JP2013145385A - Camera - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a camera that is able to prevent defocus.SOLUTION: A camera 1 to which a plurality of interchangeable lenses 200 are selectively attached comprises storing means 116 configured such that a plurality of characteristic values of an interchangeable lens, which are determined according to a plurality of photographic states of the camera are stored so as to be associated with information identifying the interchangeable lens. The camera also includes focus detection means 108 configured such that based on a luminous flux via the optical system of the attached interchangeable lens, the focus adjustment state of the optical system is detected. The focus detection means corrects the focus adjustment state based on a characteristic value.

Description

  The present invention relates to a camera.

  In focus detection by the phase difference detection method, it is known that the curvature of field data stored in the interchangeable lens is used to correct the defocus amount based on the size of the detection aperture of the focus detection means and the data of the focus detection position. (See Patent Document 1).

  However, depending on the shooting conditions, there is a problem that the defocus amount is not properly corrected and the focus position is shifted.

Japanese Patent No. 3214099

  The problem to be solved by the present invention is to provide a camera capable of detecting a focus with higher accuracy.

  The present invention solves the above problems by the following means. In addition, although the code | symbol corresponding to drawing which shows embodiment of this invention is attached | subjected and demonstrated, this code | symbol is only for making an understanding of this invention easy, and is not the meaning which limits this invention.

[1] A camera according to the present invention has a plurality of characteristic values of an interchangeable lens determined according to each of a plurality of photographing states of the camera in a camera (1) capable of selectively mounting a plurality of interchangeable lenses (200). And a storage means (116) for storing in association with information for identifying the interchangeable lens.

  In the above invention, the focus detection means (108) for detecting the focus adjustment state of the optical system based on the light flux through the optical system of the attached interchangeable lens is provided, and the focus detection means adjusts the focus based on the characteristic value. It can be configured to correct the condition.

  In the above invention, the focus detection means can detect a focus adjustment state for each of a plurality of focus detection positions set corresponding to a plurality of positions in the image plane by the optical system, and the storage means A characteristic value corresponding to each of the focus detection positions can be stored.

  In the above invention, the storage means can store a plurality of characteristic values corresponding to different shooting distances of the interchangeable lens optical system or a plurality of characteristic values corresponding to the focal length of the interchangeable lens optical system.

  In the above invention, the storage means can add and store characteristic values.

  In the above invention, the characteristic value may be a value representing a deviation of the image plane position of the optical system due to, for example, aberration of the optical system.

  According to the present invention, it is possible to detect a focus with high accuracy regardless of shooting conditions.

It is a block diagram which shows the camera which concerns on embodiment of this invention. It is a figure which shows the AF module shown in FIG. It is a figure which shows the defocus amount calculation area of the camera which concerns on embodiment of this invention. It is a flowchart which shows operation | movement of the camera which concerns on embodiment of this invention. It is a flowchart which shows operation | movement of the camera which concerns on other embodiment of this invention. It is a flowchart which shows the operation | movement of the camera which concerns on further another embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a block diagram showing a camera according to an embodiment of the present invention. The camera 1 according to this embodiment includes a camera body 100 and an interchangeable lens 200 that is detachably attached to the camera body 100.

  The interchangeable lens 200 is provided with a focus lens 202 that can move along the optical axis 3 and a lens drive motor 204 that moves the focus lens 202 along the optical axis 3.

  The specific configuration of the moving mechanism along the optical axis 3 of the focus lens 202 is not particularly limited. As an example, a rotating cylinder is rotatably inserted into a fixed cylinder fixed to the lens barrel 200, and the inner periphery of the rotating cylinder A helicoid groove (spiral groove) is formed on the surface, and the end of the lens frame that fixes the focus lens 202 is fitted into the helicoid groove. The focus lens fixed to the lens frame moves straight along the optical axis 3 by rotating the rotating cylinder by the lens driving motor 204.

  The lens barrel 200 is provided with a lens group other than the focus lens 202. Here, the embodiment will be described by taking the focus lens 202 as an example.

