JPH02214830A - Camera for preventing blurring of photographing and measuring instrument for shutter speed not causing blurring of photographing - Google Patents

Abstract

PURPOSE:To automatically determine an exposing time capable of preventing the blurring of photographing by providing a sensor on the object image forming surface of an optical system and measuring the moving speed of an object before photographing. CONSTITUTION:Light beams which pass through the central part of the finder mirror 1 of a single lens reflex camera form an object image on a sensor 4 and the sensor 4 which is composed of many photoelectric conversion elements records the image of an object central part. When a shutter button is depressed, a sensor circuit 100 measures the moving speed of an object image moving on the sensor surface, and outputs the measured shutter speed to a shutter speed and stroboscopic signal circuit 104. A memory device stores blurring photograph preventing conditions in advance, and they are outputted to the shutter speed and stroboscopic signal circuit 104, which determines the shutter speed and whether a stroboscope is lit or not. Thus, a blurring photographing caused by the moving of a camera or an object is prevented and a distinct still picture can be recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a camera that prevents blurred photography in a camera that records still images or moving images of a subject, and a device that measures a shutter speed that does not cause blurred photography.

[Conventional technology]

What is camera shake photography? A still camera or electronic still camera that records still images of a subject, or a movie camera or video camera that continuously records still images of the subject to create a video, records the image of the subject. This is when the subject image moves during one frame, resulting in a moving image being recorded instead of a still image. This is one of the causes of deteriorating the clarity of photographs, and remains an unresolved problem even today, when camera functions have advanced to near perfection.

The causes of blurred shots can be classified into two categories. One is that the camera itself moves during the time when the camera is recording the subject image, and the other is that the camera does not move but the subject moves. However, even though these phenomena are different, the relative positional relationship between the camera and the subject can be considered to be the same.

As a conventional camera shake prevention device, for example, a helicopter
When photographing the exterior of a moving aircraft from inside, stabilization devices using gyroscopes and other devices have been put into practical use to allow the camera to capture the movement of the aircraft. In addition, two acceleration sensors are installed inside the lens barrel as a special lens,
Some cameras have a mechanism that detects camera shake and moves a correction optical system inside the lens to cancel the amount of shake. All of these methods require special lenses and dedicated holding devices, and do not take any measures against movement on the subject's side.

For this reason, conventional photographers use shutter speeds as fast as possible to avoid blurry shots.
People have been careful about how they press the shutter button and how they hold the camera, and they have been forced to use the shutter release to avoid following a moving subject with the camera.

[Problem to be solved by the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for automatically preventing blurred photography without relying on the photographer's skill or attention or special equipment, and without placing any burden on the photographer.

Furthermore, in cameras that generally have an aperture and a shutter as means for adjusting the image plane exposure, there are often several combinations of the aperture and shutter that can obtain the same image plane exposure. Conventionally, which combination is best for photographing has been selected by the photographer based on experience, or by using a predetermined program.

In general, it is desirable that the aperture be as small as possible in order to deepen the depth of field, and for this purpose, it is desirable that the shutter speed be as slow as possible without blurring the image. It is an object of the present invention to provide a camera that can automatically determine the best combination of aperture and shutter speed by measurement, which in the past could only be determined empirically.

[Means to solve the problem]

In order to achieve the above object, in the camera of the present invention, a sensor is installed on the object image forming plane of the optical system that forms an image of the object, and this sensor measures the moving speed of the image immediately before shooting. , control the exposure time on film or electrical recording time using a solid-state image sensor, etc. to prevent blurring based on preset conditions, and control the auxiliary light irradiation time when exposure is mainly using auxiliary light such as a strobe. It is something to do.

In the case of a lens-shutter type camera, it is desirable that the imaging optical system is provided separately from the photographic lens. When using single-lens reflex cameras, VTR cameras, etc. that require interchangeable lenses, it is desirable to share the same photographic lens. When using a VTR camera with a fixed zoom lens, it is desirable to share all or part of the photographic lens. As described above, there are various methods depending on the type of camera, and these are not necessarily absolute.

