JP2009145670A - Focusing device and focusing method - Google Patents

Abstract

To provide a focusing device capable of accurately and quickly focusing on the same fixed focal length even when the angle of view is changed.
An imaging optical system, an imaging means for converting a subject image formed by the imaging optical system into an electrical signal and outputting the electrical signal, and a focusing means for determining the degree of focus based on the electrical signal from the imaging means And a focusing instruction receiving means for receiving a focusing instruction, the focusing means determines a focus fixing distance based on an electric signal from the imaging means, and the focusing instruction receiving means receives the focusing instruction. If the depth of field at the time of receiving the focus instruction is larger than the depth of field at the time of determining the focus fixing distance when determining the focus fixing distance, the focus distance of the imaging optical system is set as the focus fixing distance. If the depth of field at the time of focusing instruction reception is narrower than the depth of field at the time of fixed focus distance, based on the electrical signal from the imaging means in a range corresponding to the depth of field at the time of fixed focus distance Determine the focus level and determine the focus distance of the imaging optical system. Characterized in that it.
[Selection] Figure 9

Description

  The present invention relates to a focusing device, an imaging device, a focusing method, and an imaging method, and in particular, a focusing device capable of accurately and quickly focusing on the same fixed focal length even when the angle of view is changed. The present invention relates to an imaging apparatus, a focusing method, and an imaging method.

In a conventional imaging apparatus such as a digital camera, focusing is performed at a focus position automatically determined by an autofocus function in the imaging apparatus.
However, a method of obtaining contrast information of a subject while driving a lens and returning the lens to a position with the highest contrast, so-called hill-climbing autofocus (hereinafter also referred to as AF) takes time, and therefore misses a photo opportunity. There was a problem.

In order to solve such a problem, there is an image pickup apparatus having a focus mode in which even a camera capable of auto-focusing can be photographed with a lens in a fixed position in an infinite mode or a snap mode.
Such an imaging apparatus has a fixed focus, can be focused without adopting a hill-climbing method for moving a lens, and can shoot a subject in a short time.
However, the imaging method using the focus mode has a problem that the focus position is fixed, and the subject at an arbitrary position cannot be focused.

  In addition, there is an image-capable device that can set the distance by specifying the distance to the image-capturing device and can shoot at a lens position fixed at that distance. .

  Therefore, Patent Document 1 discloses a camera that uses an autofocus function and includes a distance measuring device. According to this configuration, the actual distance to be measured is input, and the input distance and the distance measurement result are compared and displayed, so that the user can focus by measuring the timing of pressing the shutter. Images can be obtained.

  However, in the invention described in Patent Document 1, since it is necessary for the user to measure the timing of pressing the shutter, it is difficult to set the lens position at a distance where the focus is actually desired. Digital cameras generally employ a “mountain climbing” AF and do not have a distance measuring device.

In Patent Document 2, a subject whose objective is to automatically determine an aperture value that focuses on a plurality of subjects is measured, and a lens position whose distance is the in-focus position is stored in the in-camera memory. Then, it measures the distance of another subject, calculates the defocus amount between the lens position whose distance is the in-focus position and the lens position stored last time, and calculates both the defocus amount and the stored lens position. A configuration for calculating an aperture value that focuses on a subject is disclosed.
In Patent Document 3, the focus position at which the in-focus state is maintained when the focal length is changed is stored in the memory for the purpose of correcting the focus position of the zoom lens and further quickly focusing on the subject. First, the focus lens is moved to infinity, and when the zoom lens is stopped to move to shorten the focal length, the focus position is fixed based on the adjustment information stored in the memory. A configuration for moving the lens is disclosed.

  However, even with the inventions described in Patent Documents 2 and 3, it is difficult to obtain a lens position at the same distance when zooming to a telephoto position from a lens position once acquired with a short focal length. It cannot be reproduced.

JP 2004-109272 A Japanese Patent Publication No. 63-172130 Japanese Patent No. 3036067

  The present invention has been made in view of the above problems in the prior art, and a focusing device, an imaging device, and an imaging device capable of accurately and quickly focusing on the same fixed focal length even when the angle of view is changed. An object is to provide a focusing method and an imaging method.

