JP2007094023A - Focus adjustment method of focus lens and imaging apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To accurately move a focus lens to an in-focus position of an object present at target distance. <P>SOLUTION: When a user inputs a predetermined photographing position, a lens position corresponding to the predetermined photographing position is set within the movement range 65 of the focus lens as a reference position A. In the case that the luminance value of the object present in the reference position A is detected and the luminance value is equal to or larger than a threshold, a search range B-C is set with the reference position A as a center on the basis of a position of a zoom lens and a data table 1, the search range B-C is corrected using the peripheral temperature of the focus lens and the data table 2, and a search range D-E after correction is set. A CPU moves the focus lens from one end D to the other end E of the search range D-E and searches an in-focus position while detecting an AF evaluation value by an AF detection circuit. After the end of search within the search range D-E, the focus lens is moved to the in-focus position found by the search. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a focus lens focus adjustment method and an imaging apparatus including a CCD, a CMOS, and the like.

  Digital cameras that record image data of captured images as digital data on a memory card using a solid-state imaging device such as a CCD or a CMOS image sensor have become widespread. In a relatively low-priced digital camera, a plastic lens is used instead of a glass lens in order to reduce the size and weight. In addition, even today's digital cameras are mainly provided with an autofocus (AF) function for automatically adjusting the focus by moving the focus lens in the optical axis direction even if the price is low.

However, with the AF function, it is difficult to focus on a moving subject. Therefore, as a method of shooting a moving subject, a temporary subject at a desired shooting distance (hereinafter referred to as a planned shooting distance) is focused in advance, the lens position at this time is stored, and a focus lens is obtained by a predetermined operation. There are a method of moving to a lens position in which the image is stored, and a method in which a photographer inputs a planned shooting distance, calculates a lens position corresponding to this distance, and automatically moves the focus lens. However, even if the focus lens is moved to the lens position where the focus lens is stored in advance or the designed lens position corresponding to the inputted planned shooting distance using the method as described above, the focus formed of plastic is used. Since the refractive index of the lens greatly changes due to temperature change, there is a problem that the photographed image is out of focus. Therefore, in Patent Document 1, the temperature around the lens is detected at the time of focus preset setting in which the position for driving the photographic lens is stored in advance, and at the time of focus preset playback in which the photographic lens is moved to the stored position. The position of the taking lens is corrected based on the temperature difference.
JP-A-3-181924

  However, the camera described in Patent Document 1 corrects the in-focus position of the focus lens with a preset correction amount based on the temperature difference of the photographing lens. The focus position has not been corrected due to assembly errors.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a focus lens focus adjustment method and an imaging apparatus capable of correcting a focus position due to manufacturing variations of the focus lens.

  In order to achieve the above object, the focus lens focus adjustment method of the present invention moves the focus lens included in the imaging optical system to a lens position corresponding to the shooting distance set by the photographer, and in the vicinity of the lens position. A focus lens focus adjustment method for searching for a focus position of the focus lens at a position where the lens position corresponding to the shooting distance is a reference position and the focus lens is movable around the reference position. A predetermined search range is set in a narrower range, the focus lens is moved within the search range, and the focus position of the focus lens is determined while detecting the focus state of the captured image of the subject at the shooting distance. After the search, the focus lens is moved to the in-focus position found by the search.

  The imaging optical system may include a zoom lens, and the in-focus position search range may be set based on a correction amount set in advance according to zooming of the zoom lens. In addition, the search lens may detect the ambient temperature of the focus lens, and set the search range based on a correction amount set according to the detected ambient temperature.

  The image pickup apparatus of the present invention includes an image pickup unit that picks up a subject image that has passed through an image pickup optical system including a focus lens and outputs image data, a distance input unit through which a photographer inputs a shooting distance, and the distance input. When the photographing distance is input by the means, the lens position of the focus lens corresponding to the photographing distance is set as a reference position, and a predetermined search is performed in a range narrower than the movable range of the focus lens with the reference position as a center. A search range setting means for setting a range and the focus lens are moved within the search range, and a focus position of the focus lens is searched based on the image data output by the imaging means in accordance with the movement. Focus search means, and after the search for the in-focus position within the search range is completed by the focus search means, It is characterized in that for moving the focus lens to the in-focus position.