There are two ways to install a sensor on the subject image formation plane: one that covers the entire shooting screen, and one that covers only the center of the screen. Sensors include a surface sensor such as a CCD, and a radial line sensor. A variety of methods are used.

Of course, the moving speed of the image on the sensor may be measured by measuring the time it takes for the image to move a certain distance on the sensor, or by measuring the distance the image moves in a certain period of time.

What are the preset conditions for preventing blurred shots?
Calculations can be made from the magnification at which the image of the subject recorded by the camera is actually displayed on a print or TV screen, the distance from which a person views it, the resolution of the eye, and other conditions, but these conditions are not absolute. Since it is not a fixed value, it is desirable to set it through many experimental studies.

Once the exposure time on the film, the electrical recording time using a solid-state image sensor, etc., or the irradiation time and light amount of auxiliary light such as a strobe are set, the shooting lens is adjusted based on the brightness of the subject, the sensitivity of the film, CCD, etc. Needless to say, the sensitivity of the aperture, CCD, etc. is adjusted.

Even if the moving speed of the subject and the moving speed of the camera are the same, the moving speed of the subject image on the film or solid-state imaging device changes depending on the image magnification of the photographic lens. That is, the focal length of the photographing lens is long (as is true, the above-mentioned movement speed becomes faster. Therefore, in conventional camera photography, it was necessary to use a faster shutter speed as the focal length of the photographing lens became longer, but with the present invention, In a type of camera in which all of the photographing lenses or the zoom optical system are shared, this problem is automatically solved without providing any additional mechanism.

On the other hand, when the imaging optical system used in the present invention is separate from the photographic lens and the focal length of the photographic lens can be changed, the focal length of the imaging optical system can be changed in accordance with the change. or an electrical means with equivalent effect is required.

[For production]

One process of photographing using the camera configured as described above is as follows. That is, when you point the camera at the subject, compose the picture, and press the shutter button, the camera automatically focuses, then measures the brightness of the subject, and then measures the speed of movement of the subject image on the sensor according to the present invention. However, the minimum shutter speed that prevents blurry photography is set based on preset conditions.

In this way, when the shutter speed is set, the aperture value of the photographing lens is set so that a predetermined image plane exposure amount is achieved based on the combination of subject brightness and photoreceptor sensitivity, and the aperture is stopped down to that aperture value. At this time, CC as an image recording element
When the image plane exposure amount is insufficient even when the aperture is wide open in a camera that uses D or the like, the sensitivity increase circuit works as necessary.

The shutter speed determined by the present invention does not necessarily have to be the minimum required shutter speed, but if there is sufficient aperture value due to high subject brightness or high photoreceptor sensitivity, the minimum required shutter speed may be used. There is no problem even if the shutter speed is several steps faster than the shutter speed.

Therefore, even if there is a certain degree of error in the measurement accuracy of the moving speed of the subject image, the initial objective can be achieved if the error is taken into account in the conditions for determining the shutter speed.

For the same reason, we set several stages in the conditions for determining the shutter speed, and when there is no margin for the aperture value based on the value measured by the exposure meter mechanism, we set the speed limit value to a correction O step, In some cases, it is desirable to provide a mechanism that can set +1 step, +2 step, etc.

Further, this setting can be performed not only manually but also automatically from the subject brightness measurement value. On the other hand, the shutter speed limit value is corrected to intentionally take a picture with a certain degree of blur.
Setting mechanisms such as 1 step, -2 steps, etc. are also possible.

When a subject repeats the same movement, by pressing a button set for that purpose, the speed of movement of the subject image is measured without shutter release, and a shutter speed that does not cause blurring can be calculated and set. You can also do that.

According to this method, blurring can be effectively prevented even when the moving object does not pass through the center of the screen, even though the part of the camera that measures the moving speed of the subject image is the center of the screen. .