In order to solve the above problems, an imaging apparatus, a focusing method, and an imaging method according to the present invention specifically have the technical features described in (1) to (10) below.
(1): an imaging optical system, an imaging means for converting a subject image formed by the imaging optical system into an electrical signal and outputting the electrical signal, and an in-focus degree determination based on the electrical signal from the imaging means. Focusing means and focusing instruction receiving means for receiving a focusing instruction, the focusing means determines a focus fixing distance based on an electrical signal from the imaging means, and the focusing instruction receiving means When the depth of field when receiving the focus instruction when receiving the focus instruction is wider than the depth of field when determining the focus fixing distance when determining the focus fixing distance, the imaging optical system When the focus distance is the focus fixing distance, and the depth of field when the focus instruction is received is smaller than the depth of field when the focus fixing distance is determined, the focus fixing distance is determined. In the range corresponding to the depth of field, the electrical signal from the imaging means The degree focusing is determined by Zui, a focusing device, characterized by determining the focusing distance of the imaging optical system.

(2): an imaging optical system, an imaging means for converting a subject image formed by the imaging optical system into an electrical signal and outputting the electrical signal, and an in-focus degree determination based on the electrical signal from the imaging means. Focusing means and focusing instruction receiving means for receiving a focusing instruction, the focusing means determines a focus fixing distance based on an electrical signal from the imaging means, and the focusing instruction receiving means When the depth of field when receiving the focus instruction when receiving the focus instruction is wider than the depth of field when determining the focus fixing distance when determining the focus fixing distance, the imaging optical system When the focus distance is the focus fixing distance, and the depth of field when the focus instruction is received is smaller than the depth of field when the focus fixing distance is determined, the focus fixing distance is determined. Perform focusing at multiple locations within the range equivalent to the depth of field. A focusing apparatus characterized.

(3): an imaging optical system, an imaging means for converting a subject image formed by the imaging optical system into an electrical signal and outputting the electrical signal, and an in-focus degree determination based on the electrical signal from the imaging means. A focusing means, a focusing instruction receiving means for receiving a focusing instruction, and a warning means. The focusing means determines a focus fixing distance based on an electrical signal from the imaging means, and the focusing When the depth of field at the time of focus instruction reception when the instruction reception means receives the focus instruction is wider than the depth of field at the time of determining the focus fixing distance when determining the focus fixing distance, The in-focus distance of the imaging optical system is the focus fixing distance, and the warning means is configured such that when the in-focus instruction reception depth of field is narrower than the in-focus fixing distance determination depth of field, The focusing device is characterized by performing a warning.

(4): an imaging optical system, an imaging means for converting a subject image formed by the imaging optical system into an electrical signal and outputting the electrical signal, and an in-focus degree determination based on the electrical signal from the imaging means. A focusing unit, and the imaging optical system includes a zoom lens, a focus lens, and a diaphragm, and the focusing unit controls the zoom lens and the diaphragm to narrow the depth of field. The focusing device is characterized in that a focus fixing distance is determined based on an electrical signal from the imaging means in a state of being set to be a focusing distance of the imaging optical system.

(5): An imaging apparatus including the focusing device according to any one of (1) to (5) and performing imaging.

(6): a focusing process for determining a degree of focusing based on an electrical signal obtained by converting a subject image formed by the imaging optical system, and a focusing instruction receiving process for receiving a focusing instruction, In the focusing step, after determining the focus fixing distance based on the electrical signal, the depth of field at the time of focusing instruction reception when the focusing instruction receiving step receives the focusing instruction is When it is wider than the depth of field at the time of determining the focus fixing distance when determining the distance, the focusing distance of the imaging optical system is set as the focus fixing distance, and the depth of field at the time of receiving the focus instruction is If the depth of field at the time of determining the focus fixing distance is narrower than the depth of field at the time of determining the focus fixing distance, the degree of focus is determined based on the electric signal in a range corresponding to the depth of field at the time of determining the focus fixing distance, Focusing characterized by determining the focusing distance of the optical system It is the law.

(7): a focusing process for determining a degree of focusing based on an electrical signal obtained by converting a subject image formed by the imaging optical system, and a focusing instruction receiving process for receiving a focusing instruction, In the focusing step, after determining the focus fixing distance based on the electrical signal, the depth of field at the time of focusing instruction reception when the focusing instruction receiving step receives the focusing instruction is When it is wider than the depth of field at the time of determining the focus fixing distance when determining the distance, the focusing distance of the imaging optical system is set as the focus fixing distance, and the depth of field at the time of receiving the focus instruction is When the focus fixing distance is determined to be narrower than the depth of field, the focusing method is performed at a plurality of positions in a range corresponding to the focus fixing distance determining depth of field. It is.

