JP2006145763A - Photographic optical system and lens position adjusting method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve focal length accuracy in a set zoom stage of the photographic optical system that is not by assembling accuracy or processing accuracy. <P>SOLUTION: The photographing optical system 10 includes a variable power lens group 11, focusing lens group 12, a first lens position-adjusting mechanism 14<SB>a</SB>, a second lens position-adjusting mechanism 14<SB>b</SB>, and a lens information memory 13. The lens information memory 13 stores first position information, regarding the position in designing the variable power lens group 11 for matching with the focal length in the zoom stage to be set and second position information, regarding the deviation between the actual position and the position in designing. A CPU 30 drives a first stepping motor 31a, based on the first position information and the second position information according to the inputted zoom step. The lens position adjusting mechanism 14<SB>a</SB>transmits the driving force for driving the variable power lens group 11 from the first stepping motor 31a to the variable power lens group 11. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a photographing optical system capable of adjusting a focal length and a lens position adjusting method.

  2. Description of the Related Art Conventionally, photographing optical systems that can correct processing errors and assembly errors of individual lenses and reduce the overall size are known. This photographing optical system is composed of a variable power lens group and a focus lens group that are independently driven. The position of the variable magnification lens group to be moved to obtain a predetermined zoom stage is obtained by calculation.

  Furthermore, in multiple zoom stages, the position of the focus lens group that focuses on an object at infinity (infinity focus position), and the relative position of the focus lens group that focuses on the distance to the subject based on the infinity focus position The target position is obtained by calculation, and the data is stored in advance in a ROM or the like.

  However, in this photographing optical system, the zoom lens group or the focus lens group may be displaced from the design position due to a processing error, an assembly error, a temperature change, or the like. Therefore, the applicant of the present application has proposed to obtain the origin positions of the variable power lens group and the focus lens group for correcting the shift of the infinity focus position, and to improve the accuracy of the infinity focus position (Patent Document 1).

However, even in the photographic optical system disclosed in Patent Document 1, the focal length for achieving a predetermined zoom stage may deviate from the design value due to a processing error, an assembly error, a temperature change, or the like.
Japanese Patent Laid-Open No. 11-30740

  Therefore, an object of the present invention is to provide a photographing optical system with high focal length accuracy for achieving a predetermined zoom stage and an adjustment method for increasing the focal length accuracy.

  The photographic optical system of the present invention is movable along the optical axis and has a lens group for adjusting the focal length, and a design movement amount from the initial position to a position where the position of the lens group is adjusted to a predetermined focal length. A memory for storing second position information corresponding to a shift amount, which is a difference between a movement amount actually required for matching with the corresponding first position information and a predetermined focal length, and a design movement amount; and a lens group. And a power transmission means for transmitting a driving force for movement along the optical axis from a lens driving means provided in the camera to the lens group. By mounting the photographic optical system having such a configuration on a camera having a corresponding function, it is possible to increase the accuracy of the focal length.

  In addition, it is preferable that the driving unit is controlled based on the first position information and the second position information stored in the memory when adjusting to a predetermined focal length.

  Further, it is preferable that the amount of deviation is calculated based on a focal length adjustment diagram captured by an imaging unit that captures a subject image on an imaging plane perpendicular to the optical axis. The accuracy of the focal length can be further increased by obtaining the amount of deviation from the actually captured image.

  In addition, two signs are provided in the focal length adjustment diagram, and the two signs taken by the imaging means when the amount of deviation is a distance between the two signs taken by the imaging means and a predetermined focal length. It is preferable to calculate based on the distance between them. Such a calculation method makes it possible to accurately calculate the amount of deviation.

  The camera of the present invention is movable along the optical axis and has a lens group for adjusting the focal length, and a design movement from the initial position to a position for adjusting the lens group to a predetermined focal length. A memory for storing first position information corresponding to the amount and second position information corresponding to a shift amount which is a difference between a movement amount actually required to match a predetermined focal length and a design movement amount; It is characterized by comprising drive means for driving the lens group along the optical axis, and control means for controlling the drive means based on the first position information and the second position information when the lens group is adjusted to a predetermined focal length.

