JP2000101899A - Digital still camera and its method for correcting the digital still camera - Google Patents

Abstract

PROBLEM TO BE SOLVED: To quickly conduct focusing in spite of maintaining high precision. SOLUTION: The digital camera is provided with photographing face range finders (2, 5) that measure a distance up to an object based on an image of the object formed on a light receiving face of a CCD 2 by a photographing lens 1 and with an external range finder 20 that measures a distance up to at least one point on the object. In the case that an MPU 5 discriminates conduction of a proximity shot, the MPU 5 moves the photographing lens 1 to a prescribed position based on the measurement result by the photographing face range finders (2, 5). Using the external range finder 20 in the case of a conventional photographing, for example, quickly attains focusing. In the case of the proximity shot, focusing is attained with high precision by using the photographing face range finders (2, 5).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device having an image sensor, and more particularly to a digital still camera capable of performing a focusing operation quickly and reliably.

[0002]

2. Description of the Related Art With the improvement of electronic technology, digital still cameras for converting a captured image into digital data and storing the digital data have been developed and are already on the market. A user can display an image captured by a digital still camera on, for example, a display of his / her personal computer, and can print the image via a printer, so that the application range is wide.

[0003]

A general digital still camera is provided with a distance measuring device, which measures a distance to a subject and moves a photographic lens to a focusing position based on the measured distance. It can be moved. Here, a distance measuring device using an infrared ray or an ultrasonic wave (hereinafter, referred to as an external distance measuring device) is employed in a normal film camera. However, in a digital still camera, a distance measuring device using an image sensor is used. In general, a distance measuring device (hereinafter, referred to as an imaging surface distance measuring device) for measuring a distance is provided.

[0004] The imaging surface distance measuring apparatus is intended to actually capture an image of a subject while moving a photographic lens, and to search for an in-focus position as an in-focus position based on the obtained subject image. Therefore, since the distance measurement can be performed using the function originally provided in the digital still camera, it is possible to achieve the focusing operation of the photographing lens without separately providing an external distance measurement device as employed in a film camera. There are advantages.

[0005]

By the way, in addition to the above structural features, the imaging surface distance measuring device and the external distance measuring device have the following advantages and disadvantages, respectively. The external ranging device projects infrared light or ultrasonic waves at one or several ranging points of a subject, detects a reflected light or a reflected wave, detects a time difference or an angle, and detects the detected value. The in-focus position is obtained by illuminating a predetermined table, and the taking lens is moved there. Therefore, while there is an advantage that distance measurement can be performed quickly, there is a disadvantage that the object is out of focus unless a subject exists at the distance measurement point.

In particular, there is always a certain amount of deviation (parallax) due to its structure between the detection optical axis of the infrared type external distance measuring device and the optical axis of the taking lens. Therefore, although there is no major problem in the case of normal shooting where the subject is far away, in the case of close-up shooting where the subject is close, due to such parallax, a portion different from the subject portion desired to be in focus is required. In addition, there is a risk of being out of focus. Furthermore, since the external distance measuring device illuminates a predetermined table and obtains the in-focus position corresponding to the measured time difference and angle, for example, when operating at extremely high or low temperature, The relationship between the measured time difference or angle and the in-focus position changes. In this case, if the in-focus position is obtained based on a predetermined table, there is a possibility that the in-focus position may deviate from the actual in-focus position. In addition, in digital still cameras, the required precision of focusing is about 1/5 of that of film cameras, and there is a fact that defocusing is extremely severe.

On the other hand, since the imaging surface distance measuring device searches for a focus position while actually taking an image as described above, the focus position can be searched for with extremely high accuracy and a change in temperature can be obtained. However, a stable position search can be performed. However, since the imaging surface ranging apparatus performs imaging while moving the imaging lens, and searches for only one in-focus position from the movable range of the imaging lens based on the obtained image, the in-focus position is determined. Has the disadvantage that it takes time to search for.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems of the prior art, and has as its object to provide a digital still camera and a digital still camera correction method capable of quickly performing a focusing operation while maintaining high accuracy. I do.

[0009]

In order to achieve the above object, a digital still camera according to the present invention measures a distance to a subject based on the subject image formed on a light receiving surface of an image sensor by a photographing lens. Imaging surface ranging means, external ranging means for measuring a distance to at least one point on the subject, determining means for determining whether normal shooting or close-up shooting is performed, and the determining means And a photographing lens driving unit that moves the photographing lens to a predetermined position based on the measurement result of the imaging surface distance measuring unit when it is determined that the photographing is performed.

[0010] The digital still camera of the present invention comprises: an imaging surface distance measuring means for measuring a distance to an object based on an object image formed on a light receiving surface of an imaging device by an imaging lens;
An external distance measuring means for measuring a distance to at least one point on the subject, a temperature measuring means for measuring a temperature, and, when the temperature measured by the temperature measuring means is out of a predetermined range, the imaging surface measuring means Photographing lens driving means for moving the photographing lens to a predetermined position based on the measurement result of the distance means.

According to the digital still camera correction method of the present invention, a step of measuring a temperature, a step of measuring a distance of an object by an external distance measuring means, a step of measuring the distance of the object by an image pickup surface distance measuring means, A step of generating temperature correction information for correcting the distance measurement result of the external distance measurement means based on the temperature and the distance measurement result of the imaging surface means.

[0012] The digital still camera of the present invention comprises: an imaging surface distance measuring means for measuring the distance to the object based on the image of the object formed on the light receiving surface of the imaging device by the imaging lens;
An external distance measuring unit that measures a distance to at least one point on the subject, a photographing condition detecting unit that detects a photographing condition, and the photographing condition detecting unit determines that photographing is performed in a state where the depth of field is shallow. In this case, there is provided a photographing lens driving unit that moves the photographing lens to a predetermined position based on the measurement result of the imaging surface distance measuring unit.

