JPH0266529A - Automatic focusing camera with external finder - Google Patents

Abstract

PURPOSE:To correct a finder field accurately and to securely perform focusing by discriminating, based on range-finding information, whether an object is within a prescribed short distance or not, activating a field frame shifting means, and warning when a field frame is being shifted, and inhibiting a photographing operation during that period of time. CONSTITUTION:An automatic focusing camera with an external finder is provided with a discriminating means 112 and a first warning means 113; based on the range- finding information, the means 112 discriminates whether the object is within the prescribed short distance or not; when the object is within the distance, the means 113 warns about that. Additionally, the automatic focusing camera is provided with the field frame shifting means 115, a second warning means 116, and photographing operation controlling means 117 and 112; the means 115 shifts the field frame to a prescribed position in response to an external switch operated based on the warning and shifts the field frame again based on the range-finding information given in range- finding area; when the frame is being shifted, the means 116 warns about that; the means 117 and 112 inhibit the photographing operation during the period that the warning is given. The finder field is accurately corrected and the object is securely focused, therefore, photographing with the intended scope is performed.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Application of the Invention) The present invention relates to an improvement in an autofocus camera having an external finder device having an optical system independent of a photographic lens having a variable focal length.

(Background of the Invention) Most of the conventional external finder devices for this type of camera are of the Albata type bright frame type, which changes the image magnification in conjunction with the zooming of the photographing lens. The balax of the finder (device) is determined by the infinity and near field frame indications printed on the optical member inside the finder as shown in Figure 3.
The photographer made corrections by switching the field of view according to the subject distance.

However, in such a method, accurate correction is difficult because correction is left to the photographer's intuitive judgment, and correction is difficult because there is no frame displayed between infinity and close range.

In FIG. 3, 21 is a visual field frame on the infinity side, 22 is a visual field frame on the closest side, and 23 is a distance measurement mark indicating the distance measurement range. The amount of misalignment increases as the focal length of the photographic lens increases and as the photographing area moves closer to the close-up side.As the magnification of zoom lenses increases in recent years and the photographing area moves closer to the close-up side, the above-mentioned problem becomes more noticeable. It has become.

Therefore, a method can be considered in which the viewfinder field frame is moved based on the distance measurement information from the AF means in the camera and vararax is corrected. However, if the AF means itself has vararax and causes distance measurement errors, Not only will it not match, but the viewfinder's balax correction will also cause an error.
It will not work as a system.

FIG. 4 is a diagram explaining the variation between the photographic lens and the external finder, where 31 is the photographic lens, 32 is the external finder, 33 is the reference lens for AF, and 34 is the AF
The AF means here is an active or passive method using triangulation.

In this state, when the same part as a certain point on the finder optical axis is imaged by the photographing lens 31, the amount of deviation (varallax) P from the photographing optical axis to the image point is approximately as follows. is expressed in

P4vf-F/(D-2f) Here, f is the focal length of the photographic lens 31, and F is the distance between the optical axes of the photographic lens 31 and the finder 32 (F,, FV).
, D is the subject distance, and balax P is the focal length of the photographic lens 31 and the distance between the photographic lens 31 and the external finder 3.
It increases almost in proportion to the distance F between the optical axes of 2, and is inversely proportional to the subject distance.

For example, f = 40mm, FY = 21mm, D =
In the case of 0.5 m, it is 1, P 41.68 mm, and the screen size is 8.8 x 6.6 J, 2 x 3 inches COD.
In the case of a camera using
”, it reaches 50% in the Y direction. Therefore, in order to perform this parallax correction, it is necessary to move the viewfinder field frame in accordance with the subject distance and the focal length of the photographing lens 31, but as shown in the AF means in FIG. 31 and vararax, the distance measurement information obtained here has an error, making it impossible to correct the finder field of view.

(Object of the Invention) An object of the present invention is to solve the above-mentioned problems, and an external finder device capable of accurately correcting the viewfinder field of view, reliably focusing on the subject, and photographing the intended range. An object of the present invention is to provide an autofocus camera having the following features.