  The lens position adjustment method of the present invention includes a first step of arranging a focal length adjustment diagram at a predetermined position on the optical axis of the camera of the present invention, a second step of photographing the focal length adjustment diagram by the camera, And a third step of calculating a shift amount based on a focal length adjustment image photographed by the camera, and a fourth step of storing in the memory second position information corresponding to the shift amount calculated in the third step. It is characterized by.

  It is preferable to arrange a collimator between the focal length adjustment diagram and the camera. In the focal length adjustment diagram, two signs that are imaged on the imaging surface of the imaging means provided in the camera through the collimator and the first lens group whose position is adjusted to have a predetermined focal length are determined in advance. Preferably, the distance is an ideal sign distance that is a distance, and the amount of deviation is preferably calculated based on the distance between two signs picked up by the image pickup means and the ideal sign distance.

  Further, the focal length adjustment diagram for calculating the shift amount of the photographing optical system of the present invention is the image of the imaging means provided in the camera through the collimator and the first lens group whose position is adjusted to be a predetermined focal length. It is characterized in that a marker having a predetermined length between two subject images formed on the imaging surface is provided.

  According to the present invention, it is possible to provide an imaging optical system with high focal length accuracy regardless of processing accuracy or assembly accuracy.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a perspective view of a camera including a photographing optical system to which an embodiment of the present invention is applied. The camera 40 is constituted by the photographing optical system 10 and the camera body 20. The photographing optical system 10 is detachable from the camera body 20.

  The camera body 20 is provided with a power button 21, a release button 22, a zoom button 23, a mode switching button 24, and an LCD monitor 25. Pressing the power button 21 switches on / off the operation of the entire camera. By operating the mode switching button 24, it is possible to switch to the photographing mode, the reproduction mode, or the image editing mode.

  A subject (not shown) can be photographed in the photographing mode, an image photographed in the reproduction mode is displayed on the LCD monitor 25, and camera settings and image editing can be performed in the image editing mode.

  In the photographing mode, a subject image is received by an image sensor (not shown) through the photographing optical system 10. The image sensor is, for example, a CCD. By operating the zoom button 23, it is possible to zoom up and down the image to be taken. The subject image received at the zoom stage determined by the photographer's operation is displayed on the LCD monitor 25. The release operation is executed by fully pressing the release button 22.

Next, the internal configuration of the camera will be described with reference to FIG. FIG. 2 is a block diagram showing the internal configuration of the camera. The camera body 20 includes an imaging device 26, AFE27, DSP28, the image memory 29, CPU 30, first stepping motor 31 _a, and a by a second stepping motor 31 _b. The image sensor 26 is connected to the DSP 28 via the AFE 27. The image memory 29 and the LCD monitor 25 are connected to the DSP 28.

  An image signal is generated in the image sensor 26 by executing the release operation in the shooting mode. The generated image signal undergoes predetermined processing such as A / D conversion and white balance in the AFE 27 and the DSP 28, and is converted into one image data for one image. Image data can be stored in the image memory 29.

CPU30 is, DSP 28, first stepping motor 31 _a, the second stepping motor 31 _b, the main switch Sw1, a release switch Sw2, is connected to the zoom switch Sw3, and the mode switch Sw4. The overall operation of the camera 40 is controlled by the CPU 30.

  The main switch Sw1, the release switch Sw2, the zoom switch Sw3, and the mode switch Sw4 are switched by operations of the power button 21, the release button 22, the zoom button 23, and the mode switching button 24, respectively.

The photographing optical system 10 includes a variable magnification lens group 11, a focus lens group 12, a lens information memory 13, a first lens position adjustment mechanism _14a , and a second lens position adjustment mechanism _14b . When the photographing optical system 10 is connected to the camera body 20, the variable power lens group 11 and the focus lens group 12 are optically connected to the image sensor 26, the lens information memory 13 and the CPU 30 are electrically connected, and the first stepping is performed. a motor 31 _a and the first lens position adjustment mechanism 14 _a, the second stepping motor 31 _b and the second lens position adjusting mechanism 14 _b and are mechanically connected.