[0013] The digital still camera of the present invention comprises: an imaging surface distance measuring means for measuring the distance to the object based on the object image formed on the light receiving surface of the imaging device by the imaging lens;
External distance measuring means for measuring the distance to at least one point on the subject, based on the measurement result of the external distance measuring means,
And a photographing condition setting means for setting photographing conditions so as to increase the depth of field when the photographing lens is moved to a predetermined position.

[0014] The digital still camera according to the present invention comprises: an imaging surface distance measuring means for measuring a distance to an object based on an object image formed on a light receiving surface of an imaging device by an imaging lens;
External distance measuring means for measuring a distance to at least one point on the subject; determining means for determining whether any of normal shooting and shooting of the moving subject is performed; and A photographing lens driving unit that moves the photographing lens to a predetermined position based on a measurement result of the external distance measuring unit when it is determined that photographing is performed;
When the determining means determines that the moving subject is to be photographed, the photographing condition setting means sets photographing conditions so that the depth of field becomes deep.

[0015] The digital still camera according to the present invention comprises: an imaging surface distance measuring means for measuring a distance to an object based on an object image formed on a light receiving surface of an imaging device by an imaging lens;
External distance measuring means for measuring a distance to at least one point on the subject, selecting means for selecting a flat subject shooting mode suitable for shooting a flat subject, and selecting means for setting the flat subject shooting mode When the selection is made, a photographing lens driving means for moving the photographing lens to a predetermined position based on the measurement result of the external distance measuring means is provided.

The digital still camera according to the present invention comprises: an imaging surface distance measuring means for measuring a distance to an object based on an object image formed on a light receiving surface of an imaging device by an imaging lens;
External distance measuring means for measuring a distance to at least one point on the subject, a finder, detecting means for detecting that a photographer is looking into the finder, and a photographer looking into the finder by the detecting means. Is detected, the external distance measuring means is operated in a predetermined cycle based on the detection of the detecting means, and immediately before photographing, the imaging surface distance measuring means is operated by the external distance measuring means. A predetermined position of the photographing lens is detected by performing a position search in a predetermined range based on the information.

The digital still camera according to the present invention comprises: an imaging surface distance measuring means for measuring a distance to an object based on an object image formed on a light receiving surface of an imaging device by an imaging lens;
An external distance measuring unit for measuring a distance to at least one point on the subject; a display device capable of displaying a subject to be photographed; and a predetermined device when the display device displays the subject to be photographed. In the cycle of the above, the external distance measuring means is operated, and immediately before photographing, the image pickup surface distance measuring means is searched for a position within a predetermined range based on information from the external distance measuring means, so that a predetermined position of the photographing lens is obtained. Is detected.

[0018]

According to the digital still camera of the present invention, based on the subject image formed on the light receiving surface of the image sensor by the taking lens, an imaging surface distance measuring means for measuring the distance to the subject, External distance measuring means for measuring the distance to one point; determining means for determining whether normal shooting or close-up shooting is to be performed; and when the determining means determines that close-up shooting is to be performed, A photographing lens driving unit that moves the photographing lens to a predetermined position based on the measurement result of the distance measuring unit. For example, in the case of normal photographing, focusing can be quickly achieved by using an external distance measuring unit. On the other hand, in the case of close-up shooting, focusing can be achieved with high accuracy by using the imaging surface distance measuring means.

According to the digital still camera of the present invention,
Based on a subject image formed on a light receiving surface of an image sensor by a taking lens, an imaging surface ranging unit that measures a distance to a subject, and an external ranging unit that measures a distance to at least one point on the subject, Temperature measuring means for measuring the temperature,
When the temperature measured by the temperature measuring unit is out of the predetermined range, based on the measurement result of the imaging surface distance measuring unit, the imaging lens driving unit that moves the imaging lens to a predetermined position, For example, when the measured temperature falls within a predetermined range, focusing is quickly achieved by using an external distance measuring unit, while when the measured temperature is outside the predetermined range, the imaging surface distance measuring unit is activated. By using this, focusing can be achieved with high accuracy.

According to the correction method of the digital still camera of the present invention, a step of measuring the temperature, a step of measuring the distance of the object by the external distance measuring means, and a step of measuring the distance of the object by the image-taking surface distance measuring means. Generating temperature correction information for correcting the distance measurement result of the external distance measurement means based on the measured temperature and the distance measurement result of the imaging surface means. By executing each step (at the time of manufacturing), temperature correction information can be obtained, and the distance measurement result of the external distance measuring means can be corrected based on the temperature correction information. It becomes possible to achieve a focus.

According to the digital still camera of the present invention,
Based on a subject image formed on a light receiving surface of an image sensor by a taking lens, an imaging surface ranging unit that measures a distance to a subject, and an external ranging unit that measures a distance to at least one point on the subject, A photographing condition detecting means for detecting a photographing condition, and when the photographing condition detecting means determines that the photographing is performed in a state where the depth of field is shallow, based on a measurement result of the photographing surface distance measuring means, Since there is provided a photographing lens driving unit for moving the photographing lens to a predetermined position, it is possible to minimize blurring of the image.

According to the digital still camera of the present invention,
Based on a subject image formed on a light receiving surface of an image sensor by a taking lens, an imaging surface ranging unit that measures a distance to a subject, and an external ranging unit that measures a distance to at least one point on the subject, When moving the taking lens to a predetermined position based on the measurement result of the external distance measuring means,
A photographing condition setting means for setting photographing conditions so as to increase the depth of field; for example, a focus position as a predetermined position obtained by the external distance measuring means is slightly shifted from an actual focus position. Even in such a case, focusing can be made as much as possible with a deep depth of field, and quick focusing can be achieved.

