JP3866844B2 - Autofocus device and camera - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
  This invention is an autofocus device.And cameraIn detail, an autofocus device applied to an imaging device such as a video camera or a still cameraCameras such as video cameras and still camerasAbout.
[0002]
[Prior art]
  Conventionally, as this type of autofocus device, so-called hill-climbing is performed in which a high-frequency component is extracted from an image pickup signal obtained from an image sensor such as a CCD, and auto-focusing is performed by driving a photographing lens so that this high-frequency component becomes maximum The method is known.
[0003]
  Such an autofocus adjustment method does not require a special optical member for focus adjustment for detecting the amount of image deviation that changes according to the light emission / light reception of the infrared rays or the focus state, and it is a distance even at a long distance. It has the advantage of being able to focus accurately without depending on.
[0004]
  In recent years, however, various improvements have been proposed for such an autofocus adjustment method. For example, Japanese Patent Laid-Open No. 1-287508 discloses a technique for determining an initial stop position of a lens according to focal length information before starting focus detection in order to increase the probability of focus detection.
[0005]
  Japanese Patent No. 187516 discloses a technique for driving a lens to an initial stop position when it is determined that the lens driving condition is satisfied so that meaningless lens position setting can be omitted.
[0006]
  Japanese Patent No. 280712 discloses a technique for stopping the lens by moving backward from the target position based on the lens position detection information and then returning backward so that the lens can be accurately positioned without the influence of backlash. ing.
[0007]
[Problems to be solved by the invention]
  By the way, in general, a lens called a zoom lens is a lens whose photographing distance does not change by zooming. On the other hand, a varifocal lens is a lens whose shooting distance changes due to zooming. In other words, the varifocal lens needs to drive the focus lens in order to prevent blur due to zooming.
[0008]
  However, even with a lens called a zoom lens, it can be said that there are almost no lenses whose shooting distance does not change completely due to zooming, but even if the change is zoomed, there is no problem with object recognition on the viewfinder. There is no level. This problem is recognized as an increase in the number of lens groups and the number of components as the zoom lens becomes higher in magnification, complicating the zoom lens cam for setting the lens group interval, and a problem in processing accuracy.
[0009]
  Therefore, a range widened to include the infinite and close focus lens positions at any zoom position is set as the focus lens movement range. However, in a camera that samples the AF evaluation value while moving the focus lens system, determines the in-focus based on the sampling result, and drives the focus lens system to the in-focus position, the movement range of the focus lens is wide. There was a problem that it took time to focus.
[0010]
  The present invention eliminates the problems caused by the above-described conventional example, and shortens the time for driving the focus lens system to the in-focus position to shorten the AF execution time.And cameraThe purpose is to obtain.
[0011]
[Means for Solving the Problems]
  In order to solve the above-described problems and achieve the object, an autofocus device according to a first aspect of the present invention captures an image of a subject in an autofocus device that performs imaging by controlling a zoom lens and a focus lens.FilmAn imaging means for obtaining an image signal, and obtained by the imaging means;FilmAn evaluation unit that obtains an AF evaluation value from a luminance signal included in the image signal; a sampling unit that samples the AF evaluation value obtained by the evaluation unit while moving the position of the focus lens;A focusing position is determined based on the AF evaluation value sampled by the sampling means, and the focusing means for driving and controlling the focus lens at the determined focusing position is associated with the position of the zoom lens. A position on the infinite side from an infinite position where the shooting distance of the adjusted focus lens is infinite, or a position on the near side from a close position where the shooting distance of the adjusted focus lens is close,By the sampling meansRuAF evaluation valueS Sampling start position setting means as a sampling start position;It is provided with.
[0012]
  According to the first aspect of the present invention, since the position of the focus lens for starting sampling of the AF evaluation value is changed according to the position of the zoom lens system, the focus lens suitable for the zoom position can be efficiently Since the focusing operation is performed, and the focusing time is shortened, the AF execution time can be shortened.According to the first aspect of the present invention, sampling is started from a position on the infinity side of the focus lens, or a position on the near side of the closest position, so that even an infinite or close subject can be focused reliably. is there.