(8): a focusing process for determining a degree of focusing based on an electrical signal obtained by converting a subject image formed by the imaging optical system, and a focusing instruction receiving process for receiving a focusing instruction, In the focusing step, after determining the focus fixing distance based on the electrical signal, the depth of field at the time of focusing instruction reception when the focusing instruction receiving step receives the focusing instruction is When it is wider than the depth of field at the time of determining the focus fixing distance when determining the distance, the focusing distance of the imaging optical system is set as the focus fixing distance, and the depth of field at the time of receiving the focus instruction is When the focus fixing distance is determined, when the depth of field is smaller than the depth of field, a warning is given.

(9): In the focusing method for determining the degree of focusing based on the electrical signal obtained by converting the subject image formed by the imaging optical system, the imaging optical system includes a zoom lens, a focus lens, and a diaphragm. And determining the focus fixing distance based on an electric signal in a state where the depth of field is narrowed by controlling the zoom lens and the diaphragm, and setting it as a focusing distance of the imaging optical system. This is the focusing method.

(10): An imaging method including the focusing process according to any one of (6) to (9) and performing imaging.

  According to the present invention, it is possible to provide a focusing device, an imaging device, a focusing method, and an imaging method capable of accurately and quickly focusing on the same fixed focal length even when the angle of view is changed.

(First embodiment)
Hereinafter, a first embodiment of an imaging apparatus according to the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram showing a partial configuration of a digital camera according to an embodiment of the present invention.
The CCD (101) (imaging means) is a solid-state imaging device for photoelectrically converting an optical image and outputting an electrical signal, and F / E (front end) -IC (102) is a correlation unit for image noise removal. From the CDS (102-1) that performs multiple sampling, the AGC (102-2) that performs gain adjustment, the A / D (102-3) that performs digital signal conversion, and the CCD1 control block (104-1), A CCD (101), which is supplied with a horizontal synchronizing signal and controlled by the CPU block (104-3), and a TG (102-4) for generating a drive timing signal for the F / E-IC (102) are included.

  The lens barrel unit (4) (imaging optical system) includes a zoom lens (4-1a) for capturing an optical image of a subject, a zoom optical system (4-1) including a zoom drive motor (4-1b), and a focus lens (4). -2a), a focus optical system (4-2) comprising a focus drive motor (4-2b), a diaphragm (4-3a), a diaphragm unit (4-3) comprising a diaphragm motor (4-3b), a mechanical shutter (4) 4a), a mechanical shutter unit (4-4) including a mechanical shutter motor (4-4b), and a motor driver (4-5) for driving each motor.

  The digital still camera processor (104) performs white balance setting and gamma setting on the output data of the F / E-IC (102) from the CCD (101) and, as described above, outputs the vertical synchronization signal and horizontal synchronization signal. CCD1 control block (104-1) to be supplied, CCD2 control block (104-2) for converting into luminance data / color difference data by filtering processing, and CPU block (104-3) for controlling the operation of each unit described above The local SRAM (104-4) for temporarily storing the data necessary for the control described above, the USB block (104-5) for USB communication with an external device such as a personal computer, and the serial with an external device such as a personal computer Serial block (104-6) for communication, JPEG CODEC for JPEG compression / decompression Block (104-7), RESIZE block (104-8) for enlarging / reducing the size of the image data by interpolation processing, TV for converting the image data into a video signal for display on an external display device such as a liquid crystal monitor or TV It has a signal display block (104-9) and a memory card block (104-10) for controlling a memory card for recording photographed image data.

  Here, the focusing means in the present invention is a part of the motor driver (4-5) and the CPU block (104-3). As the warning means in the present invention, any known means can be used as long as it is a means that issues a warning under the control of the CPU block (104-3), and can be placed at any location inside the digital camera.

The SDRAM (103) temporarily stores image data when the digital still camera processor (104) performs various processes on the image data. For example, the image data to be stored is acquired from the CCD (101) via the F / E-IC (102), and the white balance setting and the gamma setting are performed by the CCD1 signal processing block (104-1). “RAW-RGB image data” in the state, “YUV image data” in which the luminance data / color difference data conversion is performed in the CCD 2 control block (104-2), and JPEG compression in the JPEG CODEC block (104-7) “JPEG image data”.
The built-in memory (107) is a memory for enabling the captured image data to be stored.

  The LCD driver (108) is a drive circuit that drives the LCD monitor (5), and converts the video signal output from the TV signal display block (104-9) into a signal for display on the LCD monitor (5). It also has a function to do. The LCD monitor (5) is a monitor for monitoring the state of the subject before photographing, confirming the photographed image, displaying the image data recorded in the memory card or the built-in memory (107), and the like. is there. The video AMP (109) is an amplifier for converting 75Ω impedance of the video signal output from the TV signal display block (104-9), and the video jack (110) is connected to an external display device such as a TV. Jack for. The operation key unit (SW1-15) is a key circuit operated by the user, and the SUB-CPU (105) (focusing instruction receiving means) is a CPU in which ROM / RAM is built in one chip, and the operation key unit An output signal such as (SW1-15) is output to the CPU block (104-3) described above as user operation information.