According to the digital still camera of the present invention,
Based on a subject image formed on a light receiving surface of an image sensor by a taking lens, an imaging surface ranging unit that measures a distance to a subject, and an external ranging unit that measures a distance to at least one point on the subject, A determination unit that determines whether one of a normal shooting and a moving subject is to be captured; and the determination unit determines that the shooting of the moving subject is to be performed. When the photographing lens driving unit that moves the photographing lens to a predetermined position and the determining unit determines that the moving object is to be photographed, the photographing conditions are set so that the depth of field becomes deep. Photographing condition setting means. Here, if the subject to be imaged is a moving subject, it may be difficult to track the subject with the imaging surface distance measuring means, and in such a case, quick measurement by the external distance measuring means is possible. Distance is suitable. However, for example, the in-focus position as the predetermined position measured by the external distance measuring means is
It may be different from the actual focus position. Therefore, even when the in-focus position obtained by the external distance measuring means slightly deviates from the actual in-focus position, it is possible to focus as much as possible with a deep depth of field.

According to the digital still camera of the present invention,
Based on a subject image formed on a light receiving surface of an image sensor by a taking lens, an imaging surface ranging unit that measures a distance to a subject, and an external ranging unit that measures a distance to at least one point on the subject, Selecting means for selecting a flat subject shooting mode suitable for shooting a flat subject, and when the selecting means selects the flat subject shooting mode, based on a measurement result of the external distance measuring means, Photographing lens driving means for moving the photographing lens to a predetermined position. Here, if the object to be imaged is a flat object, there is a low possibility that a distance measurement error will occur even if external distance measuring means is used. Therefore, when the planar subject photographing mode is set, the external distance measuring means performs the distance measurement, whereby it is possible to achieve quick focusing, for example.

According to the digital still camera of the present invention,
Based on a subject image formed on a light receiving surface of an image sensor by a taking lens, an imaging surface ranging unit that measures a distance to a subject, and an external ranging unit that measures a distance to at least one point on the subject, A finder, detecting means for detecting that the photographer is looking into the finder, and when the detecting means detects that the photographer is looking into the finder, a predetermined value is determined based on the detection of the detecting means. In the cycle of the above, the external distance measuring means is operated, and immediately before photographing, the image pickup surface distance measuring means is searched for a position within a predetermined range based on information from the external distance measuring means, so that a predetermined position of the photographing lens is obtained. Therefore, when the detecting means detects that the photographer is looking into the viewfinder, it can be regarded as a preparation stage of photographing. By performing the distance, for example, a rough in-focus position as a predetermined position is obtained, and immediately before photographing, in the vicinity of the rough in-focus position obtained by the external distance measuring means, the in-focus position is obtained by the imaging surface distance measuring means. By performing the search, the in-focus position can be quickly and accurately obtained.

According to the digital still camera of the present invention,
Based on a subject image formed on a light receiving surface of an image sensor by a taking lens, an imaging surface ranging unit that measures a distance to a subject, and an external ranging unit that measures a distance to at least one point on the subject, A display device capable of displaying a subject to be photographed, and when the display device is displaying the subject to be photographed, the external distance measuring means is operated in a predetermined cycle. By detecting a predetermined position of the photographing lens by causing the imaging surface distance measuring means to search for a position within a predetermined range based on information from the external distance measuring means, the display device displays a subject to be photographed. When the camera is in the shooting state, it can be regarded as a preparatory stage for shooting. In rough focus position near obtained the external ranging unit, by causing the focus position searching on the imaging surface distance measuring device, it can be determined quickly and accurately focus position.

[0027]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a configuration of the digital still camera according to the present embodiment. In FIG. 1, a CCD 2, which is an image sensor on which an optical image is formed on a light receiving surface by a photographing lens 1, performs so-called photoelectric conversion that outputs an analog signal corresponding to the optical image, and is an A / D converter. Numeral 3 is for converting an analog signal input from the CCD 2 into a digital signal and outputting it. Note that, in the A / D conversion circuit 3 according to the present embodiment, it is assumed that the higher the intensity of light incident on the photoelectric conversion means 2, the higher the value of the light is converted to a digital signal. The image data obtained via the A / D conversion circuit 3 is temporarily stored in the image memory 4.

The image data stored in the image memory 4 is subjected to various types of image processing by the MPU 5 serving as control means, and is finally stored in the nonvolatile memory 6 such as a memory card connected to the MPU 5. You. In addition, MPU5
Receives power from a power supply 7 such as a built-in battery, and can communicate with the outside using IrDA (infrared communication) or serial communication via an interface device 8. The MPU 5 starts operating by turning on the power switch 16, receives a release signal from the release button 10, and drives a shutter device (not shown) to perform photographing. Further, the MPU 5 controls the driving of an image display device (display means) 9 such as a liquid crystal monitor,
An image is displayed. Also, MPU
Reference numeral 5 denotes an AE (automatic exposure device) 11 for driving an aperture 11a.
To control the opening amount. Further, the MPU 5 starts charging the strobe device 13 from the power supply 7 and controls the light emission timing. The MPU 5 is connected to a sensor 14 that can detect an object approaching a finder (FIG. 2), and can detect a position of a normal shooting / close-up shooting switching switch 22 operated by a photographer. I have. By moving and operating the normal shooting / close-up shooting switching switch 22, a close-up shooting mode for shooting a subject existing in a close position and a normal shooting mode for shooting a subject farther from the close position can be set. I have.

Further, the digital still camera shown in FIG. 1 has an external distance measuring device 20. External distance measuring device 20
Has a function of irradiating infrared rays, detecting infrared rays reflected from the subject, and measuring the distance to the subject based on the time difference. However, it is also possible to use an external distance measuring device that performs distance measurement using, for example, ultrasonic waves.
A temperature sensor 21 is provided as temperature measuring means for measuring the temperature of the external distance measuring device 20, the temperature of the photographing lens 1, and the temperature of the motor 12, and transmits an output signal to the MPU 5 based on the measured temperature. ing.