The subject image passes through the variable power lens group 11 and the focus lens group 12 and forms an image on the imaging surface of the image sensor 26. The variable power lens group 11 and the focus lens group 12 are respectively arranged along the optical axis by _a first lens position adjusting mechanism 14 _a and a second lens position adjusting mechanism 14 _b each having a conventionally known helicoid mechanism and rack and pinion mechanism. It is supported movably independently.

  The focal length of the entire photographing optical system is adjusted by moving the variable magnification lens group 11 along the optical axis, and the subject image is zoomed up or down. By moving the focus lens group 12 along the optical axis, focusing on the imaging surface of the subject image is executed.

  An arbitrary position within the moving range of the variable magnification lens group 11 is determined as a design reference position. In addition, the reference position of the focus lens group 12 is set to a position that focuses on a subject image at infinity with respect to the reference position of the zoom lens group 11.

Photosensors (not shown) are provided as reference position detection means at the reference positions of the zoom lens group 11 and the focus lens group 12. The positions of the zoom lens group 11 and the focus lens group 12 are defined and measured by the number of pulses of the stepping motors 31 _a and 31 _b from the reference position detected by the photosensor. The lens information memory 13 stores origin information corresponding to the origin position with respect to the reference position as the initial positions of the variable power lens group 11 and the focus lens group 12.

  Multiple stages, for example, 10 stages, are set for zooming from the wide end that maximizes the angle of view to the tele end that minimizes the angle of view. The focal length of the entire photographing optical system 10 is determined for each set zoom stage. The lens information memory 13 also stores first position information corresponding to a design distance from the origin position of the variable magnification lens group 11 that sets the focal length of the entire photographing optical system 10 to a predetermined focal length.

  The first position information is information about the position calculated by design. Therefore, there is a deviation (focal length deviation) between the position of the zoom lens group 11 that actually gives a determined focal length and the position corresponding to the first position information due to processing errors and assembly errors for each actual product. Will occur. The lens information memory 13 also stores second position information corresponding to the movement amount for correcting the focal distance deviation.

  The first position information is information corresponding to the position calculated for each zoom stage, and the second position information is information for correcting the focus position shift actually measured at the wide end and the tele end.

  Further, the position of the focus lens group 12 for focusing on a subject other than infinity is the subject distance with reference to the relative position of the focus lens group 12 for focusing on the subject at infinity with respect to the variable magnification lens group 11. Each position is obtained by calculation and stored in the lens information memory 13 as third position information.

  In the shooting mode of the camera 40, the first to third position information stored in the lens information memory 13 is read into the CPU 30 as necessary. When the release button 22 is pressed halfway, the distance to the subject is detected by a distance measuring sensor (not shown), and at the same time, the third position information is read into the CPU 30, and the subject image at the measured distance is displayed on the imaging surface. The relative position of the focus lens group 12 to be focused with respect to the variable magnification lens group 11 is obtained based on the third position information.

  When the zoom button 23 is operated, the origin information and the first and second position information are read by the CPU 30, and the position of the zoom lens group 11 is set so that the focal length is determined for each zoom stage. It is obtained based on the origin information and the first and second position information.

  More specifically, the position of the zoom lens group 11 is obtained based on the origin information, the first position information, and the second position information at the wide end when the zoom stage is set to a stage other than the tele end. When set at the tele end stage, it is obtained based on the origin information, the first position information, and the second position information at the tele end.

  The focal length deviation is different at each zoom stage. However, the focal length deviation at each zoom stage is substantially equal to the focal distance deviation at the wide end, and the position of the variable magnification lens group 11 is obtained using the focal length deviation at the wide end at each zoom stage. This is because the position of the zoom lens group 11 obtained in this way is within an allowable range with respect to the actual position giving the focal length determined in each zoom stage. However, since the tele end is frequently used, the position of the zoom lens group 11 is obtained using the focal length shift at the tele end, which is further finely adjusted from the focal length shift at the wide end.

