JPH02234140A - Automatic focusing camera - Google Patents

Abstract

PURPOSE:To inspect a focused object image even after a viewing angle is varied without necessitating a troublesome operation by automatically focusing an object image projected on a finder part the instant that the viewing angle is varied. CONSTITUTION:The camera is provided with zooming means such as a finder zooming mechanism part 3 and a zooming motor 10, operating means such as a zooming teleswitch 26, and focus adjusting means such as a finder AF mechanism part 2 and an image pickup AF mechanism part 6. Further, a control means 23 is provided which instructs the focus adjusting means to focus the object image after the zooming means detects that the viewing angle varying operation is completed in response to the operation of the operating means. The instant that the viewing angle is varied, the object image projected on the finder part is automatically focused. Thus, without necessitating the troublesome operation, the focused object image can be inspected even after the viewing angle is varied.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Application of the Invention) The present invention relates to an improvement in an autofocus camera equipped with a zoom means for changing the angle of view of a finder section.

(Background of the Invention) Generally, in autofocus cameras equipped with a zoom lens, in the case of non-single-lens reflex cameras, the surface angle of the finder is often zoomed in conjunction with the zooming of the photographic lens.

With a zoom finder like this, the longer the focal length, the shallower the depth of field. Therefore, if you adjust the focus to infinity, objects located relatively close to you will not be in focus. This tendency is particularly strong when the zoom magnification is high. For this reason, in the past, it was necessary to adjust the focus each time the subject distance changed by pressing the release switch halfway.

For example, if you are looking at a relatively close object at the short focal length (wide-angle) end and try to zoom in, the subject will become out of focus. Therefore, you have to press the release switch halfway to focus the viewfinder. Also, after looking at a nearby subject, there are often cases where you want to zoom in on something far away, but in this case as well, you have to zoom in and press the release switch halfway to focus.

While zooming to decide on the shooting composition,
There was a problem in that it was difficult to concentrate on deciding the composition because an operation had to be performed to adjust the focus. To provide an autofocus camera which enables observation of an in-focus subject image even after changing the angle of view, without requiring , and allows the user to concentrate on deciding the composition.

(Features of the Invention) In order to achieve the above object, the present invention detects the end of the angle of view variable operation by the zoom means performed in response to the operation of the operation means, and immediately causes the focus adjustment means to focus the subject image. The present invention is characterized in that a control means is provided to perform this, so that immediately after the angle of view variable operation is performed, the subject image displayed in the finder section is automatically focused. (Embodiments of the Invention) The present invention will be described in detail below based on illustrated embodiments. FIG. 1 is a block diagram showing one embodiment of the present invention, in which the present invention is applied to a still video camera. In FIG. 1, 1 to 4 are finder sections, 1 is a finder lens, 2 is a finder AP mechanism section, 3 is a finder zoom mechanism section, and 4 is a finder eyepiece. 5
is an imaging lens, 6 is an imaging AF mechanism section, 7 is an imaging zoom mechanism section, 8 is an exposure control mechanism including an aperture and a shutter mechanism, 9
10 is a zoom motor that drives the finder zoom mechanism 3 and the imaging zoom mechanism 7; 11 is a driver circuit that drives the AF motor; 12 is a zoom motor 13 is an exposure control drive circuit that drives the aperture and shutter mechanism; 14 is an image sensor such as a COD that converts a subject image into an electrical signal; 15 is an image sensor 14;
Gamma correction, planking processing,
Signal processing circuit that performs various signal processing including addition of synchronization signals, l6 is a magnetic sheet, 17 is signal processing circuit 1
a recording circuit 18 that performs modulation, etc. to make the signal processed by 5 into a form suitable for recording on the magnetic sheet 16;
19 is a magnetic head, 19 is a motor for rotating the magnetic sheet 16, 2o is a motor control circuit that controls the rotation of the motor 19, and 2l is a magnetic head 18 that moves in the radial direction of the magnetic sheet 16 to change the recording track. 22 is a drive circuit for the head transport motor 21; 23 is a control unit that controls the entire system;
4 is a standby switch, 25 is a recording trigger switch,
26 is a zoom tele switch for zooming the lens to the telephoto side, and 27 is a zoom wide switch for zooming the lens to the wide angle side. Next, the operation will be explained using the flowchart shown in FIG.

First, clear the AF flag that remembers that AF operation was performed in #1. Next, check the standby switch 24 in #2 and if it is OFF, proceed to #3, and if it is ON, proceed to #ll. Check the zoom tele switch 26 in #3 and if it is ON, switch to #7 to switch the zoom motor 1.
0 to the telephoto side and move to #lO.