The external distance measuring device 20 converts the measured distance value into
The in-focus position of the photographic lens 1 is obtained by referring to a table stored therein, and a drive signal is output to the motor 12. The motor 12 moves the photographing lens 1 to the in-focus position determined by the external distance measuring device 20 in accordance with the drive signal.
Is to be moved.

The digital still camera according to the present embodiment
It has another distance measuring device. Although this distance measuring device is a so-called imaging surface distance measuring device, it does not have a configuration dedicated to distance measurement, but performs distance measurement using functions of the CCD 2 and the MPU 5. Imaging surface ranging device (2,
According to 5), while moving the taking lens 1, the CC is gradually increased.
By converting the image data into image data in D2 and analyzing the image data in the MPU 5, the position where the image is sharpest is detected as the in-focus position. The operation of obtaining the focus position while moving the photographing lens 1 is called position search.

The MPU 5 outputs a drive signal corresponding to the in-focus position obtained by the position search to the motor 12. The motor 12 moves the photographing lens 1 to the determined in-focus position according to the drive signal.

FIG. 2 is a perspective view of an electronic camera provided with the image display device of the present embodiment. The electronic camera 100
A release button 10, a normal shooting / close-up shooting switching switch 22, and a power switch 16 are provided on the upper surface, and the liquid crystal monitor 9 is arranged on the back surface. On the side of the liquid crystal monitor 9, a monitor display button 9a and a frame feed button 9b are provided. The release button 10 can output different signals to the MPU 5 according to a two-step operation of half-press and full-press.

An optical finder 15 is provided above the liquid crystal monitor 9, and a sensor 14 is arranged adjacent to the optical finder 15. The electronic camera 10
A battery case cover 101 is disposed on the left side of the battery pack 0, and the battery can be replaced by opening the cover 101.

In this embodiment, the external distance measuring device 2
0 and the imaging plane distance measuring device (2, 5) are selectively used depending on the case in consideration of its advantages and disadvantages. More specifically, the distance measuring operation will be described.

As described above, due to the deviation (parallax) between the optical axis of the photographing lens 1 and the detection optical axis of the external distance measuring device 20, in the case of close-up photography in which the subject is in close proximity, focus is achieved. There is a possibility that a part different from the part where the image is desired is focused.

Therefore, in the present embodiment, if the MPU 5 determines that the close-up shooting mode is set and the close-up shooting is performed by moving the normal shooting / close-up shooting switching switch 22 by the photographer, Distance measurement is performed using the image pickup surface distance measurement device (2, 5), thereby achieving accurate focusing. On the other hand, if the MPU 5 determines that the normal shooting mode is set and the normal shooting is performed by moving the normal shooting / close-up shooting switching switch 22 by the photographer, the external ranging device 20
Can be used to measure the distance, thereby achieving quick focusing. Note that close-up photography refers to photography in which the distance to the subject is within about 30 to 40 cm.

As a modification of the present embodiment, the distance is measured by the external distance measuring device 20 without being based on the signal from the normal photographing / close-up photographing switch 22. When the object is in the close position, the MPU 5 When it is determined, the distance can be measured by using the imaging surface distance measuring device (2, 5), thereby achieving accurate focusing. Further, as another modified example, when the MPU 5 determines that the close-up photographing is to be performed by setting the close-up photographing mode or based on the distance measurement result of the external distance measuring device 20, the measurement by the external distance measuring device 20 is performed. By obtaining a rough focus position based on the distance result and performing a position search in the vicinity thereof using the imaging surface distance measuring device (2, 5), it is possible to achieve quick and accurate focusing.

Here, when the close-up photographing mode is set, the MPU 5 can narrow the range of the position search so as to enable focusing at a short distance within 30 to 40 cm, thereby achieving quick focusing. Can be achieved. However, there is a case where the subject has no contrast and the focus position cannot be detected, or the case where the subject is more than 40 cm and the focus position cannot be detected. As described above, when the release operation is performed when the in-focus position cannot be detected, the MPU 5 determines that the subject is 30 to 40 cm (the farthest side in the close-up shooting area).
The photographing lens 1 is driven via the motor 12 so as to focus on the virtual subject. The reason will be described below.

The taking lens 1 according to the distance to the subject
Can be moved in multiple stages. However,
Due to the general optical characteristics of the lens, the distance to the subject and the amount of movement of the lens do not have a linear relationship. For example, if the distance to the subject is relatively large, the subject is in focus with the movement of the lens. Changes greatly. On the other hand, when the distance to the subject is relatively small as in close-up shooting, the change in the position of the subject that is in focus with respect to the movement amount of the lens is small.

When a subject at a certain distance is focused, an image of the subject is sharply defined in a predetermined range before and after the subject to such an extent that the subject is practically acceptable. This predetermined range is called a depth of field. On the other hand, corresponding to this depth of field, there is a range on the focal side where a clear image is formed at equal intervals in the optical axis direction from the focal point. Such a range is called a depth of focus.
The depth of field d can be represented by the following equation. d = (2δ ′ · F _NO・ u ²・ f ² ) / (f ⁴・ u ² δ ′ ²・
F _NO ² ) where u: distance from the front principal point to the subject, δ ': allowable circle of confusion, f: focal length of the taking lens, F _NO : open F value of the taking lens. Note that the depth of focus t can be expressed by the following equation. t = ± δ'F _NO

From the expression representing the depth of field d, the following can be derived. (1) Since the depth of field is proportional to the square of the shooting distance,
The farther the depth, the deeper. (2) Since the depth of field is proportional to the open F-number of the taking lens, the smaller the aperture, the deeper the depth. (3) Since the depth of field is almost proportional to the square of the focal length, the seismic intensity is deeper for a wide-angle lens.