  Further, the focus searching means may search the in-focus position by moving the focus lens from one end to the other end of the search range. The photographing optical system may include a zoom lens, and the search range setting means may set the search range based on a zoom position of the zoom lens. In addition, a temperature detection unit that detects a temperature of the imaging optical system is provided in the vicinity of the imaging optical system, and the search range setting unit sets the search range based on a detection result of the temperature detection unit. May be.

  According to the focus lens focus adjustment method of the present invention, the focus lens included in the imaging optical system is moved to a lens position corresponding to the shooting distance set by the photographer, and the focus position of the focus lens is set in the vicinity of the lens position. A focus lens focus adjustment method for searching, wherein a lens position corresponding to a shooting distance is set as a reference position, a predetermined search range is set within a range narrower than the movable range of the focus lens with the reference position as a center, and a search is performed. Move the focus lens within the range, search the focus position of the focus lens while detecting the focus state of the captured image of the subject at the shooting distance, then move the focus lens to the focus position found by this search As a result, it is possible to prevent out-of-focus images from being shot due to variations in focus lens manufacturing or assembly errors. It is possible.

  In addition, the imaging optical system includes a zoom lens, and the focus position search range is set based on a correction amount set in advance according to zoom lens magnification. Therefore, it is possible to prevent the image from being out of focus. Further, the ambient temperature of the focus lens is detected, and the search range is set based on the correction amount set in accordance with the detected ambient temperature, so that it is possible to prevent a focus shift of a captured image caused by a temperature change. Can do.

  The image pickup apparatus of the present invention includes an image pickup means for picking up a subject image that has passed through an image pickup optical system including a focus lens and outputting image data, a distance input means for a photographer to input a shooting distance, and a distance input means. When the shooting distance is input by, the lens position of the focus lens corresponding to the shooting distance is used as a reference position, and a search is performed in which a predetermined search range is set in a range narrower than the movable range of the focus lens around the reference position. A focus setting unit that includes a range setting unit and a focus searching unit that moves the focus lens within the search range and searches for the in-focus position of the focus lens based on image data output by the imaging unit in accordance with the movement. After the search for the in-focus position within the search range is completed, the focus lens is moved to the in-focus position found by this search. It is possible to prevent the shift of focus of the photographic image caused by such manufacturing variations or assembling errors of Okasurenzu.

  In addition, since the focus searching unit searches the in-focus position by moving the focus lens from one end to the other end of the search range, the in-focus position can be reliably detected. Further, the photographing optical system includes a zoom lens, and the search range setting means sets the search range based on the zooming position of the zoom lens, so that it is possible to prevent the photographed image from being out of focus. . Further, a temperature detection unit for detecting the temperature of the imaging optical system is provided in the vicinity of the imaging optical system, and the search range setting unit sets the search range based on the detection result of the temperature detection unit, so that the temperature change Therefore, it is possible to prevent a focus shift of a photographed image caused by the above.

  1 and 2, a lens barrier 10 that can be slid in the direction of an arrow is provided on the front of a digital camera 2 to which the present invention is applied. The digital camera 2 slides the lens barrier 10 to the open position shown in FIG. 1 so that the lens barrel 12 holding the imaging lens 11 is extended to the front, and the strobe light emitting unit 13 is exposed to be in a state where photographing is possible. . The imaging lens 11 is a plastic lens that is inexpensive and has excellent workability. Further, inside the lens barrel 12, a temperature sensor 14 that is a temperature detecting means for detecting the ambient temperature of the imaging lens 11 is installed.

  Behind the imaging lens 11, a CCD 38 (see FIG. 3) as an imaging means is arranged. The imaging signal from the CCD 38 is converted into digital image data by an A / D converter 42 (see FIG. 3). This image data is displayed as a so-called through image on a liquid crystal display (LCD) 15 provided on the back of the digital camera 2 shown in FIG. Further, the digital camera 2 is provided with a finder objective window 16 and a finder eyepiece window 17 that constitute an optical finder, through which a subject image is framed.