If #3 is OFF, #4 is the zoom wide switch 27
If it is ON, use #8 to drive the Zoom Tanabata 10 to the wide-angle side. If it is OFF in #4, the zoom motor 10 is stopped in #5, and the AF flag mentioned above is checked in #6. If the AF flag is not set, AF operation is performed in #9. I will not discuss the AP operation in detail here because it can be a well-known general operation, but for example, it emits infrared light, receives the reflected light, measures the distance to the subject, and moves the lens to a position according to that distance. This is the action of driving and focusing. If the AP flag is set in #6, #18
It ends with . After executing the AP operation in #9, the AF flag is set in #10, and the process returns to ■, that is, #2.

Next, if the switch 24 is ON in #2, the process moves to #11, but in #11 the zoom motor 10 is stopped, and in #12 the brightness of the subject is measured (photometering). In #l3, the AF flag is checked, and if it is not set, the process moves to #9, and if it is set, the process moves to #l4.

In #l4, the recorder checks the switch 25, and this is OF.
If it is F, return to ■, that is, #2, but if it is ON, #l
Proceed to step 5. In #l5, the exposure control mechanism 8 is driven to control the exposure amount, and in #l6, recording is performed on the magnetic sheet 16. At #l7, the head transport motor 21 is driven to transport the magnetic head 18 to the next track, and the process returns to (2), that is, #2.

According to the above sequence, the AP operation is performed once when the zoom tele switch 26 or the zoom wide switch 27 is turned from ON to OFF.

In the embodiment described above, the zoom operation was stopped when the standby switch 24 was pressed because priority was given to recording standby.
You can also accept zoom operations by pressing .
A flowchart in this case is shown in FIG.

Since it is almost the same as Figure 2, detailed explanation will be omitted here. Furthermore, although the above embodiments have been described with respect to implementation in a still video camera, this may be applied to a normal silver halide camera or a movie video camera.

Alternatively, a single-lens reflex camera may be used as long as it has a zoom switch.

Furthermore, in the case of non-SLR cameras, the AF drive of the viewfinder and the AF drive of the imaging lens are made independent, so that only the AF of the finder is driven after zooming or when operating the standby switch, and only the AF of the imaging system is driven when shooting. You can. This has the advantage of reducing the mechanical load during each drive and making it possible to downsize the moke and the like. The flowchart in this case is shown in FIG. Since this is also almost the same as FIGS. 2 and 3, detailed explanation will be omitted.

Furthermore, in the above embodiment, the AP operation includes driving the lens, but if the distance measured in the next AF operation after driving the lens in the AF operation does not change significantly from the previous distance. The lens may not be driven.

According to this embodiment, each time the zooming operation is completed,
Since the AF drive is performed immediately after that, the focus shift due to zooming can be corrected automatically without any manual operation (conventionally, pressing the release switch halfway). This has the effect of greatly improving operability, such as allowing you to concentrate solely on determining the composition.

(Correspondence between the invention and the embodiments) In this embodiment, the finder zoom mechanism section 3, the zoom motor 101 and the zoom driver circuit 12 serve as the zoom means of the present invention, the zoom teleswitch 26 and the zoom wide switch 27 serve as the operation means, and the finder AF Mechanism section 2, imaging A
The F mechanism section 6, the AF motor 9, and the driver circuit 11 correspond to a focus adjustment means, and the control section 23 corresponds to a control means.

(Effects of the Invention) As described above, according to the present invention, by detecting the end of the angle-of-view variable operation by the zoom means performed in response to the operation of the operation means, the subject image is immediately brought into focus by the focus adjustment means. A control means is provided to perform this, and as soon as the angle of view is changed, the subject image displayed in the viewfinder is automatically focused, eliminating the need for troublesome operations. Even after changing the angle of view, you can still observe the subject image in focus, allowing you to concentrate on deciding on the composition.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of the present invention, FIG. 2 is a flowchart showing its operation, FIG. 3 is a flowchart showing the operation in another embodiment of the invention, and FIG. 4 is another embodiment of the invention. 2 is a flowchart showing the operation in the embodiment. 2...Finder AF mechanism section, 3...
Finder zoom mechanism section, 6... Imaging AF mechanism section, 9... AF motor, 10... Zoom motor, 11... Driver circuit, l2...・
...Zoom driver circuit, 26...Zoom tele switch, 27...Zoom wide switch,
23...Control unit.

Claims (1)

[Claims] (1) A finder section for observing the subject image, a zoom means for changing the angle of view of the finder section, an operating means for changing the angle of view, and a focus for the subject image projected on the finder section. In an automatic focus camera equipped with a focus adjustment means, by detecting the completion of an angle-of-view variable operation by the zoom means performed in response to an operation of the operation means, the subject image is immediately focused on the focus adjustment means. An automatic focusing camera characterized by being provided with a control means for controlling the camera.