[0013]
  According to a second aspect of the present invention, there is provided an autofocus apparatus for capturing an image of a subject in the autofocus apparatus that performs imaging by controlling a zoom lens and a focus lens.FilmAn imaging means for obtaining an image signal, and obtained by the imaging means;FilmAn evaluation unit that obtains an AF evaluation value from a luminance signal included in the image signal; a sampling unit that samples the AF evaluation value obtained by the evaluation unit while moving the position of the focus lens;A focusing position is determined based on the AF evaluation value sampled by the sampling means, and the focusing means for driving and controlling the focus lens at the determined focusing position is associated with the position of the zoom lens. A position on the infinite side from an infinite position where the shooting distance of the adjusted focus lens is infinite, or a position on the near side from a close position where the shooting distance of the adjusted focus lens is close,By the sampling meansRuAF evaluation valueA sampling end position setting means as a sampling end position;It is provided with.
[0014]
  According to the second aspect of the present invention, since the position of the focus lens where sampling of the AF evaluation value is finished is changed according to the position of the zoom lens system, the focus lens suitable for the zoom position can be efficiently used. Since the focusing operation is performed, and the focusing time is shortened, the AF execution time can be shortened.According to the second aspect of the present invention, sampling ends from a position on the infinity side of the focus lens, or a position closer to the closest position than the closest position, so that even an infinite or close subject can be focused reliably. is there.
[0015]
According to a third aspect of the present invention, in the autofocus device according to the first or second aspect, the movement for changing the sampling interval during the sampling operation of the AF evaluation value according to the position of the zoom lens. It further comprises an amount changing means, wherein the sampling means samples at the sampling interval changed by the movement amount changing means.
[0016]
According to a fourth aspect of the present invention, there is provided a camera comprising the autofocus device according to any one of the first to third aspects.
[0017]
According to the invention of claim 4, it is possible to obtain an effect similar to that of the autofocus device according to any one of claims 1 to 3 in the camera.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
  Exemplary embodiments of the present invention will be described below in detail with reference to the accompanying drawings.
  First, the configuration of an imaging apparatus to which the autofocus apparatus of the present invention is applied will be described. FIG. 1 is a block diagram showing an internal configuration of an imaging apparatus according to an embodiment of the present invention. Here, a digital camera is taken as an example of an imaging apparatus.
[0019]
  FIG. 1 is a configuration diagram of a digital camera to which an autofocus device according to this embodiment is applied. In the figure, reference numeral 100 denotes a digital camera. The digital camera 100 includes a lens system 101, a mechanical mechanism 102 including an aperture / filter unit, a CCD 103, a CDS circuit 104, a variable gain amplifier (AGC amplifier) 105, an A / A. D converter 106, IPP 107, DCT 108, coder 109, MCC 110, DRAM 111, PC card interface 112, CPU 121, display unit 122, operation unit 123, SG (control signal generation) unit 126, strobe device 127, battery 128, DC-DC A converter 129, an EEPROM 130, a focus driver 131, a pulse motor 132, a zoom driver 133, a pulse motor 134, and a motor driver 135 are provided. A detachable PC card 150 is connected via the PC card interface 112.
[0020]
  The lens unit includes a mechanical mechanism 102 including a lens 101 system, a diaphragm / filter unit, and the mechanical shutter of the mechanical mechanism 102 performs simultaneous exposure of two fields. The lens system 101 is composed of, for example, a varifocal lens, and includes a focus lens system 101a and a zoom lens system 101b.
[0021]
  The focus driver 131 drives the pulse motor 132 according to the control signal supplied from the CPU 121 to move the focus lens system 101a in the optical axis direction. The zoom driver 131 drives the pulse motor 132 according to the control signal supplied from the CPU 121 to move the zoom lens system 101b in the optical axis direction. Further, the motor driver 135 drives the mechanical mechanism 102 in accordance with a control signal supplied from the CPU 121, and sets, for example, an aperture value of the aperture.