  As described above, the focus lens 202 fixed to the lens frame by moving the rotating cylinder with respect to the lens barrel 200 moves straight in the direction of the optical axis 3, and the lens driving motor 204 (actuator) as a driving source thereof is moved. Is provided in the lens barrel 200. The lens driving motor 204 and the rotating cylinder are connected by a transmission composed of a plurality of gears, for example. When the driving shaft of the lens driving motor 204 is driven to rotate in any one direction, it is transmitted to the rotating cylinder at a predetermined gear ratio, and When the rotating cylinder rotates in any one direction, the focus lens 202 fixed to the lens frame moves straight in any direction of the optical axis 3. When the drive shaft of the lens drive motor 204 is rotationally driven in the reverse direction, the plurality of gears constituting the transmission also rotate in the reverse direction, and the focus lens 202 moves straight in the reverse direction of the optical axis 3.

  The focus lens 202 can move in the optical axis direction from the end on the camera body side (also referred to as the closest end) to the end on the subject side (also referred to as the infinite end) by the rotation of the rotating cylinder described above. This movement is controlled by a command from the lens drive control unit 112 of the camera body 100.

  The camera body 100 is provided with an image sensor 102 composed of a two-dimensional CCD image sensor, MOS sensor, CID, or the like, and an electrical image signal photoelectrically converted by the image sensor 102 is stored in a memory (not shown).

  On the front surface of the image sensor 102, a half mirror 104 that can be rotated by a predetermined angle and a total reflection mirror 106 that rotates together with the half mirror 104 are provided. The half mirror 104 and the total reflection mirror 106 are in the positions indicated by the solid lines in the autofocus mode in which the automatic focusing operation is performed. When the shutter is pressed in this state, the half mirror 104 and the total reflection mirror 106 are rotated to the positions indicated by the two-dot chain lines. An image is formed on the imaging device 102.

  In addition, the camera body 100 is provided with an autofocus module 108 (hereinafter also referred to as an AF module) for performing automatic focusing adjustment, and a total reflection mirror 110 that reflects the light beam from the total reflection mirror 106 to the AF module 108. Is provided.

  In the autofocus mode, the half mirror 104 and the total reflection mirror 106 are positioned at the position indicated by the solid line in the figure, so that the light flux from the subject is guided to the half mirror 104 through the focus lens 202, and one of them. The part passes through the half mirror 104 and is input to the AF module 108 by the total reflection mirrors 106 and 110. In the AF module 108, automatic focusing control by a phase difference detection method using the subject light is executed.

  On the other hand, part of the subject light reflected by the half mirror 104 passes through the finder screen 122, is guided to the finder penta prism 118, is bent by the penta prism 118, and then passes through the eyepiece 120. Led to the eyeball. As a result, the subject and its background can be observed through the viewfinder.

  FIG. 2 is a diagram showing the configuration of the AF module 108 shown in FIG. 1, which is a so-called phase difference type focus detection element. The AF module 108 of this example includes a converter lens 108a, a diaphragm mask 108b in which a pair of openings 108b and 108c are formed, a pair of re-imaging lenses, and a pair of line sensors 108g and 108h. Two partial light fluxes are taken out from, and the focus state is detected based on the difference in the imaging position of each partial light flux.

  Then, as shown in the figure, when the subject image is formed on the equivalent plane 108i of the image sensor 102, it becomes in-focus state. However, when the imaging lens 202 moves in the optical axis direction, the image formation point is moved from the equivalent plane 108i. If it is displaced toward the subject 2 (referred to as the front pin) or displaced toward the camera body 100 (referred to as the rear pin), it will be out of focus.

  When the image point of the subject image is shifted to the subject 2 side from the equivalent surface 108i, the interval L between the output values detected by the pair of line sensors 108g and 108h becomes shorter than the interval L in the focused state. Conversely, when the image point of the subject image is shifted toward the camera body 100, the interval L between the output values detected by the pair of line sensors 108g and 108h becomes longer than the interval L in the focused state.

  That is, the output values detected by the pair of line sensors 108g and 108h overlap with the center of the line sensor in the focused state, but the output values deviate from the center of the line sensor in the out-of-focus state. Since a phase difference occurs, focus is adjusted by moving the focus lens 202 so that the phase difference (deviation amount) becomes zero.

  In the autofocus mode, the lens drive control unit 112 sends a drive command to the lens drive motor 204 while taking in the phase difference ΔL from the AF module 108 described above, and the phase difference ΔL detected by the AF module 108 is zero. At this position, the focus lens 202 is stopped.