  A release button 18 is provided on the upper surface of the digital camera 2. The release button 18 is a two-stage push switch. When the release button 18 is lightly pressed (half-pressed) after framing by the LCD 15 or the optical viewfinder, automatic exposure adjustment (AE), automatic focus adjustment (AF), etc. Various shooting preparation processes are performed.

  The image pickup signal subjected to the image pickup preparation process is data-locked until the release button 18 is released. In this state, when the release button 18 is pressed once more (fully pressed), the imaging signal for one screen subjected to the imaging preparation process is converted into image data, and then is detachably attached to the memory card slot 19. The data is stored in a storage medium such as the memory card 20 or the SDRAM 46 (see FIG. 3) to be loaded.

  On the back of the digital camera 2, in addition to the LCD 15, a power button 21 for switching power on / off, and a zoom operation button for zooming the zoom lens 11 b (see FIG. 3) of the imaging lens 11 to the wide side and the tele side. 22, a mode changeover switch 23 for selecting various modes, a cursor operation plate 24 for moving a cursor in a menu screen displayed on the LCD 15, a determination button 25 for determining setting values and the like during menu screens and various setting processes, and setting values An operation unit 27 (a portion surrounded by a one-dot chain line) including a cancel button 26 is provided. The distance input means includes a cursor operation plate 24 and an enter button 25.

  The digital camera 2 can select a still image shooting mode for shooting still images, a moving image shooting mode for shooting movies, a playback mode for displaying captured images on the LCD 15, a setup mode for performing various settings, and the like. These modes are switched by sliding the mode switch 23.

  In FIG. 3, an imaging lens 11 that is a photographing optical system includes a main lens 11a, a zoom lens 11b, and a focus lens 11c. A zoom motor 30 and a focus motor 31 are connected to the zoom lens 11b and the focus lens 11c. An iris motor 32 is connected to the diaphragm 33. These motors 30 to 32 are stepping motors, are controlled in operation by drive pulses transmitted from motor drivers 35 to 37 connected to the CPU 34, and perform shooting preparation processing by half-pressing the release button 18.

  The position sensor 28 detects the position of the zoom lens 11b in the optical axis direction, and transmits this position data to the CPU 34. The position sensor 29 detects the position of the focus lens 11 c in the optical axis direction, and transmits position data to the CPU 34.

  The zoom motor 30 performs zooming of the imaging lens 11 by moving the zoom lens 11b to the wide side or the tele side (for example, 13 stages) in conjunction with the operation of the zoom operation button 22. The focus motor 31 moves the focus lens 11c according to the subject distance and zooming magnification of the zoom lens 11b, and adjusts the focus of the imaging lens 11 so that the photographing conditions are optimized. The iris motor 32 operates the aperture 33 to adjust the exposure of the imaging lens 11.

  Behind the imaging lens 11, a CCD 38 that images subject light transmitted through the imaging lens 11 is arranged. A timing generator (TG) 39 controlled by the CPU 34 is connected to the CCD 38, and the shutter speed of the electronic shutter is determined by a timing signal (clock pulse) input from the TG 39.

  The imaging signal output from the CCD 38 is input to a correlated double sampling circuit (CDS) 40, and is output as R, G, B image data that accurately corresponds to the accumulated charge amount of each cell of the CCD 38. The image data output from the CDS 40 is amplified by an amplifier (AMP) 41 and converted into digital data by an A / D converter (A / D) 42.

  The image input controller 43 is connected to the CPU 34 via the bus 44, and controls the CCD 38, the CDS 40, the AMP 41, and the A / D converter 42 in accordance with a control command from the CPU 34. The image data output from the A / D converter 42 is displayed on the LCD 15 via the LCD driver 45. Alternatively, it is displayed on the optical viewfinder via an optical viewfinder driver (not shown). Alternatively, it is stored in the SDRAM 46.