[0022]
  A CCD (charge coupled device) 103 converts an image input via the lens unit into an electrical signal (analog image data). A CDS (correlated double sampling) circuit 104 is a circuit for reducing the noise of the CCD type image pickup device.
[0023]
  In addition, the AGC amplifier 105 corrects the level of the signal that has been correlated and sampled by the CDS circuit 104. Further, the A / D converter 106 converts analog image data from the CCD 103 input via the AGC amplifier 105 into digital image data. That is, the output signal of the CCD 103 is converted into a digital signal through the CDS circuit 104 and the AGC amplifier 105 and by the A / D converter 105 at an optimum sampling frequency (for example, an integer multiple of the subcarrier frequency of the NTSC signal). Is done.
[0024]
  Further, an IPP (Image Pre-Processor) 107, a DCT (Discrete Cosine Transform) 108, and a coder (Huffman Encoder / Decoder) 109, which are digital signal processing units, are provided for digital image data input from the A / D converter 106. Data processing for various processing, correction, and image compression / decompression is performed separately for color difference (Cb, Cr) and luminance (Y). The image compression / decompression unit 107 performs, for example, orthogonal transformation, which is a process of JPEG-compliant image compression / decompression, and Huffman encoding / decoding, which is a process of JPEG-compliant image compression / decompression.
[0025]
  Further, an MCC (Memory Card Controller) 110 temporarily stores the compressed image and records it on the PC card 150 or reads it from the PC card 150 via the PC card interface 112.
[0026]
  The CPU 121 uses the RAM as a work area according to a program stored in the ROM, and controls all the operations inside the digital camera according to an instruction from the operation unit 123 or an external operation instruction such as a remote controller (not shown). Specifically, the CPU 121 controls an imaging operation, an automatic exposure (AE) operation, an automatic white balance (AWB) adjustment operation, an AF operation, and the like.
[0027]
  Camera power is input from a battery 128, such as NiCd, nickel metal hydride, or lithium battery, to the DC-DC converter 129 and supplied to the digital camera.
[0028]
  The display unit 122 is implemented by an LCD, LED, EL, or the like, and displays captured digital image data, decompressed recorded image data, and the like. The operation unit 123 includes buttons for externally performing function selection, shooting instruction, and other various settings. In the EEPROM 130, adjustment data and the like used when the CPU 121 controls the operation of the digital camera are written.
[0029]
  The digital camera 100 (CPU 121) described above has a recording mode for recording image data obtained by imaging a subject on the PC card 150, a display mode for displaying image data recorded on the PC card 150, and the like.
[0030]
  FIG. 2 is a diagram illustrating an example of a specific configuration of the IPP 107. As shown in FIG. 2, the IPP 107 includes a color separation unit 1071 that separates digital image data input from the A / D converter 106 into R, G, and B color components, and separated R, G, and B images. A signal interpolation unit 1072 that interpolates data, a pedestal adjustment unit 1073 that adjusts the black level of each of the R, G, and B image data, a white balance adjustment unit 1074 that adjusts the white level of each of the R and B image data, , A digital gain adjustment unit 1075 that corrects R, G, and B image data with a gain set by the CPU 121, a gamma conversion unit 1076 that performs γ conversion of the R, G, and B image data, and an RGB image A matrix unit 1077 that separates data into color difference signals (Cb, Cr) and luminance signals (Y), and a video signal based on the color difference signals (Cb, Cr) and luminance signals (Y). It includes a video signal processing unit 1078 to be output to the form display unit 122, a.