  The interchangeable camera 200 of the present embodiment is provided with a lens information output unit 208, and when a request signal is input from the defocus amount correction unit 114 of the camera body 100, lens type information indicating the type of the interchangeable lens. Corresponds to the zoom position information indicating the current focal distance, the lens distance position information indicating the lens distance position, the focal distance and the lens distance position changing according to the movement of the focus lens. The spherical aberration information and the curvature of field information are sent to the defocus amount correction unit 114.

  On the other hand, the camera body 100 is provided with a memory 116 composed of a ROM and a RAM. Here, the lens type information of a specific interchangeable lens owned by the user and its associated interchangeable lens Stores the amount of defocus specific to the interchangeable lens. The defocus amount unique to the interchangeable lens is a defocus amount still remaining in the focusing operation performed by the AF module 108 when a specific interchangeable lens owned by the user is attached to the camera body. Such an out-of-focus amount unique to the interchangeable lens is considered to be caused by spherical aberration that is influenced by the individual interchangeable lenses, the focus detection position of the photographing screen, the focal length, the photographing distance, and the like.

  The information can be stored in the memory 116 by a user manually using a camera menu screen or by a manufacturer at a service center or the like.

  The defocus amount correction unit 114 compares the lens type information of the interchangeable lens 200 acquired from the lens information output unit 208 with the information stored in the memory 116, and matches the lens type information of the interchangeable lens 200. If there is information, the amount of defocus inherent to the interchangeable lens is read from the memory 116, a correction amount corresponding to the amount of shift is calculated, and the correction amount is sent to the lens drive control unit 112.

  The lens drive control unit 112 moves the focus lens 202 to a position where the phase difference Δ from the AF module 108 becomes zero while considering the correction amount from the defocus amount correction unit 114.

<< First Embodiment >>
The lens-specific focus shift amount of the interchangeable lens 200 is different for each area when, for example, a plurality of areas for calculating the defocus amount are set. FIG. 3 is a front view of the image sensor 102 showing the defocus amount calculation area of the camera 1 according to the present embodiment.

  In this example, the defocus amount calculation areas are set to four areas, a left area 102-1, a central horizontal area 102-2, a central vertical area 102-3, and a right area 102-4. It is assumed that defocus amounts Df1, DF2, Df3, and DF4 are detected. The specific positions and numbers of the defocus amount calculation areas 102-1 to 102-4 shown in the figure are not limited at all.

  In this case, the information stored in the memory 116 includes at least the lens type information of the specific interchangeable lens owned by the user, the left area 102-1 described above, the central horizontal area 102-2, and the central vertical lens. The defocus amounts Pz1, Pz2, Pz3, and Pz4 of the specific lens corresponding to each of the area 102-3 and the right area 102-4.

  FIG. 4 is a flowchart showing the operation of the camera according to this embodiment. A request signal is sent from the defocus amount correction unit 114 to the lens information output unit 208 of the interchangeable lens 200 in a state where the focus shift amount for each of the four defocus amount calculation areas and for each specific interchangeable lens is stored in the memory 116. Then, the lens type information of the interchangeable lens 200 is read from the lens information output unit 208 (step S401).

  The defocus amount correction unit 114 compares the lens type information read from the lens information output unit 208 with the lens type information stored in the memory 116, and if there is matching information, the process proceeds to step S403 (step S402). .

  In step S403, the left side area 102-1, the central horizontal area 102-2, the central vertical area 102-3, and the right area 102-4 are stored in the memory 116 in association with the lens type information. The focus shift amounts Pz1, Pz2, Pz3, and Pz4 of the specific lens are read out, corrected by the following correction formula, and the corrected defocus amounts Df1, DF2, Df3, and DF4 (the left side of the following correction formula) are converted into a lens drive control unit. To 112.

(Equation 1)
Df1 = Df1-Pz1
Df2 = Df2-Pz2
Df3 = Df3-Pz3
Df4 = Df4-Pz4
The lens drive control unit 112 moves the focus lens 202 to a position where the phase difference Δ from the AF module 108 becomes zero while considering the correction amount from the defocus amount correction unit 114.

  If the lens type information read from the lens information output unit 208 does not correspond to the lens type information stored in the memory 116 in step S402, the process jumps to step S403 to perform correction processing. finish.

  In the present embodiment, since the amount of defocus is corrected for each interchangeable lens and for each defocus amount calculation area, defocus can be prevented.

<< Second Embodiment >>
FIG. 5 is a flowchart showing the operation of a camera according to another embodiment of the present invention. In this example, when the zoom lens position of the interchangeable lens 200 changes, the zoom lens position is also different.