  The image signal processing circuit 47 performs various kinds of image processing such as gradation conversion, white balance correction, and γ correction processing on the image data. The image data that has been subjected to various processes in the image signal processing circuit 47 is converted into a luminance signal Y and color difference signals Cr and Cb by a YC conversion processing circuit 48. The compression / decompression processing circuit 49 performs image compression on the converted image data in a predetermined compression format (for example, JPEG format). The compressed image data is recorded on the memory card 20 via the media controller 50.

  In addition to the release button 18 and the operation unit 27 described above, an EEPROM 51 is connected to the CPU 34. The EEPROM 51 stores various control programs and setting information. The CPU 34 reads these pieces of information from the EEPROM 51 to the SDRAM 46 which is a working memory, and executes various processes.

  The bus 44 detects whether the exposure amount, that is, the shutter speed of the electronic shutter and the aperture value of the aperture 33 are appropriate for shooting, and detects whether the white balance correction is appropriate for shooting. The circuit 52, an AF detection circuit 53 that detects whether or not the focus adjustment of the focus lens 11c is appropriate for photographing, and a strobe control circuit 55 that controls the operation of the strobe device 54 are connected.

  The AE / AWB detection circuit 52 detects the luminance value of the subject based on the image data output from the A / D converter 41 and transmits the detection result to the CPU 34. Based on the transmitted luminance value, the CPU 34 performs automatic exposure adjustment by controlling the shutter speed of the electronic shutter and the aperture value of the aperture 33 so that the exposure amount of the CCD 38 is optimized.

  The AF detection circuit 53 detects the focus alignment state of the subject based on the contrast of the image data digitized by the A / D converter 42 and transmits the detection result to the CPU 34 as an AF evaluation value. The CPU 34 moves the focus lens 11c to a position where the AF evaluation value is maximum (peak), and automatic focus adjustment is performed. Note that the AE / AWB output circuit 52 and the AF detection circuit 53 sequentially transmit detection results to the CPU 34 via the bus 44 when the release button 18 is half-pressed.

  The strobe control circuit 55 transmits a light emission signal to the strobe device 54 based on the AE evaluation value obtained by the AE / AWB detection circuit 52 when the subject brightness is low. The strobe device 54 emits strobe light based on this light emission signal.

  The temperature sensor 14 installed in the lens barrel 12 is connected to the CPU 34 via the A / D converter 56. The temperature sensor 14 detects the ambient temperature of the focus lens 11c at a predetermined period set in advance, and this is detected at the same time in synchronization with the pressing operation of the decision button when setting the planned shooting distance described later. The ambient temperature is transmitted to the A / D converter 56. The A / D converter 56 converts the transmitted ambient temperature into digital temperature data and transmits it to the CPU 34. The A / D converter 56 may be built in the CPU 34.

  In the digital camera 2, in the still image shooting mode, in addition to the normal (auto) shooting mode, the manual shooting mode, etc., the planned shooting distance (the distance that the photographer wants to shoot) is input, so that the digital camera 2 is at the planned shooting distance. A preset shooting mode is provided in which the focus lens 11c automatically moves to a focus position on the subject. In this embodiment, the preset shooting mode will be described. However, since the other shooting modes are known, the description thereof will be omitted.

  When the preset shooting mode is selected, as shown in FIG. 4, a mode display 60 indicating the preset shooting mode, a distance bar 61, and a cursor 62 are displayed on the LCD 15 together with the through image 59. The distance bar 61 indicates the distance to the subject, one end of which corresponds to 0.6 m, and the other end corresponds to the distance of ∞. The distance bar 61 is provided with 15 scales at predetermined intervals. The distance corresponding to one scale of the distance bar 61 and the number of scales are preferably set as appropriate.

  The cursor 62 moves along the distance bar 61 by a pressing operation on the left and right portions of the cursor operation plate 24. When the cursor operation plate 24 is pressed once, the cursor 62 moves by one scale of the distance bar 61. By moving the cursor 62, the photographer sets the scheduled shooting distance. This planned shooting distance is set by operating the enter button 25 after moving the cursor 62. Further, when canceling the scheduled shooting distance once set, the cancel button 26 is operated, and the scheduled shooting distance can be selected again by the cursor operation plate 24.