Focus lens group 12, or the position of the variator lens group 11 is required, the first stepping motor 31 _a and the second stepping motor 31 _b is driven by CPU 30. The driving force of the stepping motors 31 _a and 31 _b is transmitted to the focus lens group 12 or the variable power lens group 11 via the lens position adjusting mechanisms 14 _a and 14 _b . The stepping motors 31 _a and 31 _b are driven by the CPU 30 so as to move the focus lens group 12 or the variable power lens group 11 to the obtained positions.

  As described above, according to the present embodiment, it is possible to correct the focal length deviation exceeding the allowable value after the individual photographing optical systems are assembled so as to be equal to or less than the allowable value. Therefore, it is possible to provide a photographic optical system with a performance as a final product, which is conventionally inferior in a focal length shift performance in a performance confirmation test and cannot be a final product.

  In the present embodiment, the photographing optical system (lens barrel) is detachable from the camera body, but may be an integrated camera. In the case of an integrated camera, the lens information memory is configured so that its function is executed by a ROM provided in the camera, and the lens position information is stored in the ROM together with other information for controlling the camera. Good.

  Next, a lens position adjustment method by obtaining the initial variable magnification lens group 11 and focus lens group 12 corresponding to the origin information and the focal length shift corresponding to the second position information and storing them in the lens information memory. explain. Each camera 40 actually assembled undergoes predetermined performance check and fine adjustment. Calculation of the origin positions and focal length deviations of the lens groups 11 and 12 and storage in the lens information memory 13 are performed as predetermined fine adjustments.

  FIG. 3 is a diagram for explaining the calculation of the origin position and focal length deviation of the lens group and the storing operation in the lens information memory. The calculation and storage work is executed by causing the CPU 30 and the DSP 28 to perform predetermined processing by inputting to the input means such as the zoom button 23 and the mode switching button 24. Alternatively, the calculation and storage operations can be performed by operating a lens position adjusting computer (not shown) connected to the camera 40.

  The camera 40, the focus adjustment chart 50, and the collimator 51 are arranged at predetermined positions. The focus adjustment chart 50 is arranged at the focal position of the collimator 51. The focus adjustment chart 50 and the collimator 51 are superimposed on the optical axis of the camera 40, and the collimator 51 is sandwiched between the camera 40 and the focus adjustment chart 50.

  First, the origin position is adjusted. By adjusting the origin position, the accuracy of the focus position at infinity is increased, and as a result, the accuracy of focusing on the subject at each zoom stage is increased. Thus, by adjusting the origin position first, it is possible to accurately detect the marker on the focal length adjustment chart that is shot for correcting the focal length deviation described later.

The CPU 30 drives the first and second stepping motors 31 _a and 31 _b so that the variable power lens group 11 and the focus lens group 12 are moved from the reference position when the camera 40 is assembled to the wide end based on the first information. Moved. In this state, the focus adjustment chart 50 is moved in the optical axis direction, and the image sensor 26 shoots the image to compare the contrast of the captured images, thereby forming an infinite object image on the imaging surface. A first shift amount with respect to the position is calculated.

  Next, the variable power lens group 11 and the focus lens group 12 are moved from the reference position by the amount of the first shift amount to be a temporary origin position. Further, based on the first position information, the variable magnification lens group 11 is moved to the tele end side where the minimum magnification is obtained. Further, the focus lens group 12 is moved based on the third position information and the position of the variable power lens group 11.

  In this state, the second shift amount with respect to the actual infinity in-focus position at the tele end is calculated by causing the image sensor 26 to photograph while moving the focus adjustment chart 50 in the optical axis direction.

  Next, the final origin position is obtained by adjusting the temporary origin position of the variable power lens group 11 and the focus lens group 12 according to the first and second deviation amounts. Position information corresponding to the determined final origin position is stored in the lens information memory 13 as origin information.

  Next, an operation for obtaining the focal length deviation is performed. In order to obtain the focal distance deviation, the focus deviation adjustment chart 50 is replaced with a focal distance adjustment chart 52 as shown in FIG. On the focal length adjustment chart 52, two crosses 53, 53 serving as markers are drawn at predetermined intervals.

  The predetermined width of the straight line is the width of the center of the two crosses 53, 53, and when the image is taken with a camera having no assembly error or processing error through the collimator 51 (not shown in FIG. 4), It is determined to be a predetermined interval. The predetermined width αmm is drawn so as to be βmm when the variable power lens group 11 is moved to the wide end, and γmm when it is moved to the telephoto end.