  In this case, the information stored in the memory 116 corresponds to at least lens type information of a specific interchangeable lens owned by the user, zoom position information Zw and Zt at the wide-angle end and the telephoto end, respectively. The focus shift amounts Pw and Pt of the specific lens.

  With the zoom position information Zw and Zt at the wide-angle end and the telephoto end and the defocus amounts Pw and Pt of the specific lens corresponding to each of them being stored in the memory 116, the lens of the interchangeable lens 200 from the defocus amount correction unit 114 is stored. A request signal is sent to the information output unit 208, and the lens type information of the interchangeable lens 200 is read from the lens information output unit 208 (step S501).

  The defocus amount correction unit 114 compares the lens type information read from the lens information output unit 208 with the lens type information stored in the memory 116, and if there is matching information, the process proceeds to step S503 (step S502). .

  In step S503, the zoom position information Zw and Zt at the wide-angle end and the telephoto end, which are stored in the memory 116 in association with the lens type information, and the defocus amounts Pw and Pt of the specific lens corresponding to these, are read. The current zoom position information Z is read from the lens information output unit 208, and the focus shift amount Pz is obtained by linear interpolation using the following equation.

(Equation 2)
Pz = Pw + (Pt−Pw) × (Z−Zw) / (Zt−Zw)
In step S504, the obtained focus shift amount Pz is corrected by the following correction equation, and the corrected defocus amount Df (left side of the correction equation below) is sent to the lens drive control unit 112.

(Equation 3)
Df = Df-Pz
The lens drive control unit 112 moves the focus lens 202 to a position where the phase difference Δ from the AF module 108 becomes zero while considering the correction amount from the defocus amount correction unit 114.

  If the lens type information read from the lens information output unit 208 does not correspond to the lens type information stored in the memory 116 in step S502, the correction is performed by jumping to steps S503 and S504. The process ends.

  In the present embodiment, since the amount of defocus for each interchangeable lens and each zoom position is corrected, defocus can be prevented.

  In the present embodiment, the zoom position information stored in the memory 116 is two places, that is, the wide-angle end and the telephoto end. However, in order to improve the correction accuracy, further intermediate zoom position information Zm and the corresponding defocus amount. Pm can also be added. In this case, the pin and the shift amount Pz are obtained using the following formula instead of the above formula 2.

(Equation 4)
When Zm ≦ Z:
Pz = Pm + (Pt−Pm) × (Z−Zm) / (Zt−Zm)
When Zm> Z:
Pz = Pw + (Pm−Pw) × (Z−Zw) / (Zm−Zw)
Further, in the case where the first embodiment described above and this example are combined and the defocus amount is calculated in a plurality of areas in this example, the focus shift amounts Pw, Pt, and Pm are made to correspond to the plurality of areas. In some cases, a plurality of focal lengths are stored, and the amount of defocus corresponding to the current zoom position is calculated using Equation 2 or Equation 4 using the amount of defocus corresponding to each area, and the defocus amount is corrected for each area. it can.

<< Third Embodiment >>
FIG. 6 is a flowchart showing the operation of a camera according to still another embodiment of the present invention. In this example, there is a difference for each focus zoom lens position when the focus lens position of the interchangeable lens 200 changes.

  In this case, the information stored in the memory 116 includes at least lens type information of a specific interchangeable lens owned by the user, lens distance position information Di and Dn at the infinity end and the closest end, and each of them. The focus shift amounts Pi and Pn of the corresponding specific lens.

  With the lens distance position information Di and Dn at the infinite end and the closest end, and the focus shift amounts Pi and Pn of the specific lens corresponding to these, stored in the memory 116, the defocus amount correction unit 114 sends the interchangeable lens 200. A request signal is sent to the lens information output unit 208, and the lens type information of the interchangeable lens 200 is read from the lens information output unit 208 (step S601).

  The defocus amount correction unit 114 compares the lens type information read from the lens information output unit 208 with the lens type information stored in the memory 116, and if there is matching information, the process proceeds to step S603 (step S602). .

  In step S603, the infinite end and close end lens distance position information Di and Dn stored in the memory 116 in association with the lens type information and the defocus amounts Pi and Pn of the specific lens corresponding to these are read. Further, the current lens distance position information D is read from the lens information output unit 208, and the focus shift amount Pd is obtained by linear interpolation using the following equation.

(Equation 5)
Pd = Pn + (Pi−Pn) × (D−Dn) / (Di−Dn)
In step S604, the obtained focus shift amount Pd is corrected by the following correction formula, and the corrected defocus amount Df (the left side of the following correction formula) is sent to the lens drive control unit 112.

(Equation 6)
Df = Df−Pd
The lens drive control unit 112 moves the focus lens 202 to a position where the phase difference Δ from the AF module 108 becomes zero while considering the correction amount from the defocus amount correction unit 114.

  If the lens type information read from the lens information output unit 208 does not correspond to the lens type information stored in the memory 116 in step S602, the process jumps to steps S603 and S604 for correction. The process ends.

  In the present embodiment, since the amount of defocus for each interchangeable lens and for each lens distance position is corrected, defocus can be prevented.

  In this embodiment, the zoom position information stored in the memory 116 is two places, the infinite end and the close end. However, in order to improve the correction accuracy, the intermediate lens distance position information Du and the corresponding focus position are also provided. A deviation amount Pu can also be added. In this case, the pin and the shift amount Pz are obtained using the following equation instead of the above equation (5).

(Equation 7)
When Du ≦ D:
Pd = Pu + (Pi−Pu) × (D−Du) / (Di−Du)
When Du> D:
Pd = Pn + (Pu−Pn) × (D−Du) / (Du−Dn)
Further, in the case where the first embodiment described above and this example are combined and the defocus amount is calculated in a plurality of areas in this example, the focus shift amounts Di, Dn, and Du are made to correspond to the plurality of areas. A plurality of each is stored, and the amount of focus deviation corresponding to the current lens distance position is calculated using Equation 5 or Equation 7 using the amount of focus deviation corresponding to each area, and the defocus amount is corrected for each area. You can also.

  Further, when the second embodiment described above and this example are combined and the defocus amount is calculated for each zoom position in this example, the defocus amounts Di, Dn, and Du are set to a plurality of zoom positions. A plurality of lens images are stored corresponding to each zoom position, and the focus shift amount corresponding to the current lens distance position is calculated by using Formula 5 or Formula 7 using the focus shift amount corresponding to each zoom position, and defocused for each zoom position. The amount can also be corrected.

  Furthermore, the first embodiment, the second embodiment, and the third embodiment can be combined. In this case, the amount of focus shift stored in the memory 116 is a combination for each area, each zoom position, and each lens distance position. Also, any two embodiments of the first to third embodiments can be combined.

DESCRIPTION OF SYMBOLS 1 ... Camera; 100 ... Camera body; 102 ... Image pick-up element; 104 ... Half mirror 106 ... Total reflection mirror; 108 ... AF module; 110 ... Total reflection mirror 112 ... Lens drive control part; 114 ... Defocus amount correction part 116 ... Memory: 118 ... Pentaprism; 120 ... Eyepiece lens 122 ... Viewfinder screen 200 ... Interchangeable lens; 202 ... Focus lens; 204 ... Lens drive motor 208 ... Lens information output unit

Claims (7)

In a camera that can selectively mount multiple interchangeable lenses,
A camera comprising storage means for storing a plurality of characteristic values of the interchangeable lens determined in accordance with each of a plurality of photographing states of the camera in association with information for identifying the interchangeable lens. The camera of claim 1,
A focus detection unit that detects a focus adjustment state of the optical system based on a light beam through the optical system of the mounted interchangeable lens;
The focus detection unit corrects the focus adjustment state based on the characteristic value. The camera according to claim 2, wherein
The focus detection means can detect the focus adjustment state for each of a plurality of focus detection positions set corresponding to a plurality of positions in an image plane by the optical system,
The camera is characterized in that the storage means stores the characteristic value corresponding to each of the plurality of focus detection positions. The camera according to any one of claims 1 to 3,
The camera is characterized in that the storage means stores a plurality of the characteristic values corresponding to different shooting distances of the optical system of the interchangeable lens. In the camera according to any one of claims 1 to 4,
The storage device stores a plurality of the characteristic values corresponding to a focal length of an optical system of the interchangeable lens. In the camera according to any one of claims 1 to 5,
The camera characterized in that the storage means can add and store the characteristic value. In the camera according to any one of claims 1 to 6,
The camera according to claim 1, wherein the characteristic value is a value representing a deviation of an image plane position of the optical system due to an aberration of the optical system.

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