As described above, when the release operation is performed when the in-focus position cannot be detected, the object is 30 to 40 cm
If the photographing lens 1 is driven via the motor 12 so as to focus on the virtual subject (the farthest side in the close-up photographing area), the depth of field increases in proportion to the square of the photographing distance. Thereby, it is possible to widen the focusing range, and it is possible to prevent the out-of-focus image from being taken as much as possible.

As described above, the external distance measuring device 20 obtains the in-focus position corresponding to the measured value in accordance with a predetermined table of the relationship between the distance measurement value and the in-focus position. However, the relationship between the measured value and the in-focus position in such a table is established only when the temperature is within a predetermined range, and when the temperature exceeds the range, the in-focus position calculated for the distance measurement value is obtained. However, there is a possibility that the focus position is different from the actual focus position.

Therefore, in the present embodiment, the temperature measured by the temperature sensor 21 around the external distance measuring device 20, the photographing lens 1, and the motor 12 indicates that the temperature has become higher or lower than a predetermined range. If the MPU 5 determines, the distance is measured using the imaging surface distance measuring device (2, 5).
Thereby, accurate focusing can be achieved. On the other hand, as a result of measuring the temperature around the external distance measuring device 20 with the temperature sensor 21, if the MPU 5 determines that the temperature is within a predetermined range, distance measurement is performed using the external distance measuring device 20. This makes it possible to achieve quick and accurate focusing without any problem in photographing.

As a modification of the present embodiment, if the MPU 5 determines that the temperature is out of the predetermined range, the MPU 5 first operates the external distance measuring device 20 and determines a rough focus position based on the distance measurement result. In this vicinity, the imaging surface distance measuring device (2, 5)
By performing the search for the focus position by using, quick and accurate focusing can be achieved.

On the other hand, the temperature compensation of the external distance measuring device 20 can be performed by using the present embodiment. That is, the digital still camera shown in FIG. 1 is turned to the chart plate CP at a certain timing, for example, at the time of manufacturing or when the power is turned on after manufacturing, and the external distance measuring device 20 and the imaging surface distance measuring device (2, 5) are turned on. To perform distance measurement at the same time. Further, the ambient temperature is raised and lowered, and the deviation of the distance measurement value of the external distance measurement device 20 when the temperature changes is obtained by the imaging surface distance measurement device (2, 5), and a compensation value for correcting the deviation is, for example, MPU5. Can also be stored in the memory. In such a case, even if a temperature change occurs during the actual imaging, the distance measurement value of the external distance measurement device 20 can be corrected based on the stored compensation value, and thereby the external distance measurement device 20 can be quickly operated. This enables accurate focusing.

Further, according to the present embodiment, the MPU 5
Is capable of recognizing an open F value of the photographing lens 1 attached to the digital still camera and an F value of the aperture 11a via detection means (not shown). In addition, MPU5
The relationship between the shutter speed and the F value of the aperture can be controlled.

Here, when a lens having a small open F value is attached to the taking lens 1, as described in relation to the depth of field, the depth of field is also proportional to the open F value. It becomes shallow and the depth of focus becomes shallow. For this reason, if the lens stop position is slightly deviated, the image will be out of focus, making it difficult to focus. Therefore, when the MPU 5 determines that a lens having a small open F value is attached to the photographing lens 1, the MPU 5 measures the distance of the subject using the image pickup surface distance measuring means (2, 5). As a result, the focus is directly confirmed and detected based on the image passed through the lens, so that the focusing accuracy is increased and the defocus is prevented as much as possible.

Similarly, if the F value of the aperture 11a is small,
Since the depth of field becomes shallower in proportion to that, it becomes difficult to focus. Therefore, in such a case, the MPU 5 measures the distance to the subject by using the imaging surface distance measuring means (2, 5). As a result, the precision of focusing is improved, and defocus is prevented as much as possible.

On the other hand, when the close-up photographing mode is set or an image is taken outside a predetermined temperature range, the MPU 5 performs an external distance measuring device 20 for performing quick distance measurement, for example.
When it is determined that the distance measurement must be performed, the aperture 11a can be controlled to forcibly close to the small aperture side. Even in such a case, in order to obtain a sufficient exposure amount, the strobe 13 may be forcibly emitted. By utilizing the depth of field which is deepened thereby, defocus can be prevented as much as possible.

Further, when the MPU 5 determines that the F-number of the aperture 11a is large from the photographing conditions (in the case where the field luminance is high or the shutter speed is low), the MPU 5 determines the distance of the external distance measuring device 20. Priority can be given, thereby enabling quick focusing operation.

According to the present embodiment, the sport mode can be set by pressing a mode setting button (not shown). The sport mode is a mode suitable for photographing a moving subject such as a moving athlete, and requires a faster focusing operation. When such a sports mode is set, the MPU 5 controls the external distance measuring device 20 to perform distance measurement and controls the aperture 11a to forcibly close to the small aperture side. Even in such a case, in order to obtain a sufficient exposure amount, the strobe 13 may be forcibly emitted. By utilizing the depth of field which is deepened thereby, defocus can be prevented as much as possible.

Further, according to the present embodiment, a flat subject photographing mode can be set by pressing a mode setting button (not shown). The plane object photographing mode is a mode suitable for photographing a planar object such as a document. In such a case, since the distance of all the objects is constant, the position of the external distance Even when the detection light is applied, the distance measurement values are almost the same. Therefore, even if focusing is performed using the external distance measuring device 20, the possibility of defocusing is low. Therefore, the MPU 5 causes the external distance measuring device 20 to perform distance measurement when the planar object photographing mode is set. Thereby, quick focusing can be achieved.