  When the scheduled shooting distance is set by the cursor 62, the search range setting unit 34a provided in the CPU 34 calculates the lens position of the focus lens 11c corresponding to the scheduled shooting distance. Then, as shown in FIG. 5, the calculated lens position is set as the reference position A within the movement range 65 of the focus lens 11c. Next, the search range setting unit 34a sets a search range around the reference position A. The search range is set using data table 1 (DT1) shown in Table 1, data table 2 (DT2) shown in Table 2, and data table 3 (DT3) shown in Table 3.

  DT1 to DT3 are stored in the SDRAM 46. DT1 indicates the relationship between the position of the zoom lens 11b and the drive amount (pulse) of the focus motor 36. P shown in DT1 indicates the position of the zoom lens 11c, P1 is the position of the tele end, and P13 is the position of the wide end. DT2 indicates the relationship between the ambient temperature of the focus lens 11c and the drive amount (pulse) of the focus motor 31. DT3 shows the relationship between the position of the zoom lens 11b, the correction amount (pulse) of the reference position, and the drive amount (pulse) of the focus motor 31. The driving amount ± indicates that the reference position A is shifted to the subject side (+) and the CCD 38 side (−).

  As shown in FIG. 5, when the search range setting unit 34a sets the reference position A (scheduled shooting distance) within the moving range 65 of the focus lens 11c in accordance with the determination of the planned shooting distance by the distance bar 61 and the cursor 62, The CPU 34 compares the luminance value of the subject at the reference position A with the threshold value stored in advance in the EEPROM 51. At this time, when it is determined that the luminance value is larger than the threshold value, the search range setting unit 34a sets the search range BC using the position data P and DT1 of the zoom lens 11b transmitted from the position sensor 28, and The search range BC is corrected using the temperature data T and DT2 transmitted from the temperature sensor 14, and the corrected search range DE is set. The CPU 34 serving as the focus search means moves the focus lens 11 c from one end to the other end of the set corrected search range DE via the focus motor 31, and detects the in-focus state by the AF detection circuit 53. While searching for the in-focus position.

  If it is determined that the luminance value is equal to or less than the threshold value, the search range setting unit 34a uses the position data P and DT3 of the zoom lens 11b transmitted from the position sensor 28 as shown in FIG. And the corrected reference position A1 is set. Further, the search range B1-C1 is set around the corrected reference position A1. Then, the search range B1-C1 set using the temperature data T and DT2 transmitted from the temperature sensor 14 is corrected, and the corrected search range FG is set. When the corrected search range FG is set, the CPU 34 moves the focus lens 11c from one end to the other end of the set corrected search range FG via the focus motor 31, and an AF detection circuit. In step 53, the in-focus position is searched while detecting the in-focus state.

  Next, the operation of the digital camera having the above configuration will be described with reference to the flowcharts of FIGS. First, after the digital camera 2 is turned on and the startup process such as the initial position setting of the zoom lens 11b is performed, when the preset shooting mode is selected under the still image shooting mode, as shown in FIG. A mode display 60, a distance bar 61, and a cursor 62 are displayed on the LCD 45 together with a through image 59.

  The photographer moves the cursor 62 along the distance bar 61 to a position corresponding to the planned shooting distance by operating the cursor operation plate 24. At this time, it is preferable that the shooting distance corresponding to the scale is displayed every time the cursor 62 moves by one scale. Then, the planned shooting position is set by pressing the enter button 25 after the cursor 61 is moved. Thereby, as shown in FIG. 5, the lens position of the focus lens 11c corresponding to the planned shooting distance is set as the reference position A within the movement range 65 of the focus lens 11c.

  When the reference position A is set, the CPU 34 moves the focus lens 11c to a lens position corresponding to the reference position A. The AE / AWB detection circuit 52 detects the luminance value of the subject from the image data obtained at the reference position A and transmits it to the CPU 34. The CPU 34 compares the brightness value with a threshold value stored in advance in the EEPROM 51.