[0031]
  Furthermore, the IPP 107 passes only a predetermined frequency component of the Y operation unit 1079 that detects the luminance data (Y) of the image data after the pedestal adjustment by the pedestal adjustment unit 1073 and the luminance data (Y) detected by the Y operation unit 1079. BPF 1080 to be output, an AF evaluation value circuit 1081 that outputs a digital count value corresponding to the luminance data (Y) that has passed through BPF 1080 to the CPU 121 as an AF evaluation value, and luminance data (Y) detected by the Y operation unit 1079 An AE evaluation value circuit 1082 that outputs a digital count value to the CPU 121 as an AE evaluation value, and a Y calculation unit that detects luminance data (Y) of each of R, G, and B image data after gain adjustment by the digital gain adjustment unit 1075 1083 and the digital data corresponding to the luminance data (Y) detected by the Y operation unit 1083. And AWB evaluation value circuit 1084 which outputs a cement value to CPU 121 as the AWB evaluation value, and a CPUI / F1085 is an interface with the CPU 121, and the DCTI / F1086 such an interface with the DCT108.
[0032]
  Here, each control will be described. In the AE control, the shutter speed and the AGC are controlled so that the AE evaluation value becomes the reference value. In this embodiment, a description will be given assuming that the diaphragm is fixed (F4; Av4) as an example.
[0033]
  In the AF control, after the shutter speed and the gain are set, the AFM (pulse motor) is driven by a specified pulse in a 1 Vd period. During the prescribed pulse drive, the digital video signal obtained in the IPP is processed to obtain a luminance signal. An AF evaluation value is obtained by integrating high frequency components from the luminance signal by the filter means. The peak of this AF evaluation value is in focus.
[0034]
  In zoom control, the ratio of which position (distance) the current focus position is from a set value “fp far calc” (infinite), which will be described later, to a set value “fp near calc” (closest; about 0.2 m) Is required. The focus position is driven to a focus position having the same ratio from “fp far def” and “fp near def” at the zoom point together with the zoom drive, and the focus shift due to the zoom of the varifocal lens is corrected.
[0035]
  Next, each set value that is an adjustment value will be described. FIG. 3 is a diagram for explaining the set values. As shown in FIG. 3, the autofocus is performed using a varifocal lens having 9 zoom steps (positions) from 00 to 08. The shooting distance range is from infinity to about 0.2 m, but only wide is about 0.01 m.
[0036]
  In the table shown in FIG. 3, “ccdaf drv data”, “fp far def”, “fp near def”, “fp far calc”, and “fp near calc” are set as six types of setting values for each zoom step. , “Nml smp”. Each set value in FIG. 3 is displayed in hexadecimal.
[0037]
  Here, “ccdaf drv data” indicates the amount of movement (number of pulses) of the focus lens system for each sampling when the AF evaluation value is sampled. “Fp far def” indicates an AF evaluation value sampling start position at each zoom step, and a difference based on the position of the focus extension pulse number “fp inf def” is input as data.
[0038]
  “Fp near def” indicates the AF evaluation value sampling end position at each zoom step, and a difference based on the position of the focus extension pulse number “fp inf def” is input as data. “Fp far calc” indicates an infinite position in each zoom step, and a difference based on the position of the focus extension pulse number “fp inf def” is input as data.
[0039]
  “Fp near calc” indicates a 0.2 m position in each zoom step, and a difference based on the position of the focus extension pulse number “fp inf def” is input as data. “Nml smp” indicates the number of samplings for performing the entire-range sampling focus lens system movement in which the AF evaluation value is always sampled regardless of the AF evaluation value sampling result.
[0040]
  Note that “fp inf def” indicates the number of focus extension pulses from the infinite side mechanical end of the focus to the start of wide AF evaluation value sampling.
[0041]
  Subsequently, the operation will be described. FIG. 4 is a flowchart for explaining the setting operation for performing the autofocus operation, and FIG. 5 is a flowchart for explaining the autofocus operation.
[0042]
  In FIG. 4, fp far init = number of focus extension pulses (fp inf def) −AF evaluation value sampling start position (fp far def [zoom]), fp near init = number of focus extension pulses (fp inf def) + AF evaluation value sampling End position (fp near def [zoom]), fp home = (fp far init) − (fp home def), and nml smp def = nml smp [zoom]. Here, zoom is a position of 9 zoom steps. When zoom = 0, “zoom” becomes “wide”, when zoom = 4, “mean”, and when zoom = 8, “tele”.