In the case of a 35mm camera, the minimum shutter speed that can be used for handheld photography without blurring is said to be 1/60 second. Assuming that the permissible blur on the film surface is 40 microns and the pitch of the sensor elements is 10 microns, a blur of 4 pitches is allowed during the exposure time of one frame. If the measurement time is too long, it will take too long from the time the shutter button is pressed until the exposure is made, so it is desirable that the measurement time be short. Assuming that this measurement time is 1/30 seconds, it is sufficient to detect movement of 8 pitches. Exposures of 1/60 seconds or less will result in camera shake, or blurry photography, so movements slower than this do not need to be measured. Exposures faster than 1/60 seconds are required, that is, the image moves more than 8 pitches in 1/30 seconds. It is also possible to take measurements in less time.

〔Example〕

Examples will be described with reference to the drawings. As shown in Fig. 1, the central part of the finder mirror 1 of an eye-reflex camera is a semi-transparent mirror, and the light that passes through it is radiated downward by a second mirror 2, and then a third semi-transparent mirror 3 is used to direct the light to the sensor. 4
An image of the subject is formed above.

The sensor 4 is a large number of photoelectric conversion elements whose surface is subdivided like a CCD, and records an image of the center of the subject. The light transmitted through the third semi-transparent mirror 3' enters the autofocus light receiving element 5 located below it.

The light receiving element 6 receives the reflected light from the surface of the focal brain shutter and performs photoelectric conversion. Based on the output, the exposure meter circuit measures the subject brightness, and uses this and the previously input photosensitive material sensitivity to determine the appropriate image plane exposure. Outputs the exposure value.

When the shutter button is pressed down, an autofocus mechanism (not shown) works to focus.
Next, a sensor circuit including sensor 4 measures the speed of movement of the subject image moving on the sensor surface.

FIG. 2 shows the pattern of the elements on the sensor 4 and the subject images before and after movement with parallel diagonal lines. At the start of measurement, the object image located in the rectangle AI A2 p, 3 A4 (this is referred to as part A) located at the center is detected and stored. Next, rectangle B
, 82B3B, (This is part B>, C, C2
C3C, (C part), Dl D2D3D4 (D part), E
The images within the rectangle are successively detected in the order of section B, section F, etc., then back to section B, section C, and section D are detected one after another, and an image that is almost the same as the first image of section A is obtained. When detected in any rectangle, the moving speed of the image on the sensor surface can be measured by measuring the time from the start point. In the figure, the subject image is moving from section A to section C. In the diagram, centering on part A,
~■Each part is equidistant.

The sensor 4 does not need to accurately and completely capture a subject image, unlike a CCD used in a VTR camera or an electronic still camera, but only needs to be able to measure its moving speed. Therefore, it is not necessarily necessary to have photoelectric conversion elements on the entire surface. For example, as shown in FIG. 3, it can be simplified so that measurements can be made within the necessary measurement range. The required measurement range here is determined by the maximum shutter speed of the camera incorporating the present invention, etc. It is meaningless to be able to measure fast movement speeds that would result in blurred images even when shooting at the highest shutter speed, and conversely, it would be pointless to be able to measure slow movement speeds that correspond to shutter speeds that would prevent handheld shooting due to camera shake. This is because it is also meaningless.

As shown in FIG. 1, the output of the light-receiving element 6 is input to the exposure meter circuit 106, and a signal of the sensitivity of the photosensitive material, which has been input in advance to the memory circuit 108, is also input to the exposure meter circuit 106.

The exposure meter circuit 106 calculates an appropriate exposure value based on these human input signals, and outputs the result to the aperture value determination circuit 110.

The aperture value determining circuit 110 calculates an appropriate aperture value based on the inputted shutter speed, appropriate exposure value, strobe lighting or non-lighting signal, and when the strobe is lit, the irradiation time signal, and outputs the calculated value to the aperture operating mechanism 112 . The aperture 114 is narrowed down to an appropriate aperture value by the aperture actuation mechanism 112.

The output of shutter speed and strobe signal circuit 104 is input to strobe 118 and shutter actuation mechanism 120 . The strobe 118 is turned on or off for a period of time dictated by the shutter speed and the signal from the strobe signal circuit 104, and the shutter 122 is operated at an appropriate speed by the shutter actuation mechanism 120.