  As shown in FIG. 7, when the CPU 34 determines that the luminance value is equal to or greater than the threshold value, the search range setting unit 34a uses the position data P and DT1 (see Table 1) of the zoom lens 11b transmitted from the position sensor 28. Then, the driving amount of the focus motor 31 is obtained, and the search range BC is set around the reference position A as shown in FIG. Next, the correction amount of the focus motor 31 is obtained from the temperature data T and DT2 (see Table 2) transmitted from the temperature sensor 14, and the search range DE corrected according to the correction amount is set. Then, the CPU 34 controls the focus motor 31 to move the focus lens 11c from one end D to the other end E of the search range DE, and in a focused state (AF evaluation value) within the search range DE. The focus position is searched while performing detection. When the movement from the one end D to the other end E is completed, the CPU 34 moves the focus lens 11c to the in-focus position found by the search, and the preset photographing preparation process ends.

  As shown in FIG. 8, when the CPU 34 determines that the luminance value is lower than the threshold value, the search range setting unit 34a transmits the position data P and DT3 of the zoom lens 11b transmitted from the position sensor 28 (see Table 1). As shown in FIG. 6, the reference position A1 is corrected to set the reference position A1. Then, the search range setting unit 34a obtains the driving amount of the focus motor 31 from DT3 based on the position data P of the zoom lens 11b, and sets the search range B1-C1 around the corrected reference position A1.

  Next, the correction amount of the focus motor 31 is obtained from the temperature data T and DT2 (see Table 2) transmitted from the temperature sensor 14, the search range B1-C1 is corrected, and the corrected search range FG is set. . Then, the CPU 34 controls the focus motor 31 to move the focus lens 11c from one end F to the other end G of the search range FG. Along with the movement of the focus lens 11c, the AF detection circuit 53 detects an AF evaluation value within the search range FG and transmits it to the CPU.

  The CPU 34 reads a predetermined value stored in advance in the EEPROM 51 and compares the AF evaluation value transmitted to the CPU 34 with the predetermined value. If the CPU 34 determines that the AF evaluation value detected in the search range FG is above the predetermined value by this comparison, the focus is set to the maximum position of the AF evaluation value detected in the search range FG. The lens 11c is moved, and the preset photographing preparation process ends. If it is determined that the AF evaluation value is lower than the predetermined value, the CPU 34 moves the focus lens 11c to the corrected reference position A1, and ends the preset photographing preparation process.

  Note that when the movement of the focus lens 11c to the in-focus position is completed, it is preferable to notify the photographer that the prefocus shooting preparation process has been completed by voice, display on the LED 15, or the like.

  When the preset photographing preparation process is completed, the photographer performs photographing by pressing the release button 18 in anticipation of the timing when the moving subject reaches the planned photographing distance. At this time, a search range is set based on the shooting conditions such as the position of the zoom lens 11b, the temperature around the focus lens 11c, the luminance value of the subject, and the input planned shooting position. Since the focus lens 11c is set at the focal position, it is not affected by manufacturing variations or assembly errors. Therefore, a good captured image can be obtained.

  The captured image data is subjected to various image processing by the image signal processing circuit 47, converted to the luminance signal Y and the color difference signals Cr and Cb by the YC conversion processing circuit 48, and compressed and decompressed by the compression / decompression processing circuit 49. Compression processing is performed. The compressed image data is recorded on the memory card 20 via the media controller 50.

  In the above embodiment, after the reference position is set based on the photographer's planned shooting position input, the luminance value of the subject is detected, and when this luminance value is equal to or greater than the threshold value, the search range is determined using DT1. When the luminance value is lower than the threshold value, the search range is set using DT3. However, the present invention is not limited to this, and when the luminance value is equal to or higher than the threshold value, the luminance value is set to the threshold value using DT3. If it is lower, the search range may be set using DT1. In this case, it is preferable to change the correction amount or the like as appropriate. Also, the search range may be set using either DT1 or DT3 regardless of the magnitude of the luminance value.

  In the above-described embodiment, when the planned shooting position is set by the photographer, the object detected based on the image data obtained at the lens position (reference position) of the focus lens 11c corresponding to the planned shooting position. The luminance value is compared with the threshold value, and the search range is set using DT1 or DT3 according to the comparison result. However, the luminance value of the subject is not detected, and the reference position is set when the reference position is set. The search range may be set using the position data P of the zoom lens 11b and either DT1 or DT3 as the center.