[0043]
  In the operation shown in FIG. 4, first, zoom reset is performed by combining the zoom position and the zoom drive pulse number, and then focus reset is performed by combining the focus position and the focus drive pulse number. Zoom reset and focus reset are performed by driving to the mechanical end.
[0044]
  The position after driving with the number of pulses greater than that driven to the mechanical end is determined as the prescribed pulse number position. Here, in the case of focus, fp max = 205 pulses at the near mechanical end. The last pulse output data when driving to the mechanical end is set as fp home state at the time of adjustment. Subsequently, the focus is set to the normal focus position (about 2.5 m), and further zooming is performed.
[0045]
  Subsequently, the operation shown in FIG. 5 is started. The operation mode shown in FIG. 5 is an autofocus mode. In the case of autofocus, first, AF initial setting (ccdaf init set) is executed (step S1), and the first release is operated. At this time, the normal focus position (about 2.5 m) at the set zoom point is calculated from the adjustment value, and the AF operation is performed. Subsequently, the AF AE is set (ccdaf ae set) (step S2).
[0046]
  When the process proceeds to step S3, the focus is driven to the home position HP (fp home). In the subsequent step S4, the focus is driven to the initial position INIT (fp far init). As described above, the focus is driven from the home position HP to the initial position INIT, so that the backlash (fp b brush = 8 (pulse)) can be removed.
[0047]
  Then, the process proceeds to step S5. Focus drive during AF evaluation value sampling is performed in synchronization with the vertical synchronization signal Vd. At this time, the focus is driven by the amount of movement (ccdaf drv data) of the focus lens system for each sampling. At this time, the focus drive is performed until the AF evaluation value corresponding to nml smp is sampled regardless of the value of the AF evaluation value (information such as a peak). The focus drive amount is (ccdaf drv data ) * (Becoming nml smp)). This is within the normal shooting distance range (from infinite to about 0.5 m).
[0048]
  Here, the peak position, the increase / decrease data of the AF evaluation value, and the like are calculated from the AF evaluation values sampled within the normal shooting distance range, and it is determined whether the in-focus position is within the normal shooting distance range. Even when focusing is performed within the macro shooting distance range, the focus lens is driven to the in-focus position after driving the focus from the in-focus position to a position for removing backlash.
[0049]
  Thereafter, the process proceeds to step S6. In step S6, when the in-focus position is within the normal shooting distance range, the AF evaluation value sampling is stopped, and the focus is driven from the in-focus position to the position where the backlash is removed, and then the focus is moved to the in-focus position. Driven.
[0050]
  In addition, when there is no in-focus position within the normal shooting distance range, AF evaluation value sampling within the macro shooting distance range (about 0.5 m to about 0.2 m) is performed (macro; up to fp near init) ). However, within the macro shooting distance range, sampling of the AF evaluation value is stopped when a peak is detected.
[0051]
  Thereafter, the process proceeds to step S7. In step S7, the focus drive is turned off (fcsm off), and the process is terminated.
[0052]
  Next, the relationship between the zoom position and the focus position will be described. 6 is a diagram showing a focus position adjustment ZF table, FIG. 7 is a graph showing the ZF (zoom focus) table of FIG. 6, and FIG. 8 is a correspondence between AF evaluation value sampling timing and focus pulse motor drive timing. It is a timing chart which shows a relationship.
[0053]
  The ZF table is used when adjusting the focus position with respect to the zoom position. The ZF table shown in FIG. 0, No. 1, No. 1 2 shows three examples. In any example, nine positions are assigned to the wide (W) end, the mean (M), and the tele (T) end with respect to two standards of infinite and close (for example, 20 cm). Each position is associated with a pulse number ZP and an adjustment value (f (mm)). This ZF table is stored and held in a ROM or the like.