  The audio CODEC (112) receives audio data compressed from the audio block (104-12) output from the audio block (104-12) of the digital still camera processor (104) from the audio block, converts it into an audio analog signal, and converts it into a speaker. Drive output to (113).

  In the strobe light emitting unit (1), the CPU controls the charging of the strobe circuit and controls the light emission, so that the charged charge is applied to the light emitting unit including a light emitting tube and a reflector to emit light.

FIG. 2 is a block diagram showing an imaging flow in the first embodiment of the imaging apparatus of the present invention, and shows processing in the imaging apparatus when a first release SW and a second release SW (not shown) are operated. Show.
When the first release SW is turned on, after performing AE for determining the exposure amount for photographing (STEP 2-1), a focusing process is performed (STEP 2-2). In the focus adjustment process, contrast-type AF is performed when not in the focus fixing mode, and in the focus fixing mode, the focus is fixed after the focus fixing distance is determined and stored in advance, and these processes will be described later. To do.
After the focusing process, AWB for determining a color for photographing is performed (STEP2-3), and waiting for the second release SW for photographing to be turned on (STEP2-4, 2-5). If the first release SW is turned off before the second release SW is turned on, the imaging is stopped.
When the second release SW is turned on, photographing and recording / saving operations are performed (STEP 2-6).

  Here, the contrast type AF (also referred to as a hill climbing type) AF will be described. In contrast type AF, first, imaging is performed while changing the position of the focus lens in minute steps, and a high-frequency portion of each imaging data is extracted. Next, a focus evaluation value for each step is calculated based on the extracted high-frequency component, and a focus lens position that focuses on the subject is determined based on a change in the focus evaluation value.

Next, a method for focusing will be described.
FIG. 3 is a graph showing the relationship between the reciprocal of the distance of the optical system and the focused lens position.
In the present embodiment, it is assumed that zooming is performed at 17 points from the wide-angle Wide end ZP1 to the telephoto telephoto end Zp17.
In general, the lens position driving amount that is geometrically focused is in a proportional relationship with the reciprocal of the distance. Therefore, in the present embodiment, the lens position driving amount and the reciprocal of the distance are considered to be in a proportional relationship and approximate to a straight line so that the lens position fp at the distance L is an arbitrary zoom position ZP (where ZP is ZP1). To ZP17) is represented by the following formula 1.

    fp = K (ZP) × (1 / L) + B (ZP) (Formula 1)

  In the imaging apparatus according to the present invention, B (ZP), which means the lens position fp at infinity with respect to each zoom position ZP, and a proportionality constant between the reciprocal distance 1 / L with respect to each zoom position ZP and the lens position fp. The inclination K (ZP) is stored.

  Here, even in the fixed focus mode, if 1 / L is specified, the lens position fp can be calculated from K (ZP) and B (ZP) in each ZP by the above equation 1, but zoom (ZP ) May be out of focus.

Specifically, as shown in FIG. 4, it is assumed that the focus fixing distance is determined by the subject located at L0 in ZP1.
When contrast AF is applied to L0 with ZP1, the lens position is fp3a depending on the stop resolution of the mechanical lens and the depth of field at the Wide end. (The horizontal broken line indicated by fp3a is a position where the lens can be stopped)
Since fp3a has a range of depth of field ± A from L1 to L2, the representative point of the distance is L3. (Contrast information cannot accurately detect distances within the depth of field ± A)
Therefore, when the zoom is changed to the telephoto end (telephoto side) ZP17 having a focal length four times that of Zp1, the depth of field is about 1 / L on the 1 / L axis when the aperture diameter of the lens is not changed. Since it is in the range of ± B of ¼, L0 where the subject is located does not enter within the depth of field of fp3b ± B obtained by K (ZP17) and B (ZP17) of L3 and ZP17, and is out of focus.

Therefore, in the imaging apparatus according to the present invention, in order to eliminate the above-described problem of defocusing, focusing is performed according to the flow described below.
FIG. 5 is a through display of the LCD monitor in the first embodiment of the imaging apparatus according to the present invention.
5A, after specifying the distance A to be photographed, the angle of view is changed as shown in FIG. 5B, the AF range is adjusted at the position of the distance C, and the focus fixed storage switch (SW) is turned on. .
The fixed focus storage switch is for determining and storing (setting) a distance to be stored in the fixed focus mode.

