axis of the photographic lens by the attitude detection means 103. The above object is achieved by calculating the lens drive amount based on this angle change amount and photographing distance information.

Further, the calculation means 101 of the focus adjustment device according to claim 2
B calculates a correction value for the photographing distance information according to the amount of angular change in the optical axis of the photographic lens detected by the attitude detection means 103, and determines whether this correction value is within the depth of field for the photographing distance information before correction. In some cases, the lens drive amount is calculated based on the shooting distance information before correction.

E1 action Calculating means 10 of the focus adjustment device according to claim 1 A is:
When the attitude detection means 103 detects the amount of angular change in the optical axis of the photographing lens, the amount of lens drive is calculated based on this amount of angular change and photographing distance information.

Further, the calculation means 101 of the focus adjustment device according to claim 2
B calculates a correction value for the photographing distance information according to the amount of angular change in the optical axis of the photographic lens detected by the attitude detection means 103, and determines whether this correction value is within the depth of field for the photographing distance information before correction. In some cases, the lens drive amount is calculated based on the shooting distance information before correction.

F. Example FIG. 2 is a block diagram showing the overall configuration of one embodiment.

In the figure, reference numeral 1 denotes a well-known focus detection section, which detects the focus within the ranging frame 52 shown in FIG. 7 and outputs the amount of defocus. Reference numeral 2 denotes a photographing distance detection section, which detects the photographing distance from the film surface of the camera to the subject. 3 is
This is the attitude detection section of the camera, and detects the amount of angular change in the optical axis of the photographic lens. Reference numeral 4 denotes a well-known photometry calculation unit that measures light within the photographic screen and outputs brightness information of the subject.

5 is a control circuit consisting of a microcomputer and its peripheral components, which executes a control program to be described later to correct the focus shift caused by changes in the camera's posture, and also adjusts the photographic lens based on the corrected distance information. Active focus. Further, 5m is a memory that stores shooting distance information. Furthermore, 6 is a drive circuit for activating the photographic lens drive motor M, and 7 is a display section provided in the finder, which displays the completion of focusing and the completion of defocus correction.

SWI is the switch that is turned on when the shutter release is pressed halfway, SW2 is the switch that is turned on when the shutter release is pressed all the way, SW3 is the switch that is operated when starting to change the camera attitude, and SW4 is the switch that is operated when the camera attitude change has finished. It is a switch that is operated occasionally.

FIG. 3 is a diagram showing an embodiment of the photographing distance detection section 2. As shown in FIG.

A resistor 2a is provided over the entire movable range of the photographing lens 10, and one end thereof is connected to a constant voltage power supply and the other end is connected to ground. 2b is 2 resistors 2
It is a brush that slides on a, and is provided so as to move together with the photographic lens 10.

A photographic lens 10 is connected to a drive motor M via a transmission gear train 11.
When activated, a voltage corresponding to the position of the photographic lens 10 is generated in the brush 2b. The photographing distance detection section 2 calculates the photographing distance from the film surface to the subject based on this voltage value and the focal length of the photographing lens. Note that an encoder may be provided on the drive motor M or the transmission gear train 11 to detect the position of the photographing lens.

FIG. 4 is a diagram showing one embodiment of the attitude detection section 3. The camera body 12 equipped with the focus adjustment device shown in FIG. 2 is fixed on a pan head 14 provided on a tripod 13. The pan head 14 is rotatable within a horizontal plane, and thereby the camera body 12 can also be panned within the same horizontal plane.

When the camera body 12 is panned, the rotation is transmitted to the well-known photointerrupter 3a via the transmission gear train 15, and the photointerrupter 3a generates a pulse signal as the camera body 12 rotates. The attitude detection unit 3 counts the number of pulses from when the above-described attitude change start switch SW3 is turned on until the attitude change end switch SW4 is turned on, and determines the rotation angle of the camera body 12, that is, the shooting angle, based on this number of pulses. The amount of angular change in the optical axis of the lens 10 is detected. Note that the change in attitude of the camera may be detected using a gyroscope, or the change in attitude may be detected based on a signal from a geomagnetic sensor or an artificial satellite.

FIG. 5(a) is a flowchart showing a control program executed by the control circuit 4. The focus adjustment operation will be explained using the same flowchart.

After aligning the distance measuring frame 52a with the subject 50 as shown in FIG. 7, the photographer presses the shutter release halfway. When the shutter release is pressed halfway, the control circuit 4 starts executing this control program. First step S
1, the focus detection section 1 is controlled to detect the defocus amount of the photographing lens 10, and the photometry section 4 is controlled to perform photometry and calculate an exposure value. In the following step S2, the photographing distance detection unit 2 is controlled to detect the photographing distance 11dl before the composition change shown in FIG. 8, and store it in the memory 5m.