[0054]
  In FIG. Infinite standard A0-1 and closest standard B0-1 are shown as a graph of 0. Infinite Standard A1-1 and Closest Standard B1-1 are shown as a graph of No. 1, The infinite reference A2-1 and the closest reference B2-1 are shown as a graph of 2. From the above graph, the number of pulses is lower in the case of using the close range as a reference than in the case of using infinity as a reference.
[0055]
  FIG. 8A shows a timing chart regarding NTSC in which the vertical synchronization signal Vd is 1/30 Hz (33 mS). FIG. 5B shows a timing chart relating to PAL (television: TV) whose Vd is 1/25 Hz (40 mS). FIG. 3C shows a timing chart regarding a PAL (liquid crystal: LCD) whose vertical synchronizing signal Vd is 1/36 Hz (28 mS).
[0056]
  According to the above timing chart, the pulse intervals of the AF evaluation value sampling timing ST and the focus pulse motor drive timing WT (wide) and TT (tele) are changed as the pulse interval of the vertical synchronization signal Vd increases. That is, when the NTSC in FIG. 8A is taken as a reference, the NTSC is 1/30 Hz, whereas the PAL (TV) in FIG. 8B is 1/25 Hz and the pulse width is increased. Accordingly, the pulse interval between the AF evaluation value sampling ST and the focus pulse motor drive timings WT and TT is wider in the PAL (TV) than in the case of NTSC.
[0057]
  On the other hand, when the NTSC in FIG. 8A is taken as a reference, the NTSC is 1/30 Hz, whereas the PAL (LCD) in FIG. Therefore, the pulse interval between the AF evaluation value sampling ST and the focus pulse motor drive timings WT and TT is narrower in the PAL (LCD) than in the case of NTSC.
[0058]
  Next, the driver will be described in detail. 9 is a circuit diagram showing a driver of the zoom pulse motor and the focus pulse motor, FIG. 10 is a diagram showing a truth table of the pulse motor driving IC, and FIG. 11 is a pulse at the time of autofocus execution in the driver shown in FIG. It is a timing chart which shows a waveform by simulation. In FIG. 9, the focus driver 131 and the zoom driver 133 define the input / output relationship according to the truth table shown in FIG.
[0059]
  According to the truth table shown in FIG. 10, the focus driver 131 and the zoom driver 133 have no input (IN1, 2) when the enable signal of their own circuit is “L” (low), and the standby state Therefore, the outputs (OUT1, 2, 3, 4) are turned off. On the other hand, when the enable signal is set to “H” (high), the outputs OUT1 to OUT4 are driven to generate an output in which two-phase excitation changes due to the logical relationship between the inputs IN1 and IN2. Here, FIGS. 11A, 11B, and 11C show pulse waveforms during wide operation, mean operation, and tele operation during AF execution, respectively. Comparing the above pulse waveforms, the enable time becomes longer in the order of wide, mean, and tele, and accordingly, the driving time of the driver becomes longer.
[0060]
  As described above, according to this embodiment, since the position of the focus lens that starts sampling of the AF evaluation value is changed according to the position of the zoom lens system, the focus lens suitable for the zoom position Efficient focusing operation. Thereby, since the focusing time is shortened, the AF execution time can be shortened.
[0061]
  In addition, since the position of the focus lens that finishes sampling the AF evaluation value is changed according to the position of the zoom lens system, the focus lens can be efficiently focused on the zoom position. Thereby, since the focusing time is shortened, the AF execution time can be shortened.
[0062]
  In addition, since the autofocus device according to this embodiment is particularly effective for a varifocal lens, it is possible to perform high-speed AF in accordance with each zoom position.
[0063]
  In addition, “fp far calc” is infinite in calculation (adjustment) and “fp near calc” is close in calculation (adjustment), but sampling of the actual AF evaluation value is started or ended. Since the focus lens position ranges from “fp far def” (infinite) to “fp near def” (closest) including adjustment errors and the like, it is possible to reliably focus on an infinite and close subject.