Further, in the present embodiment, the sensor 1
4 are provided. The function of the sensor 14 will be described. For example, when the photographer looks into the optical viewfinder 15, it can be determined that the photographer is going to photograph. Therefore, when the sensor 14 detects such a photographer, it is possible to start an operation necessary for photographing, assuming that the photographing preparation stage has been started. However, if the distance measurement is started from this stage, the shutter may not be released for a long time, and the power used for the distance measurement may be wasted.

Therefore, in the present embodiment, when the sensor 14 detects the photographer, the MPU 5 starts the distance measurement of the external distance measurement device 20 in a predetermined cycle, and detects a rough focus position. I do. Further, when the photographer half-presses the release button 10, a position search is performed near the approximate in-focus position obtained by the external distance measuring device 20 by using the imaging surface distance measuring device (2, 5) at that time. By doing so, the photographing lens 1 is driven in order to obtain an accurate in-focus position, and then, when fully pressed, an image is taken. As described above, according to the present embodiment, quick and accurate focusing can be achieved.

Further, in this embodiment, if the LCD as the image display device 9 provided on the back of the digital still camera displays a subject to be imaged,
It can be determined that the photographer is about to shoot. Therefore,
When the LCD is displaying a subject to be imaged, it is possible to start an operation necessary for image capturing, assuming that a shooting preparation stage has been entered.

Therefore, in the present embodiment, the LCD
Displays the subject to be imaged, the MPU5
Starts the distance measurement of the external distance measurement device 20 in a predetermined cycle, and detects a rough focus position. Further, when the photographer half-presses the release button 10, a position search is performed near the approximate in-focus position obtained by the external distance measuring device 20 by using the imaging surface distance measuring device (2, 5) at that time. By doing
The photographing lens 1 is driven to obtain an accurate in-focus position, and then, when fully pressed, an image is taken. As described above, according to the present embodiment, quick and accurate focusing can be achieved.

Although the present invention has been described with reference to the embodiments, it should be understood that the present invention should not be construed as being limited to the above-described embodiments, and that modifications and improvements can be made as appropriate. is there.

[0060]

According to the digital still camera of the present invention, based on the subject image formed on the light receiving surface of the image sensor by the taking lens, the imaging surface distance measuring means for measuring the distance to the subject, External distance measuring means for measuring a distance to at least one point, determining means for determining whether normal shooting or close-up shooting is to be performed, and determining whether the close-up shooting is to be performed. A photographing lens driving unit that moves the photographing lens to a predetermined position based on the measurement result of the surface distance measuring unit; for example, in the case of normal photographing, quick focusing can be performed by using an external distance measuring unit. On the other hand, in the case of close-up photography, focusing can be achieved with high accuracy by using the imaging surface distance measuring means.

According to the digital still camera of the present invention,
Based on a subject image formed on a light receiving surface of an image sensor by a taking lens, an imaging surface ranging unit that measures a distance to a subject, and an external ranging unit that measures a distance to at least one point on the subject, Temperature measuring means for measuring the temperature,
When the temperature measured by the temperature measuring unit is out of the predetermined range, based on the measurement result of the imaging surface distance measuring unit, the imaging lens driving unit that moves the imaging lens to a predetermined position, For example, when the measured temperature falls within a predetermined range, focusing is quickly achieved by using an external distance measuring unit, while when the measured temperature is outside the predetermined range, the imaging surface distance measuring unit is activated. By using this, focusing can be achieved with high accuracy.

According to the correction method of the digital still camera of the present invention, a step of measuring the temperature, a step of measuring the distance of the object by the external distance measuring means, and a step of measuring the distance of the object by the image pickup surface distance measuring means. Generating temperature correction information for correcting the distance measurement result of the external distance measurement means based on the measured temperature and the distance measurement result of the imaging surface means. By executing each step (at the time of manufacturing), temperature correction information can be obtained, and the distance measurement result of the external distance measuring means can be corrected based on the temperature correction information. It becomes possible to achieve a focus.

According to the digital still camera of the present invention,
Based on a subject image formed on a light receiving surface of an image sensor by a taking lens, an imaging surface ranging unit that measures a distance to a subject, and an external ranging unit that measures a distance to at least one point on the subject, A photographing condition detecting means for detecting a photographing condition, and when the photographing condition detecting means determines that the photographing is performed in a state where the depth of field is shallow, based on a measurement result of the photographing surface distance measuring means, Since there is provided a photographing lens driving unit for moving the photographing lens to a predetermined position, it is possible to minimize blurring of the image.

According to the digital still camera of the present invention,
Based on a subject image formed on a light receiving surface of an image sensor by a taking lens, an imaging surface ranging unit that measures a distance to a subject, and an external ranging unit that measures a distance to at least one point on the subject, When moving the taking lens to a predetermined position based on the measurement result of the external distance measuring means,
And a photographing condition setting means for setting photographing conditions so that the depth of field becomes deep, so that the focus position obtained by the external distance measuring means is slightly shifted from the actual focus position. In such a case, focusing can be made as much as possible with a deep depth of field, and quick focusing can be achieved.

According to the digital still camera of the present invention,
Based on a subject image formed on a light receiving surface of an image sensor by a taking lens, an imaging surface ranging unit that measures a distance to a subject, and an external ranging unit that measures a distance to at least one point on the subject, A determination unit that determines whether one of a normal shooting and a moving subject is to be captured; and the determination unit determines that the shooting of the moving subject is to be performed. When the photographing lens driving unit that moves the photographing lens to a predetermined position and the determining unit determines that the moving object is to be photographed, the photographing conditions are set so that the depth of field becomes deep. Photographing condition setting means. Here, if the subject to be imaged is a moving subject, it may be difficult to track the subject with the imaging surface distance measuring means, and in such a case, quick measurement by the external distance measuring means is possible. Distance is suitable. However, the focus position measured by the external distance measurement means may be different from the actual focus position. Therefore, even when the in-focus position obtained by the external distance measuring means slightly deviates from the actual in-focus position, it is possible to focus as much as possible with a deep depth of field.