In step S3, the amount of drive of the photographic lens 10 is calculated based on the amount of defocus detected in the above step, and the motor drive circuit 6 is controlled to drive the lens drive motor M for focusing. When the active focusing of the photographic lens is completed, the process advances to step S4, and the display section 7 displays the focus.

Next, in step S5, the posture change start switch S
It is determined whether W3 has been operated, and if it has not been operated, the process proceeds to step S6; otherwise, if it has not been operated, the process proceeds to step S12.
Proceed to. In step S6, the attitude detection unit 3 is controlled to start counting the number of pulses generated from the photo interrupter 3d, and the focus of the photographing lens 10 is locked to prohibit lens driving. In the following step S7, it is determined whether the switch SW4 has been operated when the attitude change is completed, and if it has been operated, the process proceeds to step S8, where the counting of the number of pulses generated by the photo interrupter 3a is finished, and a photograph is taken based on the count value of the number of pulses. The amount of angular change θ of the optical axis of the lens 10 is calculated. Furthermore, in step S9, a correction value d2 of the photographing distance is determined according to the above-mentioned equation (1).

In step SIO, a lens rotation amount correction value is determined based on the corrected photographing distance d2 calculated in the above step, and the motor parking circuit 6 is controlled to drive the photographing lens drive motor M for correction. When this correction drive is completed, the process proceeds to step S, and a correction complete Y is displayed on the display section 7.

Next, switch SL2 is used as the main guide, and switch S (incl. 2) determines whether the shutter release is fully pressed. Exposure is performed based on the exposure value determined. When the above processing is completed, execution of the program is terminated.

In the following embodiments, the correction value d2 of the photographing distance due to the change in composition was calculated and the compensation drive of the photographic lens 10 was carried out.
If the depth of field Δd with respect to dl is within the range, no correction may be performed. The control program in this case is the fifth one.
Shown in Figure (b). Incidentally, steps that perform the same processing as in the program shown in FIG. 5(a) are given the same reference numerals, and the explanation will focus on the differences.

The program up to step S9 is the same as the program shown in FIG. Based on the aperture value calculated in S1, the depth of field Δd for the photographing hole fidl before correction is set by 7 degrees. In the following step S9b,
The difference in shooting distance before and after correction (dl-d2) is the depth of field Δd
It is determined whether the shooting distance d2 after correction is within the depth of field Δd with respect to the shooting distance d1 before correction. If the depth of field is within Δd, the following steps S], 0 and Step S1. 1 is skipped and the process proceeds to step S12, where the shutter release is waited for and exposure is performed. If the depth of field is outside the depth of field Δd, the process proceeds to step SIO and processes subsequent to the lens correction drive described above are performed.

In the above embodiments, a case will be described in which, as shown in FIG. 7, after focusing the subject 50 on the distance measuring frame 52a at the center of the photographing screen and adjusting the focus, the posture of the camera is changed until a desired composition is obtained. However, as shown in FIG. 6(a), the distance measurement frames 21a, 21b, 2
A case will be described in which the composition is changed after focusing the main subject 50b on the distance measuring frame 2]-b on the left side of the screen in 1c and adjusting the focus.

As shown in FIG. 6(b), the angle between the optical axis 22a of the photographing lens 10 with composition [M+ change resistance and the straight line connecting the main subject 50h and the camera body 12] is 01, and the optical axis after composition change is assumed to be 01. Assuming that 22b is 22b, the correction value d2 of the photographing distance after changing the composition is obtained by the following equation.

d2=dl*cos (θ1+θ) / e o s
θ1... (2) Here, 0 is a positive sign when the attitude of the camera 12 is changed so that the optical axis 22a moves away from the subject 50b, and a negative sign when the attitude is changed when the optical axis 22a approaches the subject 50b. do.

In this way, the present invention can also be applied to a camera having a plurality of focus detection areas in the object field.

As explained above, when the attitude detection unit 3 detects the angle change θ of the optical axis of the photographic lens 10 after focus adjustment, this angle detection amount θ and the photographing distance d before the camera composition is changed.
The photographing distance d2 after the composition change is calculated based on 1 and 1, and the lens active amount is determined based on this photographing distance d2 and the photographing lens 10 is driven. You can adjust the focus accurately and always take photos with the main subject in focus.

In the above modification, when the shooting distance d2 after the composition change is within the depth of field for the shooting distance d1 before the composition change, the shooting distance is not corrected, and the shooting distance d1 before the composition change is Since the lens frame movement amount is determined based on the amount of movement of the lens frame and the photographic lens 10 is driven for focusing, it is possible to shorten the focus adjustment time while maintaining high focusing accuracy for the main subject.