(Focus process)
FIG. 6 is a block diagram showing a flow up to determining and storing a focus fixing distance in the focus fixing mode.
Prior to the imaging flow shown in FIG. 2, when the fixed focus storage switch (SW) is turned on, if the zoom position is not the Tele position, automatic zooming is performed to the Tele position so that the depth of field is reduced. (STEP 6-1, 6-2)
If the aperture is not open, the aperture is opened to reduce the depth of field. (STEP 6-3, 6-4)

If the zoom or aperture is changed after turning on the fixed focus memory switch, the exposure is calculated by adjusting the gain of the circuit and the electronic shutter of the image sensor so that the image sensor has the appropriate exposure.・ Perform by setting. (STEP 6-5)
Next, contrast-type AF (mountain climbing AF) is performed, and the focus fixing distance is obtained and determined from the resulting lens position, and stored in the camera. (STEP 6-6, 6-7, 6-8)

  After the focus fixing distance is determined, the camera user can freely change the zoom position, and when the subject comes to a desired position as shown in FIG. 5C, the release SW is turned on, so that the imaging flow shown in FIG. Done.

FIG. 7 is a block diagram showing a flow of focusing in the first embodiment of the imaging apparatus according to the present invention.
In the focusing process (STEP 2-2) in FIG. 2, it is determined whether or not the focus fixing mode is set (STEP 7-1). If the focus fixing mode is set, the zoom position at that time and the above-described zoom position are set. The lens position is calculated from the focus fixing distance stored in the flow shown in FIG. 6, and the lens is driven without performing contrast AF (STEP 7-2, 7-3, 7-4). If the focus fixed mode is not set, the contrast AF is performed to focus.
Here, as shown in STEP 7-3, the lens position fp is a function f (ZP, focus fixing distance) of ZP and the focus fixing distance, and is expressed by the following formula 2.

    fp = f (ZP, focus fixing distance) = K (ZP) × (1 / focus fixing distance) + B (ZP) (Expression 2)

  Also, it is determined whether or not the focus fixing mode is set (STEP 7-1). If the focus fixing mode is not set, contrast AF is performed (STEP 7-5), and the focusing is finished. .

(Second Embodiment)
In the present embodiment, the configuration is the same as that of the first embodiment except for the fixed focus mode and the flow in focusing.
(Focus process)
FIG. 8 is a block diagram showing a flow of a fixed focus mode in the second embodiment of the imaging apparatus according to the present invention.
The fixed focus storage switch is for setting a distance to be stored in the fixed focus mode. In the present embodiment, prior to the imaging flow shown in FIG. 2, when the fixed focus memory switch (SW) is turned on, contrast AF (mountain climbing AF) is performed (STEP 8-1), and the focus is determined from the resulting lens position. The fixing distance is obtained and stored in the digital camera (STEPs 8-2 and 8-3).

At the same time, the zoom position and aperture value at this time are stored in the digital camera (STEPs 8-4 and 8-5).
Note that the depth of field ± δ1 / L at the distance L is expressed by the following Equation 3 using the F value of the lens determined from the zoom position and the aperture, the focal length of the lens, and the allowable circle of confusion diameter σ on the image sensor. I want.

± δ1 / L = ± {(σ × F value) / (focal length) ² } (Formula 3)

FIG. 9 is a block diagram showing a flow of focusing in the second embodiment of the imaging apparatus according to the present invention.
In the focusing process (STEP 2-2) performed by receiving the focusing instruction in FIG. 2, it is determined whether or not the focus fixing mode is set (STEP 9-1), and if the focus fixing mode is set, The depth of field ± δ1 / L ₁ at the time of receiving a focusing instruction obtained from the current lens F value and the zoom focal length is the focal point obtained from the lens F value and the zoom focal length when the focus fixing distance is obtained. Compared to the depth of field ± δ1 / L ₂ when fixing distance is determined (STEP 9-2, 9-3), if it is wider (considering the example of FIG. 4, the depth of field ± δ1 when receiving a focus instruction) / L ₁ is ± A, the depth of field ± δ1 / L ₂ is ± B when determining the focus fixing distance), the lens position fp is calculated from the focus fixing distance (STEP 9-4), and contrast type AF is performed. The lens is driven without any change (STEP 9-5).

