JPS61286809A - Focusing controlling method and optical device - Google Patents

Abstract

PURPOSE:To easily realize focusing and to maintain the focusing state after focusing by eliminating the uncertain information on the focus by a camera shake. CONSTITUTION:The information on the extent of the movement of a focusing lens 1 calculated by an arithmetic circuit 22 for focusing from the non-focusing quantity detected by a focus error detecting circuit 19 and the information on the present focal length from a linear encoder 6 in accordance with the output from a focus detecting element 18 is transmitted through a gate circuit 23 to a driving control circuit 24 when there are no oscillations. The lens 1 is moved by the output from the circuit 24 and the extent of the movement of the lens detected by an encoder 5 is fed back. The conduction of electricity to a driving device 4 is interrupted when the prescribed extent of the movement is attained. The gate circuit 23 prohibits the input of the output of the circuit 22 to the circuit 24 when a focusing discrimination circuit 25 discriminates the stop of the focusing from the oscillation level detected in a blurred image detecting circuit 21 by the output from an acceleration detecting element 20 and the information in the focal length from the encoder 6 if there is the oscillation. The operation of the device 4 is therefore prohibited.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Application) The present invention relates to a method and an optical device for preventing adverse effects on images due to camera shake when adjusting the focus of a photographic lens using the output of an autofocus aJm device.

(Technical background) Cameras with built-in automatic focus adjustment devices have already become everyday tools, but recently single-lens reflex cameras have appeared that are capable of high-performance, high-speed focusing.

One of the advantages of a single-lens reflex camera is that the lens can be replaced, but if you attach a telephoto lens to the camera body and try to take a picture handheld, the focus detection device will detect the problem due to camera shake. Because the focus information was uncertain, it was difficult to focus on the subject.

Furthermore, in car cameras that are structured so that even after focusing once, refocusing is performed before the shutter release is completed, there is also the problem that the focus state fluctuates due to fluctuations in focus information due to camera shake.

(Purpose) An object of the present invention is to easily achieve focusing by eliminating uncertain focusing information, or to maintain that state once in-focus is achieved.

In order to achieve the above object, the photographing optical system uses photoelectrically converted object information based on focal length information by the focal length detection means for detecting the focal length of the photographing optical system and vibration level information detected by the vibration detecting means. A configuration is adopted that limits the adjustment operation of an automatic focus adjustment means that performs focus adjustment.

(Embodiment) An embodiment of the present invention will be described below according to the drawings.In Figure 60, l is a positive power focusing lens, 2A is a variator, 2B is a compensator, 3 is a relay lens,
These lenses constitute an interchangeable zoom lens, and the variator 2A and the sensor 2B move in a predetermined relationship to realize zooming. A lens driver 4 moves the focusing lens 1 via a coupling member to adjust the focus of the zoom lens. 5 is a rotary encoder, which is connected to the lens driver 4 and indirectly controls the focusing lens 1.
Detect the position of. A linear encoder 6 is coupled to, for example, a variator lens 1 to indirectly detect the focal length of the zoom lens. Note that in this example, the lens drive 5a14
．． Rotary encoder5. Although the linear encoder 6 is shown as being housed in the lens barrel, it may be modified so that it is housed in the camera body and detected via a relay member.Also, if the lens is a short focus lens, When a lens is replaced, its focal length is detected.

On the other hand, on the camera body side, 10 is a quick return mirror, 11 is a submirror, and the submirror 11 is swingably coupled to the quick return mirror 10. 12 is an image receiving surface of a silver halide film or a video solid-state image sensor. 13 is a condenser lens, 14 is a pentagonal prism, and 15 is an eyepiece. 16 is a field lens arranged on the image formation plane, 17 is a secondary imaging system that forms a plurality of images with suggestions, and 18 19 is a focus detection element equipped with a sensor array that receives a plurality of images, and 19 is a focus error detection circuit that detects the phase difference of the images from the photoelectric conversion signal of the focus detection element 18 and outputs information according to the amount of out-of-focus. Yes, please.
The focus detection method may be any other method.

Reference numeral 20 denotes an acceleration detection element that is characteristic of this example, and is preferably arranged near the image receiving surface 12. For example, a gravity meter used in a shed for vibration measurement is effective as the acceleration detection element 20. An example of a zero gravity meter is a gravity meter in which the holder of the mass point is deflected due to the inertia of the mass point, and the strain attached to the surface of the holder is It measures acceleration by utilizing the property that the resistance value changes as the gauge expands and contracts.