The output of the sensor 4 is input to a sensor circuit 100 to calculate the speed of the subject and output it to a shutter speed and strobe signal circuit 104. The storage device 102 stores blur photography prevention conditions in advance, and outputs them to the printer speed and strobe signal circuit 104. The shutter speed and strobe signal circuit 104 determines the shutter speed that does not cause blurring based on the input values, and determines whether or not to turn on the strobe and, if it does, how long the strobe should be emitted.

FIG. 3 shows other element patterns on the surface of the sensor 4 and images of the subject before and after movement. When the subject image moves on the elements arranged in a radial pattern, the moving speed of the parts of the subject image with strong contratos on four vertical, horizontal, and diagonal lines is detected, and the fast inner part of the subject image is also determined as the moving speed. do.

The anti-shake condition is preset as follows, and this method is similar to calculating the depth of field.

Whether or not it is a blurred shot depends on whether your eyes perceive the blur caused by the blurred shooting. Therefore, in the case of still photographs, the size of the photograph that is printed or projected on a slide varies greatly depending on the distance from which it is viewed. -As an example, if you calculate the viewing angle of the photograph at 50 degrees and the resolution is about 1', then 0.03 to 0.04 for 35 mnn + film.
mm is the allowable blur amount.

However, this is a fairly strict condition, so for cameras for the general public, it would be a good idea to expand the allowable value even further. When shooting moving images using a video camera, the ability of the eyes to perceive blur is reduced, and the viewing angle for viewing television is narrowed by a few minutes compared to when shooting still photos, so the amount of permissible blurring will increase by an order of magnitude or more.

In any case, these blur prevention conditions should be determined through various experiments.

The thus determined object image movement speed and anti-shake conditions are input to the shutter speed and strobe irradiation signal circuit, and the anti-shake shutter speed or strobe irradiation signal is output. After the mirror 1.2 rises out of the photographing optical path, the shutter operating mechanism operates at the shutter speed in response to this output, and the strobe emits light for the time output at the same time as the irradiation signal is received. Prior to these exposures, the aperture value determination circuit manually inputs the appropriate exposure value determined by the exposure meter circuit and the shutter speed or strobe exposure time signal, inputs the aperture value to the aperture operation mechanism, and then inputs the aperture value to the aperture operation mechanism, The aperture is narrowed down to that aperture value before .

The operation of the mirror and shutter after measuring the moving speed of the subject image may cause blurring in the photograph, but since these momentums are almost unique to each camera, it is necessary to take into account their effects in advance in the conditions for determining the shooting speed. It can be included inside.

When the subject brightness measured by the exposure meter circuit including the light-receiving element 6 is low and a shutter speed that does not cause blurring even when the aperture is wide open is not obtained, a strobe is used. At this time, the strobe irradiation time, synchronized shutter speed, and aperture value for achieving the appropriate image plane exposure amount are determined, and the controller operates as determined.

Cameras are generally equipped with various photoelectric conversion elements for measuring subject brightness, autofocusing, and recording subject images, and the sensor for the present invention can also be used in common with these elements. It is also possible to simplify the optical system.

In the embodiment shown in FIG. 4, the imaging optical system 7 for the present invention is provided separately from the photographing optical system and is also used as a finder optical system. At this time, if the photographing optical system 8 is a zoom lens or the focal length can be changed by other methods, the imaging optical system 7
The focal length of the camera may be changed, or an equivalent condition may be added to the necessary blurring prevention condition for determining the shutter speed using electrical means or the like.

In the embodiment shown in FIG. 5, there is a beam splitter after the zoom section of the photographing optical system, and the split light is imaged on the sensor 4. In such an optical system, the photographed image magnification and the image magnification on the sensor 4 are always proportional.

For cameras with mechanized shutters such as video cameras, in order to obtain a shutter speed faster than 1/60 second, there is a method of discarding excess accumulated charge and reading out only the charge accumulated within the required time. However, this method can be used as is in the camera of the present invention.