In the above embodiments, - after first adjusting the focus of the photographic lens on the main subject, the difference in photographing distance that occurs due to a change in composition is corrected, and based on this correction value, the photographic lens is driven for correction after changing the composition. , the photographing path jl is corrected after the composition is changed without focusing the photographic lens before changing the composition.
Focus adjustment may be performed at once based on td2. That is, the photographing path mdi is calculated from the focus detection result for the main subject before the composition is changed, and the posture of the camera is changed until the desired composition is obtained without driving the photographic lens for focusing. Then, based on the amount of angular change θ of the optical axis of the photographing lens, the photographing distance d before the composition change obtained previously is corrected, and the photographing lens 10 is driven to focus at once based on the correct photographing distance d2 after the composition change. do.

In this way, the focus adjustment time can be further shortened.

Further, in the above embodiment, the range of attitude change of the camera is determined by the pan head 14.
Although we used a rotatable plane above, if we use the above-mentioned gyroscope, geomagnetic sensor, position signals from artificial @stars, etc., it will be possible to adjust the main subject after changing the composition no matter how the camera's attitude changes. It is possible to correct out of focus.

In the configuration of the above embodiment, the photographing distance detection section 2 serves as the distance information detection means 100, and the control circuit 5 serves as the calculation means 101A.
, 1. The motor drive circuit 6 and the motor M drive the lens drive means 102, and the attitude detection section 3 drives the attitude detection means 1.
03 respectively.

G. Detailed Description of the Invention According to the present invention, when the attitude detection means detects the angle change of the optical axis of the photographing lens, the lens active amount is determined based on the angle change and the photographing distance information. is calculated, it is possible to accurately adjust the focus on the main subject after changing the composition, and a photograph can always be taken with the main subject in focus. Further, according to the present invention, it becomes possible to measure the distance over the entire tI5 shooting screen with a camera having a limited range of distance measurement frames.

In addition, a correction value for shooting distance information is calculated according to the amount of angular change in the optical axis of the photographing lens detected by the attitude detection means, and when this correction value is within the depth of field for the shooting distance information before correction. Since the lens active amount is calculated based on the shooting distance information before correction, it is no longer necessary to drive the shooting lens for correction when changing the composition, ensuring focus accuracy for the main subject and reducing focus adjustment time. can.

[Brief explanation of the drawing]

FIG. 1 is a complaint correspondence diagram. FIG. 2 is a block diagram showing the overall configuration of one embodiment, FIG. 3 is a diagram showing one embodiment of the shooting distance detection section, FIG. 4 is a diagram showing one embodiment of the attitude detection section, and FIG. a) is a flowchart showing a focus adjustment control program, FIG. 5(b) is a flowchart showing a modification thereof, and FIGS. 6(a) and (b) explain focus adjustment operation by a camera having a plurality of ranging frames. FIG. 7 is a diagram illustrating the conventional focus adjustment operation when changing the composition, and FIG. 8 is a diagram illustrating the difference in shooting distance for the main subject before and after changing the composition. 1; Focus detection section 2: Shooting distance detection section 2a: Resistor
2b = Brush 3: Attitude detection unit 3a: Photo interrupter 5; Control circuit 5m = Memory 6: Motor drive circuit 7: Display unit 10: Photographic lens 11, 15: Transmission gear train 12: Camera body 13: Tripod 14: Pan head 21a, 21b, 21c, 52, 52a: Distance measurement frame 22a, 22b: Optical axis 50.50a, 50b: Main subject 51: Shooting screen SW3: Attitude change start switch SW4: Attitude change start switch

Claims (1)

[Claims] 1) Distance information detection means for detecting information corresponding to the photographing distance to the subject; and a system for driving the photographing lens to focus based on the photographing distance information detected by the distance information detection means. In a focus adjustment device comprising a calculation means for calculating a lens drive amount, and a lens drive means for driving the photographing lens according to the lens drive amount calculated by the calculation means, The calculation means includes an attitude detection means for detecting an amount of angular change of the axis, and when the amount of angular change of the optical axis of the photographic lens is detected by the attitude detection means, the calculation means calculates the amount of angular change and the photographing distance information. A focus detection device that calculates a lens drive amount based on. 2) In the focus adjustment device according to claim 1, the calculation means calculates a correction value of the photographic distance information according to the amount of angular change of the optical axis of the photographic lens detected by the attitude detection means, A focusing device characterized in that when this correction value is within the depth of field for the photographing distance information before correction, a lens driving amount is calculated based on the photographing distance information before correction.