On the other hand, the depth of field ± δ1 / L ₁ at the time of receiving a focus instruction obtained from the current lens F value and the zoom focal length is obtained from the lens F value and the zoom focal length when the focus fixing distance is obtained. If it is narrower than the depth of field ± δ1 / L ₂ at the time of determining the focus fixing distance, specifically, considering the example of FIG. 4, the depth of field ± δ1 / L ₁ at the time of receiving the focus instruction is When the depth of field ± δ1 / L ₂ at the time of determining the fixed distance for ± B and ± A is ± A, the far point fp3b-2 on ZP17 corresponding to the far side distance of 1 / L3-A and 1 / L3 + A And the near point fp3b + 2 on the ZP17 corresponding to the near side distance of is calculated (STEP 9-6, 9-7). Next, an error range corresponding to the fp range b in FIG. 4 is obtained (STEP 9-8), and a suitable focusing distance is determined by performing contrast-based AF of the error ranges fp3b-2 to fp3b + 2 (STEP 9-). 9).

  Further, it is determined whether or not the focus fixing mode is set (STEP 9-1). If the focus fixing mode is not set, the contrast AF is performed (STEP 9-10), and the focusing is finished. .

(Third embodiment)
In the present embodiment, the configuration is the same as that of the second embodiment except for the flow in focusing.
(Focus process)
FIG. 10 is a block diagram showing a flow of focusing in the third embodiment of the imaging apparatus according to the present invention.
The fixed focus storage switch is for setting a distance to be stored in the fixed focus mode, and in this embodiment, has the same configuration as the flow of the fixed focus mode in the second embodiment. Contrast AF is performed, and the focus fixing distance, zoom position, and aperture value are stored in the digital camera.

When the continuous shooting flag = 0, that is, when the flag for performing continuous shooting is not established (STEP 10-1), in the focusing process (STEP 2-2) performed by receiving the focusing instruction in FIG. 2, the focus fixing mode is set. It is determined whether or not the focus is set (STEP 10-2), and if the focus fixing mode is set, the focus instruction obtained from the current lens F value and the zoom focal length in the focusing process of FIG. The depth of field ± δ1 / L ₁ at the time of reception is compared with the depth of field ± δ1 / L ₂ at the time of determining the focus fixing distance obtained from the lens F value when the focus fixing distance is obtained and the focal length of the zoom. (STEP 10-3, 10-4), if wide (considering the example of FIG. 4, the depth of field ± δ1 / L ₁ at the time of receiving the focus instruction is ± A, and the field at the time of determining the focus fixing distance Depth ± δ1 / L ₂ is ± B) For fixed focus The lens position fp is calculated from the distance (STEP 10-5), and the lens is driven without performing contrast AF (STEP 10-6).

On the other hand, the depth of field ± δ1 / L ₁ at the time of receiving a focus instruction obtained from the current lens F value and the zoom focal length is obtained from the lens F value and the zoom focal length when the focus fixing distance is obtained. If it is narrower than the depth of field ± δ1 / L ₂ at the time of determining the focus fixing distance, specifically, considering the example of FIG. 4, the depth of field ± δ1 / L ₁ at the time of receiving the focus instruction is When the depth of field ± δ1 / L ₂ at the time of determining the fixed distance for ± B and ± A is ± A, the far point fp3b-2 on ZP17 corresponding to the far side distance of 1 / L3-A and 1 / L3 + A The near point fp3b + 2 on the ZP17 corresponding to the near side distance is calculated (STEP 10-7). Next, an error range (photographing lens range fp3b-2 to fp3b + 2) corresponding to the fp range b in FIG. Drive to position fp3b-2.

  Then, by setting a flag indicating that the error range is continuously shot (STEP 10-10) and continuously shooting within the error range, a shot image with an optimum focus can be obtained from a plurality of shot images.

FIG. 11 is a block diagram showing a continuous shooting flow in the third embodiment of the imaging apparatus according to the present invention. Here, FIG. 11 is a block diagram for explaining in detail the photographing and recording storage operations of STEP 2-6 in FIG. 2 during continuous photographing.
When the second release SW is turned on and the actual shooting is performed (STEP 11-1), the image capturing process, the image signal process, the file process, and the storage process are performed from the error range start position fp3b-2 (STEP 11- 2) It is determined whether or not the photographing lens range is finished (whether or not it is the error range end position) (STEP 11-3). If not finished, the lens is driven +1 (STEP 11-4), and the position after driving Take a picture with, and repeat until the photographic lens range ends. When the photographing lens range is finished, the continuous photographing is finished.

  Further, it is determined whether or not the focus fixing mode is set (STEP 10-2). If the focus fixing mode is not set, the contrast AF is performed (STEP 10-11), and the focusing is finished. .

(Fourth embodiment)
In the present embodiment, the configuration is the same as that of the second embodiment except for the flow in focusing.