According to the digital still camera of the present invention,
Based on a subject image formed on a light receiving surface of an image sensor by a taking lens, an imaging surface ranging unit that measures a distance to a subject, and an external ranging unit that measures a distance to at least one point on the subject, Selecting means for selecting a flat subject shooting mode suitable for shooting a flat subject, and when the selecting means selects the flat subject shooting mode, based on a measurement result of the external distance measuring means, Photographing lens driving means for moving the photographing lens to a predetermined position. Here, if the object to be imaged is a flat object, there is a low possibility that a distance measurement error will occur even if external distance measuring means is used. Therefore, when the planar subject photographing mode is set, it is possible to cause the external distance measuring means to perform distance measurement, thereby achieving quick focusing.

According to the digital still camera of the present invention,
Based on a subject image formed on a light receiving surface of an image sensor by a taking lens, an imaging surface ranging unit that measures a distance to a subject, and an external ranging unit that measures a distance to at least one point on the subject, A finder, detecting means for detecting that the photographer is looking into the finder, and when the detecting means detects that the photographer is looking into the finder, a predetermined value is determined based on the detection of the detecting means. In the cycle of the above, the external distance measuring means is operated, and immediately before photographing, the image pickup surface distance measuring means is searched for a position within a predetermined range based on information from the external distance measuring means, so that a predetermined position of the photographing lens is obtained. Therefore, when the detecting means detects that the photographer is looking into the viewfinder, it can be regarded as a preparation stage of photographing. By obtaining a distance, a rough focus position is obtained, and immediately before shooting, near the rough focus position obtained by the external distance measurement means, the imaging plane distance measurement means performs a focus position search. Thus, the in-focus position can be quickly and accurately obtained.

According to the digital still camera of the present invention,
Based on a subject image formed on a light receiving surface of an image sensor by a taking lens, an imaging surface ranging unit that measures a distance to a subject, and an external ranging unit that measures a distance to at least one point on the subject, A display device capable of displaying a subject to be photographed, and when the display device is displaying the subject to be photographed, the external distance measuring means is operated in a predetermined cycle. By detecting a predetermined position of the photographing lens by causing the imaging surface distance measuring means to search for a position within a predetermined range based on information from the external distance measuring means, the display device displays a subject to be photographed. In this case, the approximate focus position is obtained by causing the external distance measuring means to measure the distance so that it can be regarded as a preparation stage of the photographing. Until Kana focus position near by causing the focus position searching on the imaging surface distance measuring device, can be determined quickly and accurately focus position.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an electronic camera according to an embodiment.

FIG. 2 is a perspective view of the electronic camera according to the embodiment.

[Explanation of symbols]

 Reference Signs List 1 shooting lens 2 CCD 3 A / D converter 4 image memory 5 MPU 6 nonvolatile memory 7 power supply (battery) 8 interface device 9 image display device (LCD) 10 release button 11 photometer 11a aperture 12 motor 13 strobe 14 sensor 15 Optical viewfinder 16 Power switch 20 External distance measuring device 21 Temperature sensor 22 Button for switching between normal shooting and close-up shooting

Claims (31)