The first and second stepping motors 31 _a and 31 _b are driven by the CPU 30, and the variable power lens group 11 is based on the origin information corresponding to the final origin position obtained in the above-described origin position adjustment and the first position information. Move to the wide end. The focus lens group 12 is also moved to a position relative to the variable magnification lens group 11 so as to focus an infinite subject image. The crosses 53 and 53 drawn on the focal length adjustment chart 52 are photographed in a state where the variable magnification lens group 11 is moved to the wide end.

  The center of the photographed crosses 53 and 53 is recognized by a known image recognition method such as detecting the luminance center of gravity. The distance between the centers of the crosses 53 and 53 recognized from the cell size of the image sensor 26 to be used is detected. The focal length deviation at the wide end is calculated based on the deviation between the detected interval and the design interval β mm.

  Second position information corresponding to the calculated focal length shift at the wide end is stored in the lens information memory 13. Next, the variable power lens group 11 is moved to the tele end based on the origin information, the first position information, and the second position information corresponding to the focal length shift at the wide end. Similarly, the focus lens group 12 is moved to a position relative to the variable power lens group 11 so as to focus an infinite subject image.

  The crosses 53 and 53 drawn on the focal length adjustment chart 52 are photographed with the zoom lens group 11 moved to the telephoto end. Similar to the work at the wide end, the distance between the centers of the crosses 53 and 53 is detected. The focal length deviation at the tele end is calculated by finely adjusting the focal length deviation at the wide end based on the deviation between the detected interval and the design interval γmm. Second position information corresponding to the calculated focal length shift at the tele end is also stored in the lens information memory 13.

  As described above, according to the lens position adjusting method of the present embodiment, a cross-shaped lens having a predetermined interval (β or γ mm) at the position of the variable power lens group having the designed focal length on the image sensor. It is possible to actually photograph the sign and easily determine the focal length deviation based on the actual sign interval and the predetermined interval of the photographed image. Therefore, by correcting the position of the variable magnification lens group by the calculated focal length deviation, it is possible to increase the accuracy of the focal length at a predetermined zoom stage of the photographing optical system.

  In the imaging optical system of the present embodiment and the lens position adjustment method of the present embodiment, the first position information and the second position information are separately stored in the lens information memory, but the second position information is the first position information. In other words, it may be stored in the lens information memory as position information obtained by correcting the first position information by the second position information.

  Note that the calculation of the focal length deviation described above is applied to a photographing optical system with a narrow magnification adjustment range. The focal length deviation calculation at both the wide end and the tele end of the photographing optical system with a wide magnification adjustment range is calculated using the focal length adjustment chart for confirmation at the wide end and the focal length adjustment chart for confirmation at the tele end. Used. The distance between the markers and the size of the pattern differ depending on the angle of view at the tele end and the wide end.

  Next, zooming and focusing at the time of shooting with the above-described camera, and initial adjustment processing for the position of the lens group will be described with reference to FIGS.

  FIG. 5 is a flowchart for explaining lens group position adjustment or initial adjustment processing performed in the CPU 30 and DSP 29 of the camera. First, in step S100, it is confirmed whether or not the mode of the camera 40 is the test mode.

  When the camera 40 is not in the test mode, the process proceeds to step S101, and the subject image received by the image sensor 26 is displayed on the LCD monitor 25. Next, in step S102, it is confirmed whether an operation with the zoom button 23 is performed or whether the release button 22 is half-pressed.

  If the release button 22 is half-pressed, the process proceeds to step S103 to perform focusing processing. That is, in step S103, the CPU 30 determines the relative position of the focus lens group 12 with respect to the variable power lens group 11 based on the position of the variable power lens group 11, the third position information, and the distance to the subject detected by the distance measuring sensor. The focus lens group 12 is moved to the obtained position. Thereafter, the process proceeds to step S105.