(Focus process)
FIG. 12 is a block diagram showing a flow of focusing in the fourth embodiment of the imaging apparatus according to the present invention.
In the focusing process (STEP 2-2) performed by receiving the focus instruction in FIG. 2, it is determined whether or not the focus fixing mode is set (STEP 11-1), and if the focus fixing mode is set, In the focusing process of FIG. 11, the depth of field ± δ1 / L ₁ at the time of receiving the focus instruction obtained from the current lens F value and the focal length of the zoom is the lens F value when the focus fixing distance is obtained. And the depth of field ± δ1 / L ₂ at the time of determining the focus fixing distance obtained from the focal length of the zoom (STEP 11-2, 11-3), if it is wider (considering the example of FIG. When receiving, the depth of field ± δ1 / L ₁ is ± A, and when determining the focus fixing distance, the depth of field ± δ1 / L ₂ is ± B) and calculating the lens position fp from the focus fixing distance (STEP 11-4) ) Ren without contrast AF Is driven (STEP 11-5).

On the other hand, the depth of field ± δ1 / L ₁ at the time of receiving a focus instruction obtained from the current lens F value and the zoom focal length is obtained from the lens F value and the zoom focal length when the focus fixing distance is obtained. If it is narrower than the depth of field ± δ1 / L ₂ at the time of determining the focus fixing distance, specifically, considering the example of FIG. 4, the depth of field ± δ1 / L ₁ at the time of receiving the focus instruction is When the depth of field ± δ1 / L ₂ is ± A when determining the focus distance for ± B, the focus may not be met, so a warning that displays a warning character on the LCD display or a warning sound (STEP 11-6).

  Further, it is determined whether or not the focus fixing mode is set (STEP 11-1). If the focus fixing mode is not set, the contrast AF is performed (STEP 11-7), and the focusing is finished. .

  According to the digital cameras of the first to fourth embodiments, it is possible to focus quickly and accurately on the same fixed focal length even if the angle of view is changed.

It is a block diagram which shows the partial structure of the digital camera by implementation of this invention. It is a block diagram which shows the imaging flow in 1st Embodiment of the imaging device of this invention. It is a graph which shows the relationship between the reciprocal number of the distance of an optical system, and the lens position which focuses. It is explanatory drawing using the graph which shows the relationship between the reciprocal number of the distance of an optical system, and the lens position which focuses. 3 is a through display of the LCD monitor in the first embodiment of the imaging apparatus according to the present invention. It is a block diagram which shows the flow to the fixed distance for focus fixation and memory | storage in a focus fixed mode. It is a block diagram which shows the flow of focusing in 1st Embodiment of the imaging device which concerns on this invention. It is a block diagram which shows the flow of the focus fixed mode in 2nd Embodiment of the imaging device which concerns on this invention. It is a block diagram which shows the flow of focusing in 2nd Embodiment of the imaging device which concerns on this invention. It is a block diagram which shows the flow of focusing in 3rd Embodiment of the imaging device which concerns on this invention. It is a block diagram which shows the flow of continuous imaging | photography in 3rd Embodiment of the imaging device which concerns on this invention. It is a block diagram which shows the flow of focusing in 4th Embodiment of the imaging device which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Strobe light emission part 4 Lens barrel unit 5 LCD monitor 101 CCD
102 F / E-IC
103 SDRAM
104 Digital Still Camera Processor 105 SUB CPU
106 Strobe Circuit 107 Built-in Memory 108 LCD Driver 109 Video AMP
110 Video Jack 112 Audio CODEC
113 Speaker

Claims (10)