[0064]
【The invention's effect】
  As described above, according to the present invention, since the position of the focus lens at which sampling of the AF evaluation value starts or ends is changed according to the position of the zoom lens system, the focus lens suitable for the zoom position Thus, since the focusing time is shortened, the AF execution time can be shortened.Furthermore, according to the present invention, sampling is performed even at a position on the infinity side of the focus lens, or at a close position, so that it is possible to reliably focus on an infinite or close subject.
[Brief description of the drawings]
FIG. 1 is a block diagram showing an internal configuration of an imaging apparatus according to an embodiment of the present invention.
FIG. 2 is a diagram illustrating an example of a specific configuration of an IPP according to an embodiment.
FIG. 3 is a diagram illustrating set values according to an embodiment.
FIG. 4 is a flowchart illustrating a setting operation for performing an autofocus operation according to the embodiment.
FIG. 5 is a flowchart illustrating an autofocus operation according to the embodiment.
FIG. 6 is a diagram illustrating a ZF table used when adjusting a focus position with respect to a zoom position in the embodiment.
FIG. 7 is a diagram showing the ZF table of FIG. 5 in a graph.
FIG. 8 is a timing chart showing a correspondence relationship between AF evaluation value sampling timing and focus pulse motor driving timing in the embodiment;
FIG. 9 is a circuit diagram illustrating drivers of a zoom pulse motor and a focus pulse motor according to an embodiment.
10 is a diagram showing a truth table of a pulse motor driving IC in the driver shown in FIG. 8. FIG.
11 is a timing chart showing, by simulation, a pulse waveform when autofocus is executed in the driver shown in FIG.
[Explanation of symbols]
101a Focus lens
101b Zoom lens
103 CCD
104 CDS
105 AGC amplifier
106 A / D
107 IPP
121 CPU
123 Operation unit
130 EEPROM
131 Focus driver
133 Zoom driver

Claims (4)

In an autofocus device that controls the zoom lens and the focus lens to perform imaging,
Imaging means for obtaining movies image signal by imaging an object,
And evaluation means for obtaining the AF evaluation value from the luminance signal contained in the resulting Film image signal by the image pickup means,
Sampling means for sampling the AF evaluation value obtained by the evaluation means while moving the position of the focus lens;
Focusing means for determining a focus position based on the AF evaluation value sampled by the sampling means, and driving and controlling the focus lens at the determined focus position;
An infinite position from an infinite position where the shooting distance of the focus lens adjusted in association with the position of the zoom lens is infinite, or a position closer to the close side than a close position where the shooting distance of the adjusted focus lens is close position, the sampling start position setting means for the sampling start position of the by that AF evaluation value to the sampling means,
An autofocus device characterized by comprising: In an autofocus device that controls the zoom lens and the focus lens to perform imaging,
Imaging means for obtaining movies image signal by imaging an object,
And evaluation means for obtaining the AF evaluation value from the luminance signal contained in the resulting Film image signal by the image pickup means,
Sampling means for sampling the AF evaluation value obtained by the evaluation means while moving the position of the focus lens;
Focusing means for determining a focus position based on the AF evaluation value sampled by the sampling means, and driving and controlling the focus lens at the determined focus position;
A position on the infinite side from the infinite position where the shooting distance of the focus lens adjusted in association with the position of the zoom lens is infinite, or a position closer to the close side than the closest position where the shooting distance of the adjusted focus lens is close position, and the sampling end position setting means to the sampling end position of the by that AF evaluation value to the sampling means,
An autofocus device characterized by comprising: A moving amount changing means for changing a sampling interval at the time of the sampling operation of the AF evaluation value according to the position of the zoom lens;
  The sampling means sampling at the sampling interval changed by the movement amount changing means;
  The autofocus device according to claim 1, wherein A camera comprising the autofocus device according to any one of claims 1 to 3.

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