  In step S102, when the operation using the zoom button 23 is performed, the process proceeds to step S104, and the zoom stage is switched. When the zoom button 23 is set and input at a stage other than the telephoto end, the position of the zoom lens group 11 is obtained based on the first position information and the second position information at the wide end, and the obtained position Then, the zoom lens group 11 is moved, and at the same time, the focus lens group 12 is moved so that the relative position with respect to the zoom lens group 11 is maintained.

  When the telephoto end stage is set, the position of the variable power lens group 11 is obtained based on the first position information and the second position information at the telephoto end, the variable power lens group 11 is moved to the obtained position, At the same time, the focus lens group 12 is moved so that the relative position with respect to the variable power lens group 11 is maintained. When the movement of the lens groups 11 and 12 for switching the zoom stage is completed, the process proceeds to step S105.

  In step S105, it is confirmed whether or not the release button 22 is fully pressed. If it is not fully pressed, the process returns to step S101, and steps S101 to S105 are repeated until it is fully pressed. If the release button 23 is fully pressed, the process proceeds to step S106, where the shooting operation is executed and the process ends.

  On the other hand, if the test mode is set in step S100, the process proceeds to step S107. In step S107, a predetermined set value set in the camera 40 is initialized. Thereafter, the process proceeds to step S200, and focus adjustment described later is performed.

  After performing the focus adjustment in step S200, the process proceeds to step S300 to adjust the focal length described later. In step S300, after the adjustment of the focal length is completed, the process proceeds to step S108, the adjustment values obtained in steps S200 and S300 are stored in the lens information memory 13, and the process is terminated.

  The focus adjustment in step S200 will be described in detail with reference to FIG. After step S107 ends, the process proceeds to step S201, and the variable power lens group 11 and the focus lens group 12 are moved to the wide end with the reference position as the origin based on the first position information.

  Next, in step S202, the focus shift adjustment chart 50 is used to determine the first shift amount with respect to the position where the object image at infinity at the wide end is focused. In step S203, the first shift amount is stored in the lens information memory 13. To do.

  Thereafter, the process proceeds to step S204, and the variable power lens group 11 and the focus lens group 12 are moved to the telephoto end based on the first position information. Next, in step S205, the second shift amount from the position where the object image at infinity at the telephoto end is focused is obtained, and in step S206, the second shift amount is stored in the lens information memory 13.

  In the next step S207, based on the reference position, the first shift amount, and the second shift amount stored in the lens information memory 13, the final origin position is calculated with respect to the reference position and stored in the lens information memory 13. . It progresses to step S208 and it is confirmed whether the process of step S201-step S207 is the 1st time.

  If it is the first time, the process returns to step S201, and the processes of steps S201 to S208 are repeated again. However, in step S201, the zoom lens group 11 and the focus lens group 12 are moved to the wide end with the final origin position obtained in step S207 as the origin instead of the reference position. If it is determined in step S208 that the processes in steps S201 to S208 are not the first time, the focus adjustment process is terminated and the process proceeds to step S300.

  The adjustment of the focal length in step S300 will be described in detail with reference to FIG. After the process of step S208 ends, in step S301, the variable power lens group 11 and the focus lens group 12 are moved to the wide end based on the first position information. Here, the reference origin position to be moved to the wide end is the origin position stored in step S207.

  In the next step S302, the focal length adjustment chart 52 is photographed, and the interval between the crosses 53, 53 drawn on the focal length adjustment chart is measured. Next, in step S <b> 303, the focal length shift at the wide end is obtained based on the measured distance between the straight lines and the distance between the crosses 53 at the wide end stored in the lens information memory 13, and stored in the lens information memory 13. . Further, the variable power lens group 11 and the focus lens group 12 are moved so as to correct the focal length deviation.

  The lens information memory 13 stores in advance the intervals at the wide end and the tele end of the crosses 53 and 53 when there is no assembly error or processing error. When the lens groups 11 and 12 are moved in step S303, the process proceeds to step S304, and the lens groups 11 and 12 are moved to the tele end based on the first position information and the focal length shift at the wide end obtained in step S303. Move.

  In the next step S305, the interval between the crosses 53 and 53 is measured in the same manner as in step S302. Proceeding to step S306, similarly to step S303, the focal length deviation at the telephoto end is obtained and stored in the lens information memory. Further, the variable power lens group 11 and the focus lens group 12 are moved so as to correct the focal length shift at the telephoto end.