  In addition, the temperature around the focus lens 11c is detected by the temperature sensor 14, and the search range is corrected using the detected temperature data T and DT2, but the search range is corrected using the temperature data and DT2. Instead, the in-focus position may be detected within the search range set using the position P of the zoom lens 11c and DT1.

  In addition, it is preferable that the position of the zoom lens 11b set in DT1 to DT3 used in the above embodiment, the driving amount (pulse) of the focus motor 31 and the correction amount (pulse) are appropriately changed.

  Although the present embodiment has been described using a digital camera, the present invention is not limited to this, and the present invention is applied to a digital video camera, an imaging device built in an electronic device such as a mobile phone or a PDA (Personal Digital Assistance). It may be used.

It is a front external perspective view of a digital camera to which the present invention is applied. It is a back external appearance perspective view of a digital camera. It is a block diagram which shows the electric constitution of a digital camera. It is explanatory drawing which shows the distance bar and cursor which are displayed on LCD when inputting imaging | photography estimated distance. It is explanatory drawing of the search range set when the brightness | luminance of a to-be-photographed object is more than a threshold value. It is explanatory drawing of the search range set when the brightness | luminance of a to-be-photographed object is lower than a threshold value. It is a flowchart which shows the process sequence of a focus position search in case the luminance value of a to-be-photographed object is more than a threshold value. It is a flowchart which shows the process sequence of an in-focus position search when the luminance value of a to-be-photographed object is lower than a threshold value.

Explanation of symbols

2 Digital camera 11 Shooting lens 11b Zoom lens 11c Focus lens 14 Temperature sensor 15 LCD
24 Cursor operation board 34 CPU
34a Search range setting section 38 CCD
52 AE / AWB detection circuit 53 AF detection circuit 61 Distance bar 62 Cursor

Claims (7)

This is a focus lens focus adjustment method in which a focus lens included in an imaging optical system is moved to a lens position corresponding to a shooting distance set by a photographer, and a focus position of the focus lens is searched in the vicinity of the lens position. And
The lens position corresponding to the shooting distance is a reference position,
Centering on the reference position, a predetermined search range is set in a range narrower than the movable range of the focus lens,
The in-focus position found by this search after moving the focus lens within the search range and searching for the in-focus position of the focus lens while detecting the in-focus state of the captured image of the subject at the imaging distance A focus lens focus adjustment method, wherein the focus lens is moved to the center. The imaging optical system includes a zoom lens,
2. The focus lens focus adjustment method according to claim 1, wherein a search range for the in-focus position is set based on a correction amount set in advance according to zooming of the zoom lens.   The focus lens focus adjustment according to claim 1 or 2, wherein an ambient temperature of the focus lens is detected, and the search range is set based on a correction amount set in accordance with the detected ambient temperature. Method. An image pickup means for picking up a subject image transmitted through an image pickup optical system including a focus lens and outputting image data;
Distance input means for the photographer to input the shooting distance;
When the shooting distance is input by the distance input unit, the lens position of the focus lens corresponding to the shooting distance is set as a reference position, and the focus lens is set in a range narrower than the movable range of the focus lens. Search range setting means for setting a predetermined search range;
A focus search unit that moves the focus lens within the search range and searches for a focus position of the focus lens based on the image data output by the imaging unit along with the movement;
An image pickup apparatus, wherein after the search for the in-focus position within the search range is completed by the focus search means, the focus lens is moved to the in-focus position found by the search.   The imaging apparatus according to claim 4, wherein the focus search unit searches the in-focus position by moving the focus lens from one end to the other end of the search range. The photographing optical system includes a zoom lens,
6. The imaging apparatus according to claim 4, wherein the search range setting unit sets the search range based on a zoom position of the zoom lens. In the vicinity of the imaging optical system, a temperature detection means for detecting the temperature of the imaging optical system is provided,
The imaging device according to claim 4, wherein the search range setting unit sets the search range based on a detection result of the temperature detection unit.

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