(Features of the Invention) In order to achieve the above object, the present invention provides a discriminating means for discriminating whether or not a subject is within a predetermined close distance from distance measurement information from a distance measuring means; A warning means for giving a warning when it is determined that the subject is within a predetermined close distance, and a field frame of the external finder device being set in a predetermined manner according to an external switch operation performed in response to the warning from the warning means. and a field frame moving means for moving the field frame again based on distance measurement information obtained by the distance measurement means in the distance measurement area changed by the movement, and a field of view by the field frame movement means. A second warning means that warns when the frame is moving, and a photographing operation control means that prohibits the photographing operation while the second warning means is warning are provided, thereby giving a warning that vararax is occurring. At the same time, in response to the external operation performed by the warning, - first move the field of view frame to a predetermined position, eliminate the disparity between the distance measurement optical axis and the photographing optical axis, and then use the distance measurement information at that position. The field frame is then moved again to eliminate the disparity between the viewfinder optical axis and the photographing optical axis, and a warning is given while the field frame is being moved, and photographing operations are prohibited during that time. shall be.

(Embodiments of the Invention) Hereinafter, the present invention will be described in detail based on illustrated embodiments.

FIG. 2(a) is a schematic configuration diagram of a field frame moving means that performs parallax correction based on distance measurement information, and FIG.
) is a diagram showing the movement state of the finder field of view at that time.

In Figure 2, 1 is the focusing lens of the photographing lens, 2
is a correction cam that is integrated with the focusing lens 1 and moves in conjunction with the focusing operation; 3 is a viewfinder field frame that moves in conjunction with the correction cam 2; 4 is fitted into the rack of the correction cam 3, and 5 is a motor for driving the gear 4, 6 is a finder optical system, and 7 is a distance measurement mark (AF field of view) printed on the field frame 3 that indicates the distance measurement range. frame), 8 is a guide bin, and 9 is a guide frame that is integrally formed with the visual field frame 3 and that, together with the guide bin 8, regulates the moving direction of the visual field frame 3. Note that the correction cam 2, gear 4, motor 5, guide bin 8, and guide frame 9 correspond to viewing frame moving means.

In the above configuration, when photographing, the motor 5 is driven and controlled based on distance measurement information obtained by the AF circuit, which will be described later, and the driving force rotates the gear 4 to perform correction integrated with the focusing lens 1. Cam 2 begins to move in the six directions of the arrow, and focusing lens 1 moves along with this.
also starts moving in the optical axis direction. In other words, the focus operation is started. Also, in conjunction with this, the finder field frame 3, which is configured to always come into contact with the cam portion of the correction cam 2,
While the direction of movement is restricted by the guide bin 8 and guide frame 9, it moves in the direction of arrow B while being guided by the cam portion thereof.

Next, a series of operations during photographing will be briefly explained using the block diagram shown in FIG.

When it is detected that the subject is in a predetermined close range based on distance measurement information from the AF circuit 111, the control circuit 112 turns on the LED.
The first warning circuit 113 consisting of the following circuit issues the warning and immediately prohibits subsequent photographing operations. When the warning is given, the photographer operates an external switch (not shown) to move the field of view frame 3 in the close direction. The frame moving means 115 is driven to move the viewing frame 3 to a predetermined close position (Fig. 1 (a) (b)
(dotted line position). Also, during this drive period (while the visual field frame 3 is moving), the control circuit 113 causes the second warning circuit 116 to issue a warning indicating this. When such a warning is issued by the second warning circuit 116, the photographing prohibition instruction circuit 117 instructs the control circuit 112 to prohibit the photographing operation during the warning period. Therefore, while the field frame 3 is moving, the photographing operation is temporarily interrupted.

When the movement of the visual field frame 3 is completed, the control circuit 112 controls the AF arranged in the AF circuit 111 based on distance measurement information from the AP circuit 111 performed at that position.
Based on the distance measurement result with almost no parallax between the sensor and the photographing lens 116, the field frame 3 is adjusted slightly (of course, along with this, the photographing lens 116
At the same time, the photographing prohibition signal inputted from the photographing prohibition instruction circuit 117 is stopped, and the photographing operation is restarted.

Here, a series of photographing operations will be briefly explained.

The subject image that has passed through the photographic lens 118 and whose light amount has been controlled by the diaphragm/shutter 119 is passed through the low-pass filter 120.
The signal is photoelectrically converted by the CCD 121 and stored as an image signal. Thereafter, the image signal is sent to the next stage signal processing circuit 122, where it is subjected to known signal processing.
The information is recorded in a recording unit 123, which is a medium such as a magnetic disk.