  After the processing in step S306, the process proceeds to step S307, and it is confirmed whether or not the processing in steps S301 to S306 is the first time. If it is the first time, the process returns to step S301, and the processes of steps S301 to S307 are repeated. If it is not the first time, the focal length adjustment process is terminated, and the process returns to step S108.

  By sequentially performing the above steps, the lens position adjusting method of the present embodiment is executed.

It is a perspective view of a camera provided with the photography optical system to which one embodiment of the present invention is applied. It is a block diagram which shows an imaging optical system and the internal structure of a camera main body. It is a figure for demonstrating the focus adjustment method. It is a figure explaining the space | interval of the cross drawn on a focal distance adjustment chart. It is a flowchart for demonstrating the lens group position adjustment in the imaging | photography mode of a camera, or an initial adjustment process. It is a flowchart for demonstrating the process for performing focus adjustment. It is a flowchart for demonstrating the process for performing a focal distance adjustment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Shooting optical system 11 Variable magnification lens group 12 Focus lens group 13 Lens information memory _14a , _14b 1st, 2nd lens position adjustment mechanism 20 Camera main body 26 Imaging element 30 CPU
31 _a, 31 _b first, second stepping motor 40 camera 51 collimator 52 focal length adjustment chart 53 cross (labeled)

Claims (9)

A lens group that can move along the optical axis and adjust the focal length;
First position information corresponding to a design movement amount from an initial position to a position to be adjusted to a predetermined focal length, and a movement amount actually required to match the predetermined focal length A memory for storing second position information corresponding to a shift amount that is a difference from the designed movement amount;
An imaging optical system comprising: a power transmission unit configured to transmit a driving force for moving the lens group along the optical axis from a lens driving unit provided in a camera to the lens group.   The photographing optical according to claim 1, wherein the driving unit is controlled based on the first position information and the second position information stored in the memory when the predetermined focal length is set. system.   The photographing optical system according to claim 1, wherein the shift amount is calculated based on a focal length adjustment diagram captured by an imaging unit that captures a subject image on an imaging surface perpendicular to the optical axis. Two markers are provided on the focal length adjustment diagram,
The amount of deviation is calculated based on the distance between the two signs picked up by the image pickup means and the distance between the two signs picked up by the image pickup means when it is the predetermined focal length. The photographing optical system according to claim 3, wherein: A lens group that can move along the optical axis and adjust the focal length;
The first position information corresponding to the design movement amount from the initial position to the position for adjusting to the predetermined focal length, and the actual movement necessary for adjusting to the predetermined focal length. A memory for storing second position information corresponding to a deviation amount, which is a difference between the amount and the designed movement amount;
Driving means for driving the lens group along the optical axis;
A camera comprising: control means for controlling the drive means based on the first position information and the second position information when adjusting to the predetermined focal length. A first step of arranging a focal length adjustment diagram at a predetermined position on the optical axis of the camera according to claim 5;
A second step of photographing the focal length adjustment diagram by the camera;
A third step of calculating the shift amount based on the focal length adjustment image captured by the camera;
And a fourth step of storing, in the memory, second position information corresponding to the amount of deviation calculated in the third step.   The lens position adjustment method according to claim 6, wherein a collimator is disposed between the focal length adjustment diagram and the camera. In the focal length adjustment diagram, there are two signs that pass through the collimator and the first lens group whose position is adjusted to be the predetermined focal length, and form an image on an imaging surface of an imaging means provided in the camera. , Provided to be an ideal signage distance that is a predetermined distance,
The lens position adjustment method according to claim 7, wherein the shift amount is calculated based on a distance between two of the signs imaged by the imaging unit and the ideal signage distance. In the focal length adjustment diagram for calculating the shift amount of the photographing optical system according to claim 1,
A distance between two subject images that pass through a collimator and the first lens group whose position has been adjusted so as to be the predetermined focal length and is imaged on an imaging surface of an imaging means provided in the camera is a predetermined length. The focal distance adjustment figure characterized by providing a certain label | marker.

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