Another example of a method for measuring the moving speed of a subject image is a method using a known slit spatial filter, as shown in FIG. The object image formed by the imaging optical system 200 is focused on two horizontal and vertical slit surfaces 204 and 206 that are in close contact with the condenser lens 202, respectively, and the light transmitted through them is sent to the photodetector 212 and 214 by the relay lens 208 and 210. In this method, light is focused on the target image, and changes in light intensity caused by the movement of the subject image are frequency-analyzed by the spectrum analyzer 220, and a composite speed is obtained from the horizontal and vertical movement speeds.

Yet another embodiment of the present invention is a soter speed measuring device shown in FIG. This device includes an imaging optical system 300 that forms a subject image, a sensor 4 installed on the imaging plane, and a sensor circuit 302 that receives the output of the sensor 4 and measures the moving speed of the subject image. , a first storage circuit 304 that stores blur prevention conditions, and an imaging optical system 30.
It has a second storage circuit 308 that stores a focal length of 0.

The shutter speed determining circuit 310 to which the outputs of the first and second memory circuits 304 and 308 and the sensor circuit 302 are input determines the shutter speed based on the signals input from these circuits, and transmits the determined shutter speed to the shutter speed display mechanism 306. Output to.

By using such a device, you can easily find out the shutter speed that will prevent blurred shots according to the moving speed of the subject, and if you incorporate it into a light meter, you can easily determine the aperture and shutter speed that will prevent blurry shots from the same exposure value. You can get a combination of speeds. However, this device cannot deal with blurred shots due to movement of the camera, so the countermeasures for this are the above-mentioned correction + 1 step, +
It is desirable to provide a setting mechanism such as 2 steps.

〔Effect of the invention〕

Since the present invention is configured as described above, it produces the effects described below.

To record a clear still image by preventing blurring caused by movement of the object or camera in a camera that records still images of a subject or a camera that continuously records still images to create a moving image.

In addition, since you can know the minimum recording time that prevents camera shake, you can obtain the best combination of aperture and recording time within the appropriate exposure value, and take a step forward in improving the performance of the camera's shooting mechanism and automating it. can be done.

[Brief explanation of the drawing]

FIG. 1 is a block diagram when the present invention is incorporated into a single-lens reflex camera, FIG. 2 is a drawing showing the movement of a subject image on the sensor 4, and FIG. 3 is another embodiment of the sensor surface pattern.
Fig. 4 is a block diagram showing an embodiment of Ike's optical system, Fig. 5 is an optical diagram of another embodiment, Fig. 6 is an explanatory diagram of a method for measuring moving speed, and Fig. 7 is a shutter speed measuring device. FIG. 1.2 Mirror semi-transparent mirror sensor Autofocus light-receiving element Light-receiving element Exposure circuit Aperture value determination circuit Strobe

Claims (1)

[Claims] 1. A sensor is installed on the object image forming surface of the imaging optical system built into the camera, and the speed at which the object image moves on the sensor surface is measured, and the sensor is measured in accordance with the speed. A camera that prevents blurred photography, characterized by controlling a subject image recording time to prevent blurred photography. 2. The camera for preventing blurred photography according to claim 1, wherein the imaging optical system is a photographing lens. 3. The camera for preventing blurred photography according to claim 1, wherein the imaging optical system is provided separately from a photographing lens. 4. The camera for preventing blurred photography according to claim 1, wherein the imaging optical system shares a part of the photographing lens. 5. The camera for preventing blurred photography according to claim 1, wherein the means for controlling the recording time is a shutter. 6. The camera for preventing blurred photography according to claim 1, wherein the recording time is mainly controlled by an auxiliary light. 7. Install a sensor on the object image forming surface of the imaging optical system,
Measure the speed at which the subject image moves on the sensor surface,
A device for measuring a shutter speed that does not cause blur in photography based on a separately set photographing lens focal length of a camera and the above-mentioned speed.