In FIG. 1, 124 is an AE circuit, and the aperture/shutter 119 is controlled based on information from this circuit. Further, 125 is a zoom drive circuit that performs zooming of a zoom lens (not shown) in the photographing lens 118, and 126 is a CCD drive circuit that drives the CCD 121.

According to this embodiment, in a camera having a photographing lens and an external viewfinder having an optical system independent of the photographing lens and an AF circuit, if a subject is detected to be within a predetermined close distance, a warning is issued. According to the operation of the external switch performed later, the field of view frame of the finder is moved to a predetermined close position, and the field of view of the finder is adjusted to correct the balax of the photographing lens and the external finder based on the distance measurement information after the movement. In addition to moving the frame, the photographing operation is interrupted while the field frame of the finder is being moved to a predetermined close position, so that the AF circuit does not have any balax between it and the photographing lens. Even in the case where the camera is configured to hold the camera, it is possible to accurately correct the finder's vararax and photograph the intended range under proper focusing.

(Correspondence between the invention and the embodiments) - In this embodiment, the control circuit 112 serves as the discrimination means of the present invention, the warning circuit 113 serves as the first warning means, the visual field frame moving means 115 serves as the visual field frame moving means, and the second visual field frame moving means warning circuit 116
corresponds to the second warning means, and the photography prohibition instruction circuit 117 and the control circuit 112 correspond to the photography operation control means, respectively.

(Effects of the Invention) As explained above, according to the present invention, there is provided a determining means for determining whether or not a subject is within a predetermined close distance from distance measurement information from a distance measuring means; A warning means for giving a warning when it is determined that the subject is within a predetermined close distance, and a field frame of the external finder device being set in a predetermined manner according to an external switch operation performed in response to the warning from the warning means. and a field frame moving means for moving the field frame again based on distance measurement information obtained by the distance measurement means in the distance measurement area changed by the movement, and a field of view by the field frame movement means. A second warning means that warns when the frame is moving, and a photographing operation control means that prohibits the photographing operation while the second warning means is warning are provided, thereby giving a warning that vararax is occurring. At the same time, in response to the external operation performed by the warning, - first move the field of view frame to a predetermined position, eliminate the disparity between the distance measurement optical axis and the photographing optical axis, and then use the distance measurement information at that position. The field frame is then moved again to eliminate the discrepancy between the viewfinder optical axis and the photographing optical axis, and a warning is given while the field frame is being moved, and photographing operations are prohibited during that time. This allows you to perform accurate viewfinder field of view correction, allowing you to reliably focus on the subject and shoot within the intended range.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of the present invention, and FIG. 2 (
a) (b) is a mechanical diagram showing a specific example of the structure of the field frame moving means shown in Figure 1, Figure 3 is a front view showing the field of view of a conventional finder, and Figure 4 is a balarax of this type of camera. FIG. 1...Focusing lens, 2...
Correction cam, 3... field frame, 4... gear, 5... motor, 8... guide bin,
9... Guide frame, 111... AF circuit, 112... Control circuit, 113... Old... First warning circuit, 114... Focusing circuit ,1
15...Field frame moving means, 116 Old...Second
Warning circuit, 117... Photography prohibition instruction circuit, 1
18... Photography lens.

Claims (1)

[Claims] (1) In an autofocus camera that has an external finder device that includes a distance measuring device that automatically measures the distance to a subject and an external finder device that has an optical system independent of the photographic lens, A determining means for determining whether or not a subject is within a predetermined close distance from ranging information, and a warning to be issued when the determining means determines that the subject is within a predetermined close distance. The field frame of the external finder device is moved to a predetermined position in accordance with the first warning means and the external switch operation performed in response to the warning of the warning means, and the distance measurement area changed by the movement is Based on the distance measurement information obtained by the distance measurement method,
a field frame moving means for moving the field frame again; a second warning means for issuing a warning while the field frame is being moved by the field frame moving means; and a photographing operation prohibited during the warning by the second warning means. An autofocus camera having an external finder device, characterized in that it is provided with a photographing operation control means.