[Claims] 1. An image pickup surface distance measuring means for measuring a distance to a subject based on a subject image formed on a light receiving surface of an image sensor by a photographing lens, and an external device for measuring a distance to at least one point on the subject. Distance measuring means, determining means for determining whether normal shooting or close-up shooting is performed, when the determining means determines that close-up shooting is performed, based on the measurement result of the imaging surface distance measuring means, A photographing lens driving means for moving the photographing lens to a predetermined position. 2. The digital still camera according to claim 1, wherein the predetermined position is a focus position of the photographing lens. 3. A switching member for switching between a normal shooting mode and a close-up shooting mode is provided, and the determination unit detects that the switching member is switched to a close-up shooting mode, and performs close-up shooting. The digital still camera according to claim 1, wherein the determination is made as follows. 4. When the determining means determines that close-up photographing is to be performed, and the image-capturing surface distance measuring means cannot detect the in-focus position of the photographing lens, the photographing lens driving means controls the photographing lens. 3. The lens according to claim 1, wherein the lens is moved to the farthest side in the short-range photographing range.
A digital still camera according to item 1. 5. The image processing apparatus according to claim 1, wherein when the distance to the subject measured by the external distance measurement unit is equal to or less than a predetermined distance, the determination unit determines that close-up shooting is performed. Digital still camera. 6. When the distance to the object measured by the external distance measuring means is equal to or less than a predetermined distance, the imaging surface distance measuring means focuses the photographing lens on the basis of information from the external distance measuring means. The digital still camera according to claim 1, wherein the position is detected. 7. The digital still camera according to claim 6, wherein the imaging surface distance measuring means detects a focus position near the focus position measured by the external distance measuring means. 8. An image pickup surface distance measuring means for measuring a distance to a subject based on a subject image formed on a light receiving surface of an image sensor by a photographing lens, and an external device for measuring a distance to at least one point on the subject. A distance measuring unit; a temperature measuring unit for measuring a temperature; and if the temperature measured by the temperature measuring unit is outside a predetermined range, the photographing lens is set to a predetermined position based on a measurement result of the imaging surface distance measuring unit. And a photographing lens driving unit that moves to a position. 9. The digital still camera according to claim 8, wherein the predetermined position is a focus position of the photographing lens. 10. The temperature measured by the temperature measuring means,
The digital still according to claim 8, wherein when the distance is outside the predetermined range, the imaging surface distance measuring unit detects a predetermined position of the photographing lens based on information from the external distance measuring unit. camera. 11. The digital still as claimed in claim 8, wherein the imaging surface distance measuring means detects a predetermined position near the in-focus position measured by the external distance measuring means. camera. 12. A step of measuring a temperature, a step of measuring a distance of an object by an external distance measuring means, a step of measuring the distance of the object by an image pickup surface distance measuring means, a measurement temperature, and a measurement of the image pickup surface means. Generating temperature correction information for correcting the distance measurement result of the external distance measuring means based on the distance result. 13. The digital still camera correction method according to claim 12, wherein each of the steps is performed when the digital still camera is manufactured or when the power is turned on after the manufacturing. 14. An image pickup surface distance measuring means for measuring a distance to a subject based on a subject image formed on a light receiving surface of an image sensor by a photographing lens, and an external device for measuring a distance to at least one point on the subject. A distance measuring unit; a photographing condition detecting unit for detecting a photographing condition; and a measuring unit for measuring the photographing surface distance measuring unit when the photographing condition detecting unit determines that photographing is performed in a state where the depth of field is shallow. And a photographing lens driving means for moving the photographing lens to a predetermined position based on the result. 15. The digital still camera according to claim 14, wherein the predetermined position is a focus position of the photographing lens. 16. When a photographing lens having an open F value smaller than a predetermined value is attached to the digital still camera, the photographing condition detecting means determines that photographing is performed with a shallow depth of field. The digital still camera according to claim 14, wherein the digital still camera is operated. 17. An imaging apparatus according to claim 14, wherein when the F value of the aperture is smaller than a predetermined value, the imaging condition detecting means determines that the imaging is performed with a small depth of field.
A digital still camera according to any one of claims 1 to 16. 18. When the photographing condition detecting means determines that photographing is performed in a state where the depth of field is deep, the photographing lens driving means controls the photographing lens based on the measurement result of the external distance measuring means. 18. The digital still camera according to claim 14, wherein the taking lens is moved to a predetermined position. 19. An image pickup surface distance measuring means for measuring a distance to a subject based on a subject image formed on a light receiving surface of an image sensor by a photographing lens, and an external device for measuring a distance to at least one point on the subject. A distance measuring unit, and a photographing condition setting unit configured to set photographing conditions such that a depth of field is increased when the photographing lens is moved to a predetermined position based on a measurement result of the external distance measuring unit. A digital still camera comprising: 20. The digital still camera according to claim 19, wherein the predetermined position is a focus position of the photographing lens. 21. When moving the photographing lens to a predetermined position based on a measurement result of the external distance measuring means, the photographing condition setting means sets the F value of the aperture smaller than a predetermined value. The digital still camera according to claim 19, wherein the digital still camera is used. 22. An image pickup surface distance measuring means for measuring a distance to a subject based on a subject image formed on a light receiving surface of an image sensor by a photographing lens, and an external device for measuring a distance to at least one point on the subject. Distance measuring means; determining means for determining whether normal shooting or moving object shooting is performed; and determining the external distance when the determining means determines that moving object shooting is to be performed. A photographing lens driving unit that moves the photographing lens to a predetermined position based on a measurement result of the unit; and when the determining unit determines that photographing of the moving subject is performed, the depth of field is increased. A digital still camera comprising: a photographing condition setting unit for setting photographing conditions. 23. The digital still camera according to claim 22, wherein the predetermined position is a focus position of the photographing lens. 24. An image pickup surface distance measuring means for measuring a distance to a subject based on a subject image formed on a light receiving surface of an image sensor by a photographing lens, and an external device for measuring a distance to at least one point on the subject. Distance measuring means; selecting means for selecting a plane object photographing mode suitable for photographing a planar object; measuring the external distance measuring means when the selecting means selects the plane object photographing mode. And a photographing lens driving means for moving the photographing lens to a predetermined position based on the result. 25. The digital still camera according to claim 24, wherein the predetermined position is a focus position of the photographing lens. 26. An image pickup surface distance measuring means for measuring a distance to a subject based on a subject image formed on a light receiving surface of an image sensor by a photographing lens, and an external device for measuring a distance to at least one point on the subject. Distance measuring means; Based on the detection, the external distance measuring means is operated in a predetermined cycle, and immediately before photographing, the imaging surface distance measuring means is caused to search for a position within a predetermined range based on information from the external distance measuring means. A digital still camera for detecting a predetermined position of a taking lens. 27. The apparatus of claim 27, wherein the predetermined position is a focus position of the photographing lens, and the predetermined range is near a focus position of the photographing lens measured by the external distance measuring means. A digital still camera according to claim 26. 28. A release button which can be pressed in two steps is provided, and when the release button is pressed in one step, the imaging surface distance measuring means starts distance measurement, and the release button is pressed in two steps. 28. The digital still camera according to claim 26, wherein photographing is performed when the photographing is performed. 29. An image pickup surface distance measuring means for measuring a distance to a subject based on a subject image formed on a light receiving surface of an image sensor by a photographing lens, and an external device for measuring a distance to at least one point on the subject. Distance measuring means, a display device capable of displaying a subject to be photographed, and when the display device displays the subject to be photographed, the external distance measuring means is operated in a predetermined cycle to perform photographing. Immediately before, the digital still camera detects a predetermined position of the photographing lens by causing the imaging surface distance measuring means to search a position within a predetermined range based on information from the external distance measuring means. 30. The apparatus according to claim 30, wherein the predetermined position is a focus position of the photographic lens, and the predetermined range is near a focus position of the photographic lens measured by the external distance measuring means. 30. The digital still camera according to claim 29. 31. A release button which can be pressed in two steps is provided, and when the release button is pressed in one step, the imaging surface distance measuring means starts distance measurement, and the release button is pressed in two steps. 31. The digital still camera according to claim 29, wherein a photographing is performed when the photographing is performed.