Reference numeral 21 denotes an image pre-detection circuit that detects a signal applied to the image receptor from the output of the acceleration detection element 20. This vibration causes image blur, but even if the vibration level is below the allowable value compared to the shutter speed, the focus detection element 1
The amount of blur of the image on the focus detection element changes depending on the focal length of the optical system.For example, if the focal length is doubled,
Due to the rotational blur, the amount of image movement is approximately doubled. In other words, in addition to evaluating the vibration level, it is also necessary to consider at least the focal length. However, when the EV value is small, the sensor accumulation time becomes longer, which may have an effect on blurring, but recently the accumulation time Elements with shorter lengths have also been developed,
Also, since the relative value has a small specific gravity compared to the above conditions, it may be ignored, or when the EV value is small, some correction amount may be reflected.In addition, components with numbers 16 and below should be placed on the lens barrel side. It may be possible to provide one. Reference numeral 22 denotes a focus adjustment calculation circuit which has a function of calculating the amount by which the focusing lens l should be moved based on the out-of-focus amount of the focus error detection circuit 18 and the current focal length information from the linear encoder 6. The calculation result is input to the drive control circuit 24 via the gate circuit 14, and the driver 4 is operated to move the focusing lens 1. The position of the focusing lens l is always measured by the rotary encoder 5 and fed back to the drive g control circuit 24.

25 is a 7A discrimination circuit, which collects vibration information during focus detection detected by the image pre-detection circuit 21, focal length information from the linear encoder 6, and 9! Preferably, if the evaluation value determined by the sampling patent information required for detection, which is detected by the focus error detection circuit 19, is below a certain value, focus adjustment is allowed, and when this value is exceeded, the gate circuit 23 is closed. , the calculation result of the focus adjustment settlement circuit 22 is prevented from being input to the drive control circuit 24. At the same time, the display 26 in the finder system is activated to inform the photographer that the focal length of the lens is too long or that the camera is not held sufficiently.

In the above configuration, when there is no vibration, the operation is as follows. Based on the output of the focus detection element 18, the out-of-focus amount detected by the focus error detection circuit 19 is calculated based on the current focal length information from the coater 6, and the focus 31 node calculation circuit 22
The movement amount information of the focusing lens 1 calculated by is transmitted to the drive control circuit 24 via the gate circuit 23.

The focusing lens l is moved by the output of the drive control circuit 24, and the lens movement amount detected by the encoder 5 is fed back, and when a predetermined movement amount is reached, the power to the driver 4 is cut off.

Here, focus detection is executed again, and it is confirmed that the amount of out-of-focus is within the allowable range. If it is not within the allowable range, the above operation is repeated until the focus is brought into focus.

If there is vibration, the adjustment determination circuit 2 uses the vibration level detected by the image pre-detection circuit 21 based on the output of the acceleration detection element 20 and the focal length information from the linear encoder 6.
When the gate circuit 5 determines to stop the focus adjustment, the gate circuit 2
3 prohibits the output of the focus 1Afts calculation circuit 22 from being input to the drive control circuit 24, so the driver 4 does not operate.

In addition, a preliminary warning will be displayed on the display 26, so if the photographer is using a zoom lens, the photographer should take measures such as resetting the focal length to a shorter one, being careful about handling the camera, or fixing the camera on a tripod. can be taken.

Note that a configuration is adopted in which the prohibition by the gate circuit 23 is canceled after a certain period of time has passed, or is canceled when the finger is released from the release button.

(Effects) According to the present invention described above, by eliminating uncertain focus information due to camera shake, focusing is achieved smoothly and the focusing time is also shortened. Alternatively, once the focus is achieved, the focus can be maintained without being confused by uncertain focus information.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram showing an embodiment of the present invention. In the figure, l is a focusing lens, 4 is a lens driver,
18 is a focus detection element, 20 is an acceleration detection element, 22 is a focus adjustment calculation circuit, 25 is an adjustment determination circuit, and 23 is a gate circuit.

Claims (2)

[Claims] (1) A step of detecting the focal length of the optical system, a step of detecting an in-focus/out-of-focus state, and a step of adjusting the focus of the optical system according to the degree of out-of-focus, and a step of detecting the focal length of the optical system; A focus adjustment control method comprising: detecting vibration; and limiting focus adjustment of the optical system based on the detected vibration level and focal length. (2) an automatic focus adjustment device that has an optical system and adjusts the focus of the optical system based on photoelectrically converted object information; vibration detection means; and focal length detection means that detects the focal length of the optical system. and an optical device that cooperates with a limiting device that limits a focus adjustment operation by the automatic focusing device based on the vibration level detected by the vibration detection device and the focal length detected by the focal length detection device.