An imaging optical system;
Imaging means for converting a subject image formed by the imaging optical system into an electrical signal and outputting the electrical signal;
Focusing means for determining the degree of focusing based on an electrical signal from the imaging means;
Focusing instruction receiving means for receiving a focusing instruction,
The focusing means determines a focus fixing distance based on an electrical signal from the imaging means,
When the depth of field at the time of focus instruction reception when the focus instruction reception unit receives the focus instruction is wider than the depth of field at the time of determining the focus fixing distance when determining the focus fixing distance Is the in-focus distance of the imaging optical system as the focus fixing distance,
When the depth of field at the time of receiving the focus instruction is narrower than the depth of field at the time of determining the focus fixing distance, the imaging means from the imaging unit within a range corresponding to the depth of field at the time of determining the focus fixing distance. A focusing device that determines a focusing distance of the imaging optical system by determining a degree of focusing based on an electrical signal. An imaging optical system;
Imaging means for converting a subject image formed by the imaging optical system into an electrical signal and outputting the electrical signal;
Focusing means for determining the degree of focusing based on an electrical signal from the imaging means;
Focusing instruction receiving means for receiving a focusing instruction,
The focusing means determines a focus fixing distance based on an electrical signal from the imaging means,
When the depth of field at the time of focus instruction reception when the focus instruction reception unit receives the focus instruction is wider than the depth of field at the time of determining the focus fixing distance when determining the focus fixing distance Is the in-focus distance of the imaging optical system as the focus fixing distance,
When the depth of field at the time of receiving the focus instruction is narrower than the depth of field at the time of determining the focus fixing distance, focusing is performed at a plurality of positions in a range corresponding to the depth of field at the time of determining the focus fixing distance. A focusing apparatus characterized by performing an operation. An imaging optical system;
Imaging means for converting a subject image formed by the imaging optical system into an electrical signal and outputting the electrical signal;
Focusing means for determining the degree of focusing based on an electrical signal from the imaging means;
A focusing instruction receiving means for receiving a focusing instruction;
A warning means,
The focusing means determines a focus fixing distance based on an electrical signal from the imaging means,
When the depth of field at the time of focus instruction reception when the focus instruction reception unit receives the focus instruction is wider than the depth of field at the time of determining the focus fixing distance when determining the focus fixing distance Is the in-focus distance of the imaging optical system as the focus fixing distance,
The focusing device is characterized in that the warning means warns when the depth of field at the time of receiving the focus instruction is narrower than the depth of field at the time of determining the focus fixing distance. An imaging optical system;
Imaging means for converting a subject image formed by the imaging optical system into an electrical signal and outputting the electrical signal;
Focusing means for determining the degree of focusing based on an electrical signal from the imaging means,
The imaging optical system has a zoom lens, a focus lens, and a diaphragm,
The focusing unit determines a focus fixing distance based on an electrical signal from the imaging unit in a state where the depth of field is narrowed by controlling the zoom lens and the diaphragm, and a focusing distance of the imaging optical system A focusing device characterized by that.   An imaging apparatus comprising the focusing device according to claim 1 and performing imaging. A focusing step for determining a degree of focusing based on an electrical signal obtained by converting a subject image formed by the imaging optical system;
A focusing instruction receiving step for receiving a focusing instruction,
In the focusing step, after determining the focus fixing distance based on the electrical signal,
When the depth of field at the time of focus instruction reception when the focus instruction reception step receives the focus instruction is wider than the depth of field at the time of determining the focus fixing distance when determining the focus fixing distance Is the in-focus distance of the imaging optical system as the focus fixing distance,
When the depth of field at the time of receiving the focus instruction is narrower than the depth of field at the time of determining the focus fixing distance, the electric signal is further converted into the electric signal in a range corresponding to the depth of field at the time of determining the focus fixing distance. An in-focus method, wherein the in-focus degree is determined based on the in-focus distance of the imaging optical system. A focusing step for determining a degree of focusing based on an electrical signal obtained by converting a subject image formed by the imaging optical system;
A focusing instruction receiving step for receiving a focusing instruction,
In the focusing step, after determining the focus fixing distance based on the electrical signal,
When the depth of field at the time of focus instruction reception when the focus instruction reception step receives the focus instruction is wider than the depth of field at the time of determining the focus fixing distance when determining the focus fixing distance Is the in-focus distance of the imaging optical system as the focus fixing distance,
When the depth of field at the time of receiving the focus instruction is narrower than the depth of field at the time of determining the focus fixing distance, focusing is performed at a plurality of positions in a range corresponding to the depth of field at the time of determining the focus fixing distance. A focusing method characterized by performing an action. A focusing step for determining a degree of focusing based on an electrical signal obtained by converting a subject image formed by the imaging optical system;
A focusing instruction receiving step for receiving a focusing instruction,
In the focusing step, after determining the focus fixing distance based on the electrical signal,
When the depth of field at the time of focus instruction reception when the focus instruction reception step receives the focus instruction is wider than the depth of field at the time of determining the focus fixing distance when determining the focus fixing distance Is the in-focus distance of the imaging optical system as the focus fixing distance,
An in-focus method characterized in that a warning is given when the depth of field at the time of receiving the in-focus instruction is narrower than the depth of field at the time of determining the focus fixing distance. In a focusing method for determining a focusing degree based on an electrical signal obtained by converting a subject image formed by an imaging optical system,
The imaging optical system has a zoom lens, a focus lens, and a diaphragm,
A focusing method characterized by determining a focus fixing distance based on an electrical signal in a state in which the zoom lens and the diaphragm are controlled to reduce the depth of field, and set it as a focusing distance of the imaging optical system.   An imaging method comprising the focusing step according to claim 6